Allow Docker destinations to use --volumes-from option.

Enables certain kind of Docker-to-Docker job executions. Thanks to Andrew Stewart.

job_conf.xml.sample_advanced

@@ -154,6 +154,11 @@
                are available to all jobs and $job_directory is also available for
                Pulsar jobs.
           -->
+          <!-- One can run docker using volumes-from tag by setting the following
+               parameter. For more information on volumes-from check out the following
+               docker tutorial. https://docs.docker.com/userguide/dockervolumes/
+          -->
+          <!-- <param id="docker_volumes_from">parent_container_name</param> -->
           <!-- Control memory allocatable by docker container with following option:
           -->
           <!-- <param id="docker_memory">24G</param> -->

lib/galaxy/tools/deps/containers.py

@@ -190,10 +190,12 @@ class DockerContainer(Container):
         volumes_raw = self.__expand_str(self.destination_info.get("docker_volumes", "$defaults"))
         # TODO: Remove redundant volumes...
         volumes = docker_util.DockerVolume.volumes_from_str(volumes_raw)
+        volumes_from = self.destination_info.get("docker_volumes_from", docker_util.DEFAULT_VOLUMES_FROM)
         return docker_util.build_docker_run_command(
             command,
             self.container_id,
             volumes=volumes,
+            volumes_from=volumes_from,
             env_directives=env_directives,
             working_directory=working_directory,
             docker_cmd=prop("cmd", docker_util.DEFAULT_DOCKER_COMMAND),

lib/galaxy/tools/deps/docker_util.py

@@ -7,6 +7,7 @@ DEFAULT_VOLUME_MOUNT_TYPE = "rw"
 DEFAULT_WORKING_DIRECTORY = None
 DEFAULT_NET = None
 DEFAULT_MEMORY = None
+DEFAULT_VOLUMES_FROM = None
 
 
 class DockerVolume(object):
@@ -55,6 +56,7 @@ def build_docker_run_command(
     tag=None,
     docker_cmd=DEFAULT_DOCKER_COMMAND,
     volumes=[],
+    volumes_from=DEFAULT_VOLUMES_FROM,
     memory=DEFAULT_MEMORY,
     env_directives=[],
     working_directory=DEFAULT_WORKING_DIRECTORY,
@@ -75,6 +77,8 @@ def build_docker_run_command(
         command_parts.extend(["-e", env_directive])
     for volume in volumes:
         command_parts.extend(["-v", str(volume)])
+    if volumes_from:
+        command_parts.extend(["--volumes-from", str(volumes_from)])
     if memory:
         command_parts.extend(["-m", memory])
     if name: