Add support for graceful reload #69
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Well, unless the main process gets the last pid before the OS cycles back to the beginning. In which case, the main pid will be much larger. |
brendan-ward
approved these changes
May 20, 2019
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@nikmolnar nicely done! Appears to work as expected.
Please add usage instructions to the README.
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| server.TLSConfig.GetCertificate = e.AutoTLSManager.GetCertificate | ||
| server.TLSConfig.NextProtos = append(server.TLSConfig.NextProtos, acme.ALPNProto) | ||
| if !e.DisableHTTP2 { |
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There's no server.StartAutoTLS to replace e.StartAutoTLS, so I stole the implementation of e.StartAutoTLS and just in-lined it here.
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And this is part of that implementation.
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This PR adds support for gracefully reloading the server configuration (without dropping any in-progress connections or refusing any new ones) upon receiving a
HUPsignal.(the main pid will always be the smaller one)
The strategy is to fork a child process on start, rather than handling requests in the main process. The main process binds a listener to the desired port and passes that listener to the child process so that it can accept new requests.
When a reload is requested, the parent process creates a replacement child process, passing it the same listener. It send the original child process a signal to gracefully shutdown, after fulfilling pending connections. It also implements a timer, ensuring the process is stopped eventually in the event of a hang. The parent is now ready for another reload signal.
As far as testing, I've continually reloaded the server, while requesting tiles via the mbtileserver service map page using a throttled connection, and have not seen any tiles drop.