diff --git a/cron/build_chrom_db.py b/cron/build_chrom_db.py
index 4cb7f34c895..91183c79d92 100644
--- a/cron/build_chrom_db.py
+++ b/cron/build_chrom_db.py
@@ -17,8 +17,8 @@ import fileinput
 import os
 import sys
 
+import requests
 from six.moves.urllib.parse import urlencode
-from six.moves.urllib.request import urlopen
 
 import parse_builds
 
@@ -36,8 +36,8 @@ def getchrominfo(url, db):
         "hgta_regionType": "",
         "position": "",
         "hgta_doTopSubmit": "get info"})
-    page = urlopen(URL)
-    for line in page:
+    page = requests.get(URL).text
+    for line in page.split('\n'):
         line = line.rstrip( "\r\n" )
         if line.startswith("#"):
             continue
diff --git a/cron/parse_builds.py b/cron/parse_builds.py
index 06566e55cb0..5d93a0281c7 100644
--- a/cron/parse_builds.py
+++ b/cron/parse_builds.py
@@ -9,18 +9,17 @@ from __future__ import print_function
 import sys
 import xml.etree.ElementTree as ElementTree
 
-from six.moves.urllib.request import urlopen
+import requests
 
 
 def getbuilds(url):
     try:
-        page = urlopen(url)
+        text = requests.get(url).text
     except:
         print("#Unable to open " + url)
         print("?\tunspecified (?)")
         sys.exit(1)
 
-    text = page.read()
     try:
         tree = ElementTree.fromstring(text)
     except:
diff --git a/cron/parse_builds_3_sites.py b/cron/parse_builds_3_sites.py
index 2a9e41533c3..1968af26808 100644
--- a/cron/parse_builds_3_sites.py
+++ b/cron/parse_builds_3_sites.py
@@ -6,7 +6,7 @@ from __future__ import print_function
 
 import xml.etree.ElementTree as ElementTree
 
-from six.moves.urllib.request import urlopen
+import requests
 
 sites = ['http://genome.ucsc.edu/cgi-bin/',
          'http://archaea.ucsc.edu/cgi-bin/',
@@ -20,11 +20,11 @@ def main():
         trackurl = sites[i] + "hgTracks?"
         builds = []
         try:
-            page = urlopen(site)
+            text = requests.get(site).text
         except:
             print("#Unable to connect to " + site)
             continue
-        text = page.read()
+
         try:
             tree = ElementTree.fromstring(text)
         except:
diff --git a/lib/galaxy/datatypes/binary.py b/lib/galaxy/datatypes/binary.py
index 9445c7875d7..d09c6d17f94 100644
--- a/lib/galaxy/datatypes/binary.py
+++ b/lib/galaxy/datatypes/binary.py
@@ -241,10 +241,8 @@ class Bam( Binary ):
 
     def _is_coordinate_sorted( self, file_name ):
         """See if the input BAM file is sorted from the header information."""
-        params = [ "samtools", "view", "-H", file_name ]
-        output = subprocess.Popen( params, stderr=subprocess.PIPE, stdout=subprocess.PIPE ).communicate()[0]
-        # find returns -1 if string is not found
-        return output.find( "SO:coordinate" ) != -1 or output.find( "SO:sorted" ) != -1
+        output = subprocess.check_output(["samtools", "view", "-H", file_name])
+        return 'SO:coordinate' in output or 'SO:sorted' in output
 
     def dataset_content_needs_grooming( self, file_name ):
         """See if file_name is a sorted BAM file"""
@@ -269,8 +267,7 @@ class Bam( Binary ):
                 return False
             index_name = tempfile.NamedTemporaryFile( prefix="bam_index" ).name
             stderr_name = tempfile.NamedTemporaryFile( prefix="bam_index_stderr" ).name
-            command = 'samtools index %s %s' % ( file_name, index_name )
-            proc = subprocess.Popen( args=command, shell=True, stderr=open( stderr_name, 'wb' ) )
+            proc = subprocess.Popen(['samtools', 'index', file_name, index_name], stderr=open(stderr_name, 'wb'))
             proc.wait()
             stderr = open( stderr_name ).read().strip()
             if stderr:
@@ -313,8 +310,8 @@ class Bam( Binary ):
         tmp_sorted_dataset_file_name_prefix = os.path.join( tmp_dir, 'sorted' )
         stderr_name = tempfile.NamedTemporaryFile( dir=tmp_dir, prefix="bam_sort_stderr" ).name
         samtools_created_sorted_file_name = "%s.bam" % tmp_sorted_dataset_file_name_prefix  # samtools accepts a prefix, not a filename, it always adds .bam to the prefix
-        command = "samtools sort %s %s" % ( file_name, tmp_sorted_dataset_file_name_prefix )
-        proc = subprocess.Popen( args=command, shell=True, cwd=tmp_dir, stderr=open( stderr_name, 'wb' ) )
+        proc = subprocess.Popen(['samtools', 'sort', file_name, tmp_sorted_dataset_file_name_prefix],
+                                cwd=tmp_dir, stderr=open(stderr_name, 'wb'))
         exit_code = proc.wait()
         # Did sort succeed?
         stderr = open( stderr_name ).read().strip()
diff --git a/lib/galaxy/datatypes/converters/interval_to_coverage.py b/lib/galaxy/datatypes/converters/interval_to_coverage.py
index 47882f7be6a..631473c7c33 100644
--- a/lib/galaxy/datatypes/converters/interval_to_coverage.py
+++ b/lib/galaxy/datatypes/converters/interval_to_coverage.py
@@ -132,8 +132,9 @@ if __name__ == "__main__":
     # Sort through a tempfile first
     temp_file = tempfile.NamedTemporaryFile(mode="r")
     environ['LC_ALL'] = 'POSIX'
-    commandline = "sort -f -n -k %d -k %d -k %d -o %s %s" % (chr_col_1 + 1, start_col_1 + 1, end_col_1 + 1, temp_file.name, in_fname)
-    subprocess.check_call(commandline, shell=True)
+    subprocess.check_call([
+        'sort', '-f', '-n', '-k', chr_col_1 + 1, '-k', start_col_1 + 1, '-k', end_col_1 + 1, '-o', temp_file.name, in_fname
+    ])
 
     coverage = CoverageWriter( out_stream=open(out_fname, "a"),
                                chromCol=chr_col_2, positionCol=position_col_2,
diff --git a/lib/galaxy/datatypes/converters/lped_to_pbed_converter.py b/lib/galaxy/datatypes/converters/lped_to_pbed_converter.py
index fc7ef10adbc..6548aad1b8c 100644
--- a/lib/galaxy/datatypes/converters/lped_to_pbed_converter.py
+++ b/lib/galaxy/datatypes/converters/lped_to_pbed_converter.py
@@ -72,9 +72,9 @@ def rgConv(inpedfilepath, outhtmlname, outfilepath, plink):
     if not missval:
         print('### lped_to_pbed_converter.py cannot identify missing value in %s' % pedf)
         missval = '0'
-    cl = '%s --noweb --file %s --make-bed --out %s --missing-genotype %s' % (plink, inpedfilepath, outroot, missval)
-    p = subprocess.Popen(cl, shell=True, cwd=outfilepath)
-    p.wait()  # run plink
+    subprocess.check_call([plink, '--noweb', '--file', inpedfilepath,
+                           '--make-bed', '--out', outroot,
+                           '--missing-genotype', missval], cwd=outfilepath)
 
 
 def main():
diff --git a/lib/galaxy/datatypes/converters/pbed_ldreduced_converter.py b/lib/galaxy/datatypes/converters/pbed_ldreduced_converter.py
index 02a6541fe42..9a913b877be 100644
--- a/lib/galaxy/datatypes/converters/pbed_ldreduced_converter.py
+++ b/lib/galaxy/datatypes/converters/pbed_ldreduced_converter.py
@@ -41,8 +41,7 @@ def pruneLD(plinktasks=[], cd='./', vclbase=[]):
     for task in plinktasks:  # each is a list
         vcl = vclbase + task
         with open(plog, 'w') as sto:
-            x = subprocess.Popen(' '.join(vcl), shell=True, stdout=sto, stderr=sto, cwd=cd)
-            x.wait()
+            subprocess.check_call(vcl, stdout=sto, stderr=sto, cwd=cd)
         try:
             lplog = open(plog, 'r').readlines()
             lplog = [elem for elem in lplog if elem.find('Pruning SNP') == -1]
diff --git a/lib/galaxy/datatypes/converters/pbed_to_lped_converter.py b/lib/galaxy/datatypes/converters/pbed_to_lped_converter.py
index ed45a204db1..dc4bec51cb3 100644
--- a/lib/galaxy/datatypes/converters/pbed_to_lped_converter.py
+++ b/lib/galaxy/datatypes/converters/pbed_to_lped_converter.py
@@ -40,9 +40,7 @@ def rgConv(inpedfilepath, outhtmlname, outfilepath, plink):
     """
     basename = os.path.split(inpedfilepath)[-1]  # get basename
     outroot = os.path.join(outfilepath, basename)
-    cl = '%s --noweb --bfile %s --recode --out %s ' % (plink, inpedfilepath, outroot)
-    p = subprocess.Popen(cl, shell=True, cwd=outfilepath)
-    p.wait()  # run plink
+    subprocess.check_call([plink, '--noweb', '--bfile', inpedfilepath, '--recode', '--out', outroot], cwd=outfilepath)
 
 
 def main():
diff --git a/lib/galaxy/datatypes/converters/sam_to_bam.py b/lib/galaxy/datatypes/converters/sam_to_bam.py
index ca3fecf5949..1ae40251ff3 100644
--- a/lib/galaxy/datatypes/converters/sam_to_bam.py
+++ b/lib/galaxy/datatypes/converters/sam_to_bam.py
@@ -33,8 +33,10 @@ def __main__():
     # convert to SAM
     unsorted_bam_filename = os.path.join( tmp_dir, 'unsorted.bam' )
     unsorted_stderr_filename = os.path.join( tmp_dir, 'unsorted.stderr' )
-    cmd = 'samtools view -bS "%s" > "%s"' % ( input_filename, unsorted_bam_filename )
-    proc = subprocess.Popen( args=cmd, stderr=open( unsorted_stderr_filename, 'wb' ), shell=True, cwd=tmp_dir )
+    proc = subprocess.Popen(['samtools', 'view', '-bS', input_filename],
+                            stdout=open(unsorted_bam_filename, 'wb'),
+                            stderr=open(unsorted_stderr_filename, 'wb'),
+                            cwd=tmp_dir)
     return_code = proc.wait()
     if return_code:
         stderr_target = sys.stderr
@@ -52,8 +54,10 @@ def __main__():
     # sort sam, so indexing will not fail
     sorted_stderr_filename = os.path.join( tmp_dir, 'sorted.stderr' )
     sorting_prefix = os.path.join( tmp_dir, 'sorted_bam' )
-    cmd = 'samtools sort -o "%s" "%s" > "%s"' % ( unsorted_bam_filename, sorting_prefix, output_filename )
-    proc = subprocess.Popen( args=cmd, stderr=open( sorted_stderr_filename, 'wb' ), shell=True, cwd=tmp_dir )
+    proc = subprocess.Popen(['samtools', 'sort', '-o', unsorted_bam_filename, sorting_prefix],
+                            stdout=open(output_filename, 'wb'),
+                            stderr=open(sorted_stderr_filename, 'wb'),
+                            cwd=tmp_dir)
     return_code = proc.wait()
 
     if return_code:
diff --git a/lib/galaxy/datatypes/sequence.py b/lib/galaxy/datatypes/sequence.py
index 1b4619d731e..ca856975f1d 100644
--- a/lib/galaxy/datatypes/sequence.py
+++ b/lib/galaxy/datatypes/sequence.py
@@ -8,6 +8,7 @@ import logging
 import os
 import re
 import string
+import subprocess
 from cgi import escape
 
 from six import PY3
@@ -662,8 +663,7 @@ class Fastq ( Sequence ):
         else:
             commands = Sequence.get_split_commands_sequential(is_gzip(input_name), input_name, output_name, start_sequence, sequence_count)
         for cmd in commands:
-            if 0 != os.system(cmd):
-                raise Exception("Executing '%s' failed" % cmd)
+            subprocess.check_call(cmd, shell=True)
         return True
     process_split_file = staticmethod(process_split_file)
 
diff --git a/lib/galaxy/datatypes/tabular.py b/lib/galaxy/datatypes/tabular.py
index ed08e8aac76..821f3d27be7 100644
--- a/lib/galaxy/datatypes/tabular.py
+++ b/lib/galaxy/datatypes/tabular.py
@@ -8,6 +8,7 @@ import gzip
 import logging
 import os
 import re
+import shutil
 import subprocess
 import tempfile
 from cgi import escape
@@ -515,15 +516,12 @@ class Sam( Tabular ):
         Multiple SAM files may each have headers. Since the headers should all be the same, remove
         the headers from files 1-n, keeping them in the first file only
         """
-        cmd = 'mv %s %s' % ( split_files[0], output_file )
-        result = os.system(cmd)
-        if result != 0:
-            raise Exception('Result %s from %s' % (result, cmd))
+        shutil.move(split_files[0], output_file)
+
         if len(split_files) > 1:
-            cmd = 'egrep -v -h "^@" %s >> %s' % ( ' '.join(split_files[1:]), output_file )
-        result = os.system(cmd)
-        if result != 0:
-            raise Exception('Result %s from %s' % (result, cmd))
+            cmd = ['egrep', '-v', '-h', '^@'] + split_files[1:] + ['>>', output_file]
+            subprocess.check_call(cmd, shell=True)
+
     merge = staticmethod(merge)
 
     # Dataproviders
diff --git a/lib/galaxy/datatypes/text.py b/lib/galaxy/datatypes/text.py
index a1dc9388d65..0be154d9d53 100644
--- a/lib/galaxy/datatypes/text.py
+++ b/lib/galaxy/datatypes/text.py
@@ -10,6 +10,8 @@ import re
 import subprocess
 import tempfile
 
+from six.moves import shlex_quote
+
 from galaxy.datatypes.data import get_file_peek, Text
 from galaxy.datatypes.metadata import MetadataElement, MetadataParameter
 from galaxy.datatypes.sniff import get_headers
@@ -144,13 +146,12 @@ class Ipynb( Json ):
             ofilename = ofile_handle.name
             ofile_handle.close()
             try:
-                cmd = 'ipython nbconvert --to html --template full %s --output %s' % (dataset.file_name, ofilename)
-                log.info("Calling command %s" % cmd)
-                subprocess.call(cmd, shell=True)
+                cmd = ['ipython', 'nbconvert', '--to', 'html', '--template', 'full', dataset.file_name, '--output', ofilename]
+                subprocess.check_call(cmd)
                 ofilename = '%s.html' % ofilename
-            except:
+            except subprocess.CalledProcessError:
                 ofilename = dataset.file_name
-                log.exception( 'Command "%s" failed. Could not convert the IPython Notebook to HTML, defaulting to plain text.' % cmd )
+                log.exception('Command "%s" failed. Could not convert the IPython Notebook to HTML, defaulting to plain text.', ' '.join(map(shlex_quote, cmd)))
             return open( ofilename )
 
     def set_meta( self, dataset, **kwd ):
diff --git a/lib/galaxy/external_services/actions.py b/lib/galaxy/external_services/actions.py
index c62dadf3e34..239c961ed26 100644
--- a/lib/galaxy/external_services/actions.py
+++ b/lib/galaxy/external_services/actions.py
@@ -1,6 +1,6 @@
 # Contains actions that are used in External Services
 import logging
-from urllib import urlopen
+import requests
 from galaxy.web import url_for
 from galaxy.util.template import fill_template
 from result_handlers.basic import ExternalServiceActionResultHandler
@@ -104,7 +104,7 @@ class ExternalServiceWebAPIActionResult( ExternalServiceResult ):
     @property
     def content( self ):
         if self._content is None:
-            self._content = urlopen( self.url ).read()
+            self._content = requests.get(self.url).text
         return self._content
 
 
diff --git a/lib/galaxy/jobs/deferred/pacific_biosciences_smrt_portal.py b/lib/galaxy/jobs/deferred/pacific_biosciences_smrt_portal.py
index 3026194f1b8..bd458c06150 100644
--- a/lib/galaxy/jobs/deferred/pacific_biosciences_smrt_portal.py
+++ b/lib/galaxy/jobs/deferred/pacific_biosciences_smrt_portal.py
@@ -2,13 +2,14 @@
 Module for managing jobs in Pacific Bioscience's SMRT Portal and automatically transferring files
 produced by SMRT Portal.
 """
-import json
 import logging
-import urllib2
 from string import Template
 
+import requests
+
 from data_transfer import DataTransfer
 
+
 log = logging.getLogger( __name__ )
 
 __all__ = [ 'SMRTPortalPlugin' ]
@@ -87,8 +88,8 @@ class SMRTPortalPlugin( DataTransfer ):
             if self._missing_params( job.params, [ 'smrt_host', 'smrt_job_id' ] ):
                 return self.job_states.INVALID
             url = 'http://' + job.params[ 'smrt_host' ] + self.api_path + '/Jobs/' + job.params[ 'smrt_job_id' ] + '/Status'
-            r = urllib2.urlopen( url )
-            status = json.loads( r.read() )
+            r = requests.get(url)
+            status = r.json()
             # TODO: error handling: unexpected json or bad response, bad url, etc.
             if status[ 'Code' ] == 'Completed':
                 log.debug( "SMRT Portal job '%s' is Completed.  Initiating transfer." % job.params[ 'smrt_job_id' ] )
diff --git a/lib/galaxy/jobs/runners/pulsar.py b/lib/galaxy/jobs/runners/pulsar.py
index 94f58b6bc2c..33b78dff5c1 100644
--- a/lib/galaxy/jobs/runners/pulsar.py
+++ b/lib/galaxy/jobs/runners/pulsar.py
@@ -8,6 +8,7 @@ from distutils.version import LooseVersion
 import errno
 import logging
 import os
+import subprocess
 from time import sleep
 
 from pulsar.client import build_client_manager
@@ -210,7 +211,7 @@ class PulsarJobRunner( AsynchronousJobRunner ):
         else:
             log.info("Loading Pulsar app configuration from %s" % pulsar_conf_path)
             with open(pulsar_conf_path, "r") as f:
-                conf.update(yaml.load(f) or {})
+                conf.update(yaml.safe_load(f) or {})
         if "job_metrics_config_file" not in conf:
             conf["job_metrics"] = self.app.job_metrics
         if "staging_directory" not in conf:
@@ -375,8 +376,7 @@ class PulsarJobRunner( AsynchronousJobRunner ):
         prepare_input_files_cmds = getattr(job_wrapper, 'prepare_input_files_cmds', None)
         if prepare_input_files_cmds is not None:
             for cmd in prepare_input_files_cmds:  # run the commands to stage the input files
-                if 0 != os.system(cmd):
-                    raise Exception('Error running file staging command: %s' % cmd)
+                subprocess.check_call(cmd, shell=True)
             job_wrapper.prepare_input_files_cmds = None  # prevent them from being used in-line
 
     def _populate_parameter_defaults( self, job_destination ):
diff --git a/lib/galaxy/jobs/runners/util/job_script/__init__.py b/lib/galaxy/jobs/runners/util/job_script/__init__.py
index a08857c2462..a41439a5af1 100644
--- a/lib/galaxy/jobs/runners/util/job_script/__init__.py
+++ b/lib/galaxy/jobs/runners/util/job_script/__init__.py
@@ -1,3 +1,4 @@
+import logging
 import os
 from string import Template
 import subprocess
@@ -7,6 +8,7 @@ from pkg_resources import resource_string
 from six import text_type
 from galaxy.util import unicodify
 
+log = logging.getLogger(__name__)
 DEFAULT_SHELL = '/bin/bash'
 
 DEFAULT_JOB_FILE_TEMPLATE = Template(
@@ -117,12 +119,13 @@ def _handle_script_integrity(path, config):
     sleep_amt = getattr(config, "check_job_script_integrity_sleep", DEFAULT_INTEGRITY_SLEEP)
     for i in range(count):
         try:
-            proc = subprocess.Popen([path], shell=True, env={"ABC_TEST_JOB_SCRIPT_INTEGRITY_XYZ": "1"})
-            proc.wait()
-            if proc.returncode == 42:
+            returncode = subprocess.call([path], env={"ABC_TEST_JOB_SCRIPT_INTEGRITY_XYZ": "1"})
+            if returncode == 42:
                 script_integrity_verified = True
                 break
 
+            log.debug("Script integrity error: returncode was %d", returncode)
+
             # Else we will sync and wait to see if the script becomes
             # executable.
             try:
@@ -130,11 +133,13 @@ def _handle_script_integrity(path, config):
                 # These have occurred both in Docker containers and on EC2 clusters
                 # under high load.
                 subprocess.check_call(INTEGRITY_SYNC_COMMAND)
-            except Exception:
-                pass
-            time.sleep(sleep_amt)
-        except Exception:
-            pass
+            except Exception as e:
+                log.debug("Error syncing the filesystem: %s", unicodify(e))
+
+        except Exception as exc:
+            log.debug("Script not available yet: %s", unicodify(exc))
+
+        time.sleep(sleep_amt)
 
     if not script_integrity_verified:
         raise Exception("Failed to write job script, could not verify job script integrity.")
diff --git a/lib/galaxy/jobs/runners/util/kill.py b/lib/galaxy/jobs/runners/util/kill.py
index 52022466552..4abce160eb2 100644
--- a/lib/galaxy/jobs/runners/util/kill.py
+++ b/lib/galaxy/jobs/runners/util/kill.py
@@ -1,7 +1,7 @@
 import os
+import subprocess
 from platform import system
 from time import sleep
-from subprocess import Popen
 
 try:
     from psutil import Process, NoSuchProcess
@@ -41,8 +41,8 @@ def _stock_kill_pid(pid):
 
 def __kill_windows(pid):
     try:
-        Popen("taskkill /F /T /PID %i" % pid, shell=True)
-    except Exception:
+        subprocess.check_call(['taskkill', '/F', '/T', '/PID', pid])
+    except subprocess.CalledProcessError:
         pass
 
 
diff --git a/lib/galaxy/jobs/transfer_manager.py b/lib/galaxy/jobs/transfer_manager.py
index ccd5c88e67f..2d2eb162af8 100644
--- a/lib/galaxy/jobs/transfer_manager.py
+++ b/lib/galaxy/jobs/transfer_manager.py
@@ -9,6 +9,8 @@ import socket
 import subprocess
 import threading
 
+from six.moves import shlex_quote
+
 from galaxy.util import listify, sleeper
 from galaxy.util.json import jsonrpc_request, validate_jsonrpc_response
 
@@ -22,8 +24,8 @@ class TransferManager( object ):
     def __init__( self, app ):
         self.app = app
         self.sa_session = app.model.context.current
-        self.command = 'python %s' % os.path.abspath( os.path.join( os.getcwd(), 'scripts', 'transfer.py' ) )
-        if app.config.get_bool( 'enable_job_recovery', True ):
+        self.command = ['python', os.path.abspath(os.path.join(os.getcwd(), 'scripts', 'transfer.py'))]
+        if app.config.get_bool('enable_job_recovery', True):
             # Only one Galaxy server process should be able to recover jobs! (otherwise you'll have nasty race conditions)
             self.running = True
             self.sleeper = sleeper.Sleeper()
@@ -67,9 +69,9 @@ class TransferManager( object ):
             # The transfer script should daemonize fairly quickly - if this is
             # not the case, this process will need to be moved to a
             # non-blocking method.
-            cmd = '%s %s' % ( self.command, tj.id )
-            log.debug( 'Transfer command is: %s' % cmd )
-            p = subprocess.Popen( cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT )
+            cmd = self.command + [tj.id]
+            log.debug('Transfer command is: %s', ' '.join(map(shlex_quote, cmd)))
+            p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
             p.wait()
             output = p.stdout.read( 32768 )
             if p.returncode != 0:
diff --git a/lib/galaxy/managers/citations.py b/lib/galaxy/managers/citations.py
index ef83443d67a..9e061364848 100644
--- a/lib/galaxy/managers/citations.py
+++ b/lib/galaxy/managers/citations.py
@@ -1,6 +1,6 @@
 import functools
 import os
-import urllib2
+import requests
 
 from beaker.cache import CacheManager
 from beaker.util import parse_cache_config_options
@@ -47,10 +47,8 @@ class DoiCache( object ):
     def _raw_get_bibtex( self, doi ):
         dx_url = "http://dx.doi.org/" + doi
         headers = {'Accept': 'text/bibliography; style=bibtex, application/x-bibtex'}
-        req = urllib2.Request(dx_url, data="", headers=headers)
-        response = urllib2.urlopen(req)
-        bibtex = response.read()
-        return bibtex
+        req = requests.get(dx_url, headers=headers)
+        return req.text
 
     def get_bibtex( self, doi ):
         createfunc = functools.partial(self._raw_get_bibtex, doi)
diff --git a/lib/galaxy/objectstore/s3.py b/lib/galaxy/objectstore/s3.py
index 9e94c69a608..b06309786f8 100644
--- a/lib/galaxy/objectstore/s3.py
+++ b/lib/galaxy/objectstore/s3.py
@@ -13,7 +13,7 @@ import time
 from datetime import datetime
 
 from galaxy.exceptions import ObjectNotFound, ObjectInvalid
-from galaxy.util import string_as_bool, umask_fix_perms, safe_relpath, directory_hash_id
+from galaxy.util import string_as_bool, umask_fix_perms, safe_relpath, directory_hash_id, which
 from galaxy.util.sleeper import Sleeper
 from .s3_multipart_upload import multipart_upload
 from ..objectstore import ObjectStore, convert_bytes
@@ -59,10 +59,9 @@ class S3ObjectStore(ObjectStore):
             self.cache_monitor_thread.start()
             log.info("Cache cleaner manager started")
         # Test if 'axel' is available for parallel download and pull the key into cache
-        try:
-            subprocess.call('axel')
+        if which('axel'):
             self.use_axel = True
-        except OSError:
+        else:
             self.use_axel = False
 
     def _configure_connection(self):
@@ -333,7 +332,7 @@ class S3ObjectStore(ObjectStore):
                 log.debug("Parallel pulled key '%s' into cache to %s", rel_path, self._get_cache_path(rel_path))
                 ncores = multiprocessing.cpu_count()
                 url = key.generate_url(7200)
-                ret_code = subprocess.call("axel -a -n %s '%s'" % (ncores, url))
+                ret_code = subprocess.call(['axel', '-a', '-n', ncores, url])
                 if ret_code == 0:
                     return True
             else:
diff --git a/lib/galaxy/tools/data/__init__.py b/lib/galaxy/tools/data/__init__.py
index cd287a84a32..441a6ea75ca 100644
--- a/lib/galaxy/tools/data/__init__.py
+++ b/lib/galaxy/tools/data/__init__.py
@@ -15,7 +15,8 @@ import hashlib
 
 from glob import glob
 from tempfile import NamedTemporaryFile
-from urllib2 import urlopen
+
+import requests
 
 from galaxy import util
 from galaxy.util.odict import odict
@@ -290,7 +291,7 @@ class TabularToolDataTable( ToolDataTable, Dictifiable ):
                 if filename:
                     tmp_file = NamedTemporaryFile( prefix='TTDT_URL_%s-' % self.name )
                     try:
-                        tmp_file.write( urlopen( filename, timeout=url_timeout ).read() )
+                        tmp_file.write(requests.get(filename, timeout=url_timeout).text)
                     except Exception as e:
                         log.error( 'Error loading Data Table URL "%s": %s', filename, e )
                         continue
diff --git a/lib/galaxy/tools/imp_exp/unpack_tar_gz_archive.py b/lib/galaxy/tools/imp_exp/unpack_tar_gz_archive.py
index 932779c0e43..46e12d83756 100644
--- a/lib/galaxy/tools/imp_exp/unpack_tar_gz_archive.py
+++ b/lib/galaxy/tools/imp_exp/unpack_tar_gz_archive.py
@@ -11,10 +11,11 @@ import sys
 import optparse
 import tarfile
 import tempfile
-import urllib2
 import math
 from base64 import b64decode
 
+import requests
+
 # Set max size of archive/file that will be handled to be 100 GB. This is
 # arbitrary and should be adjusted as needed.
 MAX_SIZE = 100 * math.pow( 2, 30 )
@@ -25,18 +26,16 @@ def url_to_file( url, dest_file ):
     Transfer a file from a remote URL to a temporary file.
     """
     try:
-        url_reader = urllib2.urlopen( url )
+        url_reader = requests.get(url, stream=True)
         CHUNK = 10 * 1024  # 10k
         total = 0
         fp = open( dest_file, 'wb')
-        while True:
-            chunk = url_reader.read( CHUNK )
-            if not chunk:
-                break
-            fp.write( chunk )
-            total += CHUNK
-            if total > MAX_SIZE:
-                break
+        for chunk in url_reader.iter_content(chunk_size=CHUNK):
+            if chunk:
+                fp.write(chunk)
+                total += CHUNK
+                if total > MAX_SIZE:
+                    break
         fp.close()
         return dest_file
     except Exception as e:
diff --git a/lib/galaxy/tools/toolbox/parser.py b/lib/galaxy/tools/toolbox/parser.py
index eafe4958fcd..4d15f02f409 100644
--- a/lib/galaxy/tools/toolbox/parser.py
+++ b/lib/galaxy/tools/toolbox/parser.py
@@ -59,7 +59,7 @@ class YamlToolConfSource(ToolConfSource):
 
     def __init__(self, config_filename):
         with open(config_filename, "r") as f:
-            as_dict = yaml.load(f)
+            as_dict = yaml.safe_load(f)
         self.as_dict = as_dict
 
     def parse_tool_path(self):
diff --git a/lib/galaxy/tours/__init__.py b/lib/galaxy/tours/__init__.py
index c497f2de284..c2f517fa519 100644
--- a/lib/galaxy/tours/__init__.py
+++ b/lib/galaxy/tours/__init__.py
@@ -68,7 +68,7 @@ class ToursRegistry(object):
         tour_id = os.path.splitext(filename)[0]
         try:
             with open(tour_path) as handle:
-                conf = yaml.load(handle)
+                conf = yaml.safe_load(handle)
                 tour = tour_loader(conf)
                 self.tours[tour_id] = tour_loader(conf)
                 log.info("Loaded tour '%s'" % tour_id)
diff --git a/lib/galaxy/util/plugin_config.py b/lib/galaxy/util/plugin_config.py
index c03633692cc..8095d279fe9 100644
--- a/lib/galaxy/util/plugin_config.py
+++ b/lib/galaxy/util/plugin_config.py
@@ -76,4 +76,4 @@ def __read_yaml(path):
         raise ImportError("Attempting to read YAML configuration file - but PyYAML dependency unavailable.")
 
     with open(path, "rb") as f:
-        return yaml.load(f)
+        return yaml.safe_load(f)
diff --git a/lib/galaxy/web/base/interactive_environments.py b/lib/galaxy/web/base/interactive_environments.py
index f9fdcf6fba3..d6b09e45dae 100644
--- a/lib/galaxy/web/base/interactive_environments.py
+++ b/lib/galaxy/web/base/interactive_environments.py
@@ -93,7 +93,7 @@ class InteractiveEnvironmentRequest(object):
                 raise Exception("[{0}] Could not find allowed_images.yml, or image tag in {0}.ini file for ".format(self.attr.viz_id))
 
         with open(fn, 'r') as handle:
-            self.allowed_images = [x['image'] for x in yaml.load(handle)]
+            self.allowed_images = [x['image'] for x in yaml.safe_load(handle)]
 
             if len(self.allowed_images) == 0:
                 raise Exception("No allowed images specified for " + self.attr.viz_id)
diff --git a/lib/galaxy/web/proxy/__init__.py b/lib/galaxy/web/proxy/__init__.py
index d46f68c6968..bd8f3a062f4 100644
--- a/lib/galaxy/web/proxy/__init__.py
+++ b/lib/galaxy/web/proxy/__init__.py
@@ -7,9 +7,10 @@ from galaxy.util import sockets
 from galaxy.util.lazy_process import LazyProcess, NoOpLazyProcess
 from galaxy.util import sqlite
 from galaxy.util import unique_id
-import urllib2
 import time
 
+import requests
+
 log = logging.getLogger( __name__ )
 
 
@@ -243,20 +244,16 @@ class RestGolangProxyIpc(object):
             'ContainerIds': container_ids,
         }
 
-        req = urllib2.Request(self.api_url)
-        req.add_header('Content-Type', 'application/json')
-
         # Sometimes it takes our poor little proxy a second or two to get
         # going, so if this fails, re-call ourselves with an increased timeout.
         try:
-            urllib2.urlopen(req, json.dumps(values))
-        except urllib2.URLError as err:
-            log.debug(err)
+            requests.get(self.api_url, headers={'Content-Type': 'application/json'}, data=json.dumps(values))
+        except requests.exceptions.ConnectionError as err:
+            log.exception(err)
             if sleep > 5:
                 excp = "Could not contact proxy after %s seconds" % sum(range(sleep + 1))
                 raise Exception(excp)
             time.sleep(sleep)
             self.handle_requests(authentication, proxy_requests, route_name, container_ids, sleep=sleep + 1)
-        pass
 
 # TODO: MQ diven proxy?
diff --git a/lib/galaxy/webapps/galaxy/controllers/async.py b/lib/galaxy/webapps/galaxy/controllers/async.py
index c0dca96de90..6eee8972a1b 100644
--- a/lib/galaxy/webapps/galaxy/controllers/async.py
+++ b/lib/galaxy/webapps/galaxy/controllers/async.py
@@ -2,9 +2,13 @@
 Upload class
 """
 
+from __future__ import absolute_import
+
 import logging
 import urllib
 
+import requests
+
 from galaxy import jobs, web
 from galaxy.util import Params
 from galaxy.util.hash_util import hmac_new
@@ -131,8 +135,7 @@ class ASync( BaseUIController ):
                 url = "%s%s%s" % ( url, url_join_char, urllib.urlencode( params.flatten() ) )
                 log.debug("connecting to -> %s" % url)
                 trans.log_event( "Async connecting to -> %s" % url )
-                text = urllib.urlopen(url).read(-1)
-                text = text.strip()
+                text = requests.get(url).text.strip()
                 if not text.endswith('OK'):
                     raise Exception( text )
                 data.state = data.blurb = data.states.RUNNING
diff --git a/lib/galaxy/webapps/galaxy/controllers/library_common.py b/lib/galaxy/webapps/galaxy/controllers/library_common.py
index 0a79ee4f60c..6ecc6acba5d 100644
--- a/lib/galaxy/webapps/galaxy/controllers/library_common.py
+++ b/lib/galaxy/webapps/galaxy/controllers/library_common.py
@@ -1,4 +1,7 @@
+from __future__ import absolute_import
+
 import glob
+import json
 import logging
 import operator
 import os
@@ -8,10 +11,9 @@ import sys
 import tarfile
 import tempfile
 import urllib
-import urllib2
 import zipfile
-from json import dumps, loads
 
+import requests
 from markupsafe import escape
 from sqlalchemy import and_, false
 from sqlalchemy.orm import eagerload_all
@@ -554,7 +556,7 @@ class LibraryCommon( BaseUIController, UsesFormDefinitionsMixin, UsesExtendedMet
             if len(em_string):
                 payload = None
                 try:
-                    payload = loads(em_string)
+                    payload = json.loads(em_string)
                 except Exception:
                     message = 'Invalid JSON input'
                     status = 'error'
@@ -1116,8 +1118,8 @@ class LibraryCommon( BaseUIController, UsesFormDefinitionsMixin, UsesExtendedMet
         json_file_path = upload_common.create_paramfile( trans, uploaded_datasets )
         data_list = [ ud.data for ud in uploaded_datasets ]
         job_params = {}
-        job_params['link_data_only'] = dumps( kwd.get( 'link_data_only', 'copy_files' ) )
-        job_params['uuid'] = dumps( kwd.get( 'uuid', None ) )
+        job_params['link_data_only'] = json.dumps(kwd.get('link_data_only', 'copy_files'))
+        job_params['uuid'] = json.dumps(kwd.get('uuid', None))
         job, output = upload_common.create_job( trans, tool_params, tool, json_file_path, data_list, folder=library_bunch.folder, job_params=job_params )
         trans.sa_session.add( job )
         trans.sa_session.flush()
@@ -2750,9 +2752,7 @@ def lucene_search( trans, cntrller, search_term, search_url, **kwd ):
     message = escape( kwd.get( 'message', '' ) )
     status = kwd.get( 'status', 'done' )
     full_url = "%s/find?%s" % ( search_url, urllib.urlencode( { "kwd" : search_term } ) )
-    response = urllib2.urlopen( full_url )
-    ldda_ids = loads( response.read() )[ "ids" ]
-    response.close()
+    ldda_ids = requests.get(full_url).json()['ids']
     lddas = [ trans.sa_session.query( trans.app.model.LibraryDatasetDatasetAssociation ).get( ldda_id ) for ldda_id in ldda_ids ]
     return status, message, get_sorted_accessible_library_items( trans, cntrller, lddas, 'name' )
 
diff --git a/lib/galaxy/webapps/galaxy/controllers/root.py b/lib/galaxy/webapps/galaxy/controllers/root.py
index 4f6829d2927..aad9c37b990 100644
--- a/lib/galaxy/webapps/galaxy/controllers/root.py
+++ b/lib/galaxy/webapps/galaxy/controllers/root.py
@@ -1,10 +1,12 @@
 """
 Contains the main interface in the Universe class
 """
+from __future__ import absolute_import
+
 import cgi
 import os
-import urllib
 
+import requests
 from paste.httpexceptions import HTTPNotFound, HTTPBadGateway
 
 from galaxy import web
@@ -482,8 +484,8 @@ class RootController( controller.JSAppLauncher, UsesAnnotations ):
     def bucket_proxy( self, trans, bucket=None, **kwd):
         if bucket:
             trans.response.set_content_type( 'text/xml' )
-            b_list_xml = urllib.urlopen('http://s3.amazonaws.com/%s/' % bucket)
-            return b_list_xml.read()
+            b_list_xml = requests.get('http://s3.amazonaws.com/%s/' % bucket)
+            return b_list_xml.text
         raise Exception("You must specify a bucket")
 
     # ---- Debug methods ----------------------------------------------------
diff --git a/lib/galaxy/webapps/galaxy/controllers/visualization.py b/lib/galaxy/webapps/galaxy/controllers/visualization.py
index 3eda0900eed..10f9880050d 100644
--- a/lib/galaxy/webapps/galaxy/controllers/visualization.py
+++ b/lib/galaxy/webapps/galaxy/controllers/visualization.py
@@ -1041,7 +1041,7 @@ class VisualizationController( BaseUIController, SharableMixin, UsesVisualizatio
                         continue
 
                     with open( image_file, 'r' ) as handle:
-                        self.gie_image_map[gie] = yaml.load( handle )
+                        self.gie_image_map[gie] = yaml.safe_load(handle)
 
         return trans.fill_template_mako(
             "visualization/gie.mako",
diff --git a/lib/galaxy/webapps/galaxy/controllers/workflow.py b/lib/galaxy/webapps/galaxy/controllers/workflow.py
index 63f5399297f..7ce86e1548f 100644
--- a/lib/galaxy/webapps/galaxy/controllers/workflow.py
+++ b/lib/galaxy/webapps/galaxy/controllers/workflow.py
@@ -1,10 +1,12 @@
+from __future__ import absolute_import
+
 import base64
 import httplib
 import json
 import logging
 import os
 import sgmllib
-import urllib2
+import requests
 
 from sqlalchemy import and_
 from sqlalchemy.sql import expression
@@ -871,7 +873,7 @@ class WorkflowController( BaseUIController, SharableMixin, UsesStoredWorkflowMix
                 # Load workflow from external URL
                 # NOTE: blocks the web thread.
                 try:
-                    workflow_data = urllib2.urlopen( url ).read()
+                    workflow_data = requests.get(url).text
                 except Exception as e:
                     message = "Failed to open URL: <b>%s</b><br>Exception: %s" % ( escape( url ), escape( str( e ) ) )
                     status = 'error'
diff --git a/lib/galaxy/webapps/reports/controllers/system.py b/lib/galaxy/webapps/reports/controllers/system.py
index 419701a9a72..72c614b9237 100644
--- a/lib/galaxy/webapps/reports/controllers/system.py
+++ b/lib/galaxy/webapps/reports/controllers/system.py
@@ -1,5 +1,6 @@
 import logging
 import os
+import subprocess
 from datetime import datetime, timedelta
 from decimal import Decimal
 
@@ -148,12 +149,11 @@ class System( BaseUIController ):
                                     message=message )
 
     def get_disk_usage( self, file_path ):
-        df_cmd = 'df -h ' + file_path
         is_sym_link = os.path.islink( file_path )
         file_system = disk_size = disk_used = disk_avail = disk_cap_pct = mount = None
-        df_file = os.popen( df_cmd )
-        while True:
-            df_line = df_file.readline()
+        df_output = subprocess.check_output(['df', '-h', file_path])
+
+        for df_line in df_output:
             df_line = df_line.strip()
             if df_line:
                 df_line = df_line.lower()
@@ -176,7 +176,6 @@ class System( BaseUIController ):
                         pass
             else:
                 break  # EOF
-        df_file.close()
         return ( file_system, disk_size, disk_used, disk_avail, disk_cap_pct, mount  )
 
     @web.expose
diff --git a/lib/galaxy/webapps/tool_shed/controllers/upload.py b/lib/galaxy/webapps/tool_shed/controllers/upload.py
index 1d005c7f7f2..84aa5bafb56 100644
--- a/lib/galaxy/webapps/tool_shed/controllers/upload.py
+++ b/lib/galaxy/webapps/tool_shed/controllers/upload.py
@@ -3,7 +3,8 @@ import os
 import shutil
 import tarfile
 import tempfile
-import urllib
+
+import requests
 
 from galaxy import util
 from galaxy import web
@@ -74,7 +75,7 @@ class UploadController( BaseUIController ):
             elif url:
                 valid_url = True
                 try:
-                    stream = urllib.urlopen( url )
+                    stream = requests.get(url, stream=True)
                 except Exception as e:
                     valid_url = False
                     message = 'Error uploading file via http: %s' % str( e )
@@ -83,11 +84,9 @@ class UploadController( BaseUIController ):
                 if valid_url:
                     fd, uploaded_file_name = tempfile.mkstemp()
                     uploaded_file = open( uploaded_file_name, 'wb' )
-                    while 1:
-                        chunk = stream.read( util.CHUNK_SIZE )
-                        if not chunk:
-                            break
-                        uploaded_file.write( chunk )
+                    for chunk in stream.iter_content(chunk_size=util.CHUNK_SIZE):
+                        if chunk:
+                            uploaded_file.write(chunk)
                     uploaded_file.flush()
                     uploaded_file_filename = url.split( '/' )[ -1 ]
                     isempty = os.path.getsize( os.path.abspath( uploaded_file_name ) ) == 0
diff --git a/lib/tool_shed/capsule/capsule_manager.py b/lib/tool_shed/capsule/capsule_manager.py
index 02b4176281b..c150005f4da 100644
--- a/lib/tool_shed/capsule/capsule_manager.py
+++ b/lib/tool_shed/capsule/capsule_manager.py
@@ -5,10 +5,10 @@ import shutil
 import tarfile
 import tempfile
 import threading
-import urllib
 from time import gmtime
 from time import strftime
 
+import requests
 from sqlalchemy import and_, false
 
 import tool_shed.repository_types.util as rt_util
@@ -820,24 +820,20 @@ class ImportRepositoryManager( object ):
                             uploaded_file=None,
                             capsule_file_name=None )
         if url:
-            valid_url = True
             try:
-                stream = urllib.urlopen( url )
+                stream = requests.get(url, stream=True)
             except Exception as e:
-                valid_url = False
                 return_dict['error_message'] = 'Error importing file via http: %s' % str( e )
                 return_dict['status'] = 'error'
                 return return_dict
-            if valid_url:
-                fd, uploaded_file_name = tempfile.mkstemp()
-                uploaded_file = open( uploaded_file_name, 'wb' )
-                while 1:
-                    chunk = stream.read( CHUNK_SIZE )
-                    if not chunk:
-                        break
-                    uploaded_file.write( chunk )
-                uploaded_file.flush()
-                uploaded_file_filename = url.split( '/' )[ -1 ]
+
+            fd, uploaded_file_name = tempfile.mkstemp()
+            uploaded_file = open( uploaded_file_name, 'wb' )
+            for chunk in stream.iter_content(chunk_size=CHUNK_SIZE):
+                if chunk:
+                    uploaded_file.write(chunk)
+            uploaded_file.flush()
+            uploaded_file_filename = url.split( '/' )[ -1 ]
         elif file_data not in ( '', None ):
             uploaded_file = file_data.file
             uploaded_file_name = uploaded_file.name
diff --git a/scripts/data_libraries/build_lucene_index.py b/scripts/data_libraries/build_lucene_index.py
index 1029c0d356e..4bf02ce9fc8 100644
--- a/scripts/data_libraries/build_lucene_index.py
+++ b/scripts/data_libraries/build_lucene_index.py
@@ -14,7 +14,8 @@ import csv
 import os
 import sys
 import urllib
-import urllib2
+
+import requests
 
 sys.path.insert(1, os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir, 'lib')))
 
@@ -39,9 +40,7 @@ def main( ini_file ):
 
 def build_index( search_url, dataset_file ):
     url = "%s/index?%s" % ( search_url, urllib.urlencode( { "docfile": dataset_file } ) )
-    request = urllib2.Request( url )
-    request.get_method = lambda: "PUT"
-    urllib2.urlopen( request )
+    requests.put(url)
 
 
 def create_dataset_file( dataset_iter ):
diff --git a/scripts/edam_mapping.py b/scripts/edam_mapping.py
index f82685a91fd..f483db8c1f5 100644
--- a/scripts/edam_mapping.py
+++ b/scripts/edam_mapping.py
@@ -16,9 +16,10 @@ from __future__ import print_function
 
 import os
 import sys
-import urllib2
 from xml import etree
 
+import requests
+
 sys.path.insert(1, os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir, 'lib')))
 
 import galaxy.model
@@ -35,7 +36,7 @@ EDAM_OWL_URL = "http://data.bioontology.org/ontologies/EDAM/submissions/25/downl
 
 
 if not os.path.exists("/tmp/edam.owl"):
-    open("/tmp/edam.owl", "w").write( urllib2.urlopen( EDAM_OWL_URL ).read() )
+    open("/tmp/edam.owl", "w").write(requests.get(EDAM_OWL_URL).text)
 
 
 owl_xml_tree = etree.ElementTree.parse("/tmp/edam.owl")
diff --git a/scripts/microbes/harvest_bacteria.py b/scripts/microbes/harvest_bacteria.py
index 3b427906969..a09e531bb0a 100644
--- a/scripts/microbes/harvest_bacteria.py
+++ b/scripts/microbes/harvest_bacteria.py
@@ -8,9 +8,9 @@ import os
 import sys
 import time
 from ftplib import FTP
-from urllib2 import urlopen
 from urllib import urlretrieve
 
+import requests
 from BeautifulSoup import BeautifulSoup
 from util import get_bed_from_genbank, get_bed_from_glimmer3, get_bed_from_GeneMarkHMM, get_bed_from_GeneMark
 
@@ -26,7 +26,7 @@ desired_ftp_files = {'GeneMark': {'ext': 'GeneMark-2.5f', 'parser': 'process_Gen
 
 # number, name, chroms, kingdom, group, genbank, refseq, info_url, ftp_url
 def iter_genome_projects( url="http://www.ncbi.nlm.nih.gov/genomes/lproks.cgi?view=1", info_url_base="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=genomeprj&cmd=Retrieve&dopt=Overview&list_uids=" ):
-    for row in BeautifulSoup( urlopen( url ) ).findAll( name='tr', bgcolor=["#EEFFDD", "#E8E8DD"] ):
+    for row in BeautifulSoup(requests.get(url).text).findAll(name='tr', bgcolor=["#EEFFDD", "#E8E8DD"]):
         row = str( row ).replace( "\n", "" ).replace( "\r", "" )
 
         fields = row.split( "</td>" )
@@ -65,7 +65,7 @@ def get_chroms_by_project_id( org_num, base_url="http://www.ncbi.nlm.nih.gov/ent
         html_count += 1
         url = "%s%s" % ( base_url, org_num )
         try:
-            html = urlopen( url )
+            html = requests.get(url).text
         except:
             print "GENOME PROJECT FAILED:", html_count, "org:", org_num, url
             html = None
diff --git a/scripts/tool_shed/api/export.py b/scripts/tool_shed/api/export.py
index 5773354558d..aa93c06969a 100644
--- a/scripts/tool_shed/api/export.py
+++ b/scripts/tool_shed/api/export.py
@@ -11,7 +11,8 @@ import argparse
 import os
 import sys
 import tempfile
-import urllib2
+
+import requests
 
 sys.path.insert( 1, os.path.join( os.path.dirname( __file__ ), os.pardir, os.pardir, os.pardir, 'lib' ) )
 from tool_shed.util import basic_util
@@ -98,24 +99,11 @@ def main( options ):
             download_url = export_dict[ 'download_url' ]
             download_dir = os.path.abspath( options.download_dir )
             file_path = os.path.join( download_dir, repositories_archive_filename )
-            src = None
-            dst = None
-            try:
-                src = urllib2.urlopen( download_url )
-                dst = open( file_path, 'wb' )
-                while True:
-                    chunk = src.read( CHUNK_SIZE )
+            src = requests.get(download_url, stream=True)
+            with open(file_path, 'wb') as dst:
+                for chunk in src.iter_content(chunk_size=CHUNK_SIZE):
                     if chunk:
-                        dst.write( chunk )
-                    else:
-                        break
-            except:
-                raise
-            finally:
-                if src:
-                    src.close()
-                if dst:
-                    dst.close()
+                        dst.write(chunk)
             print "Successfully exported revision ", options.changeset_revision, " of repository ", options.name, " owned by ", options.owner
             print "to location ", file_path
     else:
diff --git a/scripts/transfer.py b/scripts/transfer.py
index 84f0c446fed..ae08e11ff80 100644
--- a/scripts/transfer.py
+++ b/scripts/transfer.py
@@ -215,6 +215,7 @@ def transfer( app, transfer_job_id ):
 def http_transfer( transfer_job ):
     """Plugin" for handling http(s) transfers."""
     url = transfer_job.params['url']
+    assert url.startswith('http://') or url.startswith('https://')
     try:
         f = urllib2.urlopen( url )
     except urllib2.URLError as e:
diff --git a/test/api/test_workflows.py b/test/api/test_workflows.py
index 6ae340f96e1..1f331e7506b 100644
--- a/test/api/test_workflows.py
+++ b/test/api/test_workflows.py
@@ -180,7 +180,7 @@ class BaseWorkflowsApiTestCase( api.ApiTestCase, ImporterGalaxyInterface ):
         )
         if jobs_descriptions is None:
             assert source_type != "path"
-            jobs_descriptions = yaml.load( has_workflow )
+            jobs_descriptions = yaml.safe_load(has_workflow)
 
         test_data = jobs_descriptions.get("test_data", {})
 
diff --git a/test/api/test_workflows_from_yaml.py b/test/api/test_workflows_from_yaml.py
index cc269146a54..a2c066b754a 100644
--- a/test/api/test_workflows_from_yaml.py
+++ b/test/api/test_workflows_from_yaml.py
@@ -55,11 +55,11 @@ steps:
         assert tool_count['random_lines1'] == 1
         assert tool_count['cat1'] == 2
 
-# FIXME:  This test fails on some machines due to (we're guessing) yaml loading
+# FIXME:  This test fails on some machines due to (we're guessing) yaml.safe_loading
 # order being not guaranteed and inconsistent across platforms.  The workflow
-# yaml loader probably needs to enforce order using something like the
+# yaml.safe_loader probably needs to enforce order using something like the
 # approach described here:
-# https://stackoverflow.com/questions/13297744/pyyaml-control-ordering-of-items-called-by-yaml-load
+# https://stackoverflow.com/questions/13297744/pyyaml-control-ordering-of-items-called-by-yaml.safe_load
 #     def test_multiple_input( self ):
 #         history_id = self.dataset_populator.new_history()
 #         self._run_jobs("""
diff --git a/test/api/workflows_format_2/converter.py b/test/api/workflows_format_2/converter.py
index 2795982914d..e8d3fd40747 100644
--- a/test/api/workflows_format_2/converter.py
+++ b/test/api/workflows_format_2/converter.py
@@ -32,7 +32,7 @@ RUN_ACTIONS_TO_STEPS = {
 
 def yaml_to_workflow(has_yaml, galaxy_interface, workflow_directory):
     """Convert a Format 2 workflow into standard Galaxy format from supplied stream."""
-    as_python = yaml.load(has_yaml)
+    as_python = yaml.safe_load(has_yaml)
     return python_to_workflow(as_python, galaxy_interface, workflow_directory)
 
 
@@ -109,7 +109,7 @@ def _python_to_workflow(as_python, conversion_context):
                 run_action_path = run_action["@import"]
                 runnable_path = os.path.join(conversion_context.workflow_directory, run_action_path)
                 with open(runnable_path, "r") as f:
-                    runnable_description = yaml.load(f)
+                    runnable_description = yaml.safe_load(f)
                     run_action = runnable_description
 
             run_class = run_action["class"]
diff --git a/test/api/workflows_format_2/main.py b/test/api/workflows_format_2/main.py
index e147c52ec23..c481cc9eab7 100644
--- a/test/api/workflows_format_2/main.py
+++ b/test/api/workflows_format_2/main.py
@@ -20,7 +20,7 @@ def convert_and_import_workflow(has_workflow, **kwds):
         if workflow_directory is None:
             workflow_directory = os.path.dirname(has_workflow)
         with open(workflow_path, "r") as f:
-            has_workflow = yaml.load(f)
+            has_workflow = yaml.safe_load(f)
 
     if workflow_directory is not None:
         workflow_directory = os.path.abspath(workflow_directory)
diff --git a/test/unit/workflows/workflow_support.py b/test/unit/workflows/workflow_support.py
index 77258905cd5..23a89a656e5 100644
--- a/test/unit/workflows/workflow_support.py
+++ b/test/unit/workflows/workflow_support.py
@@ -73,7 +73,7 @@ class TestToolbox( object ):
 
 def yaml_to_model(has_dict, id_offset=100):
     if isinstance(has_dict, str):
-        has_dict = yaml.load(has_dict)
+        has_dict = yaml.safe_load(has_dict)
 
     workflow = model.Workflow()
     workflow.steps = []