matrix-docker-ansible-deploy/roles/matrix-postgres/tasks/util/migrate_db_to_postgres.yml

---

- name: Fail if Postgres not enabled
  ansible.builtin.fail:
    msg: "Postgres via the matrix-postgres role is not enabled (`matrix_postgres_enabled`). Cannot migrate."
  when: "not matrix_postgres_enabled | bool"

- name: Fail if util called incorrectly (missing matrix_postgres_db_migration_request)
  ansible.builtin.fail:
    msg: "The `matrix_postgres_db_migration_request` variable needs to be provided to this util."
  when: "matrix_postgres_db_migration_request is not defined"

- name: Fail if util called incorrectly (invalid matrix_postgres_db_migration_request)
  ansible.builtin.fail:
    msg: "The `matrix_postgres_db_migration_request` variable needs to contain `{{ item }}`."
  with_items:
    - src
    - dst
    - caller
    - engine_variable_name
    - systemd_services_to_stop
  when: "item not in matrix_postgres_db_migration_request"

- name: Check if the provided source database file exists
  ansible.builtin.stat:
    path: "{{ matrix_postgres_db_migration_request.src }}"
  register: matrix_postgres_db_migration_request_src_stat_result

- name: Fail if provided source database file doesn't exist
  ansible.builtin.fail:
    msg: "File cannot be found on the server at {{ matrix_postgres_db_migration_request.src }}"
  when: "not matrix_postgres_db_migration_request_src_stat_result.stat.exists"

- block:
    - name: Ensure pgloader repository is present on self-build
      ansible.builtin.git:
        repo: "{{ matrix_postgres_pgloader_container_image_self_build_repo }}"
        dest: "{{ matrix_postgres_pgloader_container_image_self_build_src_path }}"
        version: "{{ matrix_postgres_pgloader_container_image_self_build_repo_branch }}"
        force: "yes"
      become: true
      become_user: "{{ matrix_user_username }}"
      register: matrix_postgres_pgloader_git_pull_results

    # If `stable` is used, we hit an error when processing /opt/src/pgloader/build/quicklisp/dists/quicklisp/software/uax-15-20201220-git/data/CompositionExclusions.txt:
    # > the octet sequence #(194) cannot be decoded
    #
    # The issue is described here and is not getting fixed for months: https://github.com/dimitri/pgloader/pull/1179
    #
    # Although we're not using the dimitri/pgloader image, the one we're using suffers from the same problem.
    - name: Switch pgloader base image from Debian stable (likely 10.x/Buster) to Bullseye
      ansible.builtin.lineinfile:
        path: "{{ matrix_postgres_pgloader_container_image_self_build_src_path }}/Dockerfile"
        regexp: "{{ item.match }}"
        line: "{{ item.replace }}"
      with_items:
        - match: '^FROM debian:stable-slim as builder$'
          replace: 'FROM debian:bullseye-slim as builder'
        - match: '^FROM debian:stable-slim$'
          replace: 'FROM debian:bullseye-slim'

    - name: Ensure pgloader Docker image is built
      docker_image:
        name: "{{ matrix_postgres_pgloader_docker_image }}"
        source: build
        force_source: "{{ matrix_postgres_pgloader_git_pull_results.changed if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
        force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_postgres_pgloader_git_pull_results.changed }}"
        build:
          dockerfile: Dockerfile
          path: "{{ matrix_postgres_pgloader_container_image_self_build_src_path }}"
          pull: true
  when: "matrix_postgres_pgloader_container_image_self_build | bool"

- name: Ensure pgloader Docker image is pulled
  docker_image:
    name: "{{ matrix_postgres_pgloader_docker_image }}"
    source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
    force_source: "{{ matrix_postgres_pgloader_docker_image_force_pull if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
    force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_postgres_pgloader_docker_image_force_pull }}"
  when: "not matrix_postgres_pgloader_container_image_self_build"

# Defaults

- name: Set postgres_start_wait_time, if not provided
  ansible.builtin.set_fact:
    postgres_start_wait_time: 15
  when: "postgres_start_wait_time | default('') == ''"

# Actual import work

# matrix-postgres is most likely started already
- name: Ensure matrix-postgres is started
  ansible.builtin.service:
    name: matrix-postgres
    state: started
    daemon_reload: true
  register: matrix_postgres_service_start_result

- name: Wait a bit, so that Postgres can start
  ansible.builtin.wait_for:
    timeout: "{{ postgres_start_wait_time }}"
  delegate_to: 127.0.0.1
  become: false
  when: "matrix_postgres_service_start_result.changed | bool"

# We only stop services here, leaving it to the caller to start them later.
#
# We can't start them, because they probably need to be reconfigured too (changing the configuration from using SQLite to Postgres, etc.),
# before starting.
#
# Since the caller will be starting them, it might make sense to leave stopping to it as well.
# However, we don't do it, because it's simpler having it here, and it also gets to happen only if we'll be doing an import.
# If we bailed out (somewhere above), nothing would have gotten stopped. It's nice to leave this running in such cases.
- name: Ensure systemd services blocking the database import are stopped
  ansible.builtin.service:
    name: "{{ item }}"
    state: stopped
  failed_when: false
  with_items: "{{ matrix_postgres_db_migration_request.systemd_services_to_stop }}"

- name: Import {{ matrix_postgres_db_migration_request.engine_old }} database from {{ matrix_postgres_db_migration_request.src }} into Postgres
  ansible.builtin.command:
    cmd: >-
      {{ matrix_host_command_docker }} run
      --rm
      --user={{ matrix_user_uid }}:{{ matrix_user_gid }}
      --cap-drop=ALL
      --network={{ matrix_docker_network }}
      --mount type=bind,src={{ matrix_postgres_db_migration_request.src }},dst=/in.db,ro
      --entrypoint=/bin/sh
      {{ matrix_postgres_pgloader_docker_image }}
      -c
      'pgloader {{ matrix_postgres_db_migration_request.pgloader_options | default([]) | join(' ') }} /in.db {{ matrix_postgres_db_migration_request.dst }}'      

- block:
    # We can't use `{{ role_path }}` here, neither with `import_tasks`, nor with `include_tasks`,
    # because it refers to the role that included this util, and not to the role this file belongs to.
    - ansible.builtin.import_tasks: "{{ role_path }}/../matrix-postgres/tasks/util/detect_existing_postgres_version.yml"

    - ansible.builtin.set_fact:
        matrix_postgres_docker_image_to_use: "{{ matrix_postgres_docker_image_latest if matrix_postgres_detected_version_corresponding_docker_image == '' else matrix_postgres_detected_version_corresponding_docker_image }}"

    - name: Execute additional Postgres SQL migration statements
      ansible.builtin.command:
        cmd: >-
          {{ matrix_host_command_docker }} run
          --rm
          --user={{ matrix_user_uid }}:{{ matrix_user_gid }}
          --cap-drop=ALL
          --env-file={{ matrix_postgres_base_path }}/env-postgres-psql
          --network={{ matrix_docker_network }}
          {{ matrix_postgres_docker_image_to_use }}
          psql --host=matrix-postgres --dbname={{ matrix_postgres_db_migration_request.additional_psql_statements_db_name }} --command='{{ item }}'          
      with_items: "{{ matrix_postgres_db_migration_request.additional_psql_statements_list }}"

  when: "matrix_postgres_db_migration_request.additional_psql_statements_list | default([])|length > 0"

- name: Archive {{ matrix_postgres_db_migration_request.engine_old }} database ({{ matrix_postgres_db_migration_request.src }} -> {{ matrix_postgres_db_migration_request.src }}.backup)
  ansible.builtin.command:
    cmd: "mv {{ matrix_postgres_db_migration_request.src }} {{ matrix_postgres_db_migration_request.src }}.backup"

- name: Inject result
  ansible.builtin.set_fact:
    matrix_playbook_runtime_results: |
      {{
        matrix_playbook_runtime_results | default([])
        +
        [
          "NOTE: Your {{ matrix_postgres_db_migration_request.engine_old }} database file has been imported into Postgres. The original database file has been moved from `{{ matrix_postgres_db_migration_request.src }}` to `{{ matrix_postgres_db_migration_request.src }}.backup`. When you've confirmed that the import went well and everything works, you should be able to safely delete this file."
        ]
      }}