Add borg-backup roles

This adds roles to implement backup with borg [1].

Our current tool "bup" has no Python 3 support and is not packaged for
Ubuntu Focal.  This means it is effectively end-of-life.  borg fits
our model of servers backing themselves up to a central location, is
well documented and seems well supported.  It also has the clarkb seal
of approval :)

As mentioned, borg works in the same manner as bup by doing an
efficient back up over ssh to a remote server.  The core of these
roles are the same as the bup based ones; in terms of creating a
separate user for each host and deploying keys and ssh config.

This chooses to install borg in a virtualenv on /opt.  This was chosen
for a number of reasons; firstly reading the history of borg there
have been incompatible updates (although they provide a tool to update
repository formats); it seems important that we both pin the version
we are using and keep clients and server in sync.  Since we have a
hetrogenous distribution collection we don't want to rely on the
packaged tools which may differ.  I don't feel like this is a great
application for a container; we actually don't want it that isolated
from the base system because it's goal is to read and copy it offsite
with as little chance of things going wrong as possible.

Borg has a lot of support for encrypting the data at rest in various
ways.  However, that introduces the possibility we could lose both the
key and the backup data.  Really the only thing stopping this is key
management, and if we want to go down this path we can do it as a
follow-on.

The remote end server is configured via ssh command rules to run in
append-only mode.  This means a misbehaving client can't delete its
old backups.  In theory we can prune backups on the server side --
something we could not do with bup.  The documentation has been
updated but is vague on this part; I think we should get some hosts in
operation, see how the de-duplication is working out and then decide
how we want to mange things long term.

Testing is added; a focal and bionic host both run a full backup of
themselves to the backup server.  Pretty cool, the logs are in
/var/log/borg-backup-<host>.log.

No hosts are currently in the borg groups, so this can be applied
without affecting production.  I'd suggest the next steps are to bring
up a borg-based backup server and put a few hosts into this.  After
running for a while, we can add all hosts, and then deprecate the
current bup-based backup server in vexxhost and replace that with a
borg-based one; giving us dual offsite backups.

[1] https://borgbackup.readthedocs.io/en/stable/

Change-Id: I2a125f2fac11d8e3a3279eb7fa7adb33a3acaa4e

doc/source/sysadmin.rst

@@ -231,12 +231,14 @@ Or use matching to cover a range of servers::
 Backups
 =======
 
-Infra uses the `bup <https://bup.github.io>`__ tool for backups.
+Infra uses the `borg <https://borgbackup.readthedocs.io>`__ backup
+tool.
 
-Hosts in the ``backup`` Ansible inventory group will be backed up to
-servers in the ``backup-server`` group with ``bup``.  The
-``playbooks/roles/backup`` and ``playbooks/roles/backup-server`` roles
-implement the required setup.
+Hosts in the ``borg-backup`` Ansible inventory group will be backed up
+to servers in the ``borg-backup-server`` group with ``borg``.  The
+``playbooks/roles/borg-backup`` and
+``playbooks/roles/borg-backup-server`` roles implement the required
+setup.
 
 The backup server has a unique Unix user for each host to be backed
 up.  The roles will setup required users, their home directories in
@@ -250,52 +252,27 @@ key setup just for backup communication (see ``/root/.ssh/config``).
 Restore from Backup
 -------------------
 
-On the server that needs items restored from backup become root, start a
-screen session as restoring can take a while, and create a working
-directory to restore the backups into. This allows us to be selective in
-how we restore content from backups::
+``borg`` has many options for restoring but a basic way to dump a host
+at a particular time is to
 
-  sudo su -
-  screen
-  mkdir /root/backup-restore-$DATE
-  cd /root/backup-restore-$DATE
-
-Root uses a separate ssh key and remote user to communicate with the
-backup server(s); the username and key to use for backup should be
-automatically configured in ``/root/.ssh/config``.  The backup server
-hostname can be taken from there.
-
-At this point we can join the tar that was split by the backup cron::
-
-  bup join -r backup.x.y.opendev.org: root > backup.tar
-
-At this point you may need to wait a while. These backups are stored on
-servers geographically distant from our normal servers resulting in less
-network throughput between servers than we are used to.
-
-Once the ``bup join`` is complete you will have a tar archive of that
-backup. It may be useful to list the files in the backup
-``tar -tf backup.tar`` to get an idea of what things are available. At
-this point you will probably either want to extract the entire backup::
-
-  tar -xvf backup.tar
-  ls -al
-
-Or selectively extract files::
-
-  # path/to/file needs to match the output given by tar -t
-  tar -xvf backup.tar path/to/file
-
-Note if you created your working directory in a path that is not
-excluded by bup you will want to remove that directory when your work is
-done. /root/backup-restore-* is excluded so the path above is safe.
+* log into the backup server
+* sudo ``su -`` to switch to the backup user for the host to be restored
+* you will now be in the home directory of that user
+* run ``/opt/borg/bin/borg list ./backup`` to list the archives available
+* these should look like ``hostname-YYYY-MM-DDTHH:MM:SS``
+* move to working directory
+* extract one of the appropriate archives with ``/opt/borg/bin/borg extract ~/backup <archive-tag>``
 
 Rotating backup storage
 -----------------------
 
-Since ``bup`` only stores differences, it does not have an effective
-way to prune old backups.  The easiest way is to simply periodically
-start the backups fresh.
+We run ``borg`` in append-only mode, so that clients can not remove
+old backups on the server.
+
+TODO(ianw) : Write instructions on how to prune server side.  We
+should monitor growth to see if automatic pruning would be
+appropriate, or periodic manual pruning, or something similar to this
+existing system where we keep a historic archive and start fresh.
 
 The backup server keeps an active volume and the previously rotated
 volume.  Each consists of 3 x 1TiB volumes grouped with LVM.  The

playbooks/roles/borg-backup-server/README.rst

@@ -0,0 +1,15 @@
+Setup backup server
+
+This role configures backup server(s) in the ``borg-backup-server`` group
+to accept backups from remote hosts.
+
+Note that the ``borg-backup`` role must have run on each host in the
+``borg-backup`` group before this role.  That role will create a
+``borg_user`` tuple in the hostvars for for each host consisting of
+the required username and public key.
+
+Each required user gets a separate home directory in ``/opt/backups``.
+Their ``authorized_keys`` file is configured with the public key to
+allow the remote host to log in and only run ``borg`` in server mode.
+
+**Role Variables**

playbooks/roles/borg-backup-server/defaults/main.yaml

@@ -0,0 +1 @@
+borg_users: []

playbooks/roles/borg-backup-server/tasks/main.yaml

@@ -0,0 +1,19 @@
+- name: Create backup directory
+  file:
+    state: directory
+    path: /opt/backups
+
+- name: Install borg
+  include_role:
+    name: install-borg
+
+- name: Build all borg users from backup hosts
+  set_fact:
+    borg_users: '{{ borg_users }} + [ {{ hostvars[item]["borg_user"] }} ]'
+  with_inventory_hostnames: 'borg-backup:!disabled'
+
+- name: Create borg users
+  include_tasks: user.yaml
+  loop: '{{ borg_users }}'
+  loop_control:
+    loop_var: borg_user

playbooks/roles/borg-backup-server/tasks/user.yaml

@@ -0,0 +1,31 @@
+# note borg_user is the parent loop variable name; this works on each
+# element from the borg_users global.
+- name: Set variables
+  set_fact:
+    user_name: '{{ borg_user[0] }}'
+    user_key: '{{ borg_user[1] }}'
+
+- name: Create borg user
+  user:
+    name: '{{ user_name }}'
+    comment: 'Backup user'
+    shell: /bin/bash
+    home: '/opt/backups/{{ user_name }}'
+    create_home: yes
+  register: homedir
+
+- name: Create borg user authorized key
+  authorized_key:
+    user: '{{ user_name }}'
+    state: present
+    key: '{{ user_key }}'
+    key_options: 'command="/opt/borg/bin/borg serve --append-only --restrict-to-path /opt/backups/{{ user_name }}/backup",restrict'
+
+# ansible-lint wants this in a handler, it should be done here and
+# now; this isn't like a service restart where multiple things might
+# call it.
+- name: Initalise borg
+  command:  /opt/borg/bin/borg init --encryption=none /opt/backups/{{ user_name }}/backup
+  become: yes
+  become_user: '{{ user_name }}'
+  when: homedir.changed

playbooks/roles/borg-backup/README.rst

@@ -0,0 +1,36 @@
+Configure a host to be backed up
+
+This role setups a host to use ``borgp`` for backup to any hosts in the
+``borg-backup-server`` group.
+
+A separate ssh key will be generated for root to connect to the backup
+server(s) and the host key for the backup servers will be accepted to
+the host.
+
+The ``borg`` tool is installed and a cron job is setup to run the
+backup periodically.
+
+Note the ``borg-backup-server`` role must run after this to create the user
+correctly on the backup server.  This role sets a tuple ``borg_user``
+with the username and public key; the ``borg-backup-server`` role uses this
+variable for each host in the ``borg-backup`` group to initalise users.
+
+**Role Variables**
+
+.. zuul:rolevar:: borg_username
+
+   The username to connect to the backup server.  If this is left
+   undefined, it will be automatically set to ``borg-$(hostname)``
+
+.. zuul:rolevar:: borg_backup_excludes_extra
+   :default: []
+
+   A list of extra items to pass as ``--exclude`` arguments to borg.
+   Appended to the global default list of excludes set with
+   ``borg_backup_excludes``.
+
+.. zuul:rolevar:: borg_backup_dirs_extra
+   :default: []
+
+   A list of extra directories to backup.  Appended to the global
+   default list of directories set with ``borg_backup_dirs``.

playbooks/roles/borg-backup/defaults/main.yaml

@@ -0,0 +1,13 @@
+borg_backup_excludes:
+  - '/home/*.cache/*'
+  - '/var/cache/*'
+  - '/var/tmp/*'
+borg_backup_excludes_extra: []
+
+borg_backup_dirs:
+  - /etc
+  - /home
+  - /root
+  - /var
+borg_backup_dirs_extra: []
+

playbooks/roles/borg-backup/tasks/main.yaml

@@ -0,0 +1,63 @@
+- name: Generate borg username for this host
+  set_fact:
+    borg_username: 'borg-{{ inventory_hostname.split(".", 1)[0] }}'
+  when: borg_username is not defined
+
+- debug:
+    var: borg_username
+
+- name: Install borg
+  include_role:
+    name: install-borg
+
+- name: Install backup script
+  template:
+    src: borg-backup.j2
+    dest: /usr/local/bin/borg-backup
+    mode: 0755
+
+- name: Generate keypair for backups
+  openssh_keypair:
+    path: /root/.ssh/id_borg_backup_ed25519
+    type: ed25519
+  register: borg_keypair
+
+- name: Configure ssh for backup server
+  blockinfile:
+    path: /root/.ssh/config
+    create: true
+    block: |
+      # {{ item }} backup server
+      Host {{ item }}
+      HostName {{ item }}
+      IdentityFile /root/.ssh/id_borg_backup_ed25519
+      User {{ borg_username }}
+    mode: 0600
+  with_inventory_hostnames: borg-backup-server
+
+- name: Generate borg_user info tuple
+  set_fact:
+    borg_user: '{{ [ borg_username, borg_keypair["public_key"] ] }}'
+
+- name: Accept hostkey of backup server
+  known_hosts:
+    state: present
+    key: '{{ item }} ssh-ed25519 {{ hostvars[item]["ansible_ssh_host_key_ed25519_public"] }}'
+    name: '{{ item }}'
+  with_inventory_hostnames: borg-backup-server
+
+- name: Install backup cron job
+  cron:
+    name: "Run borg backup"
+    job: "/usr/local/bin/borg-backup {{ item }} 2>> /var/log/borg-backup-{{ item }}.log"
+    user: root
+    hour: '5'
+    minute: '{{ 59|random(seed=item) }}'
+  with_inventory_hostnames: borg-backup-server
+
+- name: Install logrotate rules
+  include_role:
+    name: logrotate
+  vars:
+    logrotate_file_name: '/var/log/borg-backup-{{ item }}.txt'
+  with_inventory_hostnames: borg-backup-server

playbooks/roles/borg-backup/templates/borg-backup.j2

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# Flags based on
+#  https://borgbackup.readthedocs.io/en/stable/quickstart.html
+
+if [ -z "$1" ]; then
+    echo "Must specify backup host"
+    exit 1
+fi
+
+BORG="/opt/borg/bin/borg"
+
+# Setting this, so the repo does not need to be given on the commandline:
+export BORG_REPO="ssh://{{ borg_username}}@${1}/opt/backups/{{ borg_username }}/backup"
+
+# some helpers and error handling:
+info() { printf "\n%s %s\n\n" "$( date )" "$*" >&2; }
+trap 'echo $( date ) Backup interrupted >&2; exit 2' INT TERM
+
+info "Starting backup"
+
+# This avoids UI prompts when first accessing the remote repository
+export BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK=1
+
+# Backup the most important directories into an archive named after
+# the machine this script is currently running on:
+${BORG} create                      \
+    --verbose                       \
+    --filter AME                    \
+    --list                          \
+    --stats                         \
+    --show-rc                       \
+    --compression lz4               \
+    --exclude-caches                \
+{% for item in borg_backup_excludes + borg_backup_excludes_extra -%}
+    --exclude '{{ item }}'          \
+{% endfor -%}
+                                    \
+    ::'{hostname}-{now}'            \
+{% for item in borg_backup_dirs + borg_backup_dirs_extra -%}
+    {{ item }} {{ '\\' if not loop.last }}
+{% endfor -%}
+
+backup_exit=$?
+
+if [ ${backup_exit} -eq 0 ]; then
+    info "Backup finished successfully"
+else
+    info "Backup finished with errors"
+fi
+
+exit ${backup_exit}
+

playbooks/roles/install-borg/README.rst

@@ -0,0 +1,11 @@
+Install borg backup tool to /opt/borg
+
+Install borg to a virtualenv; the binary will be available at
+``/opt/borg/bin/borg``.
+
+**Role Variables**
+
+.. zuul:rolevar:: borg_version
+
+   The version of ``borg`` to install.  This should likely be pinned
+   to be the same between server and client.

playbooks/roles/install-borg/defaults/main.yaml

@@ -0,0 +1 @@
+borg_version: 1.1.13

playbooks/roles/install-borg/tasks/main.yaml

@@ -0,0 +1,24 @@
+# We install into a virtualenv here for two reasons; we want a
+# specific version pinned between server and client -- borg has had
+# updates that required transitions so we don't want to use system
+# packages where thing might get out of sync.  Secondly we want to
+# keep as few things as possible to go wrong when running backups.
+- name: Install build deps
+  package:
+    name:
+      - python3-dev
+      - libssl-dev
+      - openssl
+      - libacl1-dev
+      - libacl1
+      - build-essential
+
+- name: Install borg
+  pip:
+    # borg build deps are a little ... interesting, it needs cython
+    # but the requirements don't bring it in.
+    name:
+      - cython
+      - 'borgbackup=={{ borg_version }}'
+    virtualenv: /opt/borg
+    virtualenv_command: /usr/bin/python3 -m venv

playbooks/service-borg-backup.yaml

@@ -0,0 +1,12 @@
+# This needs to happen in order.  Backup hosts export their username/key
+# combos which are installed onto the backup server
+- hosts: "borg-backup:!disabled"
+  name: "Base: Generate borg backup users and keys"
+  roles:
+    - iptables
+    - borg-backup
+- hosts: "borg-backup-server:!disabled"
+  name: "Generate borg configuration"
+  roles:
+    - iptables
+    - borg-backup-server

playbooks/zuul/templates/gate-groups.yaml.j2

@@ -20,3 +20,10 @@ groups:
   backup:
     - backup-test01.opendev.org
     - backup-test02.opendev.org
+
+  borg-backup-server:
+    - borg-backup01.region.provider.opendev.org
+
+  borg-backup:
+    - borg-backup-test01.opendev.org
+    - borg-backup-test02.opendev.org

testinfra/test_borg_backups.py

@@ -0,0 +1,77 @@
+# Copyright 2019 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import os.path
+import pytest
+
+testinfra_hosts = ['borg-backup01.region.provider.opendev.org',
+                   'borg-backup-test01.opendev.org',
+                   'borg-backup-test02.opendev.org']
+
+
+def test_borg_installed(host):
+    f = host.file('/opt/borg/bin/borg')
+    assert f.exists
+
+    cmd = host.run('/opt/borg/bin/borg --version')
+    assert cmd.succeeded
+    # NOTE(ianw): deliberately pinned; we want to be careful if we
+    # update that the new version is compatible with old repos.
+    assert '1.1.13' in cmd.stdout
+
+def test_borg_server_users(host):
+    hostname = host.backend.get_hostname()
+    if hostname.startswith('borg-backup-test'):
+        pytest.skip()
+
+    for username in 'borg-borg-backup-test01', 'borg-borg-backup-test02':
+        homedir = os.path.join('/opt/backups/', username)
+        borg_repo = os.path.join(homedir, 'backup')
+        authorized_keys = os.path.join(homedir, '.ssh', 'authorized_keys')
+
+        user = host.user(username)
+        assert user.exists
+        assert user.home == homedir
+
+        f = host.file(authorized_keys)
+        assert f.exists
+        assert f.contains("ssh-ed25519")
+
+        f = host.file(borg_repo)
+        assert f.exists
+
+def test_borg_backup_host_config(host):
+    hostname = host.backend.get_hostname()
+    if hostname == 'borg-backup01.region.provider.opendev.org':
+        pytest.skip()
+
+    f = host.file('/usr/local/bin/borg-backup')
+    assert f.exists
+
+    f = host.file('/root/.ssh/id_borg_backup_ed25519')
+    assert f.exists
+
+    f = host.file('/root/.ssh/config')
+    assert f.exists
+    assert f.contains('Host borg-backup01.region.provider.opendev.org')
+
+def test_borg_backup(host):
+    hostname = host.backend.get_hostname()
+    if hostname == 'borg-backup01.region.provider.opendev.org':
+        pytest.skip()
+
+    cmd = host.run(
+        '/usr/local/bin/borg-backup borg-backup01.region.provider.opendev.org 2>> '
+        '/var/log/borg-backup-borg-backup01.region.provider.opendev.org.log')
+    assert cmd.succeeded

zuul.d/infra-prod.yaml

@@ -285,6 +285,19 @@
       - playbooks/roles/backup-server/
       - playbooks/roles/iptables/
 
+- job:
+    name: infra-prod-service-borg-backup
+    parent: infra-prod-service-base
+    description: Run service-borg-backup.yaml playbook.
+    vars:
+      playbook_name: service-borg-backup.yaml
+    files:
+      - inventory/
+      - playbooks/service-borg-backup.yaml
+      - playbooks/roles/borg-backup/
+      - playbooks/roles/borg-backup-server/
+      - playbooks/roles/iptables/
+
 - job:
     name: infra-prod-service-registry
     parent: infra-prod-service-base

zuul.d/project.yaml

@@ -13,6 +13,7 @@
         - system-config-run-base-ansible-devel:
             voting: false
         - system-config-run-backup
+        - system-config-run-borg-backup
         - system-config-run-dns
         - system-config-run-eavesdrop:
             dependencies:
@@ -235,6 +236,7 @@
         - infra-prod-service-mirror
         - infra-prod-service-static
         - infra-prod-service-backup
+        - infra-prod-service-borg-backup
         - infra-prod-service-registry
         - infra-prod-service-zookeeper
         - infra-prod-service-zuul
@@ -276,6 +278,7 @@
         - infra-prod-service-mirror-update
         - infra-prod-service-mirror
         - infra-prod-service-static
+        - infra-prod-service-borg-backup
         - infra-prod-service-backup
         - infra-prod-service-zookeeper
         - infra-prod-service-review

zuul.d/system-config-run.yaml

@@ -342,6 +342,38 @@
       - playbooks/zuul/templates/host_vars/backup
       - testinfra/test_backups.py
 
+- job:
+    name: system-config-run-borg-backup
+    parent: system-config-run
+    description: |
+      Run the playbook for borg backup configuration
+    nodeset:
+      nodes:
+        - name: bridge.openstack.org
+          label: ubuntu-bionic
+        - name: borg-backup01.region.provider.opendev.org
+          label: ubuntu-focal
+        - name: borg-backup-test01.opendev.org
+          label: ubuntu-focal
+        - name: borg-backup-test02.opendev.org
+          label: ubuntu-bionic
+    vars:
+      run_playbooks:
+        - playbooks/service-borg-backup.yaml
+    files:
+      - playbooks/install-ansible.yaml
+      - playbooks/roles/borg-backup
+      - playbooks/zuul/templates/host_vars/borg-backup
+      - testinfra/test_borg_backups.py
+    host-vars:
+      borg-backup-test01.opendev.org:
+        host_copy_output:
+          '/var/log/borg-backup-borg-backup01.region.provider.opendev.org.log': logs
+      borg-backup-test02.opendev.org:
+        host_copy_output:
+          '/var/log/borg-backup-borg-backup01.region.provider.opendev.org.log': logs
+
+
 - job:
     name: system-config-run-mirror-base
     parent: system-config-run