juju 1.17.5 tries to execute non-existant hooks

[Dave Cheney]

Simple case, deploying cs:precise/ubuntu failed

  u0:
    charm: cs:precise/ubuntu-4
    exposed: false
    units:
      u0/0:
        agent-state: error
        agent-state-info: 'hook failed: "config-changed"'
        agent-version: 1.17.5.1
        machine: "1"
        public-address: ec2-54-206-179-139.ap-southeast-2.compute.amazonaws.com

Log

ubuntu@ip-10-249-71-95:~$ tail /var/log/juju/unit-u0-0.log
2014-03-17 02:54:31 INFO juju.worker.uniter modes.go:421 ModeConfigChanged starting
2014-03-17 02:54:31 DEBUG juju.worker.uniter.filter filter.go:440 discarded config event
2014-03-17 02:54:32 INFO juju.worker.uniter uniter.go:474 running "config-changed" hook
2014-03-17 02:54:32 ERROR juju.worker.uniter uniter.go:480 hook failed: fork/exec /var/lib/juju/agents/unit-u0-0/charm/hooks/config-changed: no such file or directory
2014-03-17 02:54:32 DEBUG juju.worker.uniter modes.go:423 ModeConfigChanged exiting
2014-03-17 02:54:32 INFO juju.worker.uniter modes.go:421 ModeHookError starting

ubuntu@ip-10-249-71-95:~$ sudo stat /var/lib/juju/agents/unit-u0-0/charm/hooks/config-changed
stat: cannot stat `/var/lib/juju/agents/unit-u0-0/charm/hooks/config-changed': No such file or directory

[Andrew Wilkins (axwalk)]

In Dave's case, this is caused by the tools being built with a version of Go > 1.2, where the behaviour of os/exec.Command has changed. Our code is relying on implementation details of Command, which until 1.3 will use LookPath uncondtionally. LookPath returns the error that we check for. In 1.3, LookPath is used conditionally (not at all in our usage).

I'm told that others have come across this before with released tools. I can't speak to that.

[Andrew Wilkins (axwalk)]

https://code.google.com/p/go/source/browse/src/pkg/os/exec/exec.go#112
https://code.google.com/p/go/source/browse/src/pkg/os/exec/exec.go?name=go1.2#110

[John A Meinel (jameinel)]

Good to fix, but not actually Critical because it only affects when using Go trunk to build the tools, which we *don't* do for releases.