Getting Started with DebOps

Welcome to DebOps! You have installed Ansible and DebOps scripts, downloaded the roles and playbooks, and are wondering where to go next? Here you can read about creating your first DebOps project, and managing remote hosts.

An example environment

Ansible and DebOps are installed on your workstation or laptop, a so called "Ansible Controller" - this machine is used to control Ansible and issue commands. The machine you will configure using DebOps is known as a "remote host".

DebOps is designed to manage a host from the ground up. A good base installation is a Debian Stable netinst, with only SSH server enabled and configured. Everything else will be installed as needed.

Note

If you are using Debian Jessie or other distributions based on it as the base install, by default OpenSSH server configured by the installer will disallow password authentication on the root account. You can either enable it manually in the /etc/ssh/sshd_config file, use public key authentication (see 'man authorized_keys' and 'man ssh-copy-id'), or configure a separate admin account and use that to bootstrap the host.

An important part of the environment is correctly configured DNS. Some of the DebOps roles expect a configured domain - it doesn't need to be a real, global domain, but it should be resolvable by the host. A good way to check if a remote host has a correctly configured domain is to use the hostname --fqdn command. If the output has at least 1 dot, you should be good to go.

Do not use the domain apex (example.com) as the host name - this will confuse Ansible and leave you with a broken configuration. Instead, create separate hostnames inside the domain (server.example.com), this will be used by Ansible correctly. It's good to use only one subdomain level per subnet, this will make wildcard certificates work without issues. If you want, you can create separate subdomains per subnet.

If your host does not have a domain configured, you will be able to do that during the bootstrapping process.

In this guide, we will manage an example host called server.example.com. This host is a virtual machine, and we can connect to it using commands like:

alice@laptop:~$ ssh root@server.example.com
alice@laptop:~$ ssh root@server

The root account requires a password, SSH keys are not installed yet and there's no administrator account.

Ansible commands are executed on the Ansible Controller from an unprivileged account alice. This user has an SSH key pair stored in ~/.ssh/id_rsa or has its SSH key available in the SSH Agent. An administrator account with the same name will be created on the remote host during the bootstrap process.

Your first project

Begin by creating a "DebOps project". It's a directory which contains all of the data related to a given environment - Ansible inventory, passwords and other secrets, custom playbooks and roles. To do this, use the debops-init command:

alice@laptop:~$ debops-init ~/myproject

This will create a new directory called myproject and populate it with some example directories and files. You will perform most of the commands from the main project directory, so let's cd into it:

alice@laptop:~$ cd ~/myproject

Ansible uses a hosts file to identify hosts that are under its control. In the project directory this file is located in ansible/inventory/hosts. Open it in your favorite text editor and add the remote host in the main DebOps host group:

[debops_all_hosts]
server    ansible_host=server.example.com

Using a short inventory name allows you to run Ansible commands without specifying the fully qualified domain name of the host.

Important inventory variables

Some of the configuration used by DebOps cannot be auto-detected - examples include IP addresses or network subnets that can connect to a SSH service remotely, the administrator e-mail account which should receive important notifications, and so on. Here you can find a list of the most important variables which, when set correctly in inventory, can save you a trip to the data center.

To make sure that these variables apply to all hosts in your environment, you can include them in ansible/inventory/group_vars/all/ directory. A common practice is to name the files inside inventory directories after variable prefixes, separately for each Ansible role. For example, variables related to debops.sshd role are stored in ansible/inventory/group_vars/all/sshd.yml, variables used by the debops.postfix role are written in ansible/inventory/group_vars/all/postfix.yml, and so on. The same scheme can be used in other inventory groups or for separate hosts.

ansible_user

This is an internal Ansible variable which is used to determine what remote user account will be used to login to the server. If it's not explicitly set, Ansible depends on SSH defaults which conventionally use the name of the current user as the remote username. It's customary to specify this variable directly in the hosts file, that way it can be unique for each host:

[debops_all_hosts]
server    ansible_ssh_host=server.example.com ansible_user=ansible-admin

In DebOps this variable can be used to change the name of the default administrator account, it's also used as a primary user account for various tasks, like database and application administrative accounts.

On a specific platforms you can set this variable to an automatically created username to make the remote host administration easier:

  • Ubuntu-based hosts usually use the ubuntu username;
  • Raspberry Pi / Pi 2 Linux distributions use the pi user account for this purpose;

However, it is advisable to not use the default user accounts, and instead either create ones based on your own username (the default behavior) or create completely separate Ansible accounts with administrative access. If you configure the ansible_user variable before bootstrapping the host, the specified username will be used to create an administrator account.

netbase__domain

If hosts that you want to manage don't have a DNS domain set, or it's incorrect (for example your VPS provider's domain instead of your own), the debops.netbase role included in the DebOps bootstrap playbook can be used to easily fix that and configure your own domain. By setting this variable to, for example:

---
netbase__domain: 'example.com'

By running the debops bootstrap command (see further down), your domain will be configured in the remote hosts' /etc/hosts file. Additionally, the hostname will be changed to the one you specified in the Ansible inventory. After that is done, it's best to reboot the machine to make sure all of the changed settings are applied and are persistent.

This variable won't have any effect on hosts that are not "bootstrapped", and are instead configured using Debian preseeding or LXC templates - these hosts will presumably get the needed information like hostname and domain from your own DHCP server.

sshd__whitelist

Protection of the SSH service is very important. Hosts configured by DebOps use a firewall and TCP Wrappers to restrict what hosts can connect to it and automatically block repeated offenders for certain amount of time.

To not block the Ansible Controller, DebOps tries to detect the IP address from which the connection is made. For the most part it should work as expected, but if you still are getting blocked, or to be sure that remote access won't be interrupted, you can define a list of IP addresses or CIDR subnets that will be allowed to connect to SSH without restrictions.

To do that, in ansible/inventory/group_vars/all/sshd.yml add:

---
sshd__whitelist: [ '192.0.2.0/24', '2001:db8::/32' ]

This will configure the debops.ferm and debops.tcpwrappers roles to allow connections to the ssh service from specified networks.

The debops.sshd role has many more variables, you can checkout to see the default configuration used by DebOps and what can be changed as needed.

ntp__timezone

By default, DebOps does not try to change the remote host timezone and tries to use the detected one in roles that need that information for the configuration. If you need to change the timezone, you can do it by setting the ntp__timezone variable like this:

---
ntp__timezone: 'America/New_York'

For UTC timezone, use this format:

---
ntp__timezone: 'Etc/UTC'

nullmailer__relayhost

The default SMTP server used by DebOps is nullmailer. It's a simple, forward-only Mail Transport Agent which sends all mail to another SMTP server for processing. It does not provide support for local mail accounts.

By default, nullmailer will send mail messages to the smtp.<your-domain> host (it does not support MX record lookups). If this host doesn't exist, or your local SMTP server has a different address, you can change it by setting the variable:

---
nullmailer__relayhost: 'internal-mx.{{ ansible_domain }}'

Only one relayhost is supported at a time. The specified host should accept messages from hosts controlled by Ansible for this to work correctly. The SMTP connections will be encrypted using STARTTLS command, therefore the SMTP should use a set of X.509 certificates which are trusted by the host.

The nullmailer service can be configured to a large extent using the debops.nullmailer role variables - you can use them to configure SMTP authentication, use multiple relay servers, and so on.

If you need a more powerful SMTP server, DebOps includes support for Postfix as well - check the debops.postfix Ansible role.

apt__default_mirrors_lookup, apt__default_sources_lookup

DebOps tries to detect the operating system a given host is using and configure it accordingly. Currently selected Debian and Ubuntu releases are recognized and the package sources for these operating systems should be configured without issues.

The Raspbian operating system is a little difficult to detect, because Ansible currently classifies it as "Debian", however its package repositories are completely different. To avoid issues with incompatible package sources on your Raspberry Pi/Pi2, you should change the default debops.apt configuration manually to use the Raspbian repositories. To do that, add these values in relevant inventory files:

---
apt__default_mirrors_lookup: 'raspbian'
apt__default_sources_lookup: 'raspbian'

Bootstrap a new host

Warning

Bootstrapping a host without a configured netbase__domain will result in a broken host configuration.

At this point you most likely have to connect to that host using the root account and specifying a password. To make that easier, you can use a special "bootstrap" Ansible playbook to prepare a host for easier management. To do this, execute the command:

alice@laptop:~/myproject$ debops bootstrap --limit server --user root --ask-pass

Or, for short:

alice@laptop:~/myproject$ debops bootstrap -l server -u root -k

This command will execute the DebOps bootstrap playbook and use it to install a base set of packages needed by Ansible like python and sudo, prepare a new administrator account named after your system user (alice in our example) and allow that account full access to the root account using sudo. Your SSH keys will be installed on both the root and administrator accounts.

Note

Bootstrapping a host this way is not needed if you already have an administrator account that can use sudo without a password. This includes hosts configured using Debian Preseed provided by DebOps as well as OpenVZ/LXC containers configured using provided templates.

When the DebOps bootstrap playbook has finished and there are no errors, you can check if you are able to connect to the server on the administrator account without a password:

alice@laptop:~/myproject$ ssh server

After logging in, check if you can run commands using sudo without a password:

alice@server:~$ sudo -l

Configure the remote host

When a new remote host has been prepared for Ansible management, you can start the configuration:

alice@laptop:~/myproject$ debops -l server

This will start the ansible-playbook command with the main DebOps playbook. This by default includes the DebOps common playbook with a default set of roles, and any additional playbooks, if they have been enabled.

The initial configuration might take 5-10 minutes on a reasonably fast machine. There are some steps, like Diffie-Hellman parameter generation, which might take significantly more time to complete.

When the playbook run has been finished, your remote host should be configured with:

  • a correct set of APT repositories for your operating system release;
  • automatic updates of the installed packages with related e-mail messages sent to your admin account;
  • a set of Diffie-Hellman parameters and SSL certificates ready to use by different services (encrypted TLS/SSL connections out of the box);
  • configured iptables/ip6tables firewall and TCP Wrappers;
  • enabled network time synchronization as needed;
  • a set of useful management software installed on the host (htop, mtr-tiny, mc, vim, among other things);

Example application - DokuWiki

Each host configured by DebOps common playbook should have the same set of base services. After a host is configured, you can enable additional Ansible roles to install and configure software and applications of your choice.

We will use DokuWiki as an example application. The role that manages the installation is called debops.dokuwiki it uses debops.nginx and debops.php roles to configure a webserver and PHP5 environment. The debops.nginx role calls some additional roles, such as debops.ferm to configure needed services.

To install DokuWiki on your new remote host, you need to enable the respective role in Ansible inventory. This is done by creating a new host group, [debops_service_dokuwiki] in the hosts file, and adding the desired hosts to it:

[debops_all_hosts]
server    ansible_ssh_host=server.example.com

[debops_service_dokuwiki]
server

As you can see, you don't need to copy the whole host entry, only the short name is enough.

The debops.dokuwiki role has many default variables you can use to customize the installation. One of the more useful ones is dokuwiki_main_domain; it's a list which specifies what DNS subdomains are used to access the wiki (each application in the DebOps set of roles is configured on a separate subdomain). By default DokuWiki will be accessible on the wiki.{{ ansible_domain }} subdomain, if you want to change it, you can do so by creating the ansible/inventory/host_vars/server/dokuwiki.yml configuration file and specifying the subdomain(s) in it:

---
dokuwiki__fqdn: 'wiki.{{ ansible_domain }}'

Remember that the chosen subdomain (wiki. or your own) needs to be configured in your DNS server to point to the specified remote host.

When everything is configured, you can execute the debops script to apply new configuration on the host:

alice@laptop:~/myproject$ debops -l server

This will apply the whole playbook with all the configuration on the specified server. However, to make this process faster, DebOps provides separate "service playbooks" for each of the roles. To use these playbooks, you can specify them as the first argument to the debops command:

alice@laptop:~/myproject$ debops service/dokuwiki -l server

This will tell the script to look for the playbook in several places:

  • playbooks/ and ansible/playbooks/ subdirectories in the project directory;
  • debops-playbooks/playbooks/ subdirectory of the project directory, if DebOps playbooks and roles are installed inside of it;
  • ~/.local/share/debops/debops-playbooks/playbooks/ directory (default install location);

The first one found will be executed. You can use this to your advantage by adding custom playbooks in playbooks/ or ansible/playbooks/ directories, they need to be named with .yml extension. Custom roles can be placed in the roles/ or ansible/roles/ subdirectories located in the project directory.

After Ansible finishes the configuration, you will need to go to the https://wiki.<domain>/install.php page to complete the installation process.

At this time you might find that the web browser you are using does not recognize the CA certificates served by the host. This happens when the server uses certificates signed by internal DebOps Certificate Authority instead of the "regular" ones. To fix that, consult the debops.pki role documentation (when it's available).

Where to go from here

You can add more hosts to the Ansible inventory and configure them in a cluster. Hosts should automatically trust each other using an internal Certificate Authority, so encrypted connections between them should work out of the box.

DebOps contains multiple Ansible roles that allow you to install and configure useful software, like GitLab, phpIPAM, ownCloud and others. You should check the documentation of the respective roles to see some example configurations and useful tips. Note that parts of the documentation are currently outdated - if a given role has only one page, you should check the role files directly.

You can check the DebOps Changelog for updates related to roles and playbooks (there's also an Atom feed available for your feed reader).