Version 2.0.0 release: adds --max-layers flag (#308)

.github/workflows/disl.yml

@@ -20,3 +20,4 @@ jobs:
       with:  # we lint this image by itself:
         image: 'wemake-services/docker-image-size-limit:latest'
         size: 405MB
+        max_layers: 10

.github/workflows/test.yml

@@ -11,6 +11,9 @@ concurrency:
   group: ${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -39,12 +42,15 @@ jobs:
         poetry run pip install -U pip
         poetry install
 
+    - name: Pull test deps
+      run: |
+        # We need this specific image for tests:
+        poetry run docker pull python:3.6.6-alpine
+
     - name: "Run checks for python ${{ matrix.python-version }}"
       run: |
         poetry run flake8 .
         poetry run mypy .
-        # We need this specific image for tests:
-        poetry run docker pull python:3.6.6-alpine
         poetry run pytest
         poetry check
         poetry run pip check

CHANGELOG.md

@@ -2,6 +2,14 @@
 
 We follow Semantic Version.
 
+
+## Version 2.0.0
+
+### Features
+
+- Adds `--max-layers` flag to lint the maximum number of layers
+
+
 ## Version 1.1.0
 
 ### Features

Dockerfile

@@ -12,13 +12,13 @@
 # This image is also available on Dockerhub:
 # https://hub.docker.com/r/wemakeservices/docker-image-size-limit
 
-FROM python:3.9.6-alpine
+FROM python:3.12.6-alpine
 
-LABEL maintainer="sobolevn@wemake.services"
+LABEL maintainer="mail@sobolevn.me"
 LABEL vendor="wemake.services"
 
 # Our own tool:
-ENV DISL_VERSION='1.0.1'
+ENV DISL_VERSION='2.0.0'
 
 RUN apk add --no-cache bash docker
 RUN pip3 install "docker-image-size-limit==$DISL_VERSION"

README.md

@@ -30,6 +30,19 @@ $ disl your-image-name:label 300MiB
 your-image-name:label exceeds 300MiB limit by 114.4 MiB
 ```
 
+Add `--max-layers` flag to also lint the maximum amount of layers possible
+in your image:
+
+```bash
+# If your image has 7 layers:
+$ disl your-image-name:label 300MiB --max-layers=5
+your-image-name:label exceeds 5 maximum layers by 2
+
+# If your image has 5 layers:
+$ disl your-image-name:label 300MiB --max-layers=5
+# ok!
+```
+
 
 ## Options
 
@@ -62,9 +75,9 @@ We also ship [PEP-561](https://www.python.org/dev/peps/pep-0561/)
 compatible type annotations with this library.
 
 
-## Github Action
+## GitHub Action
 
-You can also use this check as a [Gihub Action](https://github.com/marketplace/actions/docker-image-size-limit):
+You can also use this check as a [GitHub Action](https://github.com/marketplace/actions/docker-image-size-limit):
 
 ```yaml
 - uses: wemake-services/docker-image-size-limit@master

action.yml

@@ -5,7 +5,7 @@
 # See: https://help.github.com/en/articles/metadata-syntax-for-github-actions
 
 name: 'docker-image-size-limit'
-description: 'Runs docker-image-size-limit as a Github Action'
+description: 'Runs docker-image-size-limit as a GitHub Action'
 branding:
   icon: 'check'
   color: 'blue'
@@ -17,6 +17,10 @@ inputs:
   size:
     description: 'Human readable size as the hard limit'
     required: true
+  max_layers:
+    description: 'The maximum number of layers in the image'
+    required: false
+    default: -1
 outputs:
   size:
     description: 'The output of docker-image-size-limit run'
@@ -27,3 +31,4 @@ runs:
   args:
     - ${{ inputs.image }}
     - ${{ inputs.size }}
+    - ${{ inputs.layers }}

docker_image_size_limit/__init__.py

@@ -1,9 +1,10 @@
 import argparse
 import os
 import sys
-from typing import NoReturn
+from typing import List, NoReturn, Tuple
 
 import docker
+from docker.models.images import Image
 from humanfriendly import format_size, parse_size
 
 from docker_image_size_limit.version import get_version
@@ -18,22 +19,48 @@ def main() -> NoReturn:
     """Main CLI entrypoint."""
     client = docker.from_env()
     arguments = _parse_args()
-    oversize = check_image_size(client, arguments.image, arguments.size)
+    extra_size, extra_layers = _check_image(
+        client,
+        image=arguments.image,
+        max_size=arguments.max_size,
+        max_layers=arguments.max_layers,
+    )
 
     exit_code = 0
-    if oversize > 0:
+    if extra_size > 0:
         print('{0} exceeds {1} limit by {2}'.format(  # noqa: WPS421
             arguments.image,
-            arguments.size,
-            format_size(oversize, binary=True),
+            arguments.max_size,
+            format_size(extra_size, binary=True),
+        ))
+        exit_code = 1
+    if extra_layers > 0:
+        print('{0} exceeds {1} maximum layers by {2}'.format(  # noqa: WPS421
+            arguments.image,
+            arguments.max_layers,
+            extra_layers,
         ))
         exit_code = 1
     sys.exit(exit_code)
 
 
-def check_image_size(
+def _check_image(
     client: docker.DockerClient,
     image: str,
+    max_size: str,
+    max_layers: int,
+) -> Tuple[int, int]:
+    image_info = client.images.get(image)
+    size_overflow = check_image_size(image_info, limit=max_size)
+    if max_layers > 0:
+        layers_overflow = check_image_layers(image_info, limit=max_layers)
+    else:
+        layers_overflow = 0
+    return size_overflow, layers_overflow
+
+
+def check_image_size(
+    image: Image,
     limit: str,
 ) -> int:
     """
@@ -42,8 +69,7 @@ def check_image_size(
     Compares it to the given size in bytes or in human readable format.
 
     Args:
-        client: docker client to work with images.
-        image: image name.
+        image: image object from docker.
         limit: human-readable size limit.
 
     Returns:
@@ -52,7 +78,7 @@ def check_image_size(
         than the actual image. We only care for values ``> 0``.
 
     """
-    image_size: int = client.images.get(image).attrs['Size']
+    image_size: int = image.attrs['Size']
 
     try:
         image_limit = int(limit)
@@ -62,6 +88,25 @@ def check_image_size(
     return image_size - image_limit
 
 
+def check_image_layers(
+    image: Image,
+    limit: int,
+) -> int:
+    """
+    Checks the number of layers in an image.
+
+    Args:
+        image: image object from docker.
+        limit: maximum number of layers.
+
+    Returns:
+        Tresshold overflow in number of layers.
+
+    """
+    layers: List[str] = image.attrs['RootFS']['Layers']
+    return len(layers) - limit
+
+
 def _parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(
         description='Keep your docker images small',
@@ -73,6 +118,12 @@ def _parse_args() -> argparse.Namespace:
         'image', type=str, help='Docker image name to be checked',
     )
     parser.add_argument(
-        'size', type=str, help='Human-readable size limit: 102 MB, 1GB',
+        'max_size', type=str, help='Human-readable size limit: 102 MB, 1GB',
+    )
+    parser.add_argument(
+        '--max-layers',
+        type=int,
+        help='Maximum number of image layers',
+        default=-1,
     )
     return parser.parse_args()

docker_image_size_limit/version.py

@@ -3,4 +3,4 @@
 
 def get_version(distribution_name: str) -> str:
     """Our helper to get version of a package."""
-    return metadata.version(distribution_name)  # type: ignore
+    return metadata.version(distribution_name)