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

[jglogan]

Feature or enhancement request details

container build should first look for an ignore file that has the same pathname as the Dockerfile, with the .dockerignore suffix. If that isn't found, then the .dockerfile in the build context directory is used, 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

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.