fix: implement an upgrade procedure for Pleroma.

This commit implements different installation paths when
running the pleroma-main role, depending on whether Pleroma
needs to be installed for the first time or upgraded.

For first time installations the playbook will run through
the normal download and installation process and also executes
the database migration. If Pleroma is already installed then,
by default, the playbook will not re-install Pleroma or re-run
the database migration. If the user wants to update Pleroma to
a newer version then they can re-run the playbook with the
command-line argument '--extra-vars enable_pleroma_upgrade=True'.

This commit also introduces a custom module used to compare the
installed and downloaded semantic versions of Pleroma.
The playbook uses this to see whether the version change is an upgrade,
a downgrade or no version change. If it's an upgrade the playbook
will proceed with the re-installation of Pleroma. If there is no
change then the playbook will skip installation. Finally if
it detects that the user is trying to downgrade Pleroma then it will
fail.

This commit resolves dananglin/pleroma-ansible-playbook#9 and also
resolves dananglin/pleroma-ansible-playbook#5

.gitignore

@@ -2,3 +2,6 @@ inventories/*
 !inventories/.gitkeep
 site.yml
 vapid-private-key.pem
+
+library/__pycache__/
+library/*.pyc

.gitlab-ci.yml

@@ -0,0 +1,13 @@
+---
+image: python:3.7.6-slim-buster
+
+stages:
+- test
+
+test:
+  stage: test
+  before_script:
+  - apt-get update && apt-get install make
+  - pip install ansible==2.9.6
+  script:
+  - make test_modules_unit

Makefile

@@ -24,3 +24,6 @@ vapid_private_key: $(VAPID_PRIVATE_KEY_FILE)
 vapid_public_key: $(VAPID_PRIVATE_KEY_FILE)
 	@echo -e "\n\nVapid public key:"
 	@openssl ec -in $(VAPID_PRIVATE_KEY_FILE) -pubout -outform DER 2> /dev/null | tail -c 65 | base64 | tr '/+' '_-' | tr -d '=' | tr -d '\n'
+
+test_modules_unit:
+	@find ./library -mindepth 1 -maxdepth 1 -type f -name test_*.py | xargs python3

library/compare_semantic_versions.py

@@ -0,0 +1,162 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+# Copyright: (c) 2020, Daniel Anglin <d.n.i.anglin@gmail.com>
+# The MIT License (see LICENSE or https://mit-license.org)
+
+ANSIBLE_METADATA = {
+  'metadata_version': '1.1',
+  'supported_by': 'community',
+  'status': ['preview']
+}
+
+DOCUMENTATION = '''
+---
+module: compare_semantic_versions
+
+short_description: Compares two semantic version values.
+
+description:
+- This module compares two semantic versions and outputs whether the change is an upgrade, a downgrade or no change.
+- The values must use valid semantic versioning in order for a successful comparison.
+
+version_added: "2.9.5"
+
+author: Daniel Anglin (@dananglin)
+
+options:
+  new_version:
+    description:
+    - The semantic version of the new software.
+    required: true
+    type: string
+  old_version:
+    description:
+    - The semantic version of the old software.
+    required: true
+    type: string
+'''
+
+EXAMPLES = '''
+- name: Simple comparison between two semantic versions.
+  compare_semantic_versions:
+    old_version: "1.7.10"
+    new_version: "1.8.0"
+  register: output1
+
+- debug:
+    msg: "{{ output1.result }}"
+
+- name: Semantic versions with the 'v' prefix are supported.
+  compare_semantic_versions:
+    old_version: "1.6.7"
+    new_version: "v3.5.9"
+  register: output2
+
+- debug:
+    msg: "{{ output2.result }}"
+
+- name: Semantic versions without minor and/or patch versions are supported.
+  compare_semantic_versions:
+    old_version: "v1.100.3"
+    new_version: "v2"
+  register: output3
+
+- debug:
+    msg: "{{ output3.result }}"
+'''
+
+RETURN = '''
+result:
+  description:
+  - The result of the comparison between the two semantic versions.
+  - The value "upgrade" is returned if the new version is higher than the old version.
+  - The value "downgrade" is returned if the new version is lower than the old version.
+  - The value "noVersionChange" is returned if the new version equals the old version.
+  returned: On success
+  type: string
+  sample: upgrade
+'''
+
+from ansible.module_utils.basic import AnsibleModule
+
+UPGRADE = "upgrade"
+DOWNGRADE = "downgrade"
+NO_VERSION_CHANGE = "noVersionChange"
+MAJOR = "major"
+MINOR = "minor"
+PATCH = "patch"
+MAX_VERSION_COMPONENTS = 3
+
+def process(semVer):
+    if semVer.startswith('v'):
+        semVer = semVer[1:]
+
+    semVerArr = semVer.split(".")
+
+    if len(semVerArr) > MAX_VERSION_COMPONENTS:
+        raise ValueError("invalid number of version components in semantic version '{}'.".format(semVer))
+
+    if len(semVerArr) < MAX_VERSION_COMPONENTS:
+        diff = MAX_VERSION_COMPONENTS - len(semVerArr)
+        for i in range(diff):
+            semVerArr.append('0')
+
+    try:
+        semVerMap = {
+                MAJOR: int(semVerArr[0]),
+                MINOR: int(semVerArr[1]),
+                PATCH: int(semVerArr[2])
+        }
+    except ValueError as e:
+        raise ValueError("unable to parse an int for semantic version '{}' due to invalid format. ({})".format(semVer, str(e)))
+
+    return semVerMap
+
+def compare_versions(old, new):
+    try:
+        oldSemVerMap = process(old)
+        newSemVerMap = process(new)
+    except:
+        raise
+
+    versions = [MAJOR, MINOR, PATCH]
+
+    for v in range(len(versions)):
+        if newSemVerMap[versions[v]] > oldSemVerMap[versions[v]]:
+            return UPGRADE
+        elif newSemVerMap[versions[v]] < oldSemVerMap[versions[v]]:
+            return DOWNGRADE
+
+    return NO_VERSION_CHANGE
+
+def run_module():
+    module_args = dict(
+        new_version = dict(type='str', required=True),
+        old_version = dict(type='str', required=True)
+    )
+
+    module = AnsibleModule(
+        argument_spec=module_args,
+        supports_check_mode=True
+    )
+
+    output = dict(
+        changed=False,
+        result=''
+    )
+
+    try:
+        result = compare_versions(module.params['old_version'], module.params['new_version'])
+    except ValueError as e:
+        module.fail_json(msg="Unable to compare semantic versions: {}".format(str(e)), **output)
+
+    output['result'] = result
+
+    module.exit_json(**output)
+
+def main():
+    run_module()
+
+if __name__ == '__main__':
+    main()

library/test_compare_semantic_versions.py

@@ -0,0 +1,33 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+# Copyright: (c) 2020, Daniel Anglin <d.n.i.anglin@gmail.com>
+# The MIT License (see LICENSE or https://mit-license.org)
+
+import unittest as u
+import compare_semantic_versions as c
+
+class TestCompareSemanticVersions(u.TestCase):
+    def test_compare_versions_results(self):
+        self.assertEqual(c.compare_versions("2.3.0", "3.0.0"), c.UPGRADE)
+        self.assertEqual(c.compare_versions("2.4.0", "2.3.0"), c.DOWNGRADE)
+        self.assertEqual(c.compare_versions("1.2.2", "1.2.3"), c.UPGRADE)
+        self.assertEqual(c.compare_versions("v2", "2.0.0"), c.NO_VERSION_CHANGE)
+        self.assertEqual(c.compare_versions("1.4.0", "v1.4"), c.NO_VERSION_CHANGE)
+        self.assertEqual(c.compare_versions("12.24.1", "v12.25.6"), c.UPGRADE)
+
+    def test_compare_versions_exceptions(self):
+        with self.assertRaises(ValueError) as ctx:
+            c.compare_versions("1.2.3.4", "1.2.3")
+        self.assertEqual("invalid number of version components in semantic version '1.2.3.4'.", str(ctx.exception))
+
+        with self.assertRaises(ValueError) as ctx:
+            c.compare_versions("10.3.1", "11..3")
+        self.assertRegex(str(ctx.exception), r'^unable to parse an int for semantic version \'11..3\' due to invalid format\..*$')
+
+        with self.assertRaises(ValueError) as ctx:
+            c.compare_versions("10.FOUR.8", "10.4.8")
+        self.assertRegex(str(ctx.exception), r'^unable to parse an int for semantic version \'10.FOUR.8\' due to invalid format\..*$')
+
+if __name__ == '__main__':
+    u.main()

roles/pleroma-main/tasks/main.yml

@@ -37,10 +37,37 @@
   - "{{ pleroma_static_dir }}/static"
   - "{{ pleroma_static_dir }}/static/themes"
 
-- name: Ensuring that the release build of pleroma is downloaded.
+- name: Checking if Pleroma is already installed.
+  stat:
+    path: "{{ pleroma_user.home }}/bin/pleroma"
+  register: pleroma_bin
+
+- debug:
+    msg: "Pleroma is currently installed."
+    verbosity: 0
+  when: pleroma_bin.stat.isreg is defined
+
+- debug:
+    msg: "Pleroma does not appear to be installed. It will be downloaded and installed."
+    verbosity: 0
+  when: pleroma_bin.stat.isreg is not defined
+
+- name: Registering the 'enable_pleroma_download' flag.
+  set_fact:
+    enable_pleroma_download: true
+  when: (pleroma_bin.stat.isreg is not defined) or
+        (enable_pleroma_upgrade | default(False))
+
+- name: Registering the 'enable_pleroma_installation' flag.
+  set_fact:
+    enable_pleroma_installation: true
+  when: pleroma_bin.stat.isreg is not defined
+
+- name: Ensuring that the stable release build of pleroma is downloaded.
   get_url:
     url: "{{ pleroma_download_url }}"
     dest: "{{ pleroma_download_dest }}"
+  when: enable_pleroma_download | default(False)
 
 - name: Unzipping the release build of pleroma.
   unarchive:
@@ -49,12 +76,71 @@
     dest: /tmp
     owner: "{{ pleroma_user.name }}"
     group: "{{ pleroma_user.group }}"
+  when: enable_pleroma_download | default(False)
+
+- name: Registering the installed version of Pleroma.
+  shell: "{{ pleroma_user.home }}/bin/pleroma version | awk '{print $2}'"
+  register: pleroma_installed_version
+  when: enable_pleroma_upgrade | default(False)
+
+- debug:
+    msg: "Version {{ pleroma_installed_version.stdout }} is installed."
+    verbosity: 0
+  when: enable_pleroma_upgrade | default(False)
+
+- name: Registering the downloaded version of Pleroma.
+  shell: /tmp/release/bin/pleroma version | awk '{print $2}'
+  register: pleroma_downloaded_version
+  when: enable_pleroma_upgrade | default(False)
+
+- debug:
+    msg: "Version {{ pleroma_downloaded_version.stdout }} is downloaded."
+    verbosity: 0
+  when: enable_pleroma_upgrade | default(False)
+
+- name: Comparing the installed and downloaded versions of Pleroma.
+  compare_semantic_versions:
+    old_version: "{{ pleroma_installed_version.stdout }}"
+    new_version: "{{ pleroma_downloaded_version.stdout }}"
+  register: comparison
+  when: enable_pleroma_upgrade | default(False)
+
+- fail:
+    msg: "This playbook does not currently support downgrading Pleroma."
+  when: comparison.result is defined and comparison.result == "downgrade"
+
+- debug:
+    msg: "Pleroma is already installed at the target version {{ pleroma_downloaded_version.stdout }}."
+    verbosity: 0
+  when: comparison.result is defined and comparison.result == "noVersionChange"
+
+- debug:
+    msg: "Pleroma will be upgraded to version {{ pleroma_downloaded_version.stdout }}."
+    verbosity: 0
+  when: comparison.result is defined and comparison.result == "upgrade"
+
+- name: Registering the 'enable_pleroma_installation' flag for the upgrade.
+  set_fact:
+    enable_pleroma_installation: true
+  when: comparison.result is defined and comparison.result == "upgrade"
+
+- name: Ensuring that the Pleroma service is stopped.
+  service:
+    name: pleroma
+    state: stopped
+  when: comparison.result is defined and comparison.result == "upgrade"
+
+- name: Ensuring that the previous version of Pleroma is uninstalled.
+  shell: |
+    find {{ pleroma_user.home }} -mindepth 1 -maxdepth 1 | xargs -I dir rm -rf dir
+  when: comparison.result is defined and comparison.result == "upgrade"
 
 - name: Ensuring that Pleroma is installed.
   shell: |
     find /tmp/release/ -mindepth 1 -maxdepth 1 | xargs -I dir mv dir {{ pleroma_user.home }}
   args:
     creates: "{{ pleroma_user.home }}/bin/pleroma"
+  when: enable_pleroma_installation is defined
 
 - name: Ensuring the configuration file is set.
   template:
@@ -71,6 +157,7 @@
     - migrate
   environment:
     PATH: "{{ ansible_env.PATH }}:/opt/pleroma/bin"
+  when: enable_pleroma_installation is defined
 
 - name: Ensuring that folder permissions are set properly in /opt/pleroma.
   shell: |
@@ -103,7 +190,7 @@
     group: "{{ pleroma_user.group }}"
     mode: '0400'
 
-- name: Setting up the Pleroma service.
+- name: Ensuring that the pleroma init file is installed.
   copy:
     src: "{{ pleroma_user.home }}/installation/init.d/pleroma"
     dest: /etc/init.d/pleroma
@@ -116,7 +203,7 @@
   service:
     name: pleroma
     enabled: yes
-    state: restarted
+    state: started
 
 - name: Cleaning up
   file: