Batch Running Custom Tasks On Swarming

Some times, we want to run a custom script on many swarming bots. Typically, this is performing maintenance on a swarming bot, like updating/removing an installed application or cleaning up disk space.

This go program, run_on_swarming_bots, makes that easy.

First, make sure you have isolate and isolated downloaded from CIPD and on your $PATH somewhere. The cipd executable comes in depot_tools, so make sure that is set up before proceeding.

# All code examples are run from the infra repo's root
$ cipd ensure --root=$HOME/bin/luci --ensure-file=cipd.ensure
$ export PATH=$PATH:$HOME/bin/luci/cipd_bin_packages

Then, run the program in dry run mode to make sure you have your dimensions correct and thus are running the script on the right set of bots. Protip: if you want a single bot, you can specify it with the id dimension (id:skia-e-gce-123).

$ go run scripts/run_on_swarming_bots/run_on_swarming_bots.go \
    --dimension docker_installed:true --dimension gce:1 \
    --dry_run
# output should include lines like:
#   run_on_swarming_bots.go:135 Dry run mode.  Would run on following bots:
#   run_on_swarming_bots.go:137 skia-e-gce-100
#   run_on_swarming_bots.go:137 skia-e-gce-101
#   run_on_swarming_bots.go:137 skia-e-gce-102
# and then the program exits.

Finally, include your script. Your script will run on all swarming bots that match the specified dimensions.

$ go run scripts/run_on_swarming_bots/run_on_swarming_bots.go \
    --dimension docker_installed:true --dimension gce:1 \
    --script=scripts/run_on_swarming_bots/cleanup_docker.py

Assuming things work out, check in the script you ran if would be useful in the future.