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Inter-Process Context

It's important to pass logging context between parts of one app, but we also need to pass context between processes and services over the network.

Request IDs

In a microservices architecture, you'll usually propagate a request ID across services so related logs can be correlated.

2023/10/01 12:34:57 severity="INFO" message="Authentication succeeded" service="auth" user="alice" request_id="ibaev4EiyaiS1Kot"
2023/10/01 12:34:57 severity="INFO" message="request served" service="api" request_id="ibaev4EiyaiS1Kot"

For HTTP services, the easiest way to propagate this ID is with a header like X-Request-ID.

Assignment

Propagate request IDs through headers and logs.

Create a new request ID middleware that reads X-Request-ID from the inbound request. If one isn't present, generate one with rand.Text. Before calling next.ServeHTTP, set the request ID on the response header with w.Header().Set.
Update your server-wide handler to use the new middleware. It should be called before the request logger middleware.
Update your request logger middleware to include the request ID (which it can get from the header) in the "request_id" attribute of the log entry.

Including the request ID in the response header makes debugging easier – clients can report the ID, and you can search your logs for it.

Restart your server with LINKO_LOG_FILE=linko.access.log set:

LINKO_LOG_FILE=linko.access.log go run .

Run and submit the CLI tests from the root of the Linko repo.