Set default data, state, config paths via env vars

Resolves https://github.com/unmojang/drasl/issues/119.

May be useful for some containerized deployments.

build_config.go

@@ -12,3 +12,15 @@ const LICENSE_URL = "https://www.gnu.org/licenses/gpl-3.0.en.html"
 const DEFAULT_DATA_DIRECTORY = "/usr/share/drasl"
 const DEFAULT_STATE_DIRECTORY = "/var/lib/drasl"
 const DEFAULT_CONFIG_DIRECTORY = "/etc/drasl"
+
+func GetDefaultDataDirectory() string {
+	return Getenv("DRASL_DEFAULT_DATA_DIRECTORY", DEFAULT_DATA_DIRECTORY)
+}
+
+func GetDefaultStateDirectory() string {
+	return Getenv("DRASL_DEFAULT_STATE_DIRECTORY", DEFAULT_STATE_DIRECTORY)
+}
+
+func GetDefaultConfigDirectory() string {
+	return Getenv("DRASL_DEFAULT_CONFIG_DIRECTORY", DEFAULT_CONFIG_DIRECTORY)
+}

common.go

@@ -65,7 +65,7 @@ var Constants = &ConstantsType{
 	MaxPlayerCountUnlimited:  -1,
 	MaxUsernameLength:        16,
 	MaxPlayerNameLength:      16,
-	ConfigDirectory:          DEFAULT_CONFIG_DIRECTORY,
+	ConfigDirectory:          GetDefaultConfigDirectory(),
 	Version:                  VERSION,
 	License:                  LICENSE,
 	LicenseURL:               LICENSE_URL,

config.go

@@ -116,7 +116,7 @@ func DefaultConfig() Config {
 		ApplicationOwner:         "Anonymous",
 		BaseURL:                  "",
 		BodyLimit:                defaultBodyLimitConfig,
-		DataDirectory:            DEFAULT_DATA_DIRECTORY,
+		DataDirectory:            GetDefaultDataDirectory(),
 		DefaultAdmins:            []string{},
 		DefaultPreferredLanguage: "en",
 		DefaultMaxPlayerCount:    1,
@@ -147,7 +147,7 @@ func DefaultConfig() Config {
 		},
 		SignPublicKeys: true,
 		SkinSizeLimit:  128,
-		StateDirectory: DEFAULT_STATE_DIRECTORY,
+		StateDirectory: GetDefaultStateDirectory(),
 		TestMode:       false,
 		TokenExpireSec: 0,
 		TokenStaleSec:  0,

util.go

@@ -163,3 +163,10 @@ func CopyPath(sourcePath string, destinationPath string) (int64, error) {
 	}
 	return bytesWritten, nil
 }
+
+func Getenv(key string, fallback string) string {
+	if value := os.Getenv(key); value != "" {
+		return value
+	}
+	return fallback
+}