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Instance Context

Different runtime context matters depending on how your app runs. For desktop or mobile apps, useful fields often include:

Host operating system
Time zone
Shared library versions

For backend services this is usually simpler, but scale still matters. Thousands of pods across regions need more context than one app on one EC2 instance.

What to Log

All of this is probably overkill for most backends, but it's worth considering:

Runtime environment name (e.g. production, staging, development)
The server's hostname
The server's IP address
Cloud region
Node name or IP (for containerized services)
Docker container name or Kubernetes pod name
Host operating system and kernel version
Host/server time zone (particularly if you deploy across geographic regions)

Gathering Runtime Information

For our purposes, we'll log two fields that are almost always useful:

Runtime environment name (e.g. production, staging, development)
Server hostname/domain (e.g. jons-macbook (local), c7a9d8b32c4a (container), or ip-172-31-22-45 (cloud server))

env := os.Getenv("ENV")
hostname, _ := os.Hostname()

logger = logger.With(
	slog.String("env", env),
	slog.String("hostname", hostname),
)

Assignment

Include runtime instance metadata in every log.

In your existing Logger.With call, add env and hostname fields after git_sha and build_time.
Use os.Getenv to read ENV (e.g. development, production).
Use os.Hostname to get the server hostname.

Build your app with -ldflags and run it with ENV and LINKO_LOG_FILE set:

go build \
  -ldflags "-X boot.dev/linko/internal/build.GitSHA=$(git rev-parse HEAD) -X boot.dev/linko/internal/build.BuildTime=$(date -u '+%Y-%m-%dT%H:%M:%SZ')" \
  -o linko &&
LINKO_LOG_FILE=linko.access.log ENV=development ./linko

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