add support for setting credentials via environment variables

Author: christian-korneck

README.md

@@ -115,6 +115,26 @@ export APIKEY__QUAY_IO=my-api-key
 docker pushrm quay.io/my-user/my-repo
 ```
 
+## Log in with environment variables (for CI)
+
+Alternatively credentials can be set as environment variables. Environment variables take precedence over the Docker credentials store. Environment variables can be specified with or without a server name. The variant without a server name takes precedence.
+
+This is intended for running `docker-pushrm` as a standalone tool in a CI environment (no full Docker installation needed).
+
+- `DOCKER_USER` and `DOCKER_PASS`
+- `DOCKER_USER__<SERVER>_<DOMAIN>` and `DOCKER_PASS__<SERVER>_<DOMAIN>`
+	(example for server `docker.io`: `DOCKER_USER__DOCKER_IO=my-user` and `DOCKER_PASS__DOCKER_IO=my-password`)
+
+The provider 'quay' needs an additional env var for the API key in form of `APIKEY__<SERVERNAME>_<DOMAIN>=<apikey>`.
+
+Example:
+
+```
+DOCKER_USER=my-user DOCKER_PASS=mypass docker-pushrm my-user/my-repo
+```
+
+
+
 #### configure Quay API key in Docker config file
 
 In the Docker config file (default: `$HOME/.docker/config.json`) add a json key `plugins.docker-pushrm.apikey_<servername>` with the api key as string value.
@@ -144,7 +164,7 @@ You can still use `docker-pushrm` as standalone executable.
 
 The only obstacle is that you need to provide it credentials in the Docker style.
 
-The easiest way for that is to set up a minimal Docker config file with the registry server logins that you need.
+The easiest way for that is to set up a minimal Docker config file with the registry server logins that you need. (Alternatively credentials can be passed [in environment variables](#log-in-with-environment-variables-for-ci) )
 
 You can either create this config file on a computer with Docker installed (by running `docker login` and then copying the `$HOME/.docker/config.json` file).
 

cmd/docker-cli-plugin-metadata.go

@@ -40,7 +40,7 @@ var dockerCliPluginMetadataCmd = &cobra.Command{
 		enc := json.NewEncoder(os.Stdout)
 		enc.SetIndent("", "    ")
 		// specs: https://docs.docker.com/engine/extend/cli_plugins/#the-docker-cli-plugin-metadata-subcommand
-		d := map[string]string{"SchemaVersion": "0.1.0", "Vendor": "Christian Korneck", "Version": "1.0.3", "ShortDescription": "Push Readme to container registry"}
+		d := map[string]string{"SchemaVersion": "0.1.0", "Vendor": "Christian Korneck", "Version": "1.1.0", "ShortDescription": "Push Readme to container registry"}
 		enc.Encode(d)
 	},
 }

cmd/pushrm.go

@@ -86,7 +86,23 @@ var pushrmCmd = &cobra.Command{
 	For some providers an API key needs to be specified
 	via env var or Docker config file.
 
+	Alternatively credentials can be set as environment
+	variables. Environment variables take precedence over
+	the Docker credentials store.
 
+	Environment variables can be specified with or without
+	a server name. The variant without a server name takes
+	precedence:
+
+	 - DOCKER_USER and DOCKER_PASS
+	 - DOCKER_USER__<SERVER>_<DOMAIN> and DOCKER_PASS__<SERVER>_<DOMAIN>
+	   (example for server 'docker.io': DOCKER_USER__DOCKER_IO=my-user
+	   and DOCKER_PASS__DOCKER_IO=my-password)
+
+	The provider 'quay' needs an additional env var for the API key
+	in form of APIKEY__<SERVERNAME>_<DOMAIN>=<apikey>.
+
+	
 	Dockerhub
 	---------
 	run 'docker login'
@@ -233,12 +249,29 @@ var pushrmCmd = &cobra.Command{
 		}
 
 		var dockerUser string
-		dockerUser = os.Getenv("DOCKER_USERNAME")
 		var dockerPasswd string
-		dockerPasswd = os.Getenv("DOCKER_PASSWORD")
 		var err error
 
+		// generic env var (no servername specified) takes precedence
+		dockerUser = os.Getenv("DOCKER_USER")
+		dockerPasswd = os.Getenv("DOCKER_PASS")
+		if dockerUser != "" && dockerPasswd != "" {
+			log.Debug("using credentials for user " + dockerUser + " from generic env var")
+		}
+
+		// env var with servername is next
+		if dockerUser == "" || dockerPasswd == "" {
+			suffix := strings.ToUpper(strings.Replace(servername, ".", "_", -1))
+			dockerUser = os.Getenv("DOCKER_USER__" + suffix)
+			dockerPasswd = os.Getenv("DOCKER_PASS__" + suffix)
+			if dockerUser != "" && dockerPasswd != "" {
+				log.Debug("using credentials for user " + dockerUser + " from env var for suffix " + suffix)
+			}
+		}
+
+		// if credentials are not found in env vars, look in the Docker credentials store
 		if dockerUser == "" || dockerPasswd == "" {
+			log.Debug("no credentials found in env vars. Trying Docker credentials store")
 			log.Debug("Using config file: ", viper.ConfigFileUsed())
 
 			if viper.ConfigFileUsed() == "" {