Add support for upgrading Postgres

Since cbee084ac19b6, this playbook supports Postgres 10.x,
but keeps existing Postgres-9.x installs on 9.x.

This playbook can now also be ran with `--tags=upgrade-postgres`
to make it upgrade from Postgres 9.x to 10.x (or other versions
in the future).

README.md

@@ -259,6 +259,28 @@ You can do it via this Ansible playbook (make sure to edit the `<your-username>`
 **Note**: `<your-username>` is just a plain username (like `john`), not your full `@<username>:<your-domain>` identifier.
 
 
+### Upgrading Postgres
+
+If you're not using an external Postgres server, this playbook initially installs Postgres for you.
+
+Once installed like that, this playbook attempts to preserve the Postgres version it starts with.
+This is because newer Postgres versions cannot start with data generated by an older Postgres version.
+An upgrade must be performed.
+
+This playbook can upgrade your existing Postgres setup with the following command:
+
+	ansible-playbook -i inventory/hosts setup.yml --tags=upgrade-postgres
+
+**The old Postgres data directory is backed up** (by renaming to `/matrix/postgres-auto-upgrade-backup`).
+It stays around forever, until you **manually decide to delete it**.
+
+As part of the upgrade, the database is dumped to `/tmp`, upgraded and then restored from that dump.
+To use a different directory, pass some extra flags to the command above, like this: `--extra-vars="postgres_dump_dir=/directory/to/dump/here"`
+
+**ONLY one database is migrated** (the one specified in `matrix_postgres_db_name`, named `homeserver` by default).
+If you've created other databases in that database instance (something this playbook never does and never advises), data will be lost.
+
+
 ## Uninstalling
 
 **Note**: If you have some trouble with your installation configuration, you can just re-run the playbook and it will try to set things up again. You don't need to uninstall and install fresh.

roles/matrix-server/tasks/main.yml

@@ -13,6 +13,10 @@
     - setup-main
     - setup-ssl
 
+- include: tasks/upgrade_postgres.yml
+  tags:
+    - upgrade-postgres
+
 - include: tasks/setup_postgres.yml
   tags:
     - setup-main

roles/matrix-server/tasks/setup_postgres.yml

@@ -33,6 +33,10 @@
     docker_postgres_image_to_use: "{{ docker_postgres_image_v9 }}"
   when: "pg_version.startswith('9.')"
 
+- debug:
+    msg: "NOTE: Your setup is on an old Postgres version ({{ docker_postgres_image_to_use }}), while {{ docker_postgres_image_latest }} is supported. You can upgrade using --tags=upgrade-postgres"
+  when: "docker_postgres_image_to_use != docker_postgres_image_latest"
+
 # Even if we don't run the internal server, we still need this for running the CLI
 - name: Ensure postgres Docker image is pulled
   docker_image:

roles/matrix-server/tasks/upgrade_postgres.yml

@@ -0,0 +1,123 @@
+---
+
+- name: Set default postgres_dump_dir, if not provided
+  set_fact:
+    postgres_dump_dir: "/tmp"
+  when: "postgres_dump_dir|default('') == ''"
+
+- name: Set postgres_dump_name, if not provided
+  set_fact:
+    postgres_dump_name: "matrix-postgres.out"
+  when: "postgres_dump_name|default('') == ''"
+
+- set_fact:
+    postgres_auto_upgrade_backup_data_path: "{{ matrix_postgres_data_path }}-auto-upgrade-backup"
+
+- name: Fail, if trying to upgrade external Postgres database
+  fail:
+    msg: "Your configuration indicates that you're using an external Postgres database. Refusing to try and upgrade that."
+  when: "matrix_postgres_use_external"
+
+- name: Check Postgres auto-upgrade backup data directory
+  stat:
+    path: "{{ postgres_auto_upgrade_backup_data_path }}"
+  register: result_auto_upgrade_path
+
+- name: Abort, if existing Postgres auto-upgrade data path detected
+  fail:
+    msg: "Detected that a left-over {{ postgres_auto_upgrade_backup_data_path }} exists. You should rename it to {{ matrix_postgres_data_path }} if the previous upgrade went wrong, or delete it if it went well."
+  when: "result_auto_upgrade_path.stat.exists"
+
+- name: Determine existing Postgres version (check PG_VERSION file)
+  stat:
+    path: "{{ matrix_postgres_data_path }}/PG_VERSION"
+  register: result_pg_version_stat
+
+- name: Abort, if no existing Postgres version detected
+  fail: msg="Could not find existing Postgres installation"
+  when: "not result_pg_version_stat.stat.exists"
+
+- name: Determine existing Postgres version (read PG_VERSION file)
+  slurp:
+    src: "{{ matrix_postgres_data_path }}/PG_VERSION"
+  register: result_pg_version
+
+- name: Determine existing Postgres version (default to empty)
+  set_fact:
+    pg_version: ""
+
+- name: Determine existing Postgres version (make sense of PG_VERSION file)
+  set_fact:
+    pg_version: "{{ result_pg_version['content']|b64decode|replace('\n', '') }}"
+
+- name: Determine Postgres version to use (default to latest)
+  set_fact:
+    docker_postgres_image_to_use: "{{ docker_postgres_image_latest }}"
+
+- name: Determine Postgres version to use (use 9.x, if detected)
+  set_fact:
+    docker_postgres_image_to_use: "{{ docker_postgres_image_v9 }}"
+  when: "pg_version.startswith('9.')"
+
+- name: Abort, if already at latest Postgres version
+  fail: msg="You are already running the latest Postgres version supported. Nothing to do"
+  when: "docker_postgres_image_to_use == docker_postgres_image_latest"
+
+- name: Ensure matrix-synapse is stopped
+  service: name=matrix-synapse state=stopped
+
+- name: Ensure matrix-postgres is started
+  service: name=matrix-postgres state=started daemon_reload=yes
+
+- name: Wait a bit, so that Postgres can start
+  wait_for:
+    timeout: 5
+  delegate_to: 127.0.0.1
+  become: false
+
+- name: Perform Postgres database dump
+  command: |
+    /usr/bin/docker run --rm --name matrix-postgres-dump \
+    --link matrix-postgres:postgres \
+    --env-file=/matrix/environment-variables/env-postgres-pgsql-docker \
+    -v {{ postgres_dump_dir }}:/out \
+    {{ docker_postgres_image_to_use }} pg_dump -h postgres {{ matrix_postgres_db_name }} -f /out/{{ postgres_dump_name }}
+
+- name: Ensure matrix-postgres is stopped
+  service: name=matrix-postgres state=stopped
+
+- name: Rename existing Postgres data directory
+  command: "mv {{ matrix_postgres_data_path }} {{ postgres_auto_upgrade_backup_data_path }}"
+
+- debug:
+    msg: "NOTE: Your Postgres data directory has been moved from `{{ matrix_postgres_data_path }}` to `{{ postgres_auto_upgrade_backup_data_path }}`. In the event of failure, you can move it back and run the playbook with --tags=setup-postgres to restore operation."
+
+- include: tasks/setup_postgres.yml
+
+- name: Ensure matrix-postgres autoruns and is restarted
+  service: name=matrix-postgres enabled=yes state=restarted daemon_reload=yes
+
+- name: Wait a bit, so that Postgres can start
+  wait_for:
+    timeout: 5
+  delegate_to: 127.0.0.1
+  become: false
+
+- name: Perform Postgres database import
+  command: |
+    /usr/bin/docker run --rm --name matrix-postgres-import \
+    --link matrix-postgres:postgres \
+    --env-file=/matrix/environment-variables/env-postgres-pgsql-docker \
+    -v {{ postgres_dump_dir }}:/in:ro \
+    {{ docker_postgres_image_to_use }} psql -h postgres -f /in/{{ postgres_dump_name }}
+
+- name: Delete Postgres database dump file
+  file:
+    path: "{{ postgres_dump_dir }}/{{ postgres_dump_name }}"
+    state: absent
+
+- name: Ensure matrix-synapse is started
+  service: name=matrix-synapse state=started daemon_reload=yes
+
+- debug:
+    msg: "NOTE: Your old Postgres data directory is preserved at `{{ postgres_auto_upgrade_backup_data_path }}`. You might want to get rid of it once you've confirmed that all is well."