Redis socket closed unexpectedly

[morganney]

This has been occurring in the test environment since initial deploy. There is plenty of references about it online, here is on example from SO. As long as the error is handled, the connection with redis is re-established, but the cause is still unknown.

Looking at the log timestamps, they seem to be occurring almost exactly every hour:

morgan@mactop busmap (develop) $ copilot svc logs -n api -e test --start-time 2024-01-06T18:00:00.272Z
copilot/api/3f10a59ec6fb4 {"level":"ERROR","time":"2024-01-06T19:16:32.272Z","pid":1,"hostname":"ip-foo.us-west-2.compute.internal","err":{"type":"SocketClosedUnexpectedlyError","message":"Socket closed unexpectedly","stack":"Error: Socket closed unexpectedly\n    at Socket.<anonymous> (/app/node_modules/@redis/client/dist/lib/client/socket.js:194:118)\n    at Object.onceWrapper (node:events:629:26)\n    at Socket.emit (node:events:514:28)\n    at TCP.<anonymous> (node:net:337:12)"},"msg":"Redis unexpected error."}
copilot/api/3f10a59ec6fb4 {"level":"INFO","time":"2024-01-06T19:16:32.273Z","pid":1,"hostname":"ip-foo.us-west-2.compute.internal","msg":"Redis reconnecting."}
copilot/api/3f10a59ec6fb4 {"level":"ERROR","time":"2024-01-06T20:16:32.276Z","pid":1,"hostname":"ip-foo.us-west-2.compute.internal","err":{"type":"SocketClosedUnexpectedlyError","message":"Socket closed unexpectedly","stack":"Error: Socket closed unexpectedly\n    at Socket.<anonymous> (/app/node_modules/@redis/client/dist/lib/client/socket.js:194:118)\n    at Object.onceWrapper (node:events:629:26)\n    at Socket.emit (node:events:514:28)\n    at TCP.<anonymous> (node:net:337:12)"},"msg":"Redis unexpected error."}
copilot/api/3f10a59ec6fb4 {"level":"INFO","time":"2024-01-06T20:16:32.277Z","pid":1,"hostname":"ip-foo.us-west-2.compute.internal","msg":"Redis reconnecting."}
copilot/api/3f10a59ec6fb4 {"level":"ERROR","time":"2024-01-06T21:16:32.284Z","pid":1,"hostname":"ip-foo.us-west-2.compute.internal","err":{"type":"SocketClosedUnexpectedlyError","message":"Socket closed unexpectedly","stack":"Error: Socket closed unexpectedly\n    at Socket.<anonymous> (/app/node_modules/@redis/client/dist/lib/client/socket.js:194:118)\n    at Object.onceWrapper (node:events:629:26)\n    at Socket.emit (node:events:514:28)\n    at TCP.<anonymous> (node:net:337:12)"},"msg":"Redis unexpected error."}
copilot/api/3f10a59ec6fb4 {"level":"INFO","time":"2024-01-06T21:16:32.286Z","pid":1,"hostname":"ip-foo.us-west-2.compute.internal","msg":"Redis reconnecting."}

The database was not initialized with a schema, so there should not be any session activity in terms of writing through the redis socket. There is probably a default timeout in play somewhere that is being triggered, and the socket closed whereupon a new one is regenerated based on the underlying default strategy employed by node-redis.

Google "Error: Socket closed unexpectedly" to get plenty of other tidbits.

Find the underlying cause, see if there is a reasonable fix, or if the solution is to simply accept there is a timeout (or that we want there to be one), understand why this occurs, live with it and move on.