Configuration

class molecule.config.Config

Config Class.

Molecule searches the current directory for molecule.yml files by globbing molecule/*/molecule.yml. The files are instantiated into a list of Molecule Config objects, and each Molecule subcommand operates on this list.

The directory in which the molecule.yml resides is the Scenario’s directory. Molecule performs most functions within this directory.

The Config object instantiates Dependency, Driver, Lint, Platforms, Provisioner, Verifier, Scenario, and State references.

Initialize a new config class and returns None.

Parameters
  • molecule_file – A string containing the path to the Molecule file to be parsed.

  • args – An optional dict of options, arguments and commands from the CLI.

  • command_args – An optional dict of options passed to the subcommand from the CLI.

  • ansible_args – An optional tuple of arguments provided to the ansible-playbook command.

Returns

None

Variable Substitution

class molecule.interpolation.Interpolator

Configuration options may contain environment variables.

For example, suppose the shell contains VERIFIER_NAME=testinfra and the following molecule.yml is supplied.

verifier:
  - name: ${VERIFIER_NAME}

Molecule will substitute $VERIFIER_NAME with the value of the VERIFIER_NAME environment variable.

Warning

If an environment variable is not set, Molecule substitutes with an empty string.

Both $VARIABLE and ${VARIABLE} syntax are supported. Extended shell-style features, such as ${VARIABLE-default} and ${VARIABLE:-default} are also supported. Even the default as another environment variable is supported like ${VARIABLE-$DEFAULT} or ${VARIABLE:-$DEFAULT}. An empty string is returned when both variables are undefined.

If a literal dollar sign is needed in a configuration, use a double dollar sign ($$).

Molecule will substitute special MOLECULE_ environment variables defined in molecule.yml.

Important

Remember, the MOLECULE_ namespace is reserved for Molecule. Do not prefix your own variables with MOLECULE_.

A file may be placed in the root of the project as .env.yml, and Molecule will read variables when rendering molecule.yml. See command usage.

Construct Interpolator.

Dependency

Testing roles may rely upon additional dependencies. Molecule handles managing these dependencies by invoking configurable dependency managers.

Ansible Galaxy

class molecule.dependency.ansible_galaxy.AnsibleGalaxy

Galaxy is the default dependency manager.

Additional options can be passed to ansible-galaxy install through the options dict. Any option set in this section will override the defaults.

Note

Molecule will remove any options matching ‘^[v]+$’, and pass -vvv to the underlying ansible-galaxy command when executing molecule –debug.

dependency:
  name: galaxy
  options:
    ignore-certs: True
    ignore-errors: True
    role-file: requirements.yml
    requirements-file: collections.yml

Use “role-file” if you have roles only. Use the “requirements-file” if you need to install collections. Note that, with Ansible Galaxy’s collections support, you can now combine the two lists into a single requirement if your file looks like this

roles:
  - dep.role1
  - dep.role2
collections:
  - ns.collection
  - ns2.collection2

If you want to combine them, then just point your role-file and requirements-file to the same path. This is not done by default because older role-file only required a list of roles, while the collections must be under the collections: key within the file and pointing both to the same file by default could break existing code.

The dependency manager can be disabled by setting enabled to False.

dependency:
  name: galaxy
  enabled: False

Environment variables can be passed to the dependency.

dependency:
  name: galaxy
  env:
    FOO: bar

Construct AnsibleGalaxy.

Shell

class molecule.dependency.shell.Shell

Shell is an alternate dependency manager.

It is intended to run a command in situations where Ansible Galaxy don’t suffice.

The command to execute is required, and is relative to Molecule’s project directory when referencing a script not in $PATH.

Note

Unlike the other dependency managers, options are ignored and not passed to shell. Additional flags/subcommands should simply be added to the command.

dependency:
  name: shell
  command: path/to/command --flag1 subcommand --flag2

The dependency manager can be disabled by setting enabled to False.

dependency:
  name: shell
  command: path/to/command --flag1 subcommand --flag2
  enabled: False

Environment variables can be passed to the dependency.

dependency:
  name: shell
  command: path/to/command --flag1 subcommand --flag2
  env:
    FOO: bar

Construct Shell.

Driver

Molecule uses Ansible to manage instances to operate on. Molecule supports any provider Ansible supports. This work is offloaded to the provisioner.

The driver’s name is specified in molecule.yml, and can be overridden on the command line. Molecule will remember the last successful driver used, and

continue to use the driver for all subsequent subcommands, or until the instances are destroyed by Molecule.

Important

The verifier must support the Ansible provider for proper Molecule integration.

The driver’s python package requires installation.

Delegated

class molecule.driver.delegated.Delegated

The class responsible for managing delegated instances.

Delegated is not the default driver used in Molecule.

Under this driver, it is the developers responsibility to implement the create and destroy playbooks. Managed is the default behaviour of all drivers.

driver:
  name: delegated

However, the developer must adhere to the instance-config API. The developer’s create playbook must provide the following instance-config data, and the developer’s destroy playbook must reset the instance-config.

- address: ssh_endpoint
  identity_file: ssh_identity_file  # mutually exclusive with password
  instance: instance_name
  port: ssh_port_as_string
  user: ssh_user
  password: ssh_password  # mutually exclusive with identity_file
  become_method: valid_ansible_become_method  # optional
  become_pass: password_if_required  # optional

- address: winrm_endpoint
  instance: instance_name
  connection: 'winrm'
  port: winrm_port_as_string
  user: winrm_user
  password: winrm_password
  winrm_transport: ntlm/credssp/kerberos
  winrm_cert_pem: <path to the credssp public certificate key>
  winrm_cert_key_pem: <path to the credssp private certificate key>
  winrm_server_cert_validation: validate/ignore

This article covers how to configure and use WinRM with Ansible: https://docs.ansible.com/ansible/latest/user_guide/windows_winrm.html

Molecule can also skip the provisioning/deprovisioning steps. It is the developers responsibility to manage the instances, and properly configure Molecule to connect to said instances.

driver:
  name: delegated
  options:
    managed: False
    login_cmd_template: 'docker exec -ti {instance} bash'
    ansible_connection_options:
      ansible_connection: docker
platforms:
  - name: instance-docker
$ docker run \
    -d \
    --name instance-docker \
    --hostname instance-docker \
    -it molecule_local/ubuntu:latest sleep infinity & wait

Use Molecule with delegated instances, which are accessible over ssh.

Important

It is the developer’s responsibility to configure the ssh config file.

driver:
  name: delegated
  options:
    managed: False
    login_cmd_template: 'ssh {instance} -F /tmp/ssh-config'
    ansible_connection_options:
      ansible_connection: ssh
      ansible_ssh_common_args: '-F /path/to/ssh-config'
platforms:
  - name: instance

Provide the files Molecule will preserve post destroy action.

driver:
  name: delegated
  safe_files:
    - foo

And in order to use localhost as molecule’s target:

driver:
  name: delegated
  options:
    managed: False
    ansible_connection_options:
      ansible_connection: local

Construct Delegated.

Lint

Starting with v3, Molecule handles project linting by invoking and external lint commands as exemplified below.

The decision to remove the complex linting support was not easily taken as we do find it very useful. The issue was that molecule runs on scenarios and linting is usually performed at repository level.

It makes little sense to perform linting in more than one place per project. Molecule was able to use up to three linters and while it was aimed to flexible about them, it ended up creating more confusions to the users. We decided to maximize flexibility by just calling an external shell command.

lint: |
  set -e
  yamllint .
  ansible-lint
  flake8

The older format is no longer supported and you have to update the molecule.yml when you upgrade. If you don’t want to do any linting, it will be enough to remove all lint related sections from the file.

# old v2 format, no longer supported
lint:
  name: yamllint
  enabled: true
provisioner:
  lint:
    name: ansible-lint
  options: ...
  env: ...
verifier:
  lint:
    name: flake8

Platforms

class molecule.platforms.Platforms

Platforms define the instances to be tested, and the groups to which the instances belong.

platforms:
  - name: instance-1

Multiple instances can be provided.

platforms:
  - name: instance-1
  - name: instance-2

Mapping instances to groups. These groups will be used by the Provisioner for orchestration purposes.

platforms:
  - name: instance-1
    groups:
      - group1
      - group2

Children allow the creation of groups of groups.

platforms:
  - name: instance-1
    groups:
      - group1
      - group2
    children:
      - child_group1

Initialize a new platform class and returns None.

Parameters

config – An instance of a Molecule config.

Returns

None

Provisioner

Molecule handles provisioning and converging the role.

Ansible

class molecule.provisioner.ansible.Ansible

Ansible is the default provisioner. No other provisioner will be supported.

Molecule’s provisioner manages the instances lifecycle. However, the user must provide the create, destroy, and converge playbooks. Molecule’s init subcommand will provide the necessary files for convenience.

Molecule will skip tasks which are tagged with either molecule-notest or notest. With the tag molecule-idempotence-notest tasks are only skipped during the idempotence action step.

Important

Reserve the create and destroy playbooks for provisioning. Do not attempt to gather facts or perform operations on the provisioned nodes inside these playbooks. Due to the gymnastics necessary to sync state between Ansible and Molecule, it is best to perform these tasks in the prepare or converge playbooks.

It is the developers responsiblity to properly map the modules’s fact data into the instance_conf_dict fact in the create playbook. This allows Molecule to properly configure Ansible inventory.

Additional options can be passed to ansible-playbook through the options dict. Any option set in this section will override the defaults.

Important

Options do not affect the create and destroy actions.

Note

Molecule will remove any options matching ‘^[v]+$’, and pass -vvv to the underlying ansible-playbook command when executing molecule –debug.

Molecule will silence log output, unless invoked with the --debug flag. However, this results in quite a bit of output. To enable Ansible log output, add the following to the provisioner section of molecule.yml.

provisioner:
  name: ansible
  log: True

The create/destroy playbooks for Docker and Podman are bundled with Molecule. These playbooks have a clean API from molecule.yml, and are the most commonly used. The bundled playbooks can still be overridden.

The playbook loading order is:

  1. provisioner.playbooks.$driver_name.$action

  2. provisioner.playbooks.$action

  3. bundled_playbook.$driver_name.$action

provisioner:
  name: ansible
  options:
    vvv: True
  playbooks:
    create: create.yml
    converge: converge.yml
    destroy: destroy.yml

Share playbooks between roles.

provisioner:
  name: ansible
  playbooks:
    create: ../default/create.yml
    destroy: ../default/destroy.yml
    converge: converge.yml

Multiple driver playbooks. In some situations a developer may choose to test the same role against different backends. Molecule will choose driver specific create/destroy playbooks, if the determined driver has a key in the playbooks section of the provisioner’s dict.

Important

If the determined driver has a key in the playbooks dict, Molecule will use this dict to resolve all provisioning playbooks (create/destroy).

provisioner:
  name: ansible
  playbooks:
    docker:
      create: create.yml
      destroy: destroy.yml
    create: create.yml
    destroy: destroy.yml
    converge: converge.yml

Important

Paths in this section are converted to absolute paths, where the relative parent is the $scenario_directory.

The side effect playbook executes actions which produce side effects to the instances(s). Intended to test HA failover scenarios or the like. It is not enabled by default. Add the following to the provisioner’s playbooks section to enable.

provisioner:
  name: ansible
  playbooks:
    side_effect: side_effect.yml

Important

This feature should be considered experimental.

The prepare playbook executes actions which bring the system to a given state prior to converge. It is executed after create, and only once for the duration of the instances life.

This can be used to bring instances into a particular state, prior to testing.

provisioner:
  name: ansible
  playbooks:
    prepare: prepare.yml

The cleanup playbook is for cleaning up test infrastructure that may not be present on the instance that will be destroyed. The primary use-case is for “cleaning up” changes that were made outside of Molecule’s test environment. For example, remote database connections or user accounts. Intended to be used in conjunction with prepare to modify external resources when required.

The cleanup step is executed directly before every destroy step. Just like the destroy step, it will be run twice. An initial clean before converge and then a clean before the last destroy step. This means that the cleanup playbook must handle failures to cleanup resources which have not been created yet.

Add the following to the provisioner’s playbooks section to enable.

provisioner:
  name: ansible
  playbooks:
    cleanup: cleanup.yml

Important

This feature should be considered experimental.

Environment variables. Molecule does its best to handle common Ansible paths. The defaults are as follows.

ANSIBLE_ROLES_PATH:
  $ephemeral_directory/roles/:$project_directory/../:~/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles
ANSIBLE_LIBRARY:
  $ephemeral_directory/modules/:$project_directory/library/:~/.ansible/plugins/modules:/usr/share/ansible/plugins/modules
ANSIBLE_FILTER_PLUGINS:
  $ephemeral_directory/plugins/filter/:$project_directory/filter/plugins/:~/.ansible/plugins/filter:/usr/share/ansible/plugins/modules

Environment variables can be passed to the provisioner. Variables in this section which match the names above will be appened to the above defaults, and converted to absolute paths, where the relative parent is the $scenario_directory.

Important

Paths in this section are converted to absolute paths, where the relative parent is the $scenario_directory.

provisioner:
  name: ansible
  env:
    FOO: bar

Modifying ansible.cfg.

provisioner:
  name: ansible
  config_options:
    defaults:
      fact_caching: jsonfile
    ssh_connection:
      scp_if_ssh: True

Important

The following keys are disallowed to prevent Molecule from improperly functioning. They can be specified through the provisioner’s env setting described above, with the exception of the privilege_escalation.

provisioner:
  name: ansible
  config_options:
    defaults:
      roles_path: /path/to/roles_path
      library: /path/to/library
      filter_plugins: /path/to/filter_plugins
    privilege_escalation: {}

Roles which require host/groups to have certain variables set. Molecule uses the same variables defined in a playbook syntax as Ansible.

provisioner:
  name: ansible
  inventory:
    group_vars:
      foo1:
        foo: bar
      foo2:
        foo: bar
        baz:
          qux: zzyzx
    host_vars:
      foo1-01:
        foo: bar

Molecule automatically generates the inventory based on the hosts defined under Platforms. Using the hosts key allows to add extra hosts to the inventory that are not managed by Molecule.

A typical use case is if you want to access some variables from another host in the inventory (using hostvars) without creating it.

Note

The content of hosts should follow the YAML based inventory syntax: start with the all group and have hosts/vars/children entries.

provisioner:
  name: ansible
  inventory:
    hosts:
      all:
        extra_host:
          foo: hello

Important

The extra hosts added to the inventory using this key won’t be created/destroyed by Molecule. It is the developers responsibility to target the proper hosts in the playbook. Only the hosts defined under Platforms should be targetted instead of all.

An alternative to the above is symlinking. Molecule creates symlinks to the specified directory in the inventory directory. This allows ansible to converge utilizing its built in host/group_vars resolution. These two forms of inventory management are mutually exclusive.

Like above, it is possible to pass an additional inventory file (or even dynamic inventory script), using the hosts key. Ansible will automatically merge this inventory with the one generated by molecule. This can be useful if you want to define extra hosts that are not managed by Molecule.

Important

Again, it is the developers responsibility to target the proper hosts in the playbook. Only the hosts defined under Platforms should be targetted instead of all.

Note

The source directory linking is relative to the scenario’s directory.

The only valid keys are hosts, group_vars and host_vars. Molecule’s schema validator will enforce this.

provisioner:
  name: ansible
  inventory:
    links:
      hosts: ../../../inventory/hosts
      group_vars: ../../../inventory/group_vars/
      host_vars: ../../../inventory/host_vars/

Override connection options:

provisioner:
  name: ansible
  connection_options:
    ansible_ssh_user: foo
    ansible_ssh_common_args: -o IdentitiesOnly=no

Add arguments to ansible-playbook when running converge:

provisioner:
  name: ansible
  ansible_args:
    - --inventory=mygroups.yml
    - --limit=host1,host2

Initialize a new ansible class and returns None.

Parameters

config – An instance of a Molecule config.

Returns

None

Scenario

Molecule treats scenarios as a first-class citizens, with a top-level configuration syntax.

class molecule.scenario.Scenario

A scenario allows Molecule test a role in a particular way, this is a fundamental change from Molecule v1.

A scenario is a self-contained directory containing everything necessary for testing the role in a particular way. The default scenario is named default, and every role should contain a default scenario.

Unless mentioned explicitly, the scenario name will be the directory name hosting the files.

Any option set in this section will override the defaults.

scenario:
  create_sequence:
    - dependency
    - create
    - prepare
  check_sequence:
    - dependency
    - cleanup
    - destroy
    - create
    - prepare
    - converge
    - check
    - destroy
  converge_sequence:
    - dependency
    - create
    - prepare
    - converge
  destroy_sequence:
    - dependency
    - cleanup
    - destroy
  test_sequence:
    - dependency
    - lint
    - cleanup
    - destroy
    - syntax
    - create
    - prepare
    - converge
    - idempotence
    - side_effect
    - verify
    - cleanup
    - destroy

Initialize a new scenario class and returns None.

Parameters

config – An instance of a Molecule config.

Returns

None

State

An internal bookkeeping mechanism.

class molecule.state.State

A class which manages the state file.

Intended to be used as a singleton throughout a given Molecule config. The initial state is serialized to disk if the file does not exist, otherwise is deserialized from the existing state file. Changes made to the object are immediately serialized.

State is not a top level option in Molecule’s config. It’s purpose is for bookkeeping, and each Config object has a reference to a State object.

Note

Currently, it’s use is significantly smaller than it was in v1 of Molecule.

Initialize a new state class and returns None.

Parameters

config – An instance of a Molecule config.

Returns

None

Verifier

Molecule handles role testing by invoking configurable verifiers.

Ansible

class molecule.verifier.ansible.Ansible

Ansible is the default test verifier.

Molecule executes a playbook (verify.yml) located in the role’s scenario.directory.

verifier:
  name: ansible

The testing can be disabled by setting enabled to False.

verifier:
  name: ansible
  enabled: False

Environment variables can be passed to the verifier.

verifier:
  name: ansible
  env:
    FOO: bar

Initialize code for all Verifier classes.

Parameters

config – An instance of a Molecule config.

Returns

None

Testinfra

class molecule.verifier.testinfra.Testinfra

Testinfra is no longer the default test verifier since version 3.0.

Additional options can be passed to testinfra through the options dict. Any option set in this section will override the defaults.

Note

Molecule will remove any options matching ‘^[v]+$’, and pass -vvv to the underlying pytest command when executing molecule --debug.

verifier:
  name: testinfra
  options:
    n: 1

The testing can be disabled by setting enabled to False.

verifier:
  name: testinfra
  enabled: False

Environment variables can be passed to the verifier.

verifier:
  name: testinfra
  env:
    FOO: bar

Change path to the test directory.

verifier:
  name: testinfra
  directory: /foo/bar/

Additional tests from another file or directory relative to the scenario’s tests directory (supports regexp).

verifier:
  name: testinfra
  additional_files_or_dirs:
    - ../path/to/test_1.py
    - ../path/to/test_2.py
    - ../path/to/directory/*

Set up the requirements to execute testinfra and returns None.

Parameters

config – An instance of a Molecule config.

Returns

None