Changeset - b70cbdc05748
[Not reviewed]
0 1 0
Branko Majic (branko) - 15 months ago 2024-09-09 15:34:34
branko@majic.rs
MAR-218: Update the get_url invocation to use the new checksum attribute.
1 file changed with 1 insertions and 1 deletions:
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docs/usage.rst
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@@ -1176,769 +1176,769 @@ role.
 

	
 
6. Ok, configuration of the role is complete. You may have noticed
 
   that we still haven't added any users to the new LDAP group called
 
   "xmpp". So let us correct this in similar way as we did for the
 
   mail server. Since we have the user entries already, no need to
 
   recreate them here. We will just update the group membership
 
   instead.
 

	
 
   .. warning::
 
      Same warning applies here as for mail server role for managing the
 
      user/group entries! Scroll up and re-read it if you missed it!
 

	
 
   ::
 

	
 
     workon mysite && ansible --become -m ldap_attrs -a '{"dn": "cn=xmpp,ou=groups,dc=example,dc=com", "state": "present", "attributes": {"uniqueMember": "uid=johndoe,ou=people,dc=example,dc=com"}}' communications
 
     workon mysite && ansible --become -m ldap_attrs -a '{"dn": "cn=xmpp,ou=groups,dc=example,dc=com", "state": "present", "attributes": {"uniqueMember": "uid=janedoe,ou=people,dc=example,dc=com"}}' communications
 

	
 

	
 

	
 
7. If no errors have been reported, at this point you should have two users
 
   capable of using the XMPP service - one with username
 
   ``john.doe@example.com`` and one with username ``jane.doe@example.com``. Same
 
   passwords are used as for when you were creating the two users for mail
 
   server. For testing you can turn to your favourite XMPP client (I don't know
 
   of any quick CLI-based tools to test the XMPP server functionality,
 
   unfortunately, but you could try using `mcabber <https://mcabber.com/>`_).
 

	
 

	
 
Taking a step back - preparing for web server
 
---------------------------------------------
 

	
 
Up until now the usage instructions have dealt almost exclusively with the
 
communications server. That is, we haven't done anything beyond the basic set-up
 
of the other servers.
 

	
 
Let us first define what we want to deploy on the web server. Here is the plan:
 

	
 
1. First off, we will set-up the web server. This will be necessary no matter
 
   what web application we decide to deploy later on.
 

	
 
2. Next, we will set-up a database server. Why? Well, most web applications
 
   need to use some sort of database to store all the data, so we might as well
 
   try to take that one out of the way.
 

	
 
3. With this basic deployment for a web server in place, we can move on to
 
   setting-up a couple of web applications. For the purpose of the usage
 
   instructions, we will deploy the following two:
 

	
 
   1. `Nextcloud <https://nextcloud.com/>`_ - extendable solution for
 
      file sharing, calendars etc. To keep things simple, we will not
 
      integrate it with our LDAP server (although this is supported
 
      and possible). Being written in PHP, this application will be
 
      used to demonstrate the role for PHP web application deployment.
 

	
 
   2. `Django Wiki <https://github.com/django-wiki/django-wiki>`_ - a wiki
 
      application written in Django. This will serve as a demo of how the WSGI
 
      role works.
 

	
 
It should be noted that the web application deployment roles are a bit more
 
complex - namely they are not meant to be used directly, but instead as a
 
dependency for a custom role. They do come with decent amount of batteries
 
included, and also play nice with the web server role.
 

	
 
As mentioned before, all roles will enforce TLS by default. The web server roles
 
will additionaly implement HSTS policy by sending connecting clients
 
``Strict-Transport-Security`` header with value set to ``max-age=31536000;
 
includeSubDomains``.
 

	
 
With all the above noted, let us finally move on to the next step.
 

	
 

	
 
Setting-up the web server
 
-------------------------
 

	
 
Finally we are moving on to the web server deployment, and we shell start
 
with... Well, erm, web server deployment! To be more precise, we will set-up
 
Nginx.
 

	
 
1. Update the playbook for web server to include the web server role.
 

	
 

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

	
 
      ---
 

	
 
      - hosts: web
 
        remote_user: ansible
 
        become: yes
 
        roles:
 
          - common
 
          - ldap_client
 
          - mail_forwarder
 
          - web_server
 

	
 
2. You know the drill, role configuration comes up next. No
 
   configuration has been deployed before for the web server, so we
 
   will be creating a new file. Only the TLS parameters are really
 
   necessary, but we'll spice things up a bit by setting custom title
 
   and message for default virtual host.
 

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

	
 
      ---
 

	
 
      default_https_tls_certificate: "{{ lookup('file', '~/mysite/tls/www.example.com_https.pem') }}"
 
      default_https_tls_key: "{{ lookup('file', '~/mysite/tls/www.example.com_https.key') }}"
 

	
 
      web_default_title: "Welcome to default page!"
 
      web_default_message: "Nothing to see here, move along..."
 

	
 
3. The only thing left now is to create the TLS private key/certificate pair
 
   that should be used for default virtual host.
 

	
 
   1. Create new template for ``certtool``:
 

	
 
      :file:`~/mysite/tls/www.example.com_https.cfg`
 
      ::
 

	
 
         organization = "Example Inc."
 
         country = SE
 
         cn = "Exampe Inc. Web Server"
 
         expiration_days = 365
 
         dns_name = "www.example.com"
 
         tls_www_server
 
         signing_key
 
         encryption_key
 

	
 
   2. Create the keys and certificates for default web server virtual host based
 
      on the template::
 

	
 
        certtool --sec-param normal --generate-privkey --outfile ~/mysite/tls/www.example.com_https.key
 
        certtool --generate-certificate --load-ca-privkey ~/mysite/tls/ca.key --load-ca-certificate ~/mysite/tls/ca.pem --template ~/mysite/tls/www.example.com_https.cfg --load-privkey ~/mysite/tls/www.example.com_https.key --outfile ~/mysite/tls/www.example.com_https.pem
 

	
 
4. Apply the changes::
 

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

	
 
5. If no errors have been reported, at this point you should have a default web
 
   page available and visible at https://www.example.com/ . By default plaintext
 
   connections are disabled, and trying to visit http://www.example.com/ should
 
   simply redirect you to the HTTPS address. Feel free to try it out with some
 
   browser. Keep in mind you will get a warning about the untrusted certificate!
 

	
 

	
 
Adding the database server
 
--------------------------
 

	
 
Since both of the web applications we want to deploy need a database, we will
 
proceed to set-up the database server role on the web server itself. *Majic
 
Ansible Roles* in particular come with a role that will deploy MariaDB database
 
server.
 

	
 
.. note::
 
   The ``database_server`` role will set-up unix socket authentication
 
   for the database ``root`` user. I.e. the ``root`` database user
 
   will have no password set, but authentication will pass only when
 
   logging-in as the operating system ``root`` user while connecting
 
   over database server unix socket.
 

	
 
1. Update the playbook for web server to include the database server role.
 

	
 

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

	
 
      ---
 

	
 
      - hosts: web
 
        remote_user: ansible
 
        become: yes
 
        roles:
 
          - common
 
          - ldap_client
 
          - mail_forwarder
 
          - web_server
 
          - database_server
 

	
 
2. This particular role has no parameters, and no additional steps are
 
   necessary to configure it. So move along...
 

	
 
3. No TLS support has been implemented for this role (yet), so simply apply the
 
   changes::
 

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

	
 
4. If no errors have been reported, you should have a database server up and
 
   running on the web server. You should be able to log-in as ``root``
 
   operating system user by running the following command on the web
 
   server itself::
 

	
 
     mysql
 

	
 
   Of course, no database has been created for either of the web applications,
 
   but we will get to that one later (there is a dedicated ``database`` role
 
   which can be combined with web app roles for this purpose).
 

	
 

	
 
Deploying a PHP web application (Nextcloud)
 
-----------------------------------------------
 

	
 
We have some basic infrastructure up and running on our web server, so
 
now we can move on to setting-up a PHP web application on it. As
 
mentioned before, we will roll-out *Nextcloud*.
 

	
 
For this we will create a local role in our site to take care of
 
it. This role will in turn utilise two roles coming from *Majic
 
Ansible Roles* that will make our life (a little) easier.
 

	
 
To make the example a bit simpler, no parameters will be introduced
 
for this role (not even the password for database) - we'll hard-code
 
everything.
 

	
 
Before we start, here is a couple of useful pointers regarding the
 
``php_website`` role:
 

	
 
* The role is designed to execute every application via dedicated user
 
  and group. The user/group name is automatically derived from the
 
  FQDN of website, for example ``web-nextcloud_example_com``.
 
* While running the application, application user's umask is set to
 
  ``0007`` (letting the administrator user be able to manage any files
 
  created while the application is running).
 
* An administrative user is created as well, and this user should be
 
  used when running maintenance and installation commands. Similar to
 
  application user, the name is also derived from the FQDN of website,
 
  for example ``admin-nextcloud_example_com``. Administrative user
 
  does not have a dedicated group, and instead belongs to same group
 
  as the application user.
 
* PHP applications are executed via FastCGI, using *PHP-FPM*.
 
* If you ever need to set some additional PHP FPM settings, this can
 
  easily be done via the ``additional_fpm_config`` role
 
  parameter. This particular example does not set any, though.
 
* Incoming request headers can be set/overridden using the
 
  ``http_header_overrides`` parameter. This can be useful for
 
  manipulating headers in specifics ways, such as disabling
 
  compression etc. on the application side.
 
* Mails delivered to local admin/application users are forwarded to
 
  ``root`` account (configurable via ``website_mail_recipients`` role
 
  parameter.
 
* If you ever find yourself mixing-up test and production websites,
 
  have a look at ``environment_indicator`` role parameter. It lets you
 
  insert small strip with environment information at bottom of each
 
  HTML page served by the web server. If the strip gets in the way, it
 
  can easily be collapsed using the arrows on the left side.
 
* Static content (non-PHP) is served directly by *Nginx*.
 
* Each web application gets distinct sub-directory under ``/var/www``,
 
  named after the FQDN. All sub-directories created under there are
 
  created with ``02750`` permissions, with ownership set to admin
 
  user, and group set to the application's group. In other words, all
 
  directories will have ``SGID`` bit set, allowing you to create
 
  files/directories that will have their group automatically set to
 
  the group of the parent directory.
 
* Files are served (both by *Nginx* and *PHP-FPM*) from sub-directory
 
  called ``htdocs`` (located in website directory). For example
 
  ``/var/www/nextcloud.example.com/htdocs/``. Normally, this can be a
 
  symlink to some other sub-directory within the website directory
 
  (useful for having multiple versions for easier downgrades etc).
 
* Combination of admin user membership in application group, ``SGID``
 
  permission, and the way ownership of sub-directories is set-up
 
  usually means that the administrator will be capable of managing
 
  application files, and application can be granted write permissions
 
  to a *minimum* of necessary files.
 

	
 
  .. warning::
 
     Just keep in mind that some file-management commands, like
 
     ``mv``, do *not* respect the ``SGID`` bit. In fact, I would
 
     recommend using ``cp`` when you deploy new files to the directory
 
     instead (don't simply move them from your home directory).
 

	
 
1. Start-off with creating the necessary directories for the new role::
 

	
 
     mkdir -p ~/mysite/roles/nextcloud/{tasks,meta,files}/
 

	
 
2. Let's set-up role dependencies, reusing some common roles to make
 
   our life easier.
 

	
 
   :file:`~/mysite/roles/nextcloud/meta/main.yml`
 
   ::
 

	
 
      ---
 

	
 
      dependencies:
 

	
 
        # Role helps us set-up Nginx virtual host for serving our app.
 
        - role: php_website
 

	
 
          # Name that will be bound to specific virtual host definition.
 
          fqdn: nextcloud.example.com
 

	
 
          # TLS key and certificate to use for the virtual host.
 
          https_tls_certificate: "{{ lookup('file', '~/mysite/tls/nextcloud.example.com_https.pem') }}"
 
          https_tls_key: "{{ lookup('file', '~/mysite/tls/nextcloud.example.com_https.key') }}"
 

	
 
          # Additional packages required for deploying and running Nextcloud.
 
          packages:
 
            - php-gd
 
            - php-json
 
            - php-mysql
 
            - php-curl
 
            - php-intl
 
            - php-mbstring
 
            - php-imagick
 
            - php-ldap
 
            - php-xml
 
            - php-zip
 
            - php-gmp
 
            - python3-pexpect
 
            - php-apcu
 
            - php-bcmath
 

	
 
          # Set-up URL rewrites for well-known URIs (see https://en.wikipedia.org/wiki/Well-known_URIs).
 
          rewrites:
 
            - '^/\.well-known/carddav /remote.php/dav/ permanent'
 
            - '^/\.well-known/caldav /remote.php/dav/ permanent'
 
            - '^/remote/(.*) /remote.php last'
 

	
 
          # Prevent specific files from ever being served by the web server (for security reasons etc).
 
          deny_files_regex:
 
            - '^/(build|tests|config|lib|3rdparty|templates|data)/'
 
            - '^/(?:\.|autotest|occ|issue|indie|db_|console)'
 

	
 
          # Custom regex defining what files shouled be processed via PHP
 
          # interpreter.
 
          php_file_regex: \.php(?:$|/)
 

	
 
          # Not necessarily needed, but in case you have a policy on uid/gid
 
          # usage, this is useful. Take note that the uid value is also used
 
          # for the application group (gid == uid).
 
          uid: 2000
 
          admin_uid: 3000
 

	
 
        # Role that sets up a new dedicated database for our web
 
        # application.
 
        - role: database
 

	
 
          # This is both the database name, _and_ name of the database user
 
          # that will be granted full privileges on the database.
 
          db_name: nextcloud
 

	
 
          # Password for user used for accessing the database. Take note
 
          # that the user can only login from localhost.
 
          db_password: nextcloud
 

	
 

	
 

	
 
3. Now for my favourite part again - creating private keys and
 
   certificates!  Why?  Because the ``php_website`` role requires a
 
   private key/certificate pair to be deployed. So... Moving on:
 

	
 
   1. Create new template for ``certtool``:
 

	
 
      :file:`~/mysite/tls/nextcloud.example.com_https.cfg`
 
      ::
 

	
 
         organization = "Example Inc."
 
         country = SE
 
         cn = "Example Inc. Cloud Service"
 
         expiration_days = 365
 
         dns_name = "nextcloud.example.com"
 
         tls_www_server
 
         signing_key
 
         encryption_key
 

	
 
   2. Create the keys and certificates for the application::
 

	
 
        certtool --sec-param normal --generate-privkey --outfile ~/mysite/tls/nextcloud.example.com_https.key
 
        certtool --generate-certificate --load-ca-privkey ~/mysite/tls/ca.key --load-ca-certificate ~/mysite/tls/ca.pem --template ~/mysite/tls/nextcloud.example.com_https.cfg --load-privkey ~/mysite/tls/nextcloud.example.com_https.key --outfile ~/mysite/tls/nextcloud.example.com_https.pem
 

	
 
4. Time to get our hands a bit more dirty... Up until now we didn't
 
   have to write custom tasks, but that ends now.
 

	
 
   :file:`~/mysite/roles/nextcloud/tasks/main.yml`
 
   ::
 

	
 
      ---
 

	
 
      # Deployment
 
      # ==========
 

	
 
      - name: Download the application archive
 
        ansible.builtin.get_url:
 
          url: "https://download.nextcloud.com/server/releases/nextcloud-29.0.4.tar.bz2"
 
          dest: "/var/www/nextcloud.example.com/nextcloud-29.0.4.tar.gz"
 
          sha256sum: "19c469e264b31ee80400f8396460854546569e88db4c15fc0854e192f96027eb"
 
          checksum: "sha256:19c469e264b31ee80400f8396460854546569e88db4c15fc0854e192f96027eb"
 
        become: yes
 
        become_user: admin-nextcloud_example_com
 

	
 
      - name: Unpack the application archive
 
        ansible.builtin.unarchive:
 
          src: "/var/www/nextcloud.example.com/nextcloud-29.0.4.tar.gz"
 
          dest: "/var/www/nextcloud.example.com/"
 
          copy: no
 
          creates: "/var/www/nextcloud.example.com/nextcloud"
 
        become: yes
 
        become_user: admin-nextcloud_example_com
 

	
 
      # Majic Ansible Roles currently only support utf8 encoding.
 
      - name: Disable opportunistic use of utf8mb4 on fresh installs
 
        ansible.builtin.lineinfile:
 
          dest: "/var/www/nextcloud.example.com/nextcloud/lib/private/Setup/MySQL.php"
 
          line: "{{ '\t\t\t' }}$this->config->setValue('mysql.utf8mb4', true);"
 
          state: absent
 

	
 
      - name: Allow application user to install and update applications
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/nextcloud/apps"
 
          mode: g+w
 

	
 
      - name: Allow CLI tool to be run by the user and group
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/nextcloud/occ"
 
          mode: u+x,g+x
 

	
 
      - name: Create directory for storing data
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/data"
 
          state: directory
 
          mode: 02770
 
          owner: "admin-nextcloud_example_com"
 
          group: "web-nextcloud_example_com"
 

	
 
      - name: Create directory for storing configuration files
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/nextcloud/config"
 
          state: directory
 
          mode: 02750
 
          owner: "admin-nextcloud_example_com"
 
          group: "web-nextcloud_example_com"
 

	
 
      - name: Create an empty log file if it does not exist
 
        ansible.builtin.copy:
 
          content: ""
 
          dest: "/var/www/nextcloud.example.com/data/nextcloud.log"
 
          force: no
 

	
 
      - name: Set-up log file permissions
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/data/nextcloud.log"
 
          owner: "admin-nextcloud_example_com"
 
          group: "web-nextcloud_example_com"
 
          mode: 0660
 

	
 
      - name: Symlink the default path used by the web server for finding application files
 
        ansible.builtin.file:
 
          src: "/var/www/nextcloud.example.com/nextcloud"
 
          dest: "/var/www/nextcloud.example.com/htdocs"
 
          state: link
 
          owner: "admin-nextcloud_example_com"
 
          group: "web-nextcloud_example_com"
 
        notify:
 
          - Restart PHP-FPM
 

	
 

	
 
      # Installation
 
      # ============
 

	
 
      - name: Get application installation status
 
        ansible.builtin.command: "/var/www/nextcloud.example.com/nextcloud/occ status"
 
        become: yes
 
        become_user: "admin-nextcloud_example_com"
 
        register: nextcloud_status
 
        changed_when: False
 
        failed_when: False
 

	
 
      - name: Check if application is installed
 
        ansible.builtin.set_fact:
 
          nextcloud_installed: "{{ 'Nextcloud is not installed' not in nextcloud_status.stderr }}"
 

	
 
      - name: Deploy installation script
 
        ansible.builtin.copy:
 
          src: "install_nextcloud.py"
 
          dest: "/var/www/nextcloud.example.com/install_nextcloud.py"
 
          owner: "admin-nextcloud_example_com"
 
          group: "web-nextcloud_example_com"
 
          mode: 0700
 
        when: "not nextcloud_installed"
 

	
 
      - name: Install application
 
        ansible.builtin.command: "/var/www/nextcloud.example.com/install_nextcloud.py"
 
        become: yes
 
        become_user: "admin-nextcloud_example_com"
 
        when: "not nextcloud_installed"
 

	
 
      - name: Remove installation script
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/install_nextcloud.py"
 
          state: absent
 

	
 
      - name: Fix data file permissions for application user/group
 
        ansible.builtin.file:
 
          path: "/var/www/nextcloud.example.com/data"
 
          mode: g+w
 
          recurse: yes
 
          follow: no
 

	
 
      - name: Deploy local configuration overrides
 
        ansible.builtin.copy:
 
          src: "local.config.php"
 
          dest: "/var/www/nextcloud.example.com/nextcloud/config/local.config.php"
 
          owner: "admin-nextcloud_example_com"
 
          group: "web-nextcloud_example_com"
 
          mode: 0640
 

	
 
5. Set-up files that are deployed by the role.
 

	
 
   :file:`~/mysite/roles/nextcloud/files/local.config.php`
 
   ::
 

	
 
      <?php
 
      $CONFIG = array (
 
        'config_is_read_only' => true,
 
        'instanceid' => 'suqw2cvca8sp',
 
        'trusted_domains' =>
 
          array (
 
            0 => 'nextcloud.example.com',
 
          ),
 
      );
 

	
 
   :file:`~/mysite/roles/nextcloud/files/install_nextcloud.py`
 
   ::
 

	
 
      #!/usr/bin/env python3
 

	
 
      import pexpect
 

	
 
      # Spawn the process.
 
      install_process = pexpect.spawnu('/var/www/nextcloud.example.com/nextcloud/occ',
 
                                       args = [ 'maintenance:install',
 
                                                '--database', 'mysql',
 
                                                '--database-name', 'nextcloud',
 
                                                '--database-user', 'nextcloud',
 
                                                '--database-host', 'localhost',
 
                                                '--database-port', '3306',
 
                                                '--admin-user', 'admin',
 
                                                '--data-dir', '/var/www/nextcloud.example.com/data'])
 

	
 
      # If we get EOF, we probably already installed application, and ran
 
      # into error at the end since no patterns matched.
 
      try:
 
          # Provide database password.
 
          install_process.expect(u'What is the password to access the database with user.*\?', timeout=10)
 
          install_process.sendline(u'nextcloud')
 

	
 
          # Provide administrator password.
 
          install_process.expect(u'What is the password you like to use for the admin account.*\?', timeout=10)
 
          install_process.sendline(u'admin')
 

	
 
          # Wait for application to finish.
 
          install_process.expect(pexpect.EOF, timeout=120)
 

	
 
      except pexpect.EOF as e:
 
          pass
 

	
 
      # Print command output. Has to be done prior to final wait for
 
      # pexpect.EOF.
 
      print(install_process.before.encode('utf-8'))
 

	
 
      # Close application. Additional wait for pexpect.EOF prevents the
 
      # process from getting killed prematurely in case it exits
 
      # immediatelly (due to wrong command line arguments etc). Some
 
      # background information can be found at (although it is a very old
 
      # post):
 
      #
 
      # https://www.heikkitoivonen.net/blog/2009/01/28/pexpect-and-inconsistent-exit-status/
 
      #
 
      install_process.expect(pexpect.EOF)
 
      install_process.close()
 

	
 
      # Return same exit code like child process.
 
      exit(install_process.exitstatus)
 

	
 
6. And... Let's add the new role to our web server.
 

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

	
 
      ---
 

	
 
      - hosts: web
 
        remote_user: ansible
 
        become: yes
 
        roles:
 
          - common
 
          - ldap_client
 
          - mail_forwarder
 
          - web_server
 
          - database_server
 
          - nextcloud
 

	
 
7. Apply the changes::
 

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

	
 
8. At this point *Nextcloud* has been installed, and you should be
 
   able to open the URL https://nextcloud.example.com/ and log-in into
 
   *Nextcloud* with username ``admin`` and password ``admin``.
 

	
 

	
 
Deploying a WSGI application (Django Wiki)
 
------------------------------------------
 

	
 
Next thing up will be to deploy a WSGI Python application.
 

	
 
Similar to the PHP application deployment, we will use a couple of roles to make
 
it easier to deploy it in a standardised manner, and we will not have any kind
 
of parameters for configuring the role to keep things simple.
 

	
 
Most of the notes on how a ``php_website`` role is deployed also stand for the
 
``wsgi_website`` role, but we will reiterate and clarify them a bit just to be
 
on the safe side:
 

	
 
* The role is designed to execute every application via dedicated user and
 
  group. The user/group name is automatically derived from the FQDN of website,
 
  for example ``web-wiki_example_com``.
 
* While running the application, application user's umask is set to ``0007``
 
  (letting the administrator user be able to manage any files created while the
 
  application is running).
 
* An administrative user is created as well, and this user should be used when
 
  running maintenance and installation commands. Similar to application user,
 
  the name is also derived from the FQDN of website, for example
 
  ``admin-wiki_example_com``. Administrative user does not have a dedicated
 
  group, and instead belongs to same group as the application user. As
 
  convenience, whenever you switch to this user the Python virtual environment
 
  will be automatically activated for you.
 
* WSGI applications are executed via *Gunicorn*. The WSGI server listens on a
 
  Unix socket, making the socket accessible by *Nginx*.
 
* If you ever need to set some environment variables, this can easily be done
 
  via the ``environment_variables`` role parameter. This particular example does
 
  not set any, though.
 
* You can also specify headers to be modified in incoming client
 
  request before it gets passed on to the WSGI application using the
 
  ``http_header_overrides`` parameter.  directive to Gunicorn running
 
  the application.
 
* Mails deliverd to local admin/application users are forwarded to ``root``
 
  account instead (this can be configured via ``website_mail_recipients`` role
 
  parameter.
 
* If you ever find yourself mixing-up test and production websites,
 
  have a look at ``environment_indicator`` role parameter. It lets you
 
  insert small strip with environment information at bottom of each
 
  HTML page served by the web server.
 
* Static content is served directly by *Nginx*.
 
* Each web application gets distinct sub-directory under ``/var/www``, named
 
  after the FQDN. All sub-directories created under there are created with
 
  ``2750`` permissions, with ownership set to admin user, and group set to the
 
  application's group. In other words, all directories will have ``SGID`` bit
 
  set, allowing you to create files/directories that will have their group
 
  automatically set to the group of the parent directory.
 
* Each WSGI website gets a dedicated virtual environment, stored in the
 
  sub-directory ``virtualenv`` of the website directory, for example
 
  ``/var/www/wiki.example.com/virtualenv``.
 
* Static files are served from sub-directory ``htdocs`` in the website
 
  directory, for example ``/var/www/wiki.example.com/htdocs/``.
 
* The base directory where your website/application code should be at is
 
  expected to be in sub-directory ``code`` in the website directory, for example
 
  ``/var/www/wiki.example.com/code/``.
 
* Combination of admin user membership in application group, ``SGID``
 
  permission, and the way ownership of sub-directories is set-up usually means
 
  that the administrator will be capable of managing application files, and
 
  application can be granted write permissions to a *minimum* of necessary
 
  files.
 

	
 
  .. warning::
 
     Just keep in mind that some file-management commands, like ``mv``, do *not*
 
     respect the ``SGID`` bit. In fact, I would recommend using ``cp`` when you
 
     deploy new files to the directory instead (don't simply move them from your
 
     home directory).
 

	
 
1. Set-up the necessary directories first::
 

	
 
     mkdir -p ~/mysite/roles/wiki/{tasks,meta,files,handlers}/
 

	
 
2. Set-up some role dependencies, reusing the common role infrastructure.
 

	
 
   :file:`~/mysite/roles/wiki/meta/main.yml`
 
   ::
 

	
 
      ---
 

	
 
      dependencies:
 
        - role: wsgi_website
 
          fqdn: wiki.example.com
 
          # TLS key and certificate to use for the virtual host.
 
          https_tls_certificate: "{{ lookup('file', '~/mysite/tls/wiki.example.com_https.pem') }}"
 
          https_tls_key: "{{ lookup('file', '~/mysite/tls/wiki.example.com_https.key') }}"
 
          # In many cases you need to have some development packages available
 
          # in order to build Python packages installed via pip
 
          packages:
 
            - build-essential
 
            - python3-dev
 
            - libjpeg62-turbo
 
            - libjpeg-dev
 
            - libpng16-16
 
            - libpng-dev
 
            - libmariadb-dev
 
            - libmariadb-dev-compat
 
            - pkg-config
 
          # Here we specify that anything accessing our website with "/static/"
 
          # URL should be treated as request to a static file, to be served
 
          # directly by Nginx instead of the WSGI server.
 
          static_locations:
 
            - /static/
 
          # Again, not mandatory, but it is good to have some sort of policy
 
          # for assigning UIDs.
 
          uid: 2001
 
          admin_uid: 3001
 
          # These are additional packages that should be installed in the
 
          # virtual environment.
 
          virtualenv_packages:
 
            - django~=4.2.0
 
            - wiki~=0.10.0
 
            - mysqlclient
 
          # This is the name of the WSGI application to
 
          # serve. wiki_example_com.wsgi will be the Python "module" that is
 
          # accesed, while application is the object instantiated within it (the
 
          # application itself). The module is referenced relative to the code
 
          # directory (in our case /var/www/wiki.example.com/code/).
 
          wsgi_application: wiki_example_com.wsgi:application
 
          # Specify explicitly requirements for installing Gunicorn.
 
          wsgi_requirements:
 
            - gunicorn==21.2.0
 
            - packaging==23.2
 
          wsgi_requirements_in:
 
            - gunicorn
 
        - role: database
 
          db_name: wiki
 
          db_password: wiki
 

	
 
3. Let's create a dedicated private key/certificate pair for the wiki website:
 

	
 
   1. Create new template for ``certtool``:
 

	
 
      :file:`~/mysite/tls/wiki.example.com_https.cfg`
 
      ::
 

	
 
         organization = "Example Inc."
 
         country = SE
 
         cn = "Exampe Inc. Wiki"
 
         expiration_days = 365
 
         dns_name = "wiki.example.com"
 
         tls_www_server
 
         signing_key
 
         encryption_key
 

	
 
   2. Create the keys and certificates for the application::
 

	
 
        certtool --sec-param normal --generate-privkey --outfile ~/mysite/tls/wiki.example.com_https.key
 
        certtool --generate-certificate --load-ca-privkey ~/mysite/tls/ca.key --load-ca-certificate ~/mysite/tls/ca.pem --template ~/mysite/tls/wiki.example.com_https.cfg --load-privkey ~/mysite/tls/wiki.example.com_https.key --outfile ~/mysite/tls/wiki.example.com_https.pem
 

	
 
4. At this point we have exhausted what we can do with the built-in roles. Time
 
   to add some custom tasks.
 

	
 
   :file:`~/mysite/roles/wiki/tasks/main.yml`
 
   ::
 

	
 
      ---
 

	
 
      - name: Create Django project directory
 
        ansible.builtin.file:
 
          dest: "/var/www/wiki.example.com/code"
 
          state: directory
 
          owner: admin-wiki_example_com
 
          group: web-wiki_example_com
 
          mode: 02750
 

	
 
      - name: Start Django project for the Wiki website
 
        ansible.builtin.command: "/var/www/wiki.example.com/virtualenv/bin/exec django-admin startproject wiki_example_com /var/www/wiki.example.com/code"
 
        args:
 
          chdir: "/var/www/wiki.example.com"
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