Allow setting some config from environment

README.md

@@ -97,6 +97,7 @@ Configuration is divided into different sections: `server`, `auth`, `ssh`, and `
 - `port` : int. Port to listen on.
 - `user` : string. User to which the server drops privileges to.
 - `cookie_secret`: string. Authentication key for the session cookie.
+- `csrf_secret`: string. Authentication key for CSRF protection.
 - `http_logfile`: string. Path to the HTTP request log. Logs are written in the [Common Log Format](https://en.wikipedia.org/wiki/Common_Log_Format). If not set logs are written to stderr.
 - `datastore`: string. Datastore connection string. See [Datastore](#datastore).
 

cmd/cashierd/main.go

@@ -334,7 +334,8 @@ func main() {
 		}
 	}
 
-	l, err := net.Listen("tcp", fmt.Sprintf("%s:%d", config.Server.Addr, config.Server.Port))
+	laddr := fmt.Sprintf("%s:%d", config.Server.Addr, config.Server.Port)
+	l, err := net.Listen("tcp", laddr)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -399,7 +400,7 @@ func main() {
 	r.PathPrefix("/").Handler(http.FileServer(static.FS(false)))
 	h := handlers.LoggingHandler(logfile, r)
 
-	log.Print("Starting server...")
+	log.Printf("Starting server on %s", laddr)
 	s := &http.Server{
 		Handler: h,
 	}

server/config/config.go

@@ -3,6 +3,8 @@ package config
 import (
 	"errors"
 	"io"
+	"os"
+	"strconv"
 
 	"github.com/hashicorp/go-multierror"
 	"github.com/spf13/viper"
@@ -82,6 +84,28 @@ func verifyConfig(u *unmarshalled) error {
 	return err
 }
 
+func setFromEnv(u *unmarshalled) {
+	port, err := strconv.Atoi(os.Getenv("PORT"))
+	if err == nil {
+		u.Server[0].Port = port
+	}
+	if os.Getenv("DATASTORE") != "" {
+		u.Server[0].Datastore = os.Getenv("DATASTORE")
+	}
+	if os.Getenv("OAUTH_CLIENT_ID") != "" {
+		u.Auth[0].OauthClientID = os.Getenv("OAUTH_CLIENT_ID")
+	}
+	if os.Getenv("OAUTH_CLIENT_SECRET") != "" {
+		u.Auth[0].OauthClientSecret = os.Getenv("OAUTH_CLIENT_SECRET")
+	}
+	if os.Getenv("CSRF_SECRET") != "" {
+		u.Server[0].CSRFSecret = os.Getenv("CSRF_SECRET")
+	}
+	if os.Getenv("COOKIE_SECRET") != "" {
+		u.Server[0].CookieSecret = os.Getenv("COOKIE_SECRET")
+	}
+}
+
 // ReadConfig parses a JSON configuration file into a Config struct.
 func ReadConfig(r io.Reader) (*Config, error) {
 	u := &unmarshalled{}
@@ -93,6 +117,7 @@ func ReadConfig(r io.Reader) (*Config, error) {
 	if err := v.Unmarshal(u); err != nil {
 		return nil, err
 	}
+	setFromEnv(u)
 	if err := verifyConfig(u); err != nil {
 		return nil, err
 	}