feat(bundle): add loader pkg from duffle

bundle/loader/loader.go

@@ -0,0 +1,81 @@
+package loader
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+
+	"github.com/deislabs/cnab-go/bundle"
+)
+
+// BundleLoader provides an interface for loading a bundle
+type BundleLoader interface {
+	// Load a bundle from a local file
+	Load(source string) (*bundle.Bundle, error)
+	// Load a bundle from raw data
+	LoadData(data []byte) (*bundle.Bundle, error)
+}
+
+// Loader loads a bundle manifest (bundle.json)
+type Loader struct{}
+
+// New creates a loader for bundle files.
+//TODO: remove if unnecessary
+func New() BundleLoader {
+	return &Loader{}
+}
+
+func NewLoader() *Loader {
+	return &Loader{}
+}
+
+// Load loads the given bundle.
+func (l *Loader) Load(filename string) (*bundle.Bundle, error) {
+	b := &bundle.Bundle{}
+	data, err := loadData(filename)
+	if err != nil {
+		return b, err
+	}
+	return l.LoadData(data)
+}
+
+// LoadData loads a Bundle from the given data.
+//
+// This loads a JSON bundle file into a *bundle.Bundle.
+func (l *Loader) LoadData(data []byte) (*bundle.Bundle, error) {
+	return bundle.Unmarshal(data)
+}
+
+// loadData is a utility method that loads a file either off of the FS (if it exists) or via a remote HTTP GET.
+//
+// If bundleFile exists on disk, this will return that file. Otherwise, it will attempt to parse the
+// file name as a URL and request it as an HTTP GET request.
+func loadData(bundleFile string) ([]byte, error) {
+	if isLocalReference(bundleFile) {
+		return ioutil.ReadFile(bundleFile)
+	}
+
+	if u, err := url.ParseRequestURI(bundleFile); err != nil {
+		// The error emitted by ParseRequestURI is icky.
+		return []byte{}, fmt.Errorf("bundle %q not found", bundleFile)
+	} else if u.Scheme == "file" {
+		// What do we do if someone passes a `file:///` URL in? Is `file` inferred
+		// if no protocol is specified?
+		return []byte{}, fmt.Errorf("bundle %q not found", bundleFile)
+	}
+
+	response, err := http.Get(bundleFile)
+	if err != nil {
+		return []byte{}, fmt.Errorf("cannot download bundle file: %v", err)
+	}
+	defer response.Body.Close()
+
+	return ioutil.ReadAll(response.Body)
+}
+
+func isLocalReference(file string) bool {
+	_, err := os.Stat(file)
+	return err == nil
+}

bundle/loader/loader_test.go

@@ -0,0 +1,50 @@
+package loader
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var testFooJSON = filepath.Join("..", "testdata", "minimal.json")
+
+func TestLoader(t *testing.T) {
+	is := assert.New(t)
+
+	l := NewLoader()
+	bundle, err := l.Load(testFooJSON)
+	if err != nil {
+		t.Fatalf("cannot load bundle: %v", err)
+	}
+
+	is.Equal("mybun", bundle.Name)
+	is.Equal("v1.0.0", bundle.Version)
+}
+func TestLoader_Remote(t *testing.T) {
+
+	data, err := ioutil.ReadFile(testFooJSON)
+	if err != nil {
+		t.Fatalf("cannot read bundle file: %v", err)
+	}
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		io.Copy(w, bytes.NewBuffer(data))
+	}))
+	defer ts.Close()
+
+	l := NewLoader()
+	bundle, err := l.Load(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	is := assert.New(t)
+
+	is.Equal("mybun", bundle.Name)
+	is.Equal("v1.0.0", bundle.Version)
+}