cli: add 'tilt dump image-deploy-ref', for determining the deploy tag…

… of an image (#3607)

helps with more complex custom_build commands as described in #3584

internal/build/docker_builder.go

@@ -37,6 +37,7 @@ type dockerImageBuilder struct {
 
 type DockerBuilder interface {
 	BuildImage(ctx context.Context, ps *PipelineState, refs container.RefSet, db model.DockerBuild, filter model.PathMatcher) (container.TaggedRefs, error)
+	DumpImageDeployRef(ctx context.Context, ref string) (reference.NamedTagged, error)
 	PushImage(ctx context.Context, name reference.NamedTagged) error
 	TagRefs(ctx context.Context, refs container.RefSet, dig digest.Digest) (container.TaggedRefs, error)
 	ImageExists(ctx context.Context, ref reference.NamedTagged) (bool, error)
@@ -68,6 +69,31 @@ func (d *dockerImageBuilder) BuildImage(ctx context.Context, ps *PipelineState,
 	return d.buildFromDf(ctx, ps, db, paths, filter, refs)
 }
 
+func (d *dockerImageBuilder) DumpImageDeployRef(ctx context.Context, ref string) (reference.NamedTagged, error) {
+	refParsed, err := container.ParseNamed(ref)
+	if err != nil {
+		return nil, errors.Wrap(err, "DumpImageDeployRef")
+	}
+
+	data, _, err := d.dCli.ImageInspectWithRaw(ctx, ref)
+	if err != nil {
+		return nil, errors.Wrap(err, "DumpImageDeployRef")
+	}
+	dig := digest.Digest(data.ID)
+
+	tag, err := digestAsTag(dig)
+	if err != nil {
+		return nil, errors.Wrap(err, "DumpImageDeployRef")
+	}
+
+	tagged, err := reference.WithTag(refParsed, tag)
+	if err != nil {
+		return nil, errors.Wrap(err, "DumpImageDeployRef")
+	}
+
+	return tagged, nil
+}
+
 // Tag the digest with the given name and wm-tilt tag.
 func (d *dockerImageBuilder) TagRefs(ctx context.Context, refs container.RefSet, dig digest.Digest) (container.TaggedRefs, error) {
 	tag, err := digestAsTag(dig)

internal/build/docker_builder_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/docker/docker/api/types"
 	"github.com/opencontainers/go-digest"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/tilt-dev/tilt/internal/container"
@@ -93,6 +94,17 @@ func TestDigestFromOutputV1_23(t *testing.T) {
 	}
 }
 
+func TestDumpImageDeployRef(t *testing.T) {
+	f := newFakeDockerBuildFixture(t)
+	defer f.teardown()
+
+	digest := digest.Digest("sha256:11cd0eb38bc3ceb958ffb2f9bd70be3fb317ce7d255c8a4c3f4af30e298aa1aab")
+	f.fakeDocker.Images["example-image:dev"] = types.ImageInspect{ID: string(digest)}
+	ref, err := f.b.DumpImageDeployRef(f.ctx, "example-image:dev")
+	require.NoError(t, err)
+	assert.Equal(t, "docker.io/library/example-image:tilt-11cd0eb38bc3ceb9", ref.String())
+}
+
 func makeDockerBuildErrorOutput(s string) string {
 	b := &bytes.Buffer{}
 	err := json.NewEncoder(b).Encode(s)

internal/cli/dump.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -10,6 +11,9 @@ import (
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/cobra/doc"
+
+	"github.com/tilt-dev/tilt/internal/container"
+	"github.com/tilt-dev/tilt/pkg/model"
 )
 
 func newDumpCmd(rootCmd *cobra.Command) *cobra.Command {
@@ -30,6 +34,7 @@ and may change frequently.
 	result.AddCommand(newDumpEngineCmd())
 	result.AddCommand(newDumpLogStoreCmd())
 	result.AddCommand(newDumpCliDocsCmd(rootCmd))
+	result.AddCommand(newDumpImageDeployRefCmd())
 
 	return result
 }
@@ -134,6 +139,54 @@ func (c *dumpCliDocsCmd) run(cmd *cobra.Command, args []string) {
 	}
 }
 
+func newDumpImageDeployRefCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "image-deploy-ref REF",
+		Short: "Determine the name and tag with which Tilt will deploy the given image",
+		Long: `Determine the name and tag with which Tilt will deploy the given image.
+
+This command is intended to be used with custom_build scripts.
+
+Once the custom_build script has built the image at $EXPECTED_REF, it can
+invoke:
+
+echo $(tilt dump image-deploy-ref $EXPECTED_REF)
+
+to print the deploy ref of the image. Tilt will read the image contents,
+determine its hash, and create a content-based tag.
+
+More info on custom build scripts: https://docs.tilt.dev/custom_build.html
+`,
+		Example: "tilt dump image-deploy-ref $EXPECTED_REF",
+		Run:     dumpImageDeployRef,
+		Args:    cobra.ExactArgs(1),
+	}
+}
+
+func dumpImageDeployRef(cmd *cobra.Command, args []string) {
+	ctx, cleanup := preCommand(context.Background())
+	defer func() {
+		_ = cleanup()
+	}()
+
+	deps, err := wireDumpImageDeployRefDeps(ctx)
+	if err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "Initialization error: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Assume that people with complex custom_build commands are using
+	// the kubernetes orchestrator.
+	deps.DockerClient.SetOrchestrator(model.OrchestratorK8s)
+	ref, err := deps.DockerBuilder.DumpImageDeployRef(ctx, args[0])
+	if err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "%v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Printf("%s", container.FamiliarString(ref))
+}
+
 func dumpWebview(cmd *cobra.Command, args []string) {
 	body := apiGet("view")
 

internal/cli/wire.go

@@ -260,3 +260,14 @@ func ProvideDownDeps(
 func provideClock() func() time.Time {
 	return time.Now
 }
+
+type DumpImageDeployRefDeps struct {
+	DockerBuilder build.DockerBuilder
+	DockerClient  docker.Client
+}
+
+func wireDumpImageDeployRefDeps(ctx context.Context) (DumpImageDeployRefDeps, error) {
+	wire.Build(BaseWireSet,
+		wire.Struct(new(DumpImageDeployRefDeps), "*"))
+	return DumpImageDeployRefDeps{}, nil
+}