How to automatically install Ansible Galaxy roles?

You should use a requirements.yml file for this use-case. Describe the roles you require, using any of a variety of install methods:

# Install a role from the Ansible Galaxy
- src: dfarrell07.opendaylight

# Install a role from GitHub
- name: opendaylight
  src: https://github.com/dfarrell07/ansible-opendaylight

# Install a role from a specific git branch
- name: opendaylight
  src: https://github.com/dfarrell07/ansible-opendaylight
  version: origin/master

# Install a role at a specific tag from GitHub
- name: opendaylight
  src: https://github.com/dfarrell07/ansible-opendaylight
  version: 1.0.0

# Install a role at a specific commit from GitHub
- name: opendaylight
  src: https://github.com/dfarrell07/ansible-opendaylight
  version: <commit hash>

Then install them:

ansible-galaxy install -r requirements.yml

Here's a working example (installing OpenDaylight using Ansible as a Vagrant provisioner). See the relevant Ansible docs for more info.

Another solution is to use git submodules. After all, Ansible Galaxy only is a directory of github repositories...

I use this command to automatically add any Galaxy role as a submodule:

ansible-galaxy info <package> | grep -A 1 github_repo | tr '\n' ' ' | sed -e "s/.*github_repo: \([^[:space:]]*\)[^\w]*github_user: \([^[:space:]]*\)[[:space:]]*/git submodule add git:\/\/github.com\/\2\/\1.git roles\/\2.\1/g" | sh

Commit the changes then to your git repo. When you clone your repo in future make sure to clone it with submodules, e.g. git clone ... --recursive

An advantage of this is, a git submodule is always referencing a specific version (git commit-hash). This will prevent you from running untested updates in your productive environment. A new version of a Galaxy role could have bugs or work completely different than before. With a git submodule you decide if and when you update a role to the new version.

Also, you won't have to additionally take care of blacklisting galaxy roles in your .gitignore to prevent committing their code to your repository.

Some time ago I had exactly the same problem, and i have created a script for that. It gathers role dependencies from the meta/main.yml file, and then downloads them from ansible galaxy.

You can find the script here: https://github.com/rtuin/ansible-install-dependencies

I hope this is a solution for your problem.

As suggested, you can use ansible galaxy for this need. If you would like to further automate it then, you can add ansible galaxy inside your playbooks.

For example:

- name: run ansible galaxy
  local_action: command ansible-galaxy install -r requirements.yml --ignore-errors

At this point in time, as far as I know there's no automatic way to download roles at runtime. Your best bet is to either commit them into your own repo or have a proper documentation listing all the requirements. You could even create a pre-flight playbook that installs your roles. :)