caddy/config/setup/log.go

package setup

import (
	"log"
	"os"

	"github.com/mholt/caddy/middleware"
	caddylog "github.com/mholt/caddy/middleware/log"
)

// Log sets up the logging middleware.
func Log(c *Controller) (middleware.Middleware, error) {
	rules, err := logParse(c)
	if err != nil {
		return nil, err
	}

	// Open the log files for writing when the server starts
	c.Startup = append(c.Startup, func() error {
		for i := 0; i < len(rules); i++ {
			var err error
			var file *os.File

			if rules[i].OutputFile == "stdout" {
				file = os.Stdout
			} else if rules[i].OutputFile == "stderr" {
				file = os.Stderr
			} else {
				file, err = os.OpenFile(rules[i].OutputFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
				if err != nil {
					return err
				}
			}

			rules[i].Log = log.New(file, "", 0)
		}

		return nil
	})

	return func(next middleware.Handler) middleware.Handler {
		return caddylog.Logger{Next: next, Rules: rules}
	}, nil
}

func logParse(c *Controller) ([]caddylog.Rule, error) {
	var rules []caddylog.Rule

	for c.Next() {
		args := c.RemainingArgs()

		if len(args) == 0 {
			// Nothing specified; use defaults
			rules = append(rules, caddylog.Rule{
				PathScope:  "/",
				OutputFile: caddylog.DefaultLogFilename,
				Format:     caddylog.DefaultLogFormat,
			})
		} else if len(args) == 1 {
			// Only an output file specified
			rules = append(rules, caddylog.Rule{
				PathScope:  "/",
				OutputFile: args[0],
				Format:     caddylog.DefaultLogFormat,
			})
		} else {
			// Path scope, output file, and maybe a format specified

			format := caddylog.DefaultLogFormat

			if len(args) > 2 {
				switch args[2] {
				case "{common}":
					format = caddylog.CommonLogFormat
				case "{combined}":
					format = caddylog.CombinedLogFormat
				default:
					format = args[2]
				}
			}

			rules = append(rules, caddylog.Rule{
				PathScope:  args[0],
				OutputFile: args[1],
				Format:     format,
			})
		}
	}

	return rules, nil
}