coder/docs/templates/agent-metadata.md

Agent Metadata (alpha)

Agent metadata is in an alpha state and may break or disappear at any time.

With Agent Metadata, template admins can expose operational metrics from their workspaces to their users. It is the dynamic complement of Resource Metadata.

See the Terraform reference.

Examples

All of these examples use heredoc strings for the script declaration. With heredoc strings, you can script without messy escape codes, just as if you were working in your terminal.

Here's a standard set of metadata snippets for Linux agents:

resource "coder_agent" "main" {
  os             = "linux"
  ...
  metadata {
    display_name = "CPU Usage"
    key  = "cpu"
    # calculates CPU usage by summing the "us", "sy" and "id" columns of
    # vmstat.
    script = <<EOT
        vmstat | awk 'FNR==3 {printf "%2.0f%%", $13+$14+$16}'
    EOT
    interval = 1
    timeout = 1
  }

  metadata {
    display_name = "Disk Usage"
    key  = "cpu"
    script = <<EOT
        df -h | awk -v mount="/" '$6 == mount { print $5 }'
    EOT
    interval = 1
    timeout = 1
  }

  metadata {
    display_name = "Memory Usage"
    key  = "mem"
    script = <<EOT
    free | awk '/^Mem/ { printf("%.0f%%", $4/$2 * 100.0) }'
    EOT
    interval = 1
    timeout = 1
  }

  metadata {
    display_name = "Load Average"
    key  = "load"
    script = <<EOT
        awk '{print $1,$2,$3}' /proc/loadavg
    >>
    interval = 1
    timeout = 1
  }
}

Utilities

vmstat is available in most Linux distributions and provides virtual memory, CPU and IO statistics. Running vmstat produces output that looks like:

procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
0  0  19580 4781680 12133692 217646944    0    2     4    32    1    0  1  1 98  0  0

dstat is considerably more parseable than vmstat but often not included in base images. It is easily installed by most package managers under the name dstat. The output of running dstat 1 1 looks like:

--total-cpu-usage-- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai stl| read  writ| recv  send|  in   out | int   csw
1   1  98   0   0|3422k   25M|   0     0 | 153k  904k| 123k  174k