Use image index not just image (#2284)

* Always try daemon push first

Daemon push is now tried always first withouth using
net.DefaultResolver.LookupHost() to guess if the registry is reachable
from the daemon. If the daemon returns error contaning "no such host"
then use manual push with custom transport.

Signed-off-by: Matej Vašek <[email protected]>

* Rework image pusher tests

Merged daemon push and non-daemon tests to one table driven test.

Signed-off-by: Matej Vašek <[email protected]>

* Use image index not just image

This results in "multi-arch" image with single architecture this may
seems weird but it helps multi-arch clusters to run pods on approprieate
nodes.

Signed-off-by: Matej Vašek <[email protected]>

* fixup: style

Signed-off-by: Matej Vašek <[email protected]>

---------

Signed-off-by: Matej Vašek <[email protected]>

pkg/docker/pusher.go

@@ -8,10 +8,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"net"
 	"net/http"
 	"os"
 	"regexp"
+	"strings"
 
 	fn "knative.dev/func/pkg/functions"
 
@@ -23,7 +23,11 @@ import (
 	"github.com/google/go-containerregistry/pkg/name"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/daemon"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
+	types2 "github.com/google/go-containerregistry/pkg/v1/types"
 	"golang.org/x/term"
 )
 
@@ -107,8 +111,72 @@ func GetRegistry(img string) (string, error) {
 	return registry, nil
 }
 
-// Push the image of the function.
-func (n *Pusher) Push(ctx context.Context, f fn.Function) (digest string, err error) {
+// Push the image index of the function.
+func (n *Pusher) Push(ctx context.Context, f fn.Function) (string, error) {
+	credentials, err := n.credentialsProvider(ctx, f.Build.Image)
+	if err != nil {
+		return "", fmt.Errorf("failed to get credentials: %w", err)
+	}
+
+	imgDigest, err := n.pushImage(ctx, f, credentials)
+	if err != nil {
+		return "", fmt.Errorf("cannot push image: %w", err)
+	}
+
+	auth := &authn.Basic{
+		Username: credentials.Username,
+		Password: credentials.Password,
+	}
+
+	remoteOpts := []remote.Option{
+		remote.WithAuth(auth),
+		remote.WithTransport(n.transport),
+	}
+
+	imgRef, err := name.ParseReference(f.ImageNameWithDigest(imgDigest))
+	if err != nil {
+		return "", fmt.Errorf("cannot parse image ref: %w", err)
+	}
+	img, err := remote.Image(imgRef, remoteOpts...)
+	if err != nil {
+		return "", fmt.Errorf("cannot get the image: %w", err)
+	}
+
+	cf, err := img.ConfigFile()
+	if err != nil {
+		return "", fmt.Errorf("cannot get config file for the image: %w", err)
+	}
+
+	newDesc, err := partial.Descriptor(img)
+	if err != nil {
+		return "", fmt.Errorf("cannot get partial descriptor for the image: %w", err)
+	}
+	newDesc.Platform = cf.Platform()
+
+	base := mutate.IndexMediaType(empty.Index, types2.DockerManifestList)
+	idx := mutate.AppendManifests(base, mutate.IndexAddendum{
+		Add:        img,
+		Descriptor: *newDesc,
+	})
+
+	idxRef, err := name.ParseReference(f.Build.Image)
+	if err != nil {
+		return "", fmt.Errorf("cannot parse image index ref: %w", err)
+	}
+	err = remote.WriteIndex(idxRef, idx, remoteOpts...)
+	if err != nil {
+		return "", fmt.Errorf("cannot write image index: %w", err)
+	}
+
+	d, err := idx.Digest()
+	if err != nil {
+		return "", fmt.Errorf("cannot obtain image index digest: %w", err)
+	}
+
+	return d.String(), nil
+}
+
+func (n *Pusher) pushImage(ctx context.Context, f fn.Function, credentials Credentials) (digest string, err error) {
 
 	var output io.Writer
 
@@ -127,19 +195,17 @@ func (n *Pusher) Push(ctx context.Context, f fn.Function) (digest string, err er
 		return "", err
 	}
 
-	credentials, err := n.credentialsProvider(ctx, f.Build.Image)
-	if err != nil {
-		return "", fmt.Errorf("failed to get credentials: %w", err)
-	}
 	fmt.Fprintf(os.Stderr, "Pushing function image to the registry %q using the %q user credentials\n", registry, credentials.Username)
 
-	// if the registry is not cluster private do push directly from daemon
-	if _, err = net.DefaultResolver.LookupHost(ctx, registry); err == nil {
-		return n.daemonPush(ctx, f, credentials, output)
+	digest, err = n.daemonPush(ctx, f, credentials, output)
+	if err == nil {
+		return digest, nil
 	}
-
-	// push with custom transport to be able to push into cluster private registries
-	return n.push(ctx, f, credentials, output)
+	if strings.Contains(err.Error(), "no such host") {
+		// push with custom transport to be able to push into cluster private registries
+		return n.push(ctx, f, credentials, output)
+	}
+	return "", err
 }
 
 func (n *Pusher) daemonPush(ctx context.Context, f fn.Function, credentials Credentials, output io.Writer) (digest string, err error) {