fix: Skip platform-specific digest resolution with --pull-policy never (#2498)

* fix: Skip platform-specific digest resolution with --pull-policy never

When using --pull-policy never, pack now skips the platform-specific
digest resolution that requires network access to fetch the manifest list.
Instead, it uses the image name directly from the daemon.

This fix addresses issue #2496 where builds fail when using --pull-policy
never because pack cannot resolve the platform-specific digest of the
lifecycle image without network access.

The trade-off is that users may encounter containerd storage issues if
Docker is configured to use containerd storage. In such cases, users
should manually pull the platform-specific digest or use a different
pull policy.

Related to PR #2467 which introduced platform-specific digest resolution
to fix containerd storage issues.

Fixes #2496

Signed-off-by: Juan Bustamante <[email protected]>

* test: Use daemon OS instead of runtime OS in PullNever test

This fixes test failures on Windows runners running Linux containers.
The test was using runtime.GOOS which returns 'windows' on Windows hosts,
but the Docker daemon may be running Linux containers. Now we use the
daemon's actual OS type queried via docker.Info().

Signed-off-by: Juan Bustamante <[email protected]>

---------

Signed-off-by: Juan Bustamante <[email protected]>

Author: jjbustamante

pkg/image/fetcher.go

@@ -257,6 +257,17 @@ func (f *Fetcher) FetchForPlatform(ctx context.Context, name string, options Fet
 		return nil, err
 	}
 
+	platformStr := options.Target.ValuesAsPlatform()
+
+	// When PullPolicy is PullNever, skip platform-specific digest resolution as it requires
+	// network access to fetch the manifest list. Instead, use the image as-is from the daemon.
+	// Note: This may cause issues with containerd storage. Users should pre-pull the platform-specific
+	// digest if they encounter errors.
+	if options.Daemon && options.PullPolicy == PullNever {
+		f.logger.Debugf("Using lifecycle %s with platform %s (skipping digest resolution due to --pull-policy never)", name, platformStr)
+		return f.Fetch(ctx, name, options)
+	}
+
 	// Build platform and registry settings from options
 	platform := imgutil.Platform{
 		OS:           options.Target.OS,
@@ -275,7 +286,6 @@ func (f *Fetcher) FetchForPlatform(ctx context.Context, name string, options Fet
 	}
 
 	// Log the resolution for visibility
-	platformStr := options.Target.ValuesAsPlatform()
 	f.logger.Debugf("Using lifecycle %s; pulling digest %s for platform %s", name, resolvedName, platformStr)
 
 	return f.Fetch(ctx, resolvedName, options)

pkg/image/fetcher_test.go

@@ -732,6 +732,49 @@ func testFetcher(t *testing.T, when spec.G, it spec.S) {
 				h.AssertError(t, err, "")
 			})
 		})
+
+		when("pull policy is PullNever with daemon", func() {
+			var localImageName string
+
+			it.Before(func() {
+				// Use a different name for the local image to avoid conflicts
+				localImageName = "pack.local/test-" + h.RandString(10)
+
+				// Create a local daemon image with platform information
+				// Use osType (daemon OS) instead of runtime.GOOS to handle cases where
+				// Windows runner is running Linux containers
+				img, err := local.NewImage(localImageName, docker, local.WithDefaultPlatform(imgutil.Platform{
+					OS:           osType,
+					Architecture: runtime.GOARCH,
+				}))
+				h.AssertNil(t, err)
+				h.AssertNil(t, img.Save())
+			})
+
+			it.After(func() {
+				h.DockerRmi(docker, localImageName)
+			})
+
+			it("skips platform-specific digest resolution and uses tag directly", func() {
+				target := dist.Target{
+					OS:   osType,
+					Arch: runtime.GOARCH,
+				}
+
+				fetchedImg, err := imageFetcher.FetchForPlatform(context.TODO(), localImageName, image.FetchOptions{
+					Daemon:     true,
+					PullPolicy: image.PullNever,
+					Target:     &target,
+				})
+
+				// Should succeed without network access (digest resolution skipped)
+				h.AssertNil(t, err)
+				h.AssertNotNil(t, fetchedImg)
+
+				// Verify debug message about skipping digest resolution
+				h.AssertContains(t, outBuf.String(), "skipping digest resolution due to --pull-policy never")
+			})
+		})
 	})
 
 	when("#CheckReadAccess", func() {