src: update CLI help for env flag

Update CLI help for env flag. Now mentioning unsetting of variable.

Signed-off-by: Matej Vasek <mvasek@redhat.com>

cmd/deploy.go

@@ -25,7 +25,9 @@ import (
 func init() {
 	root.AddCommand(deployCmd)
 	deployCmd.Flags().BoolP("confirm", "c", false, "Prompt to confirm all configuration options (Env: $FUNC_CONFIRM)")
-	deployCmd.Flags().StringArrayP("env", "e", []string{}, "Environment variable to set in the form NAME=VALUE. You may provide this flag multiple times for setting multiple environment variables.")
+	deployCmd.Flags().StringArrayP("env", "e", []string{}, "Environment variable to set in the form NAME=VALUE. " +
+		"You may provide this flag multiple times for setting multiple environment variables. " +
+		"To unset, specify the environment variable name followed by a \"-\" (e.g., NAME-).")
 	deployCmd.Flags().StringP("image", "i", "", "Full image name in the form [registry]/[namespace]/[name]:[tag] (optional). This option takes precedence over --registry (Env: $FUNC_IMAGE")
 	deployCmd.Flags().StringP("namespace", "n", "", "Namespace of the function to undeploy. By default, the namespace in func.yaml is used or the actual active namespace if not set in the configuration. (Env: $FUNC_NAMESPACE)")
 	deployCmd.Flags().StringP("path", "p", cwd(), "Path to the project directory (Env: $FUNC_PATH)")

cmd/run.go

@@ -13,7 +13,9 @@ import (
 func init() {
 	// Add the run command as a subcommand of root.
 	root.AddCommand(runCmd)
-	runCmd.Flags().StringArrayP("env", "e", []string{}, "Environment variable to set in the form NAME=VALUE. You may provide this flag multiple times for setting multiple environment variables.")
+	runCmd.Flags().StringArrayP("env", "e", []string{}, "Environment variable to set in the form NAME=VALUE. " +
+		"You may provide this flag multiple times for setting multiple environment variables. " +
+		"To unset, specify the environment variable name followed by a \"-\" (e.g., NAME-).")
 	runCmd.Flags().StringP("path", "p", cwd(), "Path to the project directory (Env: $FUNC_PATH)")
 }
 

docs/guides/commands.md

@@ -38,7 +38,7 @@ kn func build [-i <image> -r <registry> -p <path>]
 
 ## `run`
 
-Runs the Function project locally in the container. If a container has not yet been created, prompts the user to run `func build`.  The user may specify a path to the project directory using the `--path` or `-p` flag.
+Runs the Function project locally in the container. If a container has not yet been created, prompts the user to run `func build`.  The user may specify a path to the project directory using the `--path` or `-p` flag. The user may set an environment variable by using `--env` or `-e` flag, e.g. `-e VAR_NAME=VAR_VALUE`. To unset a variable dash `-` suffix is used, e.g. `-e VAR_NAME-`.
 
 Similar `kn` command: none.
 
@@ -54,7 +54,7 @@ kn func run [-p <path>]
 
 ## `deploy`
 
-Deploys the Function project in the current directory. The user may specify a path to the project directory using the `--path` or `-p` flag. Reads the `func.yaml` configuration file to determine the image name. An image and registry may be specified on the command line using the  `--image` or `-i` and `--registry` or `-r` flag.
+Deploys the Function project in the current directory. The user may specify a path to the project directory using the `--path` or `-p` flag. Reads the `func.yaml` configuration file to determine the image name. An image and registry may be specified on the command line using the  `--image` or `-i` and `--registry` or `-r` flag. The user may set an environment variable by using `--env` or `-e` flag, e.g. `-e VAR_NAME=VAR_VALUE`. To unset a variable dash `-` suffix is used, e.g. `-e VAR_NAME-`.
 
 Derives the service name from the project name. There is no mechanism by which the user can specify the service name. The user must have already initialized the  function using `func create` or they will encounter an error.
 

docs/guides/func_yaml.md

@@ -33,12 +33,13 @@ it's typically unnecessary to modify the `builder` field, using values from
 The `env` field allows you to set environment variables that will be
 available to your function at runtime. For example, to set a `MODE` environment
 variable to `debug` when the function is deployed, your `func.yaml` file
-may look like this.
+may look like this. To unset variables use a dash suffix. For example, to unset `MODE`, use `MODE-`.
 
 ```yaml
 env:
   MODE: debug
   API_KEY: {{ env.API_KEY }}
+  VAR_TO_UNSET-: ""
 ```
 
 ### `image`