scripts/run_on_swarming_bots/README.md

# 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.