refactor(logging): add a logging abstraction and move the job logger onto it (#1295)

Add `act/common/logging`: a printf-style `Logger` on a slog-shaped `Handler`, with a logrus-backed handler as the only backend, plus a `logtest` handler for tests. Move the job logger onto it: `common.Logger` returns `*logging.Logger`, the job log formatters and the `Reporter` hook become handlers, and composite step IDs travel in the context.

Logging is tightly coupled to logrus types (hooks, formatters, `Entry.Data`). Going through our own interface first lets the remaining call sites move over with unchanged behavior, and lets the backend be swapped for `log/slog` in one place afterwards. The global process logger and its masking formatter stay on logrus for now.

Assisted-by: Codet
Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1295
Reviewed-by: bircni <[email protected]>

act/common/logging/logger.go

@@ -0,0 +1,106 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package logging
+
+import (
+	"context"
+	"fmt"
+	"runtime"
+	"time"
+)
+
+const badKey = "!BADKEY"
+
+// Logger writes printf-style messages with structured attributes to a Handler.
+type Logger struct {
+	h   Handler
+	ctx context.Context
+}
+
+func New(h Handler) *Logger {
+	return &Logger{h: h, ctx: context.Background()}
+}
+
+// With returns a Logger that adds the key/value pairs to every record, like slog.Logger.With.
+func (l *Logger) With(args ...any) *Logger {
+	if len(args) == 0 {
+		return l
+	}
+	return &Logger{h: l.h.WithAttrs(argsToAttrs(args)), ctx: l.ctx}
+}
+
+func (l *Logger) WithError(err error) *Logger {
+	return l.With("error", err)
+}
+
+// WithContext returns a Logger that passes ctx to its Handler.
+func (l *Logger) WithContext(ctx context.Context) *Logger {
+	return &Logger{h: l.h, ctx: ctx}
+}
+
+func (l *Logger) Enabled(level Level) bool {
+	return l.h.Enabled(l.ctx, level)
+}
+
+func (l *Logger) Tracef(format string, args ...any) { l.logf(LevelTrace, format, args) }
+func (l *Logger) Debugf(format string, args ...any) { l.logf(LevelDebug, format, args) }
+func (l *Logger) Infof(format string, args ...any)  { l.logf(LevelInfo, format, args) }
+func (l *Logger) Warnf(format string, args ...any)  { l.logf(LevelWarn, format, args) }
+func (l *Logger) Errorf(format string, args ...any) { l.logf(LevelError, format, args) }
+
+// Trace and the methods below format their arguments like fmt.Sprint.
+func (l *Logger) Trace(args ...any) { l.log(LevelTrace, args) }
+func (l *Logger) Debug(args ...any) { l.log(LevelDebug, args) }
+func (l *Logger) Info(args ...any)  { l.log(LevelInfo, args) }
+func (l *Logger) Warn(args ...any)  { l.log(LevelWarn, args) }
+func (l *Logger) Error(args ...any) { l.log(LevelError, args) }
+
+func (l *Logger) logf(level Level, format string, args []any) {
+	if !l.Enabled(level) {
+		return
+	}
+	l.emit(callerPC(4), level, fmt.Sprintf(format, args...))
+}
+
+func (l *Logger) log(level Level, args []any) {
+	if !l.Enabled(level) {
+		return
+	}
+	l.emit(callerPC(4), level, fmt.Sprint(args...))
+}
+
+// emit drops the Handler error, as a logger has nowhere to report it.
+func (l *Logger) emit(pc uintptr, level Level, msg string) {
+	_ = l.h.Handle(l.ctx, Record{Time: time.Now(), Level: level, Message: msg, PC: pc})
+}
+
+// callerPC returns the program counter skip frames up, 4 being the caller of an exported method.
+func callerPC(skip int) uintptr {
+	var pcs [1]uintptr
+	runtime.Callers(skip, pcs[:])
+	return pcs[0]
+}
+
+func argsToAttrs(args []any) []Attr {
+	attrs := make([]Attr, 0, len(args)/2+1)
+	for len(args) > 0 {
+		switch k := args[0].(type) {
+		case Attr:
+			attrs = append(attrs, k)
+			args = args[1:]
+		case string:
+			if len(args) == 1 {
+				attrs = append(attrs, Attr{Key: badKey, Value: k})
+				args = nil
+			} else {
+				attrs = append(attrs, Attr{Key: k, Value: args[1]})
+				args = args[2:]
+			}
+		default:
+			attrs = append(attrs, Attr{Key: badKey, Value: k})
+			args = args[1:]
+		}
+	}
+	return attrs
+}