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dockerfilelint

dockerfilelint documentation

dockerfilelint - GitHub

Configuration in Mega-Linter

Variable Description Default value
DOCKERFILE_DOCKERFILELINT_ARGUMENTS User custom arguments to add in linter CLI call
Ex: -s --foo "bar"
DOCKERFILE_DOCKERFILELINT_FILTER_REGEX_INCLUDE Custom regex including filter
Ex: (src|lib)
Include every file
DOCKERFILE_DOCKERFILELINT_FILTER_REGEX_EXCLUDE Custom regex excluding filter
Ex: (test|examples)
Exclude no file
DOCKERFILE_DOCKERFILELINT_FILE_EXTENSIONS Allowed file extensions. "*" matches any extension, "" matches empty extension. Empty list excludes all files
Ex: [".py", ""]
Exclude every file
DOCKERFILE_DOCKERFILELINT_FILE_NAMES_REGEX File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files
Ex: ["Dockerfile(-.+)?", "Jenkinsfile"]
["Dockerfile"]
DOCKERFILE_DOCKERFILELINT_CONFIG_FILE dockerfilelint configuration file name
Use LINTER_DEFAULT to let the linter find it
.dockerfilelintrc
DOCKERFILE_DOCKERFILELINT_RULES_PATH Path where to find linter configuration file Workspace folder, then Mega-Linter default rules
DOCKERFILE_DOCKERFILELINT_DISABLE_ERRORS Run linter but consider errors as warnings false

Mega-Linter Flavours

This linter is available in the following flavours

Flavor Description Embedded linters Info
all Default Mega-Linter Flavor 83 Docker Image Size (tag) Docker Pulls
ci_light Optimized for CI items (Dockerfile, Jenkinsfile, JSON/YAML schemas,XML 11 Docker Image Size (tag) Docker Pulls
dart Optimized for DART based projects 37 Docker Image Size (tag) Docker Pulls
documentation Mega-Linter for documentation projects 36 Docker Image Size (tag) Docker Pulls
dotnet Optimized for C, C++, C# or VB based projects 42 Docker Image Size (tag) Docker Pulls
go Optimized for GO based projects 38 Docker Image Size (tag) Docker Pulls
java Optimized for JAVA based projects 37 Docker Image Size (tag) Docker Pulls
javascript Optimized for JAVASCRIPT or TYPESCRIPT based projects 45 Docker Image Size (tag) Docker Pulls
php Optimized for PHP based projects 40 Docker Image Size (tag) Docker Pulls
python Optimized for PYTHON based projects 43 Docker Image Size (tag) Docker Pulls
ruby Optimized for RUBY based projects 37 Docker Image Size (tag) Docker Pulls
rust Optimized for RUST based projects 37 Docker Image Size (tag) Docker Pulls
salesforce Optimized for Salesforce based projects 37 Docker Image Size (tag) Docker Pulls
scala Optimized for SCALA based projects 37 Docker Image Size (tag) Docker Pulls
swift Optimized for SWIFT based projects 37 Docker Image Size (tag) Docker Pulls
terraform Optimized for TERRAFORM based projects 39 Docker Image Size (tag) Docker Pulls

Behind the scenes

How are identified applicable files

  • File names (regex): Dockerfile

Example calls

dockerfilelint Dockerfile

Help content

Usage: dockerfilelint [files | content..] [options]

Options:
  -o, --output   Specify the format to use for output of linting results. Valid values
                 are `json` or `cli` (default).                               [string]
  -j, --json     Output linting results as JSON, equivalent to `-o json`.    [boolean]
  -c, --config   Path for .dockerfilelintrc configuration file                [string]
  -v, --version  Show version number                                         [boolean]
  -h, --help     Show help                                                   [boolean]

Examples:
  dockerfilelint Dockerfile         Lint a Dockerfile in the current working directory

  dockerfilelint test/example/* -j  Lint all files in the test/example directory and
                                    output results in JSON

  dockerfilelint 'FROM latest'      Lint the contents given as a string on the command
                                    line

  dockerfilelint < Dockerfile       Lint the contents of Dockerfile via stdin

Installation on mega-linter Docker image

Example success log

Results of dockerfilelint linter (version 1.8.0)
See documentation on https://nvuillam.github.io/mega-linter/descriptors/dockerfile_dockerfilelint/
-----------------------------------------------

[SUCCESS] .automation/test/docker/good/Dockerfile

    File:   .automation/test/docker/good/Dockerfile
    Issues: None found 👍

[SUCCESS] .automation/test/docker/good/Dockerfile.dev

    File:   .automation/test/docker/good/Dockerfile.dev
    Issues: None found 👍

Example error log

Results of dockerfilelint linter (version 1.8.0)
See documentation on https://nvuillam.github.io/mega-linter/descriptors/dockerfile_dockerfilelint/
-----------------------------------------------

[ERROR] .automation/test/docker/bad/Dockerfile

    File:   .automation/test/docker/bad/Dockerfile
    Issues: 5

    Line 1: from node:latest
    Issue  Category      Title                 Description
        1  Clarity       Capitalize            For clarity and readability, all instructions in a Dockerfile
                         Dockerfile            should be uppercase.
                         Instructions          This is a convention adopted by most of the official images and
                                               greatly improves readability in long Dockerfiles.  For an example
                                               of
                                               why this makes a difference, check out the current [redis
                                               Dockerfile](https://github.com/docker-library/redis/blob/b375650fb6
                                               9b7db819e90c0033433c705b28656e/3.0/Dockerfile)
                                               and you should be able to easily see the instructions used.

    Line 4: run mkdir -p /usr/src/app
    Issue  Category      Title                 Description
        2  Clarity       Capitalize            For clarity and readability, all instructions in a Dockerfile
                         Dockerfile            should be uppercase.
                         Instructions          This is a convention adopted by most of the official images and
                                               greatly improves readability in long Dockerfiles.  For an example
                                               of
                                               why this makes a difference, check out the current [redis
                                               Dockerfile](https://github.com/docker-library/redis/blob/b375650fb6
                                               9b7db819e90c0033433c705b28656e/3.0/Dockerfile)
                                               and you should be able to easily see the instructions used.

    Line 8: copy package.json /usr/src/app/ /here/there
    Issue  Category      Title                 Description
        3  Clarity       Capitalize            For clarity and readability, all instructions in a Dockerfile
                         Dockerfile            should be uppercase.
                         Instructions          This is a convention adopted by most of the official images and
                                               greatly improves readability in long Dockerfiles.  For an example
                                               of
                                               why this makes a difference, check out the current [redis
                                               Dockerfile](https://github.com/docker-library/redis/blob/b375650fb6
                                               9b7db819e90c0033433c705b28656e/3.0/Dockerfile)
                                               and you should be able to easily see the instructions used.

    Line 9: RUN sudo npm install
    Issue  Category      Title                 Description
        4  Possible Bug  Use Of sudo Is Not    Use of `sudo` is not allowed in a Dockerfile.  From the official
                         Allowed               document [Best practices for writing
                                               Dockerfiles](https://docs.docker.com/engine/userguide/eng-image/doc
                                               kerfile_best-practices/):
                                               > You should avoid installing or using `sudo` since it has
                                               unpredictable TTY and signal-forwarding behavior that can cause
                                               more problems than it solves.
                                               > If you absolutely need functionality similar to `sudo` (e.g.,
                                               initializing the daemon as root but running it as non-root), you
                                               may be able to use `gosu`.

    Line 14: ENtrypoint /tmp/here.sh
    Issue  Category      Title                 Description
        5  Clarity       Capitalize            For clarity and readability, all instructions in a Dockerfile
                         Dockerfile            should be uppercase.
                         Instructions          This is a convention adopted by most of the official images and
                                               greatly improves readability in long Dockerfiles.  For an example
                                               of
                                               why this makes a difference, check out the current [redis
                                               Dockerfile](https://github.com/docker-library/redis/blob/b375650fb6
                                               9b7db819e90c0033433c705b28656e/3.0/Dockerfile)
                                               and you should be able to easily see the instructions used.