.. _usage:

Usage

=====

Majic Ansible Roles are targeted at sysadmins who wish to deploy services for

their own, small-scale use. This chapter gives a simple tutorial-like set of

instructions for using all of the roles available.

.. contents:: :local:

Overview

--------

There is a number of different roles that can prove useful for setting-up a

small infrastructure of your own.

Some roles are suited for one-off operations during installation, like the

``preseed`` and ``bootstrap``, while some are better suited for periodic runs

for maintaining the users and integrity of the system.

By the end of following the instructions, you will have the following:

* Ansible server, used as controller for configuring and managing the

  remaining servers.

* Communications server, providing the LDAP, mail, and XMPP services.

* Web server, providing the web services.

* Backup server, used for storing all of the backups.

.. warning::

   Majic Ansible Roles support *only* Python 3 - both on the

   controller side and on the managed servers side.

   It is important to make sure that both the controller Python

   virtual environment used for Ansible *and* the interpreter for

   remote servers are *both* set-up to use Python 3.

   Python 3 is specified explicitly during virtual environment

   creation and in ``ansible.cfg`` configuration file

   (``interpreter_python`` option under ``defaults`` section).

Pre-requisites

--------------

For the set-up outlined in this usage guide you'll need the following:

  be installed on top of this server. The server will be set-up

  manually (this is currently out of scope for the *Majic Ansible

  Roles* automated set-up).

* Three servers where the services will be set-up. All servers must be able to

  communicate over network with each-other, the Ansible servers, and with

  usage instructions.

* All servers should be on the same network.

* IP addresses for all servers should be known.

* Netmask for all servers should be known.

* Gateway for all servers should be known.

In case of the servers listed above, it might be safest to have them as VMs -

this is cheapest thing to do, and simplest (who wants to deal with pesky hardware anyway?).

Usage instructions assume the following:

* Domain used for all servers is ``example.com``. If you wish to use a different

  domain, adjust the instructions accordingly.

* Server hostnames are ``ansible``, ``comms``, ``www``, and ``bak`` (for Ansible

  server, communications server, web server, and backup server, respectively).

Installing the OS on Ansible server

-----------------------------------

Start-off by installing the operating system on the Ansible server:

1. Fire-up the ``ansible`` server, and boot from the network installation CD.

2. Select the **Install** option.

3. Pick **English** as language.

4. Pick the country you are living in (or whatever else you want).

5. Pick the **en_US.UTF-8** locale.

6. Pick the **American English** keymap.

7. Configure the network if necessary.

8. Set the hostname to ``ansible``.

9. Set the domain to ``example.com``.

10. Set the root password.

11. Create a new user. For simplicity, call the user **Ansible user**, with

    username **ansible**.

12. Set-up partitioning in any way you want. You can go for **Guided - use

    entire disk** if you want to keep it simple and are just testing things.

13. Wait until the base system has been installed.

14. Pick whatever Debian archive mirror is closest to you.

15. If you have an HTTP proxy, provide its URL.

16. Pick if you want to participate in package survey or not.

17. Make sure that at least the **standard system utilities** and **SSH server**

    options are selected on task selection screen.

18. Wait for packages to be installed.

19. Install the GRUB boot loader on MBR.

20. Finalise the server install, and remove the installation media from server.

Installing required packages

----------------------------

With the operating system installed, it is necessary to install a couple of

packages, and to prepare the environment a bit on the Ansible server:

1. Install the necessary system packages (using the ``root`` account)::

     apt-get install -y virtualenv virtualenvwrapper git python3-pip python3-dev libffi-dev libssl-dev

   .. warning::

      If you are already logged-in as user ``ansible`` in the server, you will

      need to log-out and log-in again in order to be able to use

      ``virtualenvwrapper`` commands!

   ::

     mkdir ~/mysite/

     mkvirtualenv -p /usr/bin/python3 -a ~/mysite/ mysite

     pip install -U pip setuptools

     pip install 'ansible~=2.9.0' dnspython

.. warning::

   The ``dnspython`` package is important since it is used internally via

   ``dig`` lookup plugin.

Cloning the *Majic Ansible Roles*

---------------------------------

With most of the software pieces in place, the only missing thing is the Majic

Ansible Roles:

1. Clone the git repository::

     git clone https://code.majic.rs/majic-ansible-roles ~/majic-ansible-roles

2. Checkout the correct version of the roles::

     cd ~/majic-ansible-roles/

     git checkout -b 7.0-dev 7.0-dev

Preparing the basic site configuration

--------------------------------------

Phew... Now that was a bit tedious and boring... But at least you are now ready

to set-up your own site :)

First of all, let's set-up some basic directory structure and configuration:

1. Create Ansible configuration file.

   .. warning::

      Since Ansible 2.x has introduced much stricter controls over security of

      deployed Python scripts, it is recommended (as in this example) to use the

      ``pipelining`` option (which should also improve performance). This is in

      particular necessary in cases where the SSH user connecting to remote

      machine is *not* ``root``, but there are tasks that use ``become`` with

      non-root ``become_user`` (which is the case in Majic Ansible Roles). See

      `official documentation

      <https://docs.ansible.com/ansible/latest/become.html#becoming-an-unprivileged-user>`_

      and other alternatives to this.

   :file:`~/mysite/ansible.cfg`

   ::

     [defaults]

     roles_path=/home/ansible/majic-ansible-roles/roles:/home/ansible/mysite/roles

     force_handlers = True

     inventory = /home/ansible/mysite/hosts

     interpreter_python = /usr/bin/python3

     [ssh_connection]

     pipelining = True

2. Create directory where retry files will be stored at (so they woudln't

   pollute your home directory)::

     mkdir ~/mysite/retry

3. Create the inventory file.

   :file:`~/mysite/hosts`

   ::

     [preseed]

     localhost ansible_connection=local

     [communications]

     comms.example.com

     [web]

     www.example.com

     [backup]

     bak.example.com

4. Create a number of directories for storing playbooks, group

   variables, SSH keys, X.509 artefacts (for TLS), and GnuPG keyring

   (we'll get to this later)::

      ---

      - hosts: preseed

        roles:

          - preseed

2. Now we need to configure the role. Two parameters are mandatory -

   one that specifies where the preseed files are to be stored, and

   one that specifies the public key that should be used to

   pre-populate the SSH authorized keys for the ``root`` account. This

   is required for the initial bootstrap of servers because Debian

   GNU/Linux does not by default allow the ``root`` user to

   authenticate via SSH using a password. We will use the SSH public

   key generated earlier via the ``ssh-keygen`` command. Create the

   configuration file:

   :file:`~/mysite/group_vars/preseed.yml`

   ::

      ---

      # Public key used to authenticate remote logins via SSH for the

      # root account.

      ansible_key: "{{ lookup('file', '~/.ssh/id_rsa.pub') }}"

      # Directory where the preseed files will be output to.

      preseed_directory: "~/mysite/preseed_files/"

3. Now we can generate the pressed files::

     workon mysite && ansible-playbook playbooks/preseed.yml

4. If all went well, you should have the following files created:

   * :file:`~/mysite/preseed_files/comms.example.com.cfg`

   * :file:`~/mysite/preseed_files/www.example.com.cfg`

   * :file:`~/mysite/preseed_files/bak.example.com.cfg`

5. You can have a look at them, but you might notice the settings in the file

   might not be to your liking. In particular, it could be using wrong timezone,

   defaulting to DHCP for network configuration etc. Let's concentrate on making

   the network configuration changes - this is the main thing that will probably

   differ in your environment. Update the preseed configuration file:

   :file:`~/mysite/group_vars/preseed.yml`

   ::

      ---

      # Public key used to authenticate remote logins via SSH for the

      # root account.

      ansible_key: "{{ lookup('file', '~/.ssh/id_rsa.pub') }}"

      # Directory where the preseed files will be output to.

      preseed_directory: "~/mysite/preseed_files/"

      # Set your default (initial) root password.

      preseed_root_password: changeit

      # Use manual network configuration (no DHCP).

      preseed_network_auto: no

      # Set the gateway for all servers.

      preseed_gateway: 10.32.64.1

      # Set the netmask for all servers.

      preseed_netmask: 255.255.255.0

      # Set the DNS for all servers.

      preseed_dns: 10.32.64.1

      # Set the domain for all servers.

      preseed_domain: example.com

      # Set the server-specific options.

      preseed_server_overrides:

        comms.example.com:

          hostname: comms

          ip: 10.32.64.19

        www.example.com:

          hostname: www

          ip: 10.32.64.20

        bak.example.com:

          hostname: bak

          ip: 10.32.64.23

6. Now re-run the preseed playbook::

     workon mysite && ansible-playbook playbooks/preseed.yml

7. The preseed files should have been updated now, and you should have the new

   customised configuration files in the ``preseed_files`` directory. You can

   now use these to install the servers.

Installing the servers with preseed files

-----------------------------------------

You have your preseed files now, so you can go ahead and install the

servers ``comms.example.com``, ``www.example.com``, and

``bak.example.com`` using them with network install CD. Have a look at

`Debian instructions

more details.

If you need to, you can easily serve the preseed files from the Ansible server

with Python's built-in HTTP server::

  cd ~/mysite/preseed_files/

  python3 -m http.server 8000

Then you can point installer to the preseed file selecting the

``Advanced options -> Automated install`` (don't press ``ENTER`` yet),

then pressing ``TAB``, and appending the following at the end (just

fill-in the correct hostname - ``comms``, ``www``, or ``bak``)::

  url=http://ansible.example.com:8000/HOSTNAME.example.com.cfg

Bootstrapping servers for Ansible set-up

----------------------------------------

In order to effectively use Ansible, a small initial bootstrap always has to be

done for managed servers. This mainly involves set-up of Ansible users on the

destination machine, and distributing the SSH public keys for authorisation.

When you use the preseed configuration files to deploy a server, you get the

benefit of having the authorized_keys set-up for the root operating system user,

making it easier to bootstrap the machines subsequently via Ansible.

Let's bootstrap our machines now:

1. For start, create a dedicated playbook for the bootstrap process.

   :file:`~/mysite/playbooks/bootstrap.yml`

   ::

      ---

      - hosts:

          - communications

          - web

          - backup

        remote_user: root

        roles:

          - bootstrap

2. The ``bootstrap`` role has only one parameter - an SSH key which

   should be deployed for the Ansible user on managed server (in the

   ``authorized_keys`` file). Since this role is applied against all

   servers, we will use the same value everywhere. Configure the role:

   :file:`~/mysite/group_vars/all.yml`

   ::

      ---

      ansible_key: "{{ lookup('file', '~/.ssh/id_rsa.pub') }}"

3. SSH into all machines at least once from the Ansible server in order to

   store the SSH fingerprints into known hosts file::

     ssh root@comms.example.com date && \

     ssh root@www.example.com date && \

     ssh root@bak.example.com date

4. Now, simply run the bootstrap role against the servers::

     workon mysite && ansible-playbook playbooks/bootstrap.yml

6. At this point you won't be able to ssh into the machines with the

   ``root`` account anymore. You will be able to ssh into the machines

   using the ``ansible`` user (from the Ansible server). The

   ``ansible`` user will also be granted ability to run the ``sudo``

   commands without providing password.

7. Now you can finally move on to configuring what you really want -

   common configuration and services for your site.

Common server configuration

---------------------------

Each server needs to share some common configuration in order to be functioning

properly. This includes set-up of some shared accounts, perhaps some hardening

etc.

.. note::

   Should you ever need to limit what hosts can connect to a server

   for some kind of maintenance or upgrade purposes, the ``common``

   role comes with ``maintenance`` and ``maintenance_allowed_hosts``

   parameters. See :ref:`rolereference` for more information.

Let's take care of this common configuration right away:

1. Create playbook for the communications server:

   :file:`~/mysite/playbooks/communications.yml`

   ::

      ---

      - hosts: communications

        remote_user: ansible

        become: yes

        roles:

          - common

2. Create playbook for the web server:

   :file:`~/mysite/playbooks/web.yml`

   ::

      ---

      - hosts: web

        remote_user: ansible

        become: yes

        roles:

          - common

3. Create playbook for the backup server:

   :file:`~/mysite/playbooks/backup.yml`

   ::

      ---

      - hosts: backup

        remote_user: ansible

        become: yes

        roles:

          - common

4. Create the global site playbook:

   :file:`~/mysite/playbooks/site.yml`

   ::

      ---

      - import_playbook: preseed.yml

      - import_playbook: communications.yml

      - import_playbook: web.yml

      - import_playbook: backup.yml

5. Time to create configuration for the role. Since this role is supposed to

   set-up a common base, we'll set-up the variables file that applies to all

   roles:

   :file:`~/mysite/group_vars/all.yml`

   ::

      ---

      ansible_key: "{{ lookup('file', '~/.ssh/id_rsa.pub') }}"

      os_users:

        - name: admin

          uid: 1000

          additional_groups:

            - sudo

          authorized_keys:

            - "{{ lookup('file', '~/.ssh/id_rsa.pub') }}"

          password: "{{ 'admin' | password_hash('sha512') }}"

      common_packages:

      ca_certificates:

        truststore: "{{ lookup('file', '~/mysite/tls/truststore.pem') }}"

   .. note::

      The ``common`` role comes with ability to set-up time

      synchronisation using NTP. This is not done by default. For

      details see the role parameter ``ntp_servers``.

   .. note::

      The ``ca_certificates`` parameter lets us deploy custom CA

      certificates on servers. The name we pick (in this case

      ``truststore``) can be set to anything. In this particular case,

      we want to deploy our own CA certificate for use as truststore,

      since this is what the services will use to validate server

      certificates when connecting to each-other.

6. That's all for configuration, time to apply the changes::

     workon mysite && ansible-playbook playbooks/site.yml

7. After this you should be able to *ssh* from Ansible server onto the

   managed servers as user ``admin`` using the *SSH* private key of

   the ``ansible`` user on controller machine. The ``admin`` user's

   password has also been set to ``admin``, and the user will be

   member of ``sudo`` group.

   .. note::

      Remote logins over SSH using password authentication are

      explicitly disabled as part of common set-up/hardening.

Introducing LDAP

----------------

Since some of the services actually depend on LDAP, we'll go ahead and set that

one up first. This includes both the LDAP *server* and *client* configuration.

1. Update the playbook for communications server to include the LDAP client and

   server roles (``ldap_client`` and ``ldap_server``, respectively).

   :file:`~/mysite/playbooks/communications.yml`

   ::

      ---

      - hosts: communications

        remote_user: ansible

        become: yes

        roles:

          - common

          - ldap_client

          - ldap_server

2. Update the playbook for web server to include the LDAP client role

   (``ldap_client``). You never know when it might come in handy :)

   :file:`~/mysite/playbooks/web.yml`

   ::

      ---

      - hosts: web

        remote_user: ansible

        become: yes

        roles:

          - common

          - ldap_client

3. Time to configure the roles. For start, let us configure the LDAP

   server role. Keep in mind that there is a lot of default variables

   set-up by the role itself, making our config rather short. The

   ``ldap_server_domain`` parameter will be used to form the base DN

   of the LDAP directory (resulting in ``dc=example,dc=com``).

   :file:`~/mysite/group_vars/communications.yml`

   ::

      ---

      ldap_admin_password: admin

      ldap_server_domain: example.com

      ldap_server_organization: "Example Inc."

      ldap_server_tls_certificate: "{{ lookup('file', '~/mysite/tls/comms.example.com_ldap.pem') }}"

      ldap_server_tls_key: "{{ lookup('file', '~/mysite/tls/comms.example.com_ldap.key') }}"

4. Phew. That was... Well, actually, easy :) Technically, only the

   LDAP admin password, domain, and TLS certificate/key *must* be set,

   but it is nice to have organisation explicitly specified as well

   (instead of using whatever Debian picks as default). Let us add the

   LDAP client configuration next. We will start off with global LDAP

   client configuration. In case of the LDAP client role, we have got

   to be a bit more explicit.

   :file:`~/mysite/group_vars/all.yml`