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Checks playbooks for practices and behaviour that could potentially be improved

Project description

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Ansible-lint

ansible-lint checks playbooks for practices and behaviour that could potentially be improved.

Visit the Ansible Lint docs site

Installing

Using Pip

pip install ansible-lint

From Source

pip install git+https://github.com/ansible/ansible-lint.git

Usage

Command Line Options

The following is the output from ansible-lint --help, providing an overview of the basic command line options:

Usage: ansible-lint playbook.yml|roledirectory ...

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -L                    list all the rules
  -q                    quieter, although not silent output
  -p                    parseable output in the format of pep8
  -r RULESDIR           specify one or more rules directories using one or
                        more -r arguments. Any -r flags override the default
                        rules in ['/path/to/ansible-
                        lint/lib/ansiblelint/rules'], unless -R is also used.
  -R                    Use default rules ['/path/to/ansible-
                        lint/lib/ansiblelint/rules'] in addition to any extra
                        rules directories specified with -r. There is no need
                        to specify this if no -r flags are used
  -t TAGS               only check rules whose id/tags match these values
  -T                    list all the tags
  -x SKIP_LIST          only check rules whose id/tags do not match these
                        values
  --exclude=EXCLUDE_PATHS
                        path to directories or files to skip. This option is
                        repeatable.
  --force-color         Try force colored output (relying on ansible's code)
  --nocolor             disable colored output
  -c /path/to/file      Specify configuration file to use.  Defaults to
                          ".ansible-lint"

Linting Playbooks and Roles

It’s important to note that ansible-lint accepts a list of Ansible playbook files or a list of role directories. Starting from a directory that contains the following, the playbook file, playbook.yml, or one of the role subdirectories, such as geerlingguy.apache, can be passed:

playbook.yml
roles/
    geerlingguy.apache/
        tasks/
        handlers/
        files/
        templates/
        vars/
        defaults/
        meta/
    geerlingguy.elasticsearch/
        tasks/
        handlers/
        files/
        templates/
        vars/
        defaults/
        meta/

The following lints the role geerlingguy.apache:

$ ansible-lint geerlingguy.apache

[ANSIBLE0013] Use shell only when shell functionality is required
/Users/chouseknecht/.ansible/roles/geerlingguy.apache/tasks/main.yml:19
Task/Handler: Get installed version of Apache.

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/.ansible/roles/geerlingguy.apache/tasks/main.yml:29
Task/Handler: include_vars apache-22.yml

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/.ansible/roles/geerlingguy.apache/tasks/main.yml:32
Task/Handler: include_vars apache-24.yml

Here’s the contents of playbook.yml, which references multiples roles:

- name: Lint multiple roles
  hosts: all
  tasks:

  - include_role:
    name: geerlingguy.apache

  - include_role:
    name: geerlingguy.elasticsearch

The following lints playbook.yml, which evaluates both the playbook and the referenced roles:

$ ansible-lint playbook.yml

[ANSIBLE0013] Use shell only when shell functionality is required
/Users/chouseknecht/roles/geerlingguy.apache/tasks/main.yml:19
Task/Handler: Get installed version of Apache.

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/roles/geerlingguy.apache/tasks/main.yml:29
Task/Handler: include_vars apache-22.yml

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/roles/geerlingguy.apache/tasks/main.yml:32
Task/Handler: include_vars apache-24.yml

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/roles/geerlingguy.elasticsearch/tasks/main.yml:17
Task/Handler: service state=started name=elasticsearch enabled=yes

Since ansible-lint accepts a list of roles or playbooks, the following works as well, producing the same output as the example above:

$ ansible-lint geerlingguy.apache geerlingguy.elasticsearch

[ANSIBLE0013] Use shell only when shell functionality is required
/Users/chouseknecht/roles/geerlingguy.apache/tasks/main.yml:19
Task/Handler: Get installed version of Apache.

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/roles/geerlingguy.apache/tasks/main.yml:29
Task/Handler: include_vars apache-22.yml

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/roles/geerlingguy.apache/tasks/main.yml:32
Task/Handler: include_vars apache-24.yml

[ANSIBLE0011] All tasks should be named
/Users/chouseknecht/roles/geerlingguy.elasticsearch/tasks/main.yml:17
Task/Handler: service state=started name=elasticsearch enabled=yes

Examples

Included in ansible-lint/examples are some example playbooks with undesirable features. Running ansible-lint on them works, as demonstrated in the following:

$ ansible-lint examples/example.yml

[ANSIBLE0004] Git checkouts must contain explicit version
examples/example.yml:15
Task/Handler: git check

[ANSIBLE0004] Git checkouts must contain explicit version
examples/example.yml:18
Task/Handler: git check 2

[ANSIBLE0004] Git checkouts must contain explicit version
examples/example.yml:30
Task/Handler: using git module

[ANSIBLE0002] Trailing whitespace
examples/example.yml:13
    action: do nothing

[ANSIBLE0002] Trailing whitespace
examples/example.yml:35
    with_items:

[ANSIBLE0006] git used in place of git module
examples/example.yml:24
Task/Handler: executing git through command

[ANSIBLE0006] git used in place of git module
examples/example.yml:27
Task/Handler: executing git through command

[ANSIBLE0006] git used in place of git module
examples/example.yml:30
Task/Handler: executing git through command
If playbooks include other playbooks, or tasks, or handlers or roles, these are also handled:
$ bin/ansible-lint examples/include.yml

[ANSIBLE0004] Checkouts must contain explicit version
/Users/will/src/ansible-lint/examples/roles/bobbins/tasks/main.yml:3
action: git a=b c=d

Configuring

Configuration File

Ansible-lint supports local configuration via a .ansible-lint configuration file. Ansible-lint checks the working directory for the presence of this file and applies any configuration found there. The configuration file location can also be overridden via the -c path/to/file CLI flag.

If a value is provided on both the command line and via a config file, the values will be merged (if a list like exclude_paths), or the True value will be preferred, in the case of something like quiet.

The following values are supported, and function identically to their CLI counterparts:

exclude_paths:
  - ./my/excluded/directory/
  - ./my/other/excluded/directory/
  - ./last/excluded/directory/
parseable: true
quiet: true
rulesdir:
  - ./rule/directory/
skip_list:
  - skip_this_tag
  - and_this_one_too
  - skip_this_id
  - '401'
tags:
  - run_this_tag
use_default_rules: true
verbosity: 1

Pre-commit Setup

To use ansible-lint with pre-commit, just add the following to your local repo’s .pre-commit-config.yaml file. Make sure to change sha: to be either a git commit sha or tag of ansible-lint containing hooks.yaml.

- repo: https://github.com/ansible/ansible-lint.git
  sha: v3.3.1
  hooks:
    - id: ansible-lint
      files: \.(yaml|yml)$

Rules

Specifying Rules at Runtime

By default, ansible-lint uses the rules found in ansible-lint/lib/ansiblelint/rules. To override this behavior and use a custom set of rules, use the -r /path/to/custom-rules option to provide a directory path containing the custom rules. For multiple rule sets, pass multiple -r options.

It’s also possilbe to use the default rules, plus custom rules. This can be done by passing the -R to indicate that the deault rules are to be used, along with one or more -r options.

Using Tags to Include Rules

Each rule has an associated set of one or more tags. To view the list of tags for each available rule, use the -T option.

The following shows the available tags in an example set of rules, and the rules associated with each tag:

$ ansible-lint -v -T

behaviour ['[ANSIBLE0016]']
bug ['[ANSIBLE0014]']
deprecated ['[ANSIBLE0015]', '[ANSIBLE0008]', '[ANSIBLE0018]', '[ANSIBLE0019]']
formatting ['[ANSIBLE0015]', '[ANSIBLE0002]', '[ANSIBLE0009]']
idempotency ['[ANSIBLE0012]']
oddity ['[ANSIBLE0017]']
readability ['[ANSIBLE0011]']
repeatability ['[ANSIBLE0004]', '[ANSIBLE0010]', '[ANSIBLE0005]']
resources ['[ANSIBLE0007]', '[ANSIBLE0006]']
safety ['[ANSIBLE0013]']

To run just the idempotency rules, for example, run the following:

$ ansible-lint -t idempotency playbook.yml

Excluding Rules

To exclude rules from the available set of rules, use the -x SKIP_LIST option. For example, the following runs all of the rules except those with the tags readability and safety:

$ ansible-lint -x readability,safety playbook.yml

It’s also possible to skip specific rules by passing the rule ID. For example, the following excludes rule ANSIBLE0011:

$ ansible-lint -x ANSIBLE0011 playbook.yml

False Positives: Muting Ansible Lint Warnings

Some rules are a bit of a rule of thumb. Advanced git, yum or apt usage, for example, is typically difficult to achieve through the modules. In this case, you should mark the task so that warnings aren’t produced.

There are two mechanisms for this - one works with all tasks, the other works with the command checking modules.

Use the warn parameter with the command or shell module.

Use skip_ansible_lint tag with any task that should be skipped.

It’s also a good practice to comment the reasons why a task is being skipped.

Here’s an example playbook showing the two techniques for muting Ansible Lint warnings:

- name: this would typically fire CommandsInsteadOfArgumentRule
  command: warn=no chmod 644 X

- name: this would typically fire CommandsInsteadOfModuleRule
  command: git pull --rebase
  args:
    warn: False

- name: this would typically fire GitHasVersionRule
  git: src=/path/to/git/repo dest=checkout
  tags:
  - skip_ansible_lint

Creating Custom Rules

Rules are described using a class file per rule. Default rules are named DeprecatedVariableRule.py, etc.

Each rule definition should have the following:

  • ID: A unique identifier
  • Short description: Brief description of the rule
  • Description: Behaviour the rule is looking for
  • Tags: one or more tags that may be used to include or exclude the rule
  • At least one of the following methods:
    • match that takes a line and returns None or False, if the line doesn’t match the test, and True or a custom message, when it does. (This allows one rule to test multiple behaviours - see e.g. the CommandsInsteadOfModulesRule.)
    • matchtask that operates on a single task or handler, such that tasks get standardized to always contain a module key and module_arguments key. Other common task modifiers, such as when, with_items, etc., are also available as keys, if present in the task.

An example rule using match is:

from ansiblelint import AnsibleLintRule

class DeprecatedVariableRule(AnsibleLintRule):

    id = 'ANSIBLE0001'
    shortdesc = 'Deprecated variable declarations'
    description = 'Check for lines that have old style ${var} ' + \
                  'declarations'
    tags = { 'deprecated' }

    def match(self, file, line):
        return '${' in line

An example rule using matchtask is:

import ansiblelint.utils
from ansiblelint import AnsibleLintRule

class TaskHasTag(AnsibleLintRule):
    id = 'ANSIBLE0008'
    shortdesc = 'Tasks must have tag'
    description = 'Tasks must have tag'
    tags = ['productivity']

    def matchtask(self, file, task):
        # If the task include another task or make the playbook fail
        # Don't force to have a tag
        if not set(task.keys()).isdisjoint(['include','fail']):
            return False

        # Task should have tags
        if not task.has_key('tags'):
              return True

    return False

The task argument to matchtask contains a number of keys - the critical one is action. The value of task[‘action’] contains the module being used, and the arguments passed, both as key-value pairs and a list of other arguments (e.g. the command used with shell).

In ansible-lint 2.0.0, task[‘action’][‘args’] was renamed task[‘action’][‘module_arguments’] to avoid a clash when a module actually takes args as a parameter key (e.g. ec2_tag)

In ansible-lint 3.0.0 task[‘action’][‘module’] was renamed task[‘action’][‘__ansible_module__’] to avoid a clash when a module take module as an argument. As a precaution, task[‘action’][‘module_arguments’] was renamed task[‘action’][‘__ansible_arguments__’].

Contributing

Please read Contribution guidelines if you wish to contribute.

Authors

ansible-lint was created by Will Thames and is now maintained as part of the Ansible by Red Hat project.

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