[Request]: `container build` should support Dockerfile-specific ignores.

[jglogan]

Feature or enhancement request details

When searching for ignore files, container build should follow this order:

• Use the file that has the same pathname as the Dockerfile, with the .dockerignore suffix, if it exists.
• Use the file named .dockerignore in the build context directory, if it exists.

The attached archive runs a set of tests to check conformance. The results for colima vs container are shown in the discussion.

Tests:

• Updated 2026-02-25 to include test that ensures app.Dockerfile.dockerignore gets used for app.Dockerfile instead of Dockerfile.dockerignore in the same directory, and same test when the Dockerfile and ignore files exist outside the context root.

20260205-dockerignore-paths.tgz

Code of Conduct

• I agree to follow this project's Code of Conduct

[jglogan]

Colima result:

% colima start
INFO[0000] starting colima                              
INFO[0000] runtime: docker                              
INFO[0002] starting ...                                  context=vm
INFO[0013] provisioning ...                              context=docker
INFO[0014] starting ...                                  context=docker
INFO[0015] done                                         

% ./test-ignore.sh 
==========================================
Running .dockerignore tests with: docker
==========================================

[TEST] Test 1: Basic .dockerignore
  $ ( cd test1-basic ; docker build -t test-ignore:latest . )
[PASS] included.txt was copied (expected)
[PASS] ignored.txt was NOT copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:6aa4121941473bd66e76654a7d612ca13e6afbc37463913cdf07ce90592f5b21

[TEST] Test 2: Dockerfile-specific ignore (Dockerfile.dockerignore)
  $ ( cd test2-specific ; docker build -t test-ignore:latest . )
[PASS] specific.txt was NOT copied (correctly ignored by Dockerfile.dockerignore)
[PASS] general.txt was copied (only ignored by .dockerignore, not Dockerfile.dockerignore)
Untagged: test-ignore:latest
Deleted: sha256:91e84b0b5514c16b999a728ed004b355201a1db8c3877890fd8ab6361e94cd0b

[TEST] Test 3: Containerfile with .containerignore
  $ ( cd test3-containerfile ; docker build -f Containerfile -t test-ignore:latest . )
[PASS] included.txt was copied (expected)
[FAIL] ignored.txt was copied (unexpected)
Untagged: test-ignore:latest
Deleted: sha256:469ee2a7edb26d8614e6d8af5a422c8fbdb06497db40461ae89086004e37ee84

[TEST] Test 4: Containerfile-specific ignore (Containerfile.containerignore)
  $ ( cd test4-containerfile-specific ; docker build -f Containerfile -t test-ignore:latest . )
[FAIL] specific.txt was copied (should be ignored by Containerfile.containerignore)
[PASS] general.txt was copied (only ignored by .containerignore, not Containerfile.containerignore)
Untagged: test-ignore:latest
Deleted: sha256:bc0d98e2a7c556c868e3d58f5e3c26c285fdcebba1c81fcabdfc3b49529e5c46

[TEST] Test 5: Build succeeds when Dockerfile is ignored
  $ ( cd test5-ignored-dockerfile ; docker build -f Dockerfile -t test-ignore:latest . )
[PASS] Build succeeded even with Dockerfile in .dockerignore
[PASS] test.txt was copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:24a42e1d15314683a08e0ccc23a11ac332f81e71884abc86a5940f4a1c91d21c

[TEST] Test 6: Build from subdirectory context
  $ ( cd test6-subdir ; docker build -f subcontext/Dockerfile -t test-ignore:latest subcontext )
[PASS] included.txt was copied (expected)
[PASS] ignored.txt was NOT copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:c79259a47ea56c1a45a0a07a385f50a4e66813f615707c7b8bdac95912f58883

[TEST] Test 7: No ignore file (all files should be copied)
  $ ( cd test7-no-ignore ; docker build -t test-ignore:latest . )
[PASS] file1.txt was copied (expected)
[PASS] file2.txt was copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:17f87e80a3e5db7b5b3cc1eb30fac9d2d6d0c99e4a14ca2a6bd312f95468097d

[TEST] Test 8: Build with --platform and Dockerfile in subdirectory
  $ ( cd test8-platform-subdir-dockerfile ; docker build --platform linux/amd64 -t test-ignore:latest -f nested/project/Dockerfile . )
[PASS] included.txt was copied (Dockerfile.dockerignore takes precedence over .dockerignore)
[PASS] secret.txt was NOT copied (correctly ignored by Dockerfile.dockerignore)
[PASS] nested/project/config.txt was copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:31943d9c942e43af952b903e88d9d8479c6908053a777ea4fe0456004d74c25a

[TEST] Test 9: Custom-named Dockerfile (app1.Dockerfile)
  $ ( cd test9-custom-dockerfile-name ; docker build -f app1.Dockerfile -t test-ignore:latest . )
[PASS] app1-specific.txt was NOT copied (correctly ignored by app1.Dockerfile.dockerignore)
[PASS] generic.txt was copied (only ignored by .dockerignore, not app1.Dockerfile.dockerignore)
[PASS] included.txt was copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:caade9c81a2b8009d2f7e31d2454896c16b1be44a801438c415420a656bbed4b

[TEST] Test 10: Custom-named Dockerfile in subdirectory
  $ ( cd test10-custom-name-subdir ; docker build -f nested/project/app2.Dockerfile -t test-ignore:latest . )
[PASS] from-app2-ignore.txt was NOT copied (correctly ignored by app2.Dockerfile.dockerignore)
[PASS] from-root-ignore.txt was copied (only ignored by .dockerignore, not app2.Dockerfile.dockerignore)
[PASS] always-included.txt was copied (expected)
[PASS] nested/project/config.yaml was copied (expected)
Untagged: test-ignore:latest
Deleted: sha256:cf8e859c727e49aa128e8bcff5532e74ec4d8e1390438af9754ce193ccbe4429

==========================================
Test Summary
==========================================
Passed: 22
Failed: 2
==========================================

[jglogan]

container result:

% TOOL=container ./test-ignore.sh
==========================================
Running .dockerignore tests with: container
==========================================

[TEST] Test 1: Basic .dockerignore
  $ ( cd test1-basic ; container build -t test-ignore:latest . )
[PASS] included.txt was copied (expected)
[PASS] ignored.txt was NOT copied (expected)

[TEST] Test 2: Dockerfile-specific ignore (Dockerfile.dockerignore)
  $ ( cd test2-specific ; container build -t test-ignore:latest . )
[FAIL] specific.txt was copied (should be ignored by Dockerfile.dockerignore)
[FAIL] general.txt was NOT copied (should be included)

[TEST] Test 3: Containerfile with .containerignore
  $ ( cd test3-containerfile ; container build -f Containerfile -t test-ignore:latest . )
[PASS] included.txt was copied (expected)
[FAIL] ignored.txt was copied (unexpected)

[TEST] Test 4: Containerfile-specific ignore (Containerfile.containerignore)
  $ ( cd test4-containerfile-specific ; container build -f Containerfile -t test-ignore:latest . )
[FAIL] specific.txt was copied (should be ignored by Containerfile.containerignore)
[PASS] general.txt was copied (only ignored by .containerignore, not Containerfile.containerignore)

[TEST] Test 5: Build succeeds when Dockerfile is ignored
  $ ( cd test5-ignored-dockerfile ; container build -f Dockerfile -t test-ignore:latest . )
[PASS] Build succeeded even with Dockerfile in .dockerignore
[PASS] test.txt was copied (expected)

[TEST] Test 6: Build from subdirectory context
  $ ( cd test6-subdir ; container build -f subcontext/Dockerfile -t test-ignore:latest subcontext )
[PASS] included.txt was copied (expected)
[PASS] ignored.txt was NOT copied (expected)

[TEST] Test 7: No ignore file (all files should be copied)
  $ ( cd test7-no-ignore ; container build -t test-ignore:latest . )
[PASS] file1.txt was copied (expected)
[PASS] file2.txt was copied (expected)

[TEST] Test 8: Build with --platform and Dockerfile in subdirectory
  $ ( cd test8-platform-subdir-dockerfile ; container build --platform linux/amd64 -t test-ignore:latest -f nested/project/Dockerfile . )
[FAIL] included.txt was NOT copied (should be included)
[PASS] secret.txt was NOT copied (correctly ignored by Dockerfile.dockerignore)
[FAIL] nested/project/config.txt was NOT copied (unexpected)

[TEST] Test 9: Custom-named Dockerfile (app1.Dockerfile)
  $ ( cd test9-custom-dockerfile-name ; container build -f app1.Dockerfile -t test-ignore:latest . )
[FAIL] app1-specific.txt was copied (should be ignored by app1.Dockerfile.dockerignore)
[FAIL] generic.txt was NOT copied (should be included)
[PASS] included.txt was copied (expected)

[TEST] Test 10: Custom-named Dockerfile in subdirectory
  $ ( cd test10-custom-name-subdir ; container build -f nested/project/app2.Dockerfile -t test-ignore:latest . )
[FAIL] from-app2-ignore.txt was copied (should be ignored by app2.Dockerfile.dockerignore)
[FAIL] from-root-ignore.txt was NOT copied (should be included)
[PASS] always-included.txt was copied (expected)
[PASS] nested/project/config.yaml was copied (expected)

==========================================
Test Summary
==========================================
Passed: 14
Failed: 10
==========================================

[JaewonHur]

Let me do it.

[jglogan]

@JaewonHur apple/container-builder-shim#67 only looks for Dockerfile.dockerignore, which isn't quite correct. I've clarified the rules in the issue description - we need to take the pathname of the Dockerfile, append the .dockerignore suffix, and use that if it exists, otherwise look for .dockerignore in the build context root directory.