Describe the bug

According to Docker's official documentation, if a file named {Dockerfile-path}.dockerignore exists, it should be used as the .dockerignore file, overriding the default .dockerignore in the root of the context.

However, the az acr build command fails to load this Dockerfile-specific ignore file under the following conditions:

• The Dockerfile is named Dockerfile (e.g., Dockerfile and Dockerfile.dockerignore).
• The Dockerfile is located in a subdirectory (e.g., /dir/dev.Dockerfile and /dir/dev.Dockerfile.dockerignore).

Consequently, files that should be excluded are incorrectly included in the build context uploaded to Azure Container Registry.

Related command

az acr build

Errors

1. Create the following files:

$ ls .
Dockerfile              Dockerfile.dockerignore a.txt                   b.txt

$ cat Dockerfile
FROM debian

WORKDIR /app
COPY . /app

CMD ["ls", "."]

$ cat Dockerfile.dockerignore
a.txt

2. Run a standard docker build (Correct Behavior)

The docker build command correctly uses Dockerfile.dockerignore and excludes a.txt from the context.

$ docker version
Client:
 Version:           27.1.1-rd
 API version:       1.45 (downgraded from 1.46)
 Go version:        go1.21.12
 Git commit:        cdc3063
 Built:             Wed Jul 24 17:06:24 2024
 OS/Arch:           darwin/arm64
 Context:           rancher-desktop

Server:
 Engine:
  Version:          26.1.3
  API version:      1.45 (minimum version 1.24)
  Go version:       go1.22.5
  Git commit:       8e96db1c328d0467b015768e42a62c0f834970bb
  Built:            Sun Jul  7 17:34:20 2024
  OS/Arch:          linux/arm64
  Experimental:     false
 containerd:
  Version:          v1.7.17
  GitCommit:        3a4de459a68952ffb703bbe7f2290861a75b6b67
 runc:
  Version:          1.1.12
  GitCommit:        51d5e94601ceffbbd85688df1c928ecccbfa4685
 docker-init:
  Version:          0.19.0
  GitCommit:

$ docker build --platform linux/arm64 -t test .
$ docker run -it test
Dockerfile  Dockerfile.dockerignore  b.txt

3. Run az acr build (Incorrect Behavior)

The az acr build command ignores Dockerfile.dockerignore and includes a.txt in the context.

$ az acr build --registry {my_registry} --platform linux/arm64 --image test:latest .
$ docker pull {my_registry}.azurecr.io/test:latest
$ docker run -it {my_registry}.azurecr.io/test:latest
Dockerfile  Dockerfile.dockerignore  a.txt  b.txt  d9105d5fca9e4ff5a7d062fcaf57dc0f_Dockerfile

Issue script & Debug output

The debug logs confirm this behavior.

• With Dockerfile.dockerignore, the debug log shows no evidence of parsing any ignore file before archiving:

$ az acr build --debug --registry {my_registry} --platform linux/arm64 --image test:latest .
...
cli.azure.cli.command_modules.acr.build: '--file or -f' is not provided. './Dockerfile' is used.
cli.azure.cli.command_modules.acr._archive_utils: Packing source code into tar to upload...
cli.azure.cli.command_modules.acr._archive_utils: Uploading archived source code from '/var/folders/xn/d4tvgf8d0r35m512_zvlb4dr0000gn/T/build_archive_176fe68807b5421e88f645afd32712c4.tar.gz'...
...

• After renaming to .dockerignore, the debug log correctly shows the ignore rules being processed:

$ az acr build --debug --registry {my_registry} --platform linux/arm64 --image test:latest .
...
cli.azure.cli.command_modules.acr.build: '--file or -f' is not provided. './Dockerfile' is used.
cli.azure.cli.command_modules.acr._archive_utils: Packing source code into tar to upload...
cli.azure.cli.command_modules.acr._archive_utils: .dockerignore: no rule for ''. parent ignore 'False'
cli.azure.cli.command_modules.acr._archive_utils: .dockerignore: no rule for 'Dockerfile'. parent ignore 'False'
cli.azure.cli.command_modules.acr._archive_utils: .dockerignore: no rule for 'b.txt'. parent ignore 'False'
cli.azure.cli.command_modules.acr._archive_utils: .dockerignore: no rule for '.dockerignore'. parent ignore 'False'
cli.azure.cli.command_modules.acr._archive_utils: .dockerignore: rule 'a.txt' matches 'a.txt'.
cli.azure.cli.command_modules.acr._archive_utils: Uploading archived source code from '/var/folders/xn/d4tvgf8d0r35m512_zvlb4dr0000gn/T/build_archive_83287bf1feb64a2c9f5608a41c9bf7d4.tar.gz'...
...

Expected behavior

The az acr build command should correctly identify and use the {Dockerfile-path}.dockerignore file, ensuring its behavior is consistent with the standard docker build command.

Cause and Suggested Fix

The issue appears to stem from incorrect path resolution logic in _archive_utils.py. The following changes should resolve the bug:

1. To support Dockerfiles named Dockerfile:
   • The if condition should be removed from this line:

   • azure-cli/src/azure-cli/azure/cli/command_modules/acr/_archive_utils.py

     Line 154 in 0122c11

     if original_docker_file_name != "Dockerfile":

2. To support Dockerfiles in subdirectories:
   • The path construction should be simplified to pass the full docker_file_path and append .dockerignore.

   • azure-cli/src/azure-cli/azure/cli/command_modules/acr/_archive_utils.py

     Lines 155 to 156 in 0122c11

     	docker_ignore_file_override = os.path.join(
     	source_location, "{}.dockerignore".format(original_docker_file_name))

Environment Summary

azure-cli 2.65.0

core 2.65.0
telemetry 1.1.0

Extensions:
bastion 0.2.5
storage-preview 1.0.0b2

Dependencies:
msal 1.31.0
azure-mgmt-resource 23.1.1

Python location '/usr/local/Cellar/azure-cli/2.65.0_2/libexec/bin/python'
Extensions directory '/Users/user/.azure/cliextensions'

Python (Darwin) 3.11.10 (main, Sep 7 2024, 01:03:31) [Clang 15.0.0 (clang-1500.3.9.4)]

Additional context

No response