131 lines
4.9 KiB
Markdown
131 lines
4.9 KiB
Markdown
---
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stage: none
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group: unassigned
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info: Any user with at least the Maintainer role can merge updates to this content. For details, see https://docs.gitlab.com/ee/development/development_processes.html#development-guidelines-review.
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---
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# Shell scripting standards and style guidelines
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GitLab consists of many various services and sub-projects. The majority of
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their backend code is written in [Ruby](https://www.ruby-lang.org) and
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[Go](https://go.dev/). However, some of them use shell scripts for
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automation of routine system administration tasks like deployment,
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installation, etc. It's being done either for historical reasons or as an effort
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to minimize the dependencies, for instance, for Docker images.
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This page aims to define and organize our shell scripting guidelines,
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based on our various experiences. All shell scripts across GitLab project
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should be eventually harmonized with this guide. If there are any per-project
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deviations from this guide, they should be described in the
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`README.md` or `PROCESS.md` file for such a project.
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## Avoid using shell scripts
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WARNING:
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This is a must-read section.
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Having said all of the above, we recommend staying away from shell scripts
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as much as possible. A language like Ruby or Python (if required for
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consistency with codebases that we leverage) is almost always a better choice.
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The high-level interpreted languages have more readable syntax, offer much more
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mature capabilities for unit-testing, linting, and error reporting.
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Use shell scripts only if there's a strong restriction on project's
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dependencies size or any other requirements that are more important
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in a particular case.
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## Scope of this guide
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According to the [GitLab installation requirements](../../install/requirements.md),
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this guide covers only those shells that are used by
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[supported Linux distributions](../../administration/package_information/supported_os.md#supported-operating-systems),
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that is:
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- [POSIX Shell](https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html)
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- [Bash](https://www.gnu.org/software/bash/)
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## Shell language choice
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- When you need to reduce the dependencies list, use what's provided by the environment. For example, for Docker images it's `sh` from `alpine` which is the base image for most of our tool images.
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- Everywhere else, use `bash` if possible. It's more powerful than `sh` but still a widespread shell.
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## Code style and format
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This section describes the tools that should be made a mandatory part of
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a project's CI pipeline if it contains shell scripts. These tools
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automate shell code formatting, checking for errors or vulnerabilities, etc.
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### Linting
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We're using the [ShellCheck](https://www.shellcheck.net/) utility in its default configuration to lint our
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shell scripts.
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All projects with shell scripts should use this GitLab CI/CD job:
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```yaml
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shell check:
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image: koalaman/shellcheck-alpine:stable
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stage: test
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before_script:
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- shellcheck --version
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script:
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- shellcheck scripts/**/*.sh # path to your shell scripts
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```
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NOTE:
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By default, ShellCheck uses the [shell detection](https://github.com/koalaman/shellcheck/wiki/SC2148#rationale)
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to determine the shell dialect in use. If the shell file is out of your control and ShellCheck cannot
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detect the dialect, use `-s` flag to specify it: `-s sh` or `-s bash`.
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### Formatting
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It's recommended to use the [shfmt](https://github.com/mvdan/sh#shfmt) tool to maintain consistent formatting.
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We format shell scripts according to the [Google Shell Style Guide](https://google.github.io/styleguide/shell.xml),
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so the following `shfmt` invocation should be applied to the project's script files:
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```shell
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shfmt -i 2 -ci -w scripts/**/*.sh
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```
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In addition to the [Linting](#linting) GitLab CI/CD job, all projects with shell scripts should also
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use this job:
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```yaml
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shfmt:
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image: mvdan/shfmt:v3.2.0-alpine
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stage: test
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before_script:
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- shfmt -version
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script:
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- shfmt -i 2 -ci -d scripts # path to your shell scripts
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```
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NOTE:
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By default, shfmt uses the [shell detection](https://github.com/mvdan/sh#shfmt) similar to one of ShellCheck
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and ignore files starting with a period. To override this, use `-ln` flag to specify the shell dialect:
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`-ln posix` or `-ln bash`.
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## Testing
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NOTE:
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This is a work in progress.
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It is an [ongoing effort](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/64016) to evaluate different tools for the
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automated testing of shell scripts (like [BATS](https://github.com/bats-core/bats-core)).
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## Code Review
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The code review should be performed according to:
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- [ShellCheck Checks list](https://github.com/koalaman/shellcheck/wiki/Checks)
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- [Google Shell Style Guide](https://google.github.io/styleguide/shell.xml)
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- [Shfmt formatting caveats](https://github.com/mvdan/sh#caveats)
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However, the recommended course of action is to use the aforementioned
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tools and address reported offenses. This should eliminate the need
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for code review.
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---
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[Return to Development documentation](../index.md).
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