config: make config more flexible

Can now be passed as a `CONFIG` environment variable in a YAML format.

Author: daniel-abramov

docker-compose.yaml

@@ -6,7 +6,8 @@ services:
     network_mode: host
     restart: always
     environment:
-      USER_ID: "@sfu:shadowfax"
-      HOMESERVER_URL: "http://localhost:8008"
-      ACCESS_TOKEN: "..."
-      TIMEOUT: 30
+      CONFIG: |
+        homeserverurl: "http://localhost:8008"
+        userid: "@sfu:shadowfax"
+        accesstoken: "..."
+        timeout: 30

src/call.go

@@ -513,7 +513,7 @@ func (c *Call) SendDataChannelMessage(msg event.SFUMessage) {
 }
 
 func (c *Call) CheckKeepAliveTimestamp() {
-	timeout := time.Second * time.Duration(config.Timeout)
+	timeout := time.Second * time.Duration(config.KeepAliveTimeout)
 	for range time.Tick(timeout) {
 		if c.lastKeepAliveTimestamp.Add(timeout).Before(time.Now()) {
 			if c.PeerConnection.ConnectionState() != webrtc.PeerConnectionStateClosed {

src/config.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/sirupsen/logrus"
+	"gopkg.in/yaml.v3"
+	"maunium.net/go/mautrix/id"
+)
+
+// The mandatory SFU configuration.
+type Config struct {
+	// The Matrix ID (MXID) of the SFU.
+	UserID id.UserID
+	// The ULR of the homeserver that SFU talks to.
+	HomeserverURL string
+	// The access token for the Matrix SDK.
+	AccessToken string
+	// Keep-alive timeout for WebRTC connections. If no keep-alive has been received
+	// from the client for this duration, the connection is considered dead.
+	KeepAliveTimeout int
+}
+
+// Load config from the provided string.
+// Returns an error if the string is not a valid YAML.
+func loadConfigFromString(configString string) (*Config, error) {
+	logrus.Info("loading config from string")
+
+	var config Config
+	if err := yaml.Unmarshal([]byte(configString), &config); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal YAML file: %w", err)
+	}
+
+	return &config, nil
+}
+
+// ErrNoConfigEnvVar is returned when the CONFIG environment variable is not set.
+var ErrNoConfigEnvVar = errors.New("environment variable not set or invalid")
+
+// Tries to load the config from environment variables.
+// Returns an error if not all environment variables are set.
+func loadConfigFromEnv() (*Config, error) {
+	configEnv := os.Getenv("CONFIG")
+	if configEnv == "" {
+		return nil, ErrNoConfigEnvVar
+	}
+
+	return loadConfigFromString(configEnv)
+}
+
+// Tries to load a config from the provided path.
+func loadConfigFromPath(path string) (*Config, error) {
+	logrus.WithField("path", path).Info("loading config")
+
+	file, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read file: %w", err)
+	}
+
+	return loadConfigFromString(string(file))
+}

src/main.go

@@ -17,29 +17,16 @@ limitations under the License.
 package main
 
 import (
-	"errors"
 	"flag"
-	"fmt"
 	"os"
 	"os/signal"
 	"runtime"
 	"runtime/pprof"
-	"strconv"
-	"strings"
 	"syscall"
 
 	"github.com/sirupsen/logrus"
-	yaml "gopkg.in/yaml.v3"
-	"maunium.net/go/mautrix/id"
 )
 
-type Config struct {
-	UserID        id.UserID
-	HomeserverURL string
-	AccessToken   string
-	Timeout       int
-}
-
 var config *Config
 
 var logTime = flag.Bool("logTime", false, "whether or not to print time and date in logs")
@@ -97,64 +84,6 @@ func initLogging(logTime *bool) {
 	logrus.SetFormatter(formatter)
 }
 
-var ErrEnvVarNotSet = errors.New("environment variable not set or invalid")
-
-func EnvVarNotSetError(variable string) error {
-	return fmt.Errorf("%s: %w", variable, ErrEnvVarNotSet)
-}
-
-// / Tries to load the config from environment variables.
-// / Returns an error if not all environment variables are set.
-func loadConfigFromEnv() (*Config, error) {
-	userID := strings.TrimSpace(os.Getenv("USER_ID"))
-	if userID == "" {
-		return nil, EnvVarNotSetError("USER_ID")
-	}
-
-	homeserverURL := strings.TrimSpace(os.Getenv("HOMESERVER_URL"))
-	if homeserverURL == "" {
-		return nil, EnvVarNotSetError("HOMESERVER_URL")
-	}
-
-	accessToken := strings.TrimSpace(os.Getenv("ACCESS_TOKEN"))
-	if accessToken == "" {
-		return nil, EnvVarNotSetError("ACCESS_TOKEN")
-	}
-
-	timeoutStr := strings.TrimSpace(os.Getenv("TIMEOUT"))
-	if timeoutStr == "" {
-		return nil, EnvVarNotSetError("TIMEOUT")
-	}
-
-	timeout, err := strconv.Atoi(timeoutStr)
-	if err != nil {
-		return nil, EnvVarNotSetError("TIMEOUT Format")
-	}
-
-	return &Config{
-		UserID:        id.UserID(userID),
-		HomeserverURL: homeserverURL,
-		AccessToken:   accessToken,
-		Timeout:       timeout,
-	}, nil
-}
-
-func loadConfig(configFilePath string) (*Config, error) {
-	logrus.WithField("path", configFilePath).Info("loading config")
-
-	file, err := os.ReadFile(configFilePath)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read file: %w", err)
-	}
-	var config Config
-
-	if err := yaml.Unmarshal(file, &config); err != nil {
-		return nil, fmt.Errorf("failed to unmarshal YAML file: %w", err)
-	}
-
-	return &config, nil
-}
-
 func killListener(c chan os.Signal, beforeExit []func()) {
 	<-c
 
@@ -192,7 +121,7 @@ func main() {
 	if err != nil {
 		logrus.WithError(err).Info("failed to load config from environment variables, trying to load from file")
 
-		if config, err = loadConfig(*configFilePath); err != nil {
+		if config, err = loadConfigFromPath(*configFilePath); err != nil {
 			logrus.WithError(err).Fatal("failed to load config file")
 		}
 	}