allow overriding configuration with environment variables (#98) (#101)

README.md

@@ -71,7 +71,12 @@ docker run --rm -it -v $PWD/rtsp-simple-server.yml:/rtsp-simple-server.yml -p 85
 
 ### Configuration
 
-To see or change the configuration, edit the `rtsp-simple-server.yml` file, provided with the executable. The default configuration is [available here](rtsp-simple-server.yml).
+To see or change the configuration, edit the `rtsp-simple-server.yml` file, provided with the executable, and also [available here](rtsp-simple-server.yml).
+
+The configuration can be overridden with environment variables in the format `RTSP_PARAMNAME`, where `PARAMNAME` is the name of a parameter, in uppercase. For instance, the `rtspPort` parameter can be overridden in the following way:
+```
+RTSP_RTSPPORT=8555 ./rtsp-simple-server
+```
 
 ### RTSP proxy mode
 

conf.go

@@ -12,6 +12,8 @@ import (
 	"github.com/aler9/gortsplib"
 	"github.com/aler9/gortsplib/headers"
 	"gopkg.in/yaml.v2"
+
+	"github.com/aler9/rtsp-simple-server/confenv"
 )
 
 type pathConf struct {
@@ -57,41 +59,46 @@ type conf struct {
 func loadConf(fpath string, stdin io.Reader) (*conf, error) {
 	conf := &conf{}
 
+	// read from file or stdin
 	err := func() error {
 		if fpath == "stdin" {
 			err := yaml.NewDecoder(stdin).Decode(conf)
 			if err != nil {
 				return err
 			}
-
-			return nil
-
-		} else {
-			// rtsp-simple-server.yml is optional
-			if fpath == "rtsp-simple-server.yml" {
-				if _, err := os.Stat(fpath); err != nil {
-					return nil
-				}
-			}
-
-			f, err := os.Open(fpath)
-			if err != nil {
-				return err
-			}
-			defer f.Close()
-
-			err = yaml.NewDecoder(f).Decode(conf)
-			if err != nil {
-				return err
-			}
-
 			return nil
 		}
+
+		// rtsp-simple-server.yml is optional
+		if fpath == "rtsp-simple-server.yml" {
+			if _, err := os.Stat(fpath); err != nil {
+				return nil
+			}
+		}
+
+		f, err := os.Open(fpath)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+
+		err = yaml.NewDecoder(f).Decode(conf)
+		if err != nil {
+			return err
+		}
+
+		return nil
 	}()
 	if err != nil {
 		return nil, err
 	}
 
+	// read from environment
+	err = confenv.Process("RTSP", conf)
+	if err != nil {
+		return nil, err
+	}
+
 	if len(conf.Protocols) == 0 {
 		conf.Protocols = []string{"udp", "tcp"}
 	}

confenv/confenv.go

@@ -0,0 +1,124 @@
+package confenv
+
+import (
+	"fmt"
+	"os"
+	"reflect"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func process(env map[string]string, envKey string, rv reflect.Value) error {
+	rt := rv.Type()
+
+	switch rt {
+	case reflect.TypeOf(time.Duration(0)):
+		if ev, ok := env[envKey]; ok {
+			d, err := time.ParseDuration(ev)
+			if err != nil {
+				return fmt.Errorf("%s: %s", envKey, err)
+			}
+			rv.Set(reflect.ValueOf(d))
+		}
+		return nil
+	}
+
+	switch rt.Kind() {
+	case reflect.String:
+		if ev, ok := env[envKey]; ok {
+			rv.SetString(ev)
+		}
+		return nil
+
+	case reflect.Int:
+		if ev, ok := env[envKey]; ok {
+			iv, err := strconv.ParseInt(ev, 10, 64)
+			if err != nil {
+				return fmt.Errorf("%s: %s", envKey, err)
+			}
+			rv.SetInt(iv)
+		}
+		return nil
+
+	case reflect.Bool:
+		if ev, ok := env[envKey]; ok {
+			switch strings.ToLower(ev) {
+			case "yes", "true":
+				rv.SetBool(true)
+
+			case "no", "false":
+				rv.SetBool(false)
+
+			default:
+				return fmt.Errorf("%s: invalid value '%s'", envKey, ev)
+			}
+		}
+		return nil
+
+	case reflect.Slice:
+		if rt.Elem().Kind() == reflect.String {
+			if ev, ok := env[envKey]; ok {
+				nv := reflect.Zero(rt)
+				for _, sv := range strings.Split(ev, ",") {
+					nv = reflect.Append(nv, reflect.ValueOf(sv))
+				}
+				rv.Set(nv)
+			}
+			return nil
+		}
+
+	case reflect.Map:
+		for k := range env {
+			if !strings.HasPrefix(k, envKey) {
+				continue
+			}
+
+			tmp := strings.Split(strings.TrimPrefix(k[len(envKey):], "_"), "_")
+			mapKey := strings.ToLower(tmp[0])
+
+			nv := rv.MapIndex(reflect.ValueOf(mapKey))
+			zero := reflect.Value{}
+			if nv == zero {
+				nv = reflect.New(rt.Elem().Elem())
+				rv.SetMapIndex(reflect.ValueOf(mapKey), nv)
+			}
+
+			err := process(env, envKey+"_"+strings.ToUpper(mapKey), nv.Elem())
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+
+	case reflect.Struct:
+		flen := rt.NumField()
+		for i := 0; i < flen; i++ {
+			fieldName := rt.Field(i).Name
+
+			// process only public fields
+			if fieldName[0] < 'A' || fieldName[0] > 'Z' {
+				continue
+			}
+
+			fieldEnvKey := envKey + "_" + strings.ToUpper(fieldName)
+			err := process(env, fieldEnvKey, rv.Field(i))
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	return fmt.Errorf("unsupported type: %v", rt)
+}
+
+func Process(envKey string, v interface{}) error {
+	env := make(map[string]string)
+	for _, kv := range os.Environ() {
+		tmp := strings.Split(kv, "=")
+		env[tmp[0]] = tmp[1]
+	}
+
+	return process(env, envKey, reflect.ValueOf(v).Elem())
+}

main_test.go

@@ -3,12 +3,14 @@ package main
 import (
 	"bytes"
 	"net"
+	"net/url"
 	"os"
 	"os/exec"
 	"strconv"
 	"testing"
 	"time"
 
+	"github.com/aler9/gortsplib"
 	"github.com/stretchr/testify/require"
 )
 
@@ -97,6 +99,70 @@ func (c *container) ip() string {
 	return string(out[:len(out)-1])
 }
 
+func TestEnvironment(t *testing.T) {
+	// string
+	os.Setenv("RTSP_RUNONCONNECT", "testcmd")
+	defer os.Unsetenv("RTSP_RUNONCONNECT")
+
+	// int
+	os.Setenv("RTSP_RTSPPORT", "8555")
+	defer os.Unsetenv("RTSP_RTSPPORT")
+
+	// bool
+	os.Setenv("RTSP_METRICS", "yes")
+	defer os.Unsetenv("RTSP_METRICS")
+
+	// duration
+	os.Setenv("RTSP_READTIMEOUT", "22s")
+	defer os.Unsetenv("RTSP_READTIMEOUT")
+
+	// slice
+	os.Setenv("RTSP_LOGDESTINATIONS", "stdout,file")
+	defer os.Unsetenv("RTSP_LOGDESTINATIONS")
+
+	// map key
+	os.Setenv("RTSP_PATHS_TEST2", "")
+	defer os.Unsetenv("RTSP_PATHS_TEST2")
+
+	// map value
+	os.Setenv("RTSP_PATHS_TEST_SOURCE", "rtsp://testing")
+	defer os.Unsetenv("RTSP_PATHS_TEST_SOURCE")
+	os.Setenv("RTSP_PATHS_TEST_SOURCEPROTOCOL", "tcp")
+	defer os.Unsetenv("RTSP_PATHS_TEST_SOURCEPROTOCOL")
+
+	p, err := newProgram([]string{}, bytes.NewBuffer(nil))
+	require.NoError(t, err)
+	defer p.close()
+
+	require.Equal(t, "testcmd", p.conf.RunOnConnect)
+
+	require.Equal(t, 8555, p.conf.RtspPort)
+
+	require.Equal(t, true, p.conf.Metrics)
+
+	require.Equal(t, 22*time.Second, p.conf.ReadTimeout)
+
+	require.Equal(t, []string{"stdout", "file"}, p.conf.LogDestinations)
+
+	pa, ok := p.conf.Paths["test2"]
+	require.Equal(t, true, ok)
+	require.Equal(t, &pathConf{
+		Source: "record",
+	}, pa)
+
+	pa, ok = p.conf.Paths["test"]
+	require.Equal(t, true, ok)
+	require.Equal(t, &pathConf{
+		Source: "rtsp://testing",
+		sourceUrl: func() *url.URL {
+			u, _ := url.Parse("rtsp://testing:554")
+			return u
+		}(),
+		SourceProtocol:       "tcp",
+		sourceProtocolParsed: gortsplib.StreamProtocolTCP,
+	}, pa)
+}
+
 func TestPublish(t *testing.T) {
 	for _, conf := range []struct {
 		publishSoft  string