Add docs/ansible.md

README.md

@@ -6,6 +6,8 @@ By running services in containers, we can have a predictable and up-to-date setu
 
 This project is fairly new and only [supports a handful of services](docs/supported-services.md) so far, but will grow to support self-hosting a large number of [FOSS](https://en.wikipedia.org/wiki/Free_and_open-source_software) pieces of software.
 
+[Installation](docs/README.md) (upgrades) and some maintenance tasks are automated using [Ansible](https://www.ansible.com/) (see [our Ansible guide](docs/ansible.md)).
+
 
 ## Supported services
 

docs/ansible.md

@@ -0,0 +1,121 @@
+
+# Running this playbook
+
+This playbook is meant to be run using [Ansible](https://www.ansible.com/).
+
+Ansible typically runs on your local computer and carries out tasks on a remote server.
+If your local computer cannot run Ansible, you can also run Ansible on some server somewhere (including the server you wish to install to).
+
+
+## Supported Ansible versions
+
+To manually check which version of Ansible you're on, run: `ansible --version`.
+
+For the **best experience**, we recommend getting the **latest version of Ansible available**.
+
+We're not sure what's the minimum version of Ansible that can run this playbook successfully.
+The lowest version that we've confirmed (on 2022-11-26) to be working fine is: `ansible-core` (`2.11.7`) combined with `ansible` (`4.10.0`).
+
+If your distro ships with an Ansible version older than this, you may run into issues. Consider [Upgrading Ansible](#upgrading-ansible) or [using Ansible via Docker](#using-ansible-via-docker).
+
+
+## Upgrading Ansible
+
+Depending on your distribution, you may be able to upgrade Ansible in a few different ways:
+
+- by using an additional repository (PPA, etc.), which provides newer Ansible versions. See instructions for [CentOS](https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#installing-ansible-on-rhel-centos-or-fedora), [Debian](https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#installing-ansible-on-debian), or [Ubuntu](https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#installing-ansible-on-ubuntu) on the Ansible website.
+
+- by removing the Ansible package (`yum remove ansible` or `apt-get remove ansible`) and installing via [pip](https://pip.pypa.io/en/stable/installation/) (`pip install ansible`).
+
+If using the `pip` method, do note that the `ansible-playbook` binary may not be on the `$PATH` (https://linuxconfig.org/linux-path-environment-variable), but in some more special location like `/usr/local/bin/ansible-playbook`. You may need to invoke it using the full path.
+
+
+**Note**: Both of the above methods are a bad way to run system software such as Ansible.
+If you find yourself needing to resort to such hacks, please consider reporting a bug to your distribution and/or switching to a sane distribution, which provides up-to-date software.
+
+
+## Using Ansible via Docker
+
+Alternatively, you can run Ansible inside a Docker container (powered by the [devture/ansible](https://hub.docker.com/r/devture/ansible/) Docker image).
+
+This ensures that you're using a very recent Ansible version, which is less likely to be incompatible with the playbook.
+
+You can either [run Ansible in a container on the server itself](#running-ansible-in-a-container-on-the-server-itself) or [run Ansible in a container on another computer (not the server)](#running-ansible-in-a-container-on-another-computer-not-the-server).
+
+
+### Running Ansible in a container on the server itself
+
+To run Ansible in a (Docker) container on the server itself, you need to have a working Docker installation.
+Docker is normally installed by the playbook, so this may be a bit of a chicken and egg problem. To solve it:
+
+- you **either** need to install [Docker](services/ansible.md) manually first. Follow [the upstream instructions](https://docs.docker.com/engine/install/) for your distribution and consider setting `mash_playbook_docker_installation_enabled: false` in your `vars.yml` file, to prevent the playbook from installing Docker
+- **or** you need to run the playbook in another way (e.g. [Running Ansible in a container on another computer (not the server)](#running-ansible-in-a-container-on-another-computer-not-the-server)) at least the first time around
+
+Once you have a working Docker installation on the server, **clone the playbook** somewhere on the server and configure it as per usual (`inventory/hosts`, `inventory/host_vars/..`, etc.), as described in [configuring the playbook](configuring-playbook.md).
+
+You would then need to add `ansible_connection=community.docker.nsenter` to the host line in `inventory/hosts`. This tells Ansible to connect to the "remote" machine by switching Linux namespaces with [nsenter](https://man7.org/linux/man-pages/man1/nsenter.1.html), instead of using SSH.
+Alternatively, you can leave your `inventory/hosts` as is and specify the connection type in **each** `ansible-playbook` call you do later, like this: `ansible-playbook --connection=community.docker.nsenter ...`
+
+Run this from the playbook's directory:
+
+```bash
+docker run -it --rm \
+--privileged \
+--pid=host \
+-w /work \
+-v `pwd`:/work \
+--entrypoint=/bin/sh \
+docker.io/devture/ansible:2.13.6-r0-3
+```
+
+Once you execute the above command, you'll be dropped into a `/work` directory inside a Docker container.
+The `/work` directory contains the playbook's code.
+
+First, consider running `git config --global --add safe.directory /work` to [resolve directory ownership issues](#resolve-directory-ownership-issues).
+
+Finally, you can execute `ansible-playbook ...` (or `ansible-playbook --connection=community.docker.nsenter ...`) commands as per normal now.
+
+
+### Running Ansible in a container on another computer (not the server)
+
+Run this from the playbook's directory:
+
+```bash
+docker run -it --rm \
+-w /work \
+-v `pwd`:/work \
+-v $HOME/.ssh/id_rsa:/root/.ssh/id_rsa:ro \
+--entrypoint=/bin/sh \
+docker.io/devture/ansible:2.13.6-r0-3
+```
+
+The above command tries to mount an SSH key (`$HOME/.ssh/id_rsa`) into the container (at `/root/.ssh/id_rsa`).
+If your SSH key is at a different path (not in `$HOME/.ssh/id_rsa`), adjust that part.
+
+Once you execute the above command, you'll be dropped into a `/work` directory inside a Docker container.
+The `/work` directory contains the playbook's code.
+
+First, consider running `git config --global --add safe.directory /work` to [resolve directory ownership issues](#resolve-directory-ownership-issues).
+
+Finally, you execute `ansible-playbook ...` commands as per normal now.
+
+
+#### If you don't use SSH keys for authentication
+
+If you don't use SSH keys for authentication, simply remove that whole line (`-v $HOME/.ssh/id_rsa:/root/.ssh/id_rsa:ro`).
+To authenticate at your server using a password, you need to add a package. So, when you are in the shell of the ansible docker container (the previously used `docker run -it ...` command), run:
+```bash
+apk add sshpass
+```
+Then, to be asked for the password whenever running an  `ansible-playbook` command add `--ask-pass` to the arguments of the command.
+
+
+#### Resolve directory ownership issues
+
+Because you're `root` in the container running Ansible and this likely differs fom the owner (your regular user account) of the playbook directory outside of the container, certain playbook features which use `git` locally may report warnings such as:
+
+> fatal: unsafe repository ('/work' is owned by someone else)
+> To add an exception for this directory, call:
+>  git config --global --add safe.directory /work
+
+These errors can be resolved by making `git` trust the playbook directory by running `git config --global --add safe.directory /work`