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目录
[二、hadolint 介绍](#二、hadolint 介绍)
[三、hadolint 使用](#三、hadolint 使用)
[3、Docker 检查方式](#3、Docker 检查方式)
[四、hadolint 命令行选项](#四、hadolint 命令行选项)
一、背景介绍
笔者在《专题三:Dockerfile 相关》及《Dockerfile 指令对 Docker 镜像层数的影响》等文章中已经介绍过 Dockerfile 相关知识及其运用。但是在实际工作中 Dockerfile 肯定不是随便写写就行了,而是推荐遵照最佳实践原则对其进行优化,以期达到减少镜像体积、提升构建效率及容器安全性等目标。
工欲善其事,必先利其器。本文将针对 Dockerfile 的优化介绍一款辅助工具,帮助大家提升工作效率。
二、hadolint 介绍
hadolint 是一款专门用于检查 Dockerfile 语法的静态分析工具,可以帮助使用者构建符合最佳实践的 Docker 镜像。
hadolint 作为一个智能的 Dockerfile 筛选器,主要工作流程如下:
-
hadolint 将 Dockerfile 解析为 AST(抽象语法树),以标识与其关联的每条指令和参数
-
hadolint 根据内置的语法规则,在 AST 之上检查每条指令和参数。这些语法规则涵盖了效率、代码质量、安全性等多个方面。此外,hadolint 还使用了著名的 Shellcheck 来检查 RUN 指令中的 Bash 代码
-
Hadolint 会标记所有不符合语法规则的指令和参数,并提供针对性的优化建议
GitHub 地址:https://github.com/hadolint/hadolint
Dockerfile 最佳实践:https://docs.docker.com/build/building/best-practices/
三、hadolint 使用
1、在线检查方式
bash
# Dockerfile 示例
FROM debian
RUN apt update && apt install -y supervisor
COPY supervisord.conf /etc/supervisor/conf.d/
EXPOSE 80000
CMD ["/usr/bin/supervisord"]
将以上 Dockerfile 内容粘贴至文本框后点击 Lint 按钮,高亮部分即为 hadolint 针对语法检查结果反馈的优化建议,并可点击跳转至详情页。




2、二进制检查方式
- 安装命令
bash
wget -O hadolint https://github.com/hadolint/hadolint/releases/download/v2.12.0/hadolint-Linux-x86_64
chmod +x hadolint && mv hadolint /usr/local/bin
hadolint -v
- 检查命令
bash
hadolint Dockerfile

- 检查命令(忽略指定规则)
bash
hadolint Dockerfile --ignore DL3006 --ignore DL3027

3、Docker 检查方式
docker run --rm -i ghcr.io/hadolint/hadolint < Dockerfile

四、hadolint 命令行选项
bash
# hadolint -h
hadolint - Dockerfile Linter written in Haskell
Usage: hadolint [-v|--version] [-c|--config FILENAME] [DOCKERFILE...]
[--file-path-in-report FILEPATHINREPORT] [--no-fail]
[--no-color] [-V|--verbose] [-f|--format ARG] [--error RULECODE]
[--warning RULECODE] [--info RULECODE] [--style RULECODE]
[--ignore RULECODE]
[--trusted-registry REGISTRY (e.g. docker.io)]
[--require-label LABELSCHEMA (e.g. maintainer:text)]
[--strict-labels] [--disable-ignore-pragma]
[-t|--failure-threshold THRESHOLD]
Lint Dockerfile for errors and best practices
Available options:
-h,--help Show this help text
-v,--version Show version
-c,--config FILENAME Path to the configuration file
--file-path-in-report FILEPATHINREPORT
The file path referenced in the generated report.
This only applies for the 'checkstyle' format and is
useful when running Hadolint with Docker to set the
correct file path.
--no-fail Don't exit with a failure status code when any rule
is violated
--no-color Don't colorize output
-V,--verbose Enables verbose logging of hadolint's output to
stderr
-f,--format ARG The output format for the results [tty | json |
checkstyle | codeclimate | gitlab_codeclimate | gnu |
codacy | sonarqube | sarif] (default: tty)
--error RULECODE Make the rule `RULECODE` have the level `error`
--warning RULECODE Make the rule `RULECODE` have the level `warning`
--info RULECODE Make the rule `RULECODE` have the level `info`
--style RULECODE Make the rule `RULECODE` have the level `style`
--ignore RULECODE A rule to ignore. If present, the ignore list in the
config file is ignored
--trusted-registry REGISTRY (e.g. docker.io)
A docker registry to allow to appear in FROM
instructions
--require-label LABELSCHEMA (e.g. maintainer:text)
The option --require-label=label:format makes
Hadolint check that the label `label` conforms to
format requirement `format`
--strict-labels Do not permit labels other than specified in
`label-schema`
--disable-ignore-pragma Disable inline ignore pragmas `# hadolint
ignore=DLxxxx`
-t,--failure-threshold THRESHOLD
Exit with failure code only when rules with a
severity equal to or above THRESHOLD are violated.
Accepted values: [error | warning | info | style |
ignore | none] (default: info)