Allow to load env file (#80)

closes https://codeberg.org/woodpecker-plugins/docker-buildx/issues/34

Reviewed-on: https://codeberg.org/woodpecker-plugins/docker-buildx/pulls/80
Reviewed-by: anbraten <anbraten@noreply.codeberg.org>
Co-authored-by: qwerty287 <ndev@web.de>
Co-committed-by: qwerty287 <ndev@web.de>

cmd/docker-buildx/main.go

@@ -20,6 +20,10 @@ func main() {
 		godotenv.Overload("/run/drone/env")
 	}
 	
+	if envFile, set := os.LookupEnv("PLUGIN_ENV_FILE"); set {
+		godotenv.Overload(envFile)
+	}
+
 	app := &cli.App{
 		Name:    "docker-buildx",
 		Usage:   "build docker container with DinD and buildx",

docs.md

@@ -122,6 +122,7 @@ If it's not a tag event, and no default branch, automated tags are skipped.
 | `add_host`                | *none*            | sets additional host:ip mapping
 | `output`                  | *none*            | sets build output in format `type=<type>[,<key>=<value>]`
 | `logins`                  | *none*            | option to log into multiple registries
+| `env_file`                | *none*            | load env vars from specified file
 
 ## Multi registry push example