Add optional configuration file

README.md

@@ -28,7 +28,12 @@ you can build from source:
 2. Build with `go build -o mautrix-syncproxy`. The resulting executable will be
    in the current directory named `mautrix-syncproxy`.
 
-Configuring is done via environment variables.
+Configuring is done via .yaml configuration file or via environment variables.
+
+If using a configuration file, see the included example-config.yaml, and pass
+`-config CONFIGURATION_FILENAME.yaml` on the command line.
+
+If using environment variables (convenient for running syncproxy in docker):
 
 * `LISTEN_ADDRESS` - The address where to listen.
 * `HOMESERVER_URL` - The address to Synapse. If using workers, it is sufficient

example-config.yaml

@@ -0,0 +1,6 @@
+listen_address: localhost:29332
+database_url:   postgres://user:pass@host/mautrixsyncproxy
+homeserver_url: http://localhost:8008
+shared_secret:  random string here
+debug:          true
+

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/jackc/pgx/v4 v4.13.0
 	github.com/mattn/go-sqlite3 v1.14.8
 	github.com/prometheus/client_golang v1.11.0
+	gopkg.in/yaml.v2 v2.4.0
 	maunium.net/go/maulogger/v2 v2.3.0
 	maunium.net/go/mautrix v0.9.22
 )

go.sum

@@ -328,6 +328,8 @@ gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.5/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.0.1-2019.2.3/go.mod h1:a3bituU0lyd329TUQxRnasdCoJDkEUEAqEt0JzvZhAg=

main.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"context"
+	"flag"
 	"net/http"
 	"os"
 	"os/signal"
@@ -27,6 +28,7 @@ import (
 
 	"github.com/gorilla/mux"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"gopkg.in/yaml.v2"
 	log "maunium.net/go/maulogger/v2"
 )
 
@@ -56,26 +58,48 @@ func getIntEnv(key string, defVal int) int {
 	return val
 }
 
+var configPath = flag.String("config", "config.yaml", "path to config file")
+
 func readConfig() {
-	cfg.ListenAddress = os.Getenv("LISTEN_ADDRESS")
-	cfg.DatabaseURL = os.Getenv("DATABASE_URL")
-	cfg.DatabaseOpts.MaxOpenConns = getIntEnv("DATABASE_MAX_OPEN_CONNS", 4)
-	cfg.DatabaseOpts.MaxIdleConns = getIntEnv("DATABASE_MAX_IDLE_CONNS", 2)
-	cfg.HomeserverURL = os.Getenv("HOMESERVER_URL")
-	cfg.SharedSecret = os.Getenv("SHARED_SECRET")
-	cfg.ExpectSynchronous = len(os.Getenv("EXPECT_SYNCHRONOUS")) > 0
-	cfg.Debug = len(os.Getenv("DEBUG")) > 0
-
-	if len(cfg.ListenAddress) == 0 {
-		log.Fatalln("LISTEN_ADDRESS environment variable is not set")
-	} else if len(cfg.DatabaseURL) == 0 {
-		log.Fatalln("DATABASE_URL environment variable is not set")
-	} else if len(cfg.HomeserverURL) == 0 {
-		log.Fatalln("HOMESERVER_URL environment variable is not set")
-	} else if len(cfg.SharedSecret) == 0 {
-		log.Fatalln("SHARED_SECRET environment variable is not set")
+	flag.Parse()
+	if *configPath == "env" {
+		cfg.ListenAddress = os.Getenv("LISTEN_ADDRESS")
+		cfg.DatabaseURL = os.Getenv("DATABASE_URL")
+		cfg.DatabaseOpts.MaxOpenConns = getIntEnv("DATABASE_MAX_OPEN_CONNS", 4)
+		cfg.DatabaseOpts.MaxIdleConns = getIntEnv("DATABASE_MAX_IDLE_CONNS", 2)
+		cfg.HomeserverURL = os.Getenv("HOMESERVER_URL")
+		cfg.SharedSecret = os.Getenv("SHARED_SECRET")
+		cfg.ExpectSynchronous = len(os.Getenv("EXPECT_SYNCHRONOUS")) > 0
+		cfg.Debug = len(os.Getenv("DEBUG")) > 0
+
+		if len(cfg.ListenAddress) == 0 {
+			log.Fatalln("LISTEN_ADDRESS environment variable is not set")
+		} else if len(cfg.DatabaseURL) == 0 {
+			log.Fatalln("DATABASE_URL environment variable is not set")
+		} else if len(cfg.HomeserverURL) == 0 {
+			log.Fatalln("HOMESERVER_URL environment variable is not set")
+		} else if len(cfg.SharedSecret) == 0 {
+			log.Fatalln("SHARED_SECRET environment variable is not set")
+		} else {
+			return
+		}
 	} else {
-		return
+		file, err := os.Open(*configPath)
+		if err != nil {
+			log.Fatalln("Failed to open config:", err)
+		}
+		err = yaml.NewDecoder(file).Decode(&cfg)
+		if err != nil {
+			log.Fatalln("Failed to read config:", err)
+		} else if len(cfg.DatabaseURL) == 0 {
+			log.Fatalln("DATABASE_URL environment variable is not set")
+		} else if len(cfg.HomeserverURL) == 0 {
+			log.Fatalln("HOMESERVER_URL environment variable is not set")
+		} else if len(cfg.SharedSecret) == 0 {
+			log.Fatalln("SHARED_SECRET environment variable is not set")
+		} else {
+			return
+		}
 	}
 
 	os.Exit(2)