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Ansible

Ansible conventions and best practices

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Ansible Conventions and Best Practices

General Instructions

  • Use Ansible to configure and manage infrastructure.
  • Use version control for your Ansible configurations.
  • Keep things simple; only use advanced features when necessary
  • Give every play, block, and task a concise but descriptive name
    • Start names with an action verb that indicates the operation being performed, such as "Install," "Configure," or "Copy"
    • Capitalize the first letter of the task name
    • Omit periods from the end of task names for brevity
    • Omit the role name from role tasks; Ansible will automatically display the role name when running a role
    • When including tasks from a separate file, you may include the filename in each task name to make tasks easier to locate (e.g., <TASK_FILENAME> : <TASK_NAME>)
  • Use comments to provide additional context about what, how, and/or why something is being done
    • Don't include redundant comments
  • Use dynamic inventory for cloud resources
    • Use tags to dynamically create groups based on environment, function, location, etc.
    • Use group_vars to set variables based on these attributes
  • Use idempotent Ansible modules whenever possible; avoid shell, command, and raw, as they break idempotency
    • If you have to use shell or command, use the creates: or removes: parameter, where feasible, to prevent unnecessary execution
  • Use fully qualified collection names (FQCN) to ensure the correct module or plugin is selected
  • Group related tasks together to improve readability and modularity
  • For modules where state is optional, explicitly set state: present or state: absent to improve clarity and consistency
  • Use the lowest privileges necessary to perform a task
    • Only set become: true at the play level or on an include: statement, if all included tasks require super user privileges; otherwise, specify become: true at the task level
    • Only set become: true on a task if it requires super user privileges

Secret Management

  • When using Ansible alone, store secrets using Ansible Vault
    • Use the following process to make it easy to find where vaulted variables are defined
      1. Create a group_vars/ subdirectory named after the group
      2. Inside this subdirectory, create two files named vars and vault
      3. In the vars file, define all of the variables needed, including any sensitive ones
      4. Copy all of the sensitive variables over to the vault file and prefix these variables with vault_
      5. Adjust the variables in the vars file to point to the matching vault_ variables using Jinja2 syntax: db_password: "{{ vault_db_password }}"
      6. Encrypt the vault file to protect its contents
      7. Use the variable name from the vars file in your playbooks
  • When using other tools with Ansible (e.g., Terraform), store secrets in a third-party secrets management tool (e.g., Hashicorp Vault, AWS Secrets Manager, etc.)
    • This allows all tools to reference a single source of truth for secrets and prevents configurations from getting out of sync

Style

  • Use 2-space indentation and always indent lists
  • Separate each of the following with a single blank line:
    • Two host blocks
    • Two task blocks
    • Host and include blocks
  • Use snake_case for variable names
  • Sort variables alphabetically when defining them in vars: maps or variable files
  • Always use multi-line map syntax, regardless of how many pairs exist in the map
    • It improves readability and reduces changeset collisions for version control
  • Prefer single quotes over double quotes
    • The only time you should use double quotes is when they are nested within single quotes (e.g. Jinja map reference), or when your string requires escaping characters (e.g., using "\n" to represent a newline)
    • If you must write a long string, use folded block scalar syntax (i.e., >) to replace newlines with spaces or literal block scalar syntax (i.e., |) to preserve newlines; omit all special quoting
  • The host section of a play should follow this general order:
    • hosts declaration
    • Host options in alphabetical order (e.g., become, remote_user, vars)
    • pre_tasks
    • roles
    • tasks
  • Each task should follow this general order:
    • name
    • Task declaration (e.g., service:, package:)
    • Task parameters (using multi-line map syntax)
    • Loop operators (e.g., loop)
    • Task options in alphabetical order (e.g. become, ignore_errors, register)
    • tags
  • For include statements, quote filenames and only use blank lines between include statements if they are multi-line (e.g., they have tags)

Linting

  • Use ansible-lint and yamllint to check syntax and enforce project standards
  • Use ansible-playbook --syntax-check to check for syntax errors
  • Use ansible-playbook --check --diff to perform a dry-run of playbook execution