Improve func build/deploy UX: validate registry before prompting (#3058)

* validate first about the registry required error for both build and deploy and also refactor the logic when ran outside the function directory using 2 layer approach

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

* fixed the linting errors

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

* refactor the logic based on the suggestion to prompt for a registry first

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

* fix the failing test and the linter errors

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

* refactor the logic based on the suggestion and move typed errors in a different file for better code readability and also add the platformrestriction error i lost while rebasing

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

* fix the linting errors

---------

Signed-off-by: RayyanSeliya <rayyanseliya786@gmail.com>

Author: RayyanSeliya

cmd/build.go

@@ -159,6 +159,18 @@ func runBuild(cmd *cobra.Command, _ []string, newClient ClientFactory) (err erro
 		f   fn.Function
 	)
 	if cfg, err = newBuildConfig().Prompt(); err != nil { // gather values into a single instruction set
+		// Layer 2: Catch technical errors and provide CLI-specific user-friendly messages
+
+		// Check if it's a "not initialized" error (no function found)
+		var errNotInit *fn.ErrNotInitialized
+		if errors.As(err, &errNotInit) {
+			return wrapNotInitializedError(err, "build")
+		}
+
+		// Check if it's a registry required error (function exists but no registry)
+		if errors.Is(err, fn.ErrRegistryRequired) {
+			return wrapRegistryRequiredError(err, "build")
+		}
 		return
 	}
 	if err = cfg.Validate(cmd); err != nil { // Perform any pre-validation
@@ -326,10 +338,6 @@ func (c buildConfig) Configure(f fn.Function) fn.Function {
 // Skipped if not in an interactive terminal (non-TTY), or if --confirm false (agree to
 // all prompts) was set (default).
 func (c buildConfig) Prompt() (buildConfig, error) {
-	if !interactiveTerminal() {
-		return c, nil
-	}
-
 	// If there is no registry nor explicit image name defined, the
 	// Registry prompt is shown whether or not we are in confirm mode.
 	// Otherwise, it is only showin if in confirm mode
@@ -341,7 +349,19 @@ func (c buildConfig) Prompt() (buildConfig, error) {
 	if err != nil {
 		return c, err
 	}
-	if (f.Registry == "" && c.Registry == "" && c.Image == "") || c.Confirm {
+
+	// Check if function exists first
+	if !f.Initialized() {
+		// Return a specific error for uninitialized function
+		return c, fn.NewErrNotInitialized(f.Root)
+	}
+
+	if !interactiveTerminal() {
+		return c, nil
+	}
+
+	// If function IS initialized AND registry/image is missing
+	if f.Registry == "" && c.Registry == "" && c.Image == "" {
 		fmt.Println("A registry for function images is required. For example, 'docker.io/tigerteam'.")
 		err := survey.AskOne(
 			&survey.Input{Message: "Registry for function images:", Default: c.Registry},
@@ -353,11 +373,11 @@ func (c buildConfig) Prompt() (buildConfig, error) {
 		fmt.Println("Note: building a function the first time will take longer than subsequent builds")
 	}
 
-	// Remainder of prompts are optional and only shown if in --confirm mode
 	if !c.Confirm {
 		return c, nil
 	}
 
+	// Remainder of prompts are optional and only shown if in --confirm mode
 	// Image Name Override
 	// Calculate a better image name message which shows the value of the final
 	// image name as it will be calculated if an explicit image name is not used.

cmd/deploy.go

@@ -254,19 +254,13 @@ func runDeploy(cmd *cobra.Command, newClient ClientFactory) (err error) {
 	if !f.Initialized() {
 		if !cfg.Remote || f.Build.Git.URL == "" {
 			// Only error if this is not a fully remote build
-			return fmt.Errorf(`no function found in current directory.
-You need to be inside a function directory to deploy it.
-
-Try this:
-  func create --language go myfunction    Create a new function
-  cd myfunction                          Go into the function directory
-  func deploy --registry <registry>      Deploy to the cloud
-
-Or if you have an existing function:
-  cd path/to/your/function              Go to your function directory
-  func deploy --registry <registry>     Deploy the function
-
-For more detailed deployment options, run 'func deploy --help'`)
+			// Layer 2: Wrap technical error with CLI-specific guidance
+			var errNotInit *fn.ErrNotInitialized
+			notInitErr := fn.NewErrNotInitialized(f.Root)
+			if errors.As(notInitErr, &errNotInit) {
+				return wrapNotInitializedError(notInitErr, "deploy")
+			}
+			return notInitErr
 		} else {
 			// TODO: this case is not supported because the pipeline
 			// implementation requires the function's name, which is in the
@@ -278,6 +272,10 @@ For more detailed deployment options, run 'func deploy --help'`)
 
 	// Now that we know function exists, proceed with prompting
 	if cfg, err = cfg.Prompt(); err != nil {
+		// Layer 2: Catch technical errors and provide CLI-specific user-friendly messages
+		if errors.Is(err, fn.ErrRegistryRequired) {
+			return wrapRegistryRequiredError(err, "deploy")
+		}
 		return
 	}
 	if err = cfg.Validate(cmd); err != nil {

cmd/errors.go

@@ -0,0 +1,98 @@
+package cmd
+
+import (
+	"fmt"
+)
+
+// wrapNotInitializedError wraps an ErrNotInitialized error with CLI-specific guidance
+func wrapNotInitializedError(err error, command string) error {
+	switch command {
+	case "build":
+		return fmt.Errorf(`%w
+
+No function found in provided path (current directory or via --path).
+You need to be in a function directory (or use --path).
+
+Try this:
+  func create --language go myfunction    Create a new function
+  cd myfunction                          Go into the function directory
+  func build --registry <registry>       Build the function container
+
+Or navigate to an existing function:
+  cd path/to/your/function
+  func build --registry <registry>
+
+Or use --path flag:
+  func build --path /path/to/function --registry <registry>
+
+For more options, run 'func build --help'`, err)
+
+	case "deploy":
+		return fmt.Errorf(`%w
+
+No function found in provided path (current directory or via --path).
+You need to be in a function directory (or use --path).
+
+Try this:
+  func create --language go myfunction    Create a new function
+  cd myfunction                          Go into the function directory
+  func deploy --registry <registry>      Deploy to the cloud
+
+Or navigate to an existing function:
+  cd path/to/your/function
+  func deploy --registry <registry>
+
+Or use --path to deploy from anywhere:
+  func deploy --path /path/to/function --registry <registry>
+
+For more options, run 'func deploy --help'`, err)
+
+	default:
+		return err
+	}
+}
+
+// wrapRegistryRequiredError wraps an ErrRegistryRequired error with CLI-specific guidance
+func wrapRegistryRequiredError(err error, command string) error {
+	switch command {
+	case "build":
+		return fmt.Errorf(`%w
+
+Try this:
+  func build --registry ghcr.io/myuser    Build with registry
+
+Or set the FUNC_REGISTRY environment variable:
+  export FUNC_REGISTRY=ghcr.io/myuser
+  func build
+
+Common registries:
+  ghcr.io/myuser       GitHub Container Registry
+  docker.io/myuser     Docker Hub
+  quay.io/myuser       Quay.io
+
+Or specify full image name:
+  func build --image ghcr.io/myuser/myfunction:latest
+
+For more options, run 'func build --help'`, err)
+
+	case "deploy":
+		return fmt.Errorf(`%w
+
+Try this:
+  func deploy --registry ghcr.io/myuser
+
+Or set the FUNC_REGISTRY environment variable:
+  export FUNC_REGISTRY=ghcr.io/myuser
+  func deploy
+
+Common registries:
+  ghcr.io/myuser       GitHub Container Registry
+  docker.io/myuser     Docker Hub
+  quay.io/myuser       Quay.io
+
+For more options, run 'func deploy --help'`, err)
+
+	default:
+		return err
+	}
+}

pkg/functions/errors.go

@@ -27,7 +27,7 @@ var (
 	// TODO: change the wording of this error to not be CLI-specific;
 	// eg "registry required".  Then catch the error in the CLI and add the
 	// cli-specific usage hints there
-	ErrRegistryRequired = errors.New("registry required to build function, please set with `--registry` or the FUNC_REGISTRY environment variable")
+	ErrRegistryRequired = errors.New("registry required")
 
 	// ErrPlatformNotSupported is returned when a platform is specified for a builder that doesn't support it
 	ErrPlatformNotSupported = errors.New("platform not supported by builder")