cas: add a GetACI function.

GetACI returns the best ACI that matches the required app name and the provided
labels.
If there are multiple matching ACIs choose the latest one (defined as the
last one imported in the store).
If no version label is requested, ACIs marked as latest in the ACIInfo are
preferred.

cas/cas.go

@@ -30,6 +30,7 @@ import (
 
 	"github.com/coreos/rocket/Godeps/_workspace/src/github.com/appc/spec/aci"
 	"github.com/coreos/rocket/Godeps/_workspace/src/github.com/appc/spec/schema"
+	"github.com/coreos/rocket/Godeps/_workspace/src/github.com/appc/spec/schema/types"
 
 	"github.com/coreos/rocket/Godeps/_workspace/src/github.com/peterbourgon/diskv"
 )
@@ -256,6 +257,76 @@ func (ds Store) GetImageManifest(key string) (*schema.ImageManifest, error) {
 	return im, nil
 }
 
+// Get the best ACI that matches app name and the provided labels. It returns
+// the blob store key of the given ACI.
+// If there are multiple matching ACIs choose the latest one (defined as the
+// last one imported in the store).
+// If no version label is requested, ACIs marked as latest in the ACIInfo are
+// preferred.
+func (ds Store) GetACI(name types.ACName, labels types.Labels) (string, error) {
+	var curaciinfo *ACIInfo
+	versionRequested := false
+	if _, ok := labels.Get("version"); ok {
+		versionRequested = true
+	}
+
+	var aciinfos []*ACIInfo
+	err := ds.db.Do(func(tx *sql.Tx) error {
+		var err error
+		aciinfos, _, err = GetACIInfosWithAppName(tx, name.String())
+		return err
+	})
+	if err != nil {
+		return "", err
+	}
+
+nextKey:
+	for _, aciinfo := range aciinfos {
+		im, err := ds.GetImageManifest(aciinfo.BlobKey)
+		if err != nil {
+			return "", fmt.Errorf("error getting image manifest: %v", err)
+		}
+
+		// The image manifest must have all the requested labels
+		for _, l := range labels {
+			ok := false
+			for _, rl := range im.Labels {
+				if l.Name == rl.Name && l.Value == rl.Value {
+					ok = true
+					break
+				}
+			}
+			if !ok {
+				continue nextKey
+			}
+		}
+
+		if curaciinfo != nil {
+			// If no version is requested prefer the acis marked as latest
+			if !versionRequested {
+				if !curaciinfo.Latest && aciinfo.Latest {
+					curaciinfo = aciinfo
+					continue nextKey
+				}
+				if curaciinfo.Latest && !aciinfo.Latest {
+					continue nextKey
+				}
+			}
+			// If multiple matching image manifests are found, choose the latest imported in the cas.
+			if aciinfo.ImportTime.After(curaciinfo.ImportTime) {
+				curaciinfo = aciinfo
+			}
+		} else {
+			curaciinfo = aciinfo
+		}
+	}
+
+	if curaciinfo != nil {
+		return curaciinfo.BlobKey, nil
+	}
+	return "", fmt.Errorf("aci not found")
+}
+
 func (ds Store) Dump(hex bool) {
 	for _, s := range ds.stores {
 		var keyCount int

cas/cas_test.go

@@ -244,3 +244,149 @@ func TestGetImageManifest(t *testing.T) {
 		t.Fatalf("expected non-nil error!")
 	}
 }
+
+// Test an image with 1 dep. The parent provides a dir not provided by the image.
+func TestGetAci(t *testing.T) {
+	type test struct {
+		name     types.ACName
+		labels   types.Labels
+		expected int // the aci index to expect or -1 if not result expected,
+	}
+
+	type acidef struct {
+		imj    string
+		latest bool
+	}
+
+	dir, err := ioutil.TempDir("", tstprefix)
+	if err != nil {
+		t.Fatalf("error creating tempdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+	ds, err := NewStore(dir)
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+
+	tests := []struct {
+		acidefs []acidef
+		tests   []test
+	}{
+		{
+			[]acidef{
+				{
+					`{
+						"acKind": "ImageManifest",
+						"acVersion": "0.1.1",
+						"name": "example.com/test01"
+					}`,
+					false,
+				},
+				{
+					`{
+						"acKind": "ImageManifest",
+						"acVersion": "0.1.1",
+						"name": "example.com/test02",
+						"labels": [
+							{
+								"name": "version",
+								"value": "1.0.0"
+							}
+						]
+					}`,
+					true,
+				},
+				{
+					`{
+						"acKind": "ImageManifest",
+						"acVersion": "0.1.1",
+						"name": "example.com/test02",
+						"labels": [
+							{
+								"name": "version",
+								"value": "2.0.0"
+							}
+						]
+					}`,
+					false,
+				},
+			},
+			[]test{
+				{
+					"example.com/unexistentaci",
+					types.Labels{},
+					-1,
+				},
+				{
+					"example.com/test01",
+					types.Labels{},
+					0,
+				},
+				{
+					"example.com/test02",
+					types.Labels{
+						{
+							Name:  "version",
+							Value: "1.0.0",
+						},
+					},
+					1,
+				},
+				{
+					"example.com/test02",
+					types.Labels{
+						{
+							Name:  "version",
+							Value: "2.0.0",
+						},
+					},
+					2,
+				},
+				{
+					"example.com/test02",
+					types.Labels{},
+					1,
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		keys := []string{}
+		// Create ACIs
+		for _, ad := range tt.acidefs {
+			aci, err := aci.NewACI(dir, ad.imj, nil)
+			if err != nil {
+				t.Fatalf("error creating test tar: %v", err)
+			}
+
+			// Rewind the ACI
+			if _, err := aci.Seek(0, 0); err != nil {
+				t.Fatalf("unexpected error %v", err)
+			}
+
+			key, err := ds.WriteACI(aci, ad.latest)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			keys = append(keys, key)
+		}
+
+		for _, test := range tt.tests {
+			key, err := ds.GetACI(test.name, test.labels)
+			if test.expected == -1 {
+				if err == nil {
+					t.Fatalf("Expected no key for appName %s, got %s", test.name, key)
+				}
+
+			} else {
+				if err != nil {
+					t.Fatalf("unexpected error on GetACI for name %s, labels: %v: %v", test.name, test.labels, err)
+				}
+				if keys[test.expected] != key {
+					t.Errorf("expected key: %s, got %s. GetACI with name: %s, labels: %v", key, keys[test.expected], test.name, test.labels)
+				}
+			}
+		}
+	}
+}