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Added info for testing collections
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audgirka committed Aug 9, 2023
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6 changes: 3 additions & 3 deletions docs/examples.md
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Expand Up @@ -275,8 +275,8 @@ platforms:

## Monolith Repo

Molecule is generally used to test roles in isolation. However, it can
also test roles from a monolith repo.
Molecule is generally used to test playbooks or roles in isolation.
However, it can also test them from a monolith repo.

```bash
$ tree monolith-repo -L 3 --prune
Expand All @@ -296,7 +296,7 @@ monolith-repo
```

The role initialized with Molecule (baz in this case) would simply
reference the dependent roles via it's `converge.yml` or meta
reference the dependent roles via its `converge.yml` or meta
dependencies.

Molecule can test complex scenarios leveraging this technique.
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178 changes: 99 additions & 79 deletions docs/getting-started.md
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@@ -1,66 +1,39 @@
# Getting Started Guide
# Getting Started With Molecule

The following guide will step through an example of developing and
testing a new Ansible collection. After reading this guide, you should be
familiar with the basics of how to use Molecule and what it can offer.

!!! note

To complete this guide by hand, you will need to additionally
install [Docker](https://docs.docker.com/). Molecule requires an
external Python dependency for the Docker driver which is provided when
installing Molecule using `pip install 'molecule-plugins[docker]'`.

## Create a collection and test with molecule

One of the recommended ways to create a collection is to place it
under the `collections/ansible_collections` directory.

To create a collection, use the `ansible-galaxy` tool.
`ansible-galaxy collection init <namespace>.<collection_name>`
Example: `ansible-galaxy collection init foo.bar`

After a collection is created, it would be under
`collections/ansible_collections/<namespace>/<collection_name>`
See [Collection structure](https://docs.ansible.com/ansible/5/dev_guide/developing_collections_structure.html#collection-structure) for details on the collection directory structure.

Inside the collection, create a directory named `extensions`
and initialize `molecule scenario` under this directory using
the command: `molecule init scenario <scenario_name>`
`scenario_name` is optional, if not provided, will create
a `default` scenario.
Molecule is a testing framework built specifically to test Ansible roles and playbooks within a collection.

Also, create an ansible configuration `ansible.cfg` file under the `extensions` directory.
Add the `collections_path` to this configuration file.
Molecule aims to test your Ansible roles and playbooks in isolation
as it launches an environment to run your playbook and then performs tests over it.
You can then run your playbook over different instance types and versions to verify if it still runs.

![Collection Structure and ansible config file collections path](images/collection_structure_and_ansible_cfg.png)
Before moving to test the playbooks or roles, the sections below provide information related to Scenarios.

## Molecule Scenarios

You will notice one new folder which is the `molecule` folder.

In this folder, there is a single `root_scenario` called `default`.
In this folder, there is a single scenario called `default`.

Scenarios are the starting point for a lot of powerful functionality
that Molecule offers. For now, we can think of a scenario as a test
suite for your newly created role. You can have as many scenarios as you
suite for roles or playbooks within a collection. You can have as many scenarios as you
like and Molecule will run one after the other.

## The Scenario Layout

Within the `molecule/default` folder, we find a number of files and
Within the `molecule/default` folder, we find several files and
directories:

```bash
$ ls
create.yml destroy.yml molecule.yml converge.yml verify.yml
create.yml destroy.yml molecule.yml converge.yml
```

- `create.yml` is a playbook file used for creating the instances
and storing data in instance-config
- `destroy.yml` has the Ansible code for destroying the instances
and removing them from instance-config
- `molecule.yml` is the central configuration entry point for Molecule.
- `molecule.yml` is the central configuration entry point for Molecule per scenario.
With this file, you can configure each tool that Molecule will
employ when testing your role.
- `converge.yml` is the playbook file that contains the call for your
Expand Down Expand Up @@ -92,7 +65,7 @@ create.yml destroy.yml molecule.yml converge.yml verify.yml
## Inspecting the `molecule.yml`

The `molecule.yml` is for configuring Molecule. It is a
[YAML](https://yaml.org/) file whose keys represent the high level
[YAML](https://yaml.org/) file whose keys represent the high-level
components that Molecule provides. These are:

- The [dependency](configuration.md#dependency) manager. Molecule
Expand All @@ -117,75 +90,81 @@ components that Molecule provides. These are:
checking tests (such as deployment smoke tests) on the target
instance.

## Run test sequence commands

Let's create the first Molecule managed instance with the Docker
driver.
The following guide will step through an example of developing and
testing a new Ansible collection. After reading this guide, you should be
familiar with the basics of how to use Molecule and what it can offer.

First, ensure that [Docker](https://docs.docker.com/) is running with
the typical sanity check:
## Create a collection

```bash
$ docker run hello-world
```
One of the recommended ways to create a collection is to place it
under the `collections/ansible_collections` directory.

Now, we can tell Molecule to create an instance with:
To create a collection, use the `ansible-galaxy` tool.
`ansible-galaxy collection init <namespace>.<collection_name>`
Example: `ansible-galaxy collection init foo.bar`

```bash
$ molecule create
```
After a collection is created, it would be under
`collections/ansible_collections/<namespace>/<collection_name>`
See [Collection structure](https://docs.ansible.com/ansible/5/dev_guide/developing_collections_structure.html#collection-structure) for details on the collection directory structure.

We can verify that Molecule has created the instance and they're up and
running with:
## Create a role inside the collection

```bash
$ molecule list
```
To initialize a role inside a collection we can again use `ansible-galaxy` tool under the `roles` directory.
`ansible-galaxy role init <namespace>.<collection_name>`
Example: `ansible-galaxy collection init my_role`

Now, let's add a task to our `tasks/main.yml` like so:
Once the role is created, add a task under `my_role/tasks/main.yml`.

```yaml
- name: Molecule Hello World!
```
---
- name: Task is running from within the role
ansible.builtin.debug:
msg: Hello, World!
msg: "This is a task from my_role."
```

We can then tell Molecule to test our role against our instance with:
## Create a playbook inside the collection

```bash
$ molecule converge
```
Under the collection, we can create a directory named `playbooks`
and create a new playbook file under it.
Example: `my_playbook.yml`

If we want to manually inspect the instance afterwards, we can run:

```bash
$ molecule login
```
---
- name: Test new role from within this playbook
hosts: localhost
gather_facts: false
tasks:
- name: Testing role
ansible.builtin.include_role:
name: foo.bar.my_role
tasks_from: main.yml
We now have a free hand to experiment with the instance state.
```

Finally, we can exit the instance and destroy it with:
## Adding Molecule to the Collection

```bash
$ molecule destroy
```
Inside the collection, create a directory named `extensions`
and initialize `molecule scenario` under this directory using
the command: `molecule init scenario <scenario_name>`
`scenario_name` is optional, if not provided, will create
a `default` scenario.

!!! note
Also, create an ansible configuration `ansible.cfg` file under the `extensions` directory.
Add the `collections_path` to this configuration file.

If Molecule reports any errors, it can be useful to pass the `--debug`
option to get more verbose output.
![Collection Structure and ansible config file collections path](images/collection_structure_and_ansible_cfg.png)

## Run a full test sequence

Molecule provides commands for manually managing the lifecycle of the
instance, scenario, development and testing tools. However, we can also
tell Molecule to manage this automatically within a
`root_scenario` sequence.
scenario sequence.

The full lifecycle sequence can be invoked with:

```bash
$ molecule test
molecule test
```

```
Expand Down Expand Up @@ -217,3 +196,44 @@ Molecule full lifecycle sequence
only. It is useful if you want to test one platform docker image.

[galaxy development guide]: https://docs.ansible.com/ansible/latest/galaxy/dev_guide.html

## Test the collection playbook or role

So you now have an isolated test environment, and can also use it for live development, by running `molecule converge`.
It will run through the same steps as above but will stop after the converge action.
Then you can make changes to your collection or the Converge play, and then run molecule converge again (and again) until you're done with your development work.

One of the default files created as part of the initialization is the `converge.yml` file.
This file is a playbook created to run your role from start to finish.
This can be modified if needed but is a good place to start if you have never used Molecule before.

To test the playbook from a collection,
let's add a task to our role under `tasks/main.yml` file like so:

```
---
- name: Include a playbook from a collection
ansible.builtin.import_playbook: foo.bar.my_playbook
```

Similarly, if we want to test only the role instead of a playbook in `converge.yml` file:

```
---
- name: Include a role from a collection
hosts: localhost
gather_facts: false
tasks:
- name: Testing role
ansible.builtin.include_role:
name: foo.bar.my_role
tasks_from: main.yml
```

```bash
molecule converge
```

The above command will run this specific playbook for us.
48 changes: 48 additions & 0 deletions docs/usage.md
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Expand Up @@ -63,3 +63,51 @@ Matrix will display the subcommand's ordered list of actions, which can
be changed in
[scenario](configuration.md#scenario)
configuration.

## Test sequence commands

We can tell Molecule to create an instance with:

```bash
molecule create
```

We can verify that Molecule has created the instance and they're up and
running with:

```bash
molecule list
```

Now, let's add a task to our role under `tasks/main.yml` file like so:

```yaml
- name: Molecule Hello World!
ansible.builtin.debug:
msg: Hello, World!
```
We can then tell Molecule to test our role against our instance with:
```bash
molecule converge
```

If we want to manually inspect the instance afterward, we can run:

```bash
molecule login
```

We now have a free hand to experiment with the instance state.

Finally, we can exit the instance and destroy it with:

```bash
molecule destroy
```

!!! note

If Molecule reports any errors, it can be useful to pass the `--debug`
option to get more verbose output.

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