logx

logx

Opinionated zerolog wrapper providing context-first structured logging, request logging middleware for echo, and consistent field naming across services. Extracted from core/pkg/logx so any repo can consume the same logging conventions without importing core.

go get github.com/theopenlane/logx

The model: loggers travel on the context

The package is built around one rule: log through the context, not through a global logger. A request-scoped (or job-scoped) logger is attached to the context.Context once — by the HTTP middleware, a job dispatcher, or your own setup code — and every log line downstream retrieves it from there. Fields attached along the way (request ID, organization, subject) then appear on every subsequent log line automatically, which is what makes production logs correlatable.

logx.FromContext(ctx).Info().Str("standard_id", id).Msg("standard updated")

FromContext never returns nil: if the context carries no logger (or a disabled one) it falls back to zerolog's global logger, so it is always safe to call. This is the method you will use most — prefer it over zerolog.Ctx, log.Ctx, or the global log.Info() in any code that has a context.

Two things ride on the context and it helps to keep them distinct:

• The logger itself — a zerolog.Logger whose accumulated fields appear on every event it logs.
• Durable fields (LogFields) — a plain map[string]any mirror of those fields that can be read back with FieldsFromContext. This exists so field state can cross process boundaries: a job queue can serialize the fields when a task is enqueued and restore them with WithFields on the worker side, keeping correlation intact across the hop.

Everyday usage

Adding fields

// one field
ctx = logx.WithField(ctx, logx.FieldOrganizationID, orgID)

// several at once
ctx = logx.WithFields(ctx, map[string]any{
	logx.FieldSubjectID: caller.SubjectID,
	logx.FieldOperation: "standard_update",
})

Both update the context logger and the durable field store, and both copy the underlying map so sibling contexts never share state. Use these for fields that should appear on every subsequent log line in the request or job; use plain zerolog chaining (.Str(...), .Int(...)) for fields that belong to a single event.

Canonical field names

Use the exported constants instead of string literals when a concept has one — this is what keeps organization_id from also appearing as org_id, owner_id, and org across services:

FieldRequestID, FieldOrganizationID, FieldSubjectID, FieldSubjectEmail, FieldCapabilities, FieldOperation, FieldRemoteIP, FieldUserAgent, FieldRequestProtocol, FieldTrueClientIP, FieldForwardedFor, FieldRealIP

Errors

Always attach errors with .Err(err) (never .Str("error", err.Error())) so error marshaling and stack traces work. For picking the level, the package classifies expected request-lifecycle failures — client disconnects and canceled work are not server faults and should not page anyone:

// logs at warn for benign errors (context.Canceled, closed/reset connections,
// sql.ErrTxDone, http.ErrAbortHandler), error for everything else
logx.ErrorEvent(ctx, err).Msg("rollback failed")

// same idea when an HTTP status is in hand: benign errors and 4xx land at warn
logx.FromContext(ctx).WithLevel(logx.RequestErrorLevel(err, status)).Err(err).Msg("request failed")

// the predicate, for your own branching
if logx.BenignError(err) { ... }

Seeding and bridging

// guarantee a context carries a logger (start of a job, background goroutine, etc.)
ctx = logx.SeedContext(ctx)

// hand a *slog.Logger to code that requires the standard library interface (e.g. echo v5's e.Logger);
// events flow through zerolog, which keeps level filtering and output unified
e.Logger = logx.SlogLogger(logger.Unwrap())

Setup at service startup

Call Configure once in main/server bootstrap; everything else flows from the context.

loggers := logx.Configure(logx.LoggerConfig{
	Level:         zerolog.InfoLevel, // zerolog.NoLevel keeps the existing global default
	Writer:        os.Stderr,         // defaults to os.Stdout
	Pretty:        cfg.PrettyLog,     // human-readable console output for local dev
	IncludeCaller: cfg.Debug,         // file:line on every event; costs a runtime.Caller per event
	IncludeStack:  true,              // render error stack traces (wires zerolog's pkgerrors marshaler)
	WithEcho:      true,              // also build the echo-compatible logger (loggers.Echo)
	SetGlobal:     true,              // make this the zerolog global, so FromContext fallback matches
})

Set SetGlobal in binaries (servers, CLIs, workers) so code paths without a context-carried logger still produce consistently formatted output. Leave it unset in tests and libraries.

Every configured logger stamps a severity field mapped for GCP Cloud Logging, so log-based metrics and alerting work without a fluentd rewrite: trace/debug → DEBUG, info → INFO, warn → WARNING, error → ERROR, fatal → CRITICAL, panic → ALERT.

Request logging middleware

Both middlewares do the same job: seed the request context with a request-scoped logger (so every handler and downstream call logs with correlation fields attached), then emit one request-summary event when the request completes, leveled via RequestErrorLevel.

echo v5 (github.com/labstack/echo/v5)

e.Use(logx.Middleware(logx.MiddlewareConfig{
	Logger:                logger,      // defaults to a stdout logger if nil
	RequestIDHeader:       "X-Request-ID", // header to read the id from (default X-Request-Id)
	RequestIDKey:          logx.FieldRequestID, // log key for the id (default request_id)
	HandleError:           true,
	AttachRequestMetadata: true,
}))

Place it after your request-ID middleware and before recovery, so panics are logged with the request-scoped logger.

echox (github.com/theopenlane/echox)

e.Use(middleware.RequestID())
e.Use(logx.LoggingMiddleware(logx.Config{
	Logger:                logger,
	HandleError:           true,
	AttachRequestMetadata: true,
}))

Behavior worth knowing

• AttachRequestMetadata: true puts client origin metadata (remote_ip, user_agent, request_protocol, and the True-Client-IP / X-Forwarded-For / X-Real-IP headers when present) on the request-scoped logger and durable fields, so every log line in the request carries them. When unset, the metadata appears only on the final request-summary event.
• HandleError: true forwards handler errors to the registered HTTPErrorHandler and then consumes them (returns nil), preventing the router from invoking the error handler a second time. Leave it false only if another middleware up the chain owns error handling.
• The request-summary event includes host, method, uri, status, latency_ms, bytes_in, bytes_out, query, and referer; failed requests are leveled by RequestErrorLevel, so benign disconnects and 4xx responses log at warn rather than error.
• Skipper short-circuits logging for matching requests (health checks, probes).

Do / don't

• Do use logx.FromContext(ctx) everywhere a context exists; don't use the zerolog global or log.Ctx in request/job paths.
• Do keep log statements on a single line; don't split builder chains across newlines.
• Do use .Err(err) and ErrorEvent; don't stringify errors into ad hoc fields.
• Do use the Field* constants for shared concepts; don't invent new spellings of an existing key.
• Do classify expected failures (via BenignError/ErrorEvent) instead of logging every failure at error level.

Pretty console output

Pretty: true routes output through the consolelog subpackage — a colorized, human-ordered console writer for local development. Production should always use the default JSON output.

Level conversion

MatchEchoLevel converts a gommon/echo log level to its zerolog equivalent, for wiring echox-configured services:

zlvl, _ := logx.MatchEchoLevel(log.WARN) // zerolog.WarnLevel

Composing outputs

Configure accepts any io.Writer, so zerolog's writer combinators apply directly — e.g. zerolog.MultiLevelWriter to tee destinations, or a lumberjack.Logger for rotated files.