[dev-tool] Throw error when proxy fails to start

[timovv]

Checklists

• Added impacted package name to the issue description

Packages impacted by this PR:

Issues associated with this PR:

• Resolves [Unified Recorder] Print a user-friendly message when the test-proxy image fails to start #19725

Describe the problem that is addressed by this PR:

When running tests using the test proxy, if the proxy tool image fails to start, the tool would exit successfully without outputting a useful error. This could happen if, for example, the Docker daemon is not running (this has happened to me a few times). This PR throws an error when the command to start the proxy tool outputs a nonzero exit code. This error will aid with debugging.

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[HarshaNalluru]

Love this PR 💗

[witemple-msft]

LGTM. I think it's a little clunky to have to check a log file written into the current directory. Could we do something like print the last N lines of the log file automatically on failure?

[timovv]

Yeah, that's fair -- I had a similar thought, but I didn't feel that it was worth the extra effort to implement that. But it would be handy to have that especially for the CI case, where it's not possible to inspect the logs. I think we can get away with dumping the entire log in the case of a failure, since it's likely to be quite short in the event of an error.

[timovv]

Alright, turns out trimming it to be only 10 lines wasn't that hard so have gone ahead and done that :)

[HarshaNalluru]

Looks good 🎉