Hide porter internal from explain command

Some outputs and parameters are really porter "plumbing". They are used
by porter to implement things, like state or persistent parameters, but
aren't intended to be set or used by the end-user.

When we print out how to use a bundle with porter explain, those
shoudn't be displayed.

* Parameters with sources - these will be set by Porter internally.
* Outputs and Parameters that support bundle state.

Signed-off-by: Carolyn Van Slyck <me@carolynvanslyck.com>

pkg/cnab/extended_bundle.go

@@ -37,17 +37,28 @@ func (b ExtendedBundle) IsPorterBundle() bool {
 	return madeByPorter
 }
 
-// IsInternalParameter determines if the provided param is an internal parameter
-// to Porter after analyzing the provided bundle
-func (b ExtendedBundle) IsInternalParameter(param string) bool {
-	if param, exists := b.Parameters[param]; exists {
+// IsInternalParameter determines if the provided parameter is internal
+// to Porter after analyzing the provided bundle.
+func (b ExtendedBundle) IsInternalParameter(name string) bool {
+	if param, exists := b.Parameters[name]; exists {
 		if def, exists := b.Definitions[param.Definition]; exists {
 			return def.Comment == PorterInternal
 		}
 	}
 	return false
 }
 
+// IsInternalOutput determines if the provided output is internal
+// to Porter after analyzing the provided bundle.
+func (b ExtendedBundle) IsInternalOutput(name string) bool {
+	if output, exists := b.Outputs[name]; exists {
+		if def, exists := b.Definitions[output.Definition]; exists {
+			return def.Comment == PorterInternal
+		}
+	}
+	return false
+}
+
 // GetParameterType determines the type of parameter accounting for
 // Porter-specific parameter types like file.
 func (b ExtendedBundle) GetParameterType(def *definition.Schema) string {

pkg/cnab/parameter_sources.go

@@ -223,3 +223,14 @@ func (b ExtendedBundle) HasParameterSources() bool {
 	_, ok := b.Custom[ParameterSourcesExtensionKey]
 	return ok
 }
+
+// ParameterHasSource determines if the specified parameter has a parameter
+// source defined.
+func (b ExtendedBundle) ParameterHasSource(paramName string) bool {
+	sources, err := b.ReadParameterSources()
+	if err != nil {
+		return false
+	}
+	_, hasSource := sources[paramName]
+	return hasSource
+}

pkg/porter/explain.go

@@ -228,9 +228,10 @@ func generatePrintable(bun cnab.ExtendedBundle, action string) (*PrintableBundle
 	sort.Sort(SortPrintableCredential(pb.Credentials))
 
 	for p, v := range bun.Parameters {
-		if bun.IsInternalParameter(p) {
+		if bun.IsInternalParameter(p) || bun.ParameterHasSource(p) {
 			continue
 		}
+
 		def, ok := bun.Definitions[v.Definition]
 		if !ok {
 			return nil, fmt.Errorf("unable to find definition %s", v.Definition)
@@ -253,6 +254,10 @@ func generatePrintable(bun cnab.ExtendedBundle, action string) (*PrintableBundle
 	sort.Sort(SortPrintableParameter(pb.Parameters))
 
 	for o, v := range bun.Outputs {
+		if bun.IsInternalOutput(o) {
+			continue
+		}
+
 		def, ok := bun.Definitions[v.Definition]
 		if !ok {
 			return nil, fmt.Errorf("unable to find definition %s", v.Definition)
@@ -330,7 +335,7 @@ func (p *Porter) printCredentialsExplainBlock(bun *PrintableBundle) error {
 	if len(bun.Credentials) == 0 {
 		return nil
 	}
-	
+
 	fmt.Fprintln(p.Out, "Credentials:")
 	err := p.printCredentialsExplainTable(bun)
 	if err != nil {