Add some config through flag/env

config/cli.go

@@ -0,0 +1,45 @@
+package config
+
+import (
+	"flag"
+)
+
+// declareFlags registers flags for the structure Options.
+func (c *Config) declareFlags() {
+	flag.BoolVar(&c.Dev, "dev", c.Dev, "Use ui directory instead of embedded assets")
+	flag.StringVar(&c.Bind, "bind", c.Bind, "Bind port/socket")
+	flag.StringVar(&c.ExternalURL, "externalurl", c.ExternalURL, "Begining of the URL, before the base, that should be used eg. in mails")
+
+	// Others flags are declared in some other files when they need specials configurations
+}
+
+func Consolidated() (cfg *Config, err error) {
+	// Define defaults options
+	cfg = &Config{
+		Bind:        ":8082",
+		ExternalURL: "http://localhost:8082",
+	}
+
+	cfg.declareFlags()
+
+	// Then, overwrite that by what is present in the environment
+	err = cfg.FromEnv()
+	if err != nil {
+		return
+	}
+
+	// Finaly, command line takes precedence
+	err = cfg.parseCLI()
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+// parseCLI parse the flags and treats extra args as configuration filename.
+func (c *Config) parseCLI() error {
+	flag.Parse()
+
+	return nil
+}

config/config.go

@@ -0,0 +1,28 @@
+package config
+
+import (
+	"flag"
+	"strings"
+)
+
+type Config struct {
+	Dev         bool
+	Bind        string
+	ExternalURL string
+}
+
+// parseLine treats a config line and place the read value in the variable
+// declared to the corresponding flag.
+func (c *Config) parseLine(line string) (err error) {
+	fields := strings.SplitN(line, "=", 2)
+	orig_key := strings.TrimSpace(fields[0])
+	value := strings.TrimSpace(fields[1])
+
+	key := strings.TrimPrefix(orig_key, "MINIFAAS_")
+	key = strings.Replace(key, "_", "-", -1)
+	key = strings.ToLower(key)
+
+	err = flag.Set(key, value)
+
+	return
+}

config/env.go

@@ -0,0 +1,21 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+// FromEnv analyzes all the environment variables to find each one
+// starting by MINIFAAS_
+func (c *Config) FromEnv() error {
+	for _, line := range os.Environ() {
+		if strings.HasPrefix(line, "MINIFAAS_") {
+			err := c.parseLine(line)
+			if err != nil {
+				return fmt.Errorf("error in environment (%q): %w", line, err)
+			}
+		}
+	}
+	return nil
+}