Manage builds with different combinations of extensions

Files were added to be built whether an extension is on or off.
New build tags were added for each extension, while minimal and extended disappeared.

added custom binary naming depending on extensions used and changed references from binary to binary-extended

added automated blackbox tests for sync, search, scrub, metrics

added contributor guidelines

Signed-off-by: Alex Stan <alexandrustan96@yahoo.ro>

pkg/extensions/sync/sync_disabled_test.go

@@ -0,0 +1,71 @@
+//go:build !sync
+// +build !sync
+
+package sync_test
+
+import (
+	"context"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+	"gopkg.in/resty.v1"
+	"zotregistry.io/zot/pkg/api"
+	"zotregistry.io/zot/pkg/api/config"
+	extconf "zotregistry.io/zot/pkg/extensions/config"
+	"zotregistry.io/zot/pkg/extensions/sync"
+	"zotregistry.io/zot/pkg/test"
+)
+
+func TestSyncExtension(t *testing.T) {
+	Convey("Make a new controller", t, func() {
+		conf := config.New()
+		port := test.GetFreePort()
+
+		baseURL := test.GetBaseURL(port)
+		globalDir := t.TempDir()
+		defaultValue := true
+
+		logFile, err := ioutil.TempFile(globalDir, "zot-log*.txt")
+		So(err, ShouldBeNil)
+		defer os.Remove(logFile.Name())
+
+		conf.HTTP.Port = port
+		conf.Storage.RootDirectory = globalDir
+		conf.Storage.Commit = true
+		conf.Extensions = &extconf.ExtensionConfig{}
+		conf.Extensions.Sync = &sync.Config{
+			Enable: &defaultValue,
+		}
+		conf.Log.Level = "warn"
+		conf.Log.Output = logFile.Name()
+
+		ctlr := api.NewController(conf)
+
+		go func() {
+			if err := ctlr.Run(context.Background()); err != nil {
+				return
+			}
+		}()
+
+		defer func() {
+			_ = ctlr.Server.Shutdown(context.Background())
+		}()
+		test.WaitTillServerReady(baseURL)
+
+		Convey("verify sync is skipped when binary doesn't include it", func() {
+			resp, err := resty.R().
+				Head(baseURL + "/v2/" + "invalid" + "/manifests/invalid:0.0.2")
+			So(err, ShouldBeNil)
+			So(resp, ShouldNotBeNil)
+
+			data, err := os.ReadFile(logFile.Name())
+			So(err, ShouldBeNil)
+
+			So(string(data), ShouldContainSubstring,
+				"skipping syncing on demand because given zot binary doesn't include "+
+					"this feature,please build a binary that does so")
+		})
+	})
+}

pkg/extensions/sync/sync_test.go

@@ -1,5 +1,5 @@
-//go:build extended
-// +build extended
+//go:build sync
+// +build sync
 
 package sync_test