Event log: enable custom timestamp (via message prefix)

[metachris]

📝 Summary

Allow custom timestamps in the event log.

If a message is prefixed with a timestamp (in sec or ms), then that part is used for ReceivedAt and the message is the remainder of the original message:

# Start the server
$ go run cmd/system-api/main.go

# Add regular event
$ echo "hello world" > pipe.fifo

# Add event with custom timestamp
$ echo "1634966400 this is a test" > pipe.fifo

# Query events
$ curl localhost:3535/logs
2024-11-21T19:48:04Z     hello world
2021-10-23T05:20:00Z     this is a test          <--- custom timestamp on this entry

Motivation

Some services might log into an (async) named pipe already before system-api has started. Without custom timestamps, those log entries would all have the timestamp when system-api started, instead of when the log message was written.

Downsides

Allows services to mess with internals through the log message, and spoof the timestamp of it's own event arbitrarily.

Discussion

Not yet sure what's the best path forward -- giving services this freedom, or simply not having 'proper' timestamps for logs received before system-api start.

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✅ I have run these commands

• make lint
• make test
• go mod tidy