github-com-improbable-eng-metahook-buildkite-plugin-v0-4-1/hooks/run-hook.sh: line 17: !var_name: unbound variable

[improbable-mattchurch]

Running plugin metahook pre-command hook
# A hook runner was written to "C:\users\buildkite-agent\tmp\d6018259-8f4c-4680-a375-53215e54e7cd\buildkite-agent-bootstrap-hook-runner-106667881" with the following:
> C:\users\buildkite-agent\tmp\d6018259-8f4c-4680-a375-53215e54e7cd\buildkite-agent-bootstrap-hook-runner-106667881
# Attempting to run C:\users\buildkite-agent\tmp\d6018259-8f4c-4680-a375-53215e54e7cd\buildkite-agent-bootstrap-hook-runner-106667881 with Bash for Windows
c:/users/buildkite-agent/AppData/Local/buildkite-agent/plugins/github-com-improbable-eng-metahook-buildkite-plugin-v0-4-1/hooks/run-hook.sh: line 17: !var_name: unbound variable

It appears as though if you do not define a pre-command hook, it tries to execute it anyways and fails.

example of my plugin declaration:

  annotate-errors-plugin: &annotate-errors-plugin
    # https://github.com/improbable-eng/metahook-buildkite-plugin
    improbable-eng/metahook#v0.4.1:
      pre-exit: python "GameOne/.buildkite/metahooks/annotate_errors.py"

https://buildkite.com/improbable/midwinter-code/builds/674#d6018259-8f4c-4680-a375-53215e54e7cd/267-271

example of error no longer occurring if plugin is defined as:

  annotate-errors-plugin: &annotate-errors-plugin
    # https://github.com/improbable-eng/metahook-buildkite-plugin
    improbable-eng/metahook#v0.4.1:
      pre-command: echo "test"
      pre-exit: python "GameOne/.buildkite/metahooks/annotate_errors.py"

https://buildkite.com/improbable/midwinter-code/builds/680#b4e799c4-2a07-4f59-aa87-f8e834ef74ff

[improbable-mattchurch]

another example of the failure happening if pre-command isn't defined: https://buildkite.com/improbable/midwinter-code/builds/678#edd0b44c-688c-43d2-b775-71637c6be737/303-307

[improbable-mattchurch]

Spoke with @ca-johnson and it seems that it's a bad idea to invoke metahook more than once in the same step. In my case I was using it for different clean up steps. If that's a problem, we should simply improve the error messaging to let users know not to do that