feat(api): Loader.List

Introduces `Loader.List(path, opts)` which returns all environments that could
possibly be found at path.

This can be used to prompt the user for the correct inline environment,
while the actual Load does not need to be concerned with this

Author: sh0rez

pkg/tanka/inline.go

@@ -18,17 +18,7 @@ import (
 type InlineLoader struct{}
 
 func (i *InlineLoader) Load(path string, opts JsonnetOpts) (*v1alpha1.Environment, error) {
-	raw, err := EvalJsonnet(path, opts)
-	if err != nil {
-		return nil, err
-	}
-
-	var data interface{}
-	if err := json.Unmarshal([]byte(raw), &data); err != nil {
-		return nil, err
-	}
-
-	envs, err := extractEnvs(data)
+	envs, err := inlineEval(path, opts)
 	if err != nil {
 		return nil, err
 	}
@@ -45,38 +35,91 @@ func (i *InlineLoader) Load(path string, opts JsonnetOpts) (*v1alpha1.Environmen
 		return nil, fmt.Errorf("Found no environments in '%s'", path)
 	}
 
-	root, err := jpath.FindRoot(path)
+	// TODO: Re-serializing the entire env here. This is horribly inefficient
+	envData, err := json.Marshal(envs[0])
 	if err != nil {
 		return nil, err
 	}
 
-	file, err := jpath.Entrypoint(path)
+	env, err := inlineParse(path, envData)
 	if err != nil {
 		return nil, err
 	}
 
-	namespace, err := filepath.Rel(root, file)
+	return env, nil
+}
+
+func (i *InlineLoader) Peek(path string, opts JsonnetOpts) (*v1alpha1.Environment, error) {
+	opts.EvalScript = EnvsOnlyEvalScript
+	return i.Load(path, opts)
+}
+
+func (i *InlineLoader) List(path string, opts JsonnetOpts) ([]*v1alpha1.Environment, error) {
+	opts.EvalScript = EnvsOnlyEvalScript
+	list, err := inlineEval(path, opts)
 	if err != nil {
 		return nil, err
 	}
 
-	// TODO: Re-serializing the entire env here. This is horribly inefficient
-	envData, err := json.Marshal(envs[0])
+	envs := make([]*v1alpha1.Environment, 0, len(list))
+	for _, raw := range list {
+		data, err := json.Marshal(raw)
+		if err != nil {
+			return nil, err
+		}
+
+		env, err := inlineParse(path, data)
+		if err != nil {
+			return nil, err
+		}
+
+		envs = append(envs, env)
+	}
+
+	return envs, nil
+}
+
+func inlineEval(path string, opts JsonnetOpts) (manifest.List, error) {
+	raw, err := EvalJsonnet(path, opts)
 	if err != nil {
 		return nil, err
 	}
 
-	env, err := spec.Parse(envData, namespace)
+	var data interface{}
+	if err := json.Unmarshal([]byte(raw), &data); err != nil {
+		return nil, err
+	}
+
+	envs, err := extractEnvs(data)
 	if err != nil {
 		return nil, err
 	}
 
-	return env, nil
+	return envs, nil
 }
 
-func (i *InlineLoader) Peek(path string, opts JsonnetOpts) (*v1alpha1.Environment, error) {
-	opts.EvalScript = EnvsOnlyEvalScript
-	return i.Load(path, opts)
+func inlineParse(path string, data []byte) (*v1alpha1.Environment, error) {
+	root, err := jpath.FindRoot(path)
+	if err != nil {
+		return nil, err
+	}
+
+	file, err := jpath.Entrypoint(path)
+	if err != nil {
+		return nil, err
+	}
+
+	namespace, err := filepath.Rel(root, file)
+	if err != nil {
+		return nil, err
+	}
+
+	env, err := spec.Parse(data, namespace)
+	if err != nil {
+		return nil, err
+	}
+
+	return env, nil
 }
 
 // extractEnvs filters out any Environment manifests

pkg/tanka/load.go

@@ -68,6 +68,18 @@ func Peek(path string, opts JsonnetOpts) (*v1alpha1.Environment, error) {
 	return loader.Peek(path, opts)
 }
 
+// List finds metadata of all environments at path that could possibly be
+// loaded. List can be used to deal with multiple inline environments, by first
+// listing them, choosing the right one and then only loading that one
+func List(path string, opts JsonnetOpts) ([]*v1alpha1.Environment, error) {
+	loader, err := DetectLoader(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return loader.List(path, opts)
+}
+
 // DetectLoader detects whether the environment is inline or static and picks
 // the approriate loader
 func DetectLoader(path string) (Loader, error) {
@@ -89,11 +101,15 @@ func DetectLoader(path string) (Loader, error) {
 
 // Loader is an abstraction over the process of loading Environments
 type Loader interface {
-	// Load the environment with path
+	// Load a single environment at path
 	Load(path string, opts JsonnetOpts) (*v1alpha1.Environment, error)
 
 	// Peek only loads metadata and omits the actual resources
 	Peek(path string, opts JsonnetOpts) (*v1alpha1.Environment, error)
+
+	// List returns metadata of all possible environments at path that can be
+	// loaded
+	List(path string, opts JsonnetOpts) ([]*v1alpha1.Environment, error)
 }
 
 type LoadResult struct {

pkg/tanka/static.go

@@ -13,7 +13,7 @@ import (
 type StaticLoader struct{}
 
 func (s StaticLoader) Load(path string, opts JsonnetOpts) (*v1alpha1.Environment, error) {
-	config, err := Peek(path, opts)
+	config, err := s.Peek(path, opts)
 	if err != nil {
 		return nil, err
 	}
@@ -39,6 +39,15 @@ func (s StaticLoader) Peek(path string, opts JsonnetOpts) (*v1alpha1.Environment
 	return config, nil
 }
 
+func (s StaticLoader) List(path string, opts JsonnetOpts) ([]*v1alpha1.Environment, error) {
+	env, err := s.Peek(path, opts)
+	if err != nil {
+		return nil, err
+	}
+
+	return []*v1alpha1.Environment{env}, nil
+}
+
 // parseStaticSpec parses the `spec.json` of the environment and returns a
 // *kubernetes.Kubernetes from it
 func parseStaticSpec(path string) (*v1alpha1.Environment, error) {