fix(prometheus): http server exit on error #590
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0xNineteen
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## Problems Prometheus does not consistently get metrics from our metrics endpoint. The metrics are intermittent.  Also, the server often crashes due to errors. In #590 I added a wrapper to catch these errors and restart the server. But sometimes an error occurs that is handled, a server restart is attempted, but the server never responds to any http requests any more, so the metrics become completely inaccessible until sig is completely restarted. Usually this is caused by `error.BrokenPipe` ## Solution > Revert "fix(prometheus): remove httpz again and fix prometheus metrics (#555)" > > This reverts commit 3502333. I understand the desire to eliminate unnecessary dependencies. In the grand scheme of things, eliminating httpz is not that important. Having a working metrics endpoint is critical though. We have a solution that works with httpz. We should test more thoroughly before replacing it.
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Currently, if the prometheus http server has an error, it just prints the name of the error to stderr and then exits the thread. Metrics stop being served. All kinds of errors could happen in here, but that doesn't mean we should stop serving metrics. It's better to log an error and then continue running. I used runService from the service manager to accomplish this, with a bit of refactoring in how the thread is spawned.