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awx/docs/custom_virtualenvs.md
Vismay Golwala ec390b049d Feature: custom virtual environment directories
Currently, users are allowed to define virtual environments in
`settings.BASE_VENV_PATH` only, because that's the only place
Tower looks for virtual environments. This feature allows users
to custom define the directory paths, using API or UI, to look
for virtual environments. Tower aggregates virtual environments
from all these paths, except environments with special name `awx`.

Signed-off-by: Vismay Golwala <vgolwala@redhat.com>
2019-03-26 12:04:17 -04:00

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Managing Custom Python Dependencies
===================================
awx installations pre-build a special [Python
virtualenv](https://pypi.python.org/pypi/virtualenv) which is automatically
activated for all `ansible-playbook` runs invoked by awx (for example, any time
a Job Template is launched). By default, this virtualenv is located at
`/var/lib/awx/venv/ansible` on the file system.
awx pre-installs a variety of third-party library/SDK support into this
virtualenv for its integration points with a variety of cloud providers (such
as EC2, OpenStack, Azure, etc...)
Periodically, awx users want to add additional SDK support into this
virtualenv; this documentation describes the supported way to do so.
Preparing a New Custom Virtualenv
=================================
awx allows a _different_ virtualenv to be specified and used on Job Template
runs. To choose a custom virtualenv, first we need to create one. Here, we are
using `/opt/my-envs/` as the directory to hold custom venvs. But you can use any
other directory and replace `/opt/my-envs/` with that. Let's create the directory
first if absent:
$ sudo mkdir /opt/my-envs
Now, we need to tell Tower to look into this directory for custom venvs. For that,
we can add this directory to the `CUSTOM_VENV_PATHS` setting as:
$ HTTP PATCH /api/v2/settings/system {'CUSTOM_VENV_PATHS': ["/opt/my-envs/"]}
If we have venvs spanned over multiple directories, we can add all the paths and
Tower will aggregate venvs from them:
$ HTTP PATCH /api/v2/settings/system {'CUSTOM_VENV_PATHS': ["/path/1/to/venv/",
"/path/2/to/venv/",
"/path/3/to/venv/"]}
Now that we have the directory setup, we can create a virtual environment in that using:
$ sudo virtualenv /opt/my-envs/custom-venv
Multiple versions of Python are supported, though it's important to note that
the semantics for creating virtualenvs in Python 3 has changed slightly:
$ sudo python3 -m venv /opt/my-envs/custom-venv
Your newly created virtualenv needs a few base dependencies to properly run
playbooks:
fact gathering):
$ sudo /opt/my-envs/custom-venv/bin/pip install psutil
From here, you can install _additional_ Python dependencies that you care
about, such as a per-virtualenv version of ansible itself:
$ sudo /opt/my-envs/custom-venv/bin/pip install -U "ansible == X.Y.Z"
...or an additional third-party SDK that's not included with the base awx installation:
$ sudo /opt/my-envs/custom-venv/bin/pip install -U python-digitalocean
If you want to copy them, the libraries included in awx's default virtualenv
can be found using `pip freeze`:
$ sudo /var/lib/awx/venv/ansible/bin/pip freeze
One important item to keep in mind is that in a clustered awx installation,
you need to ensure that the same custom virtualenv exists on _every_ local file
system at `/opt/my-envs/`. For container-based deployments, this likely
means building these steps into your own custom image building workflow, e.g.,
```diff
diff --git a/Makefile b/Makefile
index aa8b304..eb05f91 100644
--- a/Makefile
+++ b/Makefile
@@ -164,6 +164,10 @@ requirements_ansible_dev:
$(VENV_BASE)/ansible/bin/pip install pytest mock; \
fi
+requirements_custom:
+ mkdir -p /opt/my-envs
+ virtualenv /opt/my-envs/my-custom-env
+ /opt/my-envs/my-custom-env/bin/pip install psutil
+
diff --git a/installer/image_build/templates/Dockerfile.j2 b/installer/image_build/templates/Dockerfile.j2
index d69e2c9..a08bae5 100644
--- a/installer/image_build/templates/Dockerfile.j2
+++ b/installer/image_build/templates/Dockerfile.j2
@@ -34,6 +34,7 @@ RUN yum -y install epel-release && \
pip install virtualenv supervisor && \
VENV_BASE=/var/lib/awx/venv make requirements_ansible && \
VENV_BASE=/var/lib/awx/venv make requirements_awx && \
+ VENV_BASE=/var/lib/awx/venv make requirements_custom && \
```
Once the AWX API is available, update the `CUSTOM_VENV_PATHS` setting as described in `Preparing a New Custom Virtualenv`.
Kubernetes Custom Virtualenvs
=============================
You can create custom virtualenvs without updating the awx images by using initContainers and a shared emptydir within Kubernetes. To start create an emptydir volume in the volumes stanza.
volumes:
- emptyDir: {}
name: custom-venv
Now create an initContainer stanza. You can subsititute your own custom images for this example we are using centos:7 as the base to build upon. The command stanza is where you will add the python modules you require in your virtualenv.
initContainers:
- image: 'centos:7'
name: init-custom-venv
command:
- sh
- '-c'
- >-
yum install -y ansible python-pip curl python-setuptools epel-release openssl openssl-devel gcc python-devel &&
curl 'https://bootstrap.pypa.io/get-pip.py' | python &&
pip install virtualenv &&
mkdir -p /opt/my-envs &&
virtualenv /opt/my-envs/custom-venv &&
source /opt/my-envs/custom-venv/bin/activate &&
/opt/my-envs/custom-venv/bin/pip install psutil &&
/opt/my-envs/custom-venv/bin/pip install -U "ansible == X.Y.Z" &&
/opt/my-envs/custom-venv/bin/pip install -U custom-python-module
volumeMounts:
- mountPath: /opt/my-envs/custom-venv
name: custom-venv
Finally in the awx-celery and awx-web containers stanza add the shared volume as a mount.
volumeMounts:
- mountPath: /opt/my-envs/custom-venv
name: custom-venv
- mountPath: /etc/tower
name: awx-application-config
readOnly: true
- mountPath: /etc/tower/conf.d
name: awx-confd
readOnly: true
Once the AWX API is available, update the `CUSTOM_VENV_PATHS` setting as described in `Preparing a New Custom Virtualenv`.
Assigning Custom Virtualenvs
============================
Once you've created a custom virtualenv, you can assign it at the Organization,
Project, or Job Template level:
PATCH https://awx-host.example.org/api/v2/organizations/N/
PATCH https://awx-host.example.org/api/v2/projects/N/
PATCH https://awx-host.example.org/api/v2/job_templates/N/
Content-Type: application/json
{
'custom_virtualenv': '/opt/my-envs/custom-venv'
}
An HTTP `GET` request to `/api/v2/config/` will provide a list of
detected installed virtualenvs:
{
"custom_virtualenvs": [
"/opt/my-envs/custom-venv",
"/opt/my-envs/my-other-custom-venv",
],
...
}