Ensure pgBackRest schedules have a running cron service

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project follows [Semantic Versioning](https://semver.org/).
 
 ## Unreleased
 
+### Fixed
+
+- Install and enable cron for pgBackRest backup and PostgreSQL log-archive schedules, and fail setup if the scheduler is not active.
+
 ## 0.9.8 - 2026-10-02
 
 ### Fixed

README.md

@@ -215,6 +215,10 @@ components:
     # schedule_incremental: "0 * * * *"
 ```
 
+pgBackRest setup installs cron, enables it at boot, and checks that it is active.
+Backup schedules run only on the primary; configured log-archive schedules run
+on each database host.
+
 Run a PITR restore:
 
 ```bash

lib/active_postgres/components/pgbackrest.rb

@@ -151,6 +151,16 @@ def install_on_host(host, create_stanza: true)
         else
           remove_backup_schedule(host)
         end
+
+        ensure_scheduler(host)
+      end
+
+      def ensure_scheduler(host)
+        install_apt_packages(host, 'cron')
+        ssh_executor.execute_on_host(host) do
+          execute :sudo, 'systemctl', 'enable', '--now', 'cron'
+          execute :sudo, 'systemctl', 'is-active', '--quiet', 'cron'
+        end
       end
 
       def setup_backup_schedules(host, pgbackrest_config)

test/components/pgbackrest_scheduler_test.rb

@@ -0,0 +1,35 @@
+require 'test_helper'
+
+class PgBackRestSchedulerTest < Minitest::Test
+  def test_install_requires_running_cron_after_configuring_primary_and_standby_schedules
+    [true, false].each do |primary|
+      host = 'db.example.com'
+      config = stub_config(primary_host: host, component_config: {
+                             pgbackrest: { repo_type: 'local', schedule_full: '0 2 * * 0' }
+                           })
+      calls = []
+      backend = Object.new
+      backend.define_singleton_method(:execute) { |*args| calls << args }
+      executor = Object.new
+      executor.define_singleton_method(:execute_on_host) { |_host, &block| backend.instance_exec(&block) }
+      executor.define_singleton_method(:upload_file) { |_host, _content, path, **_options| calls << [:upload, path] }
+      component = ActivePostgres::Components::PgBackRest.new(config, executor, ActivePostgres::Secrets.new(config))
+      component.define_singleton_method(:upload_template) { |*_args, **_options| nil }
+
+      component.send(:install_on_host, host, create_stanza: primary)
+
+      cron_install = calls.index { |args| args.include?('apt-get') && args.last == 'cron' }
+      cron_enable = calls.index([:sudo, 'systemctl', 'enable', '--now', 'cron'])
+      cron_check = calls.index([:sudo, 'systemctl', 'is-active', '--quiet', 'cron'])
+      schedule = if primary
+                   calls.index([:upload, '/etc/cron.d/pgbackrest-backup'])
+                 else
+                   calls.index([:sudo, 'rm', '-f', '/etc/cron.d/pgbackrest-backup-incremental'])
+                 end
+      assert_operator schedule, :<, cron_install
+      assert_operator cron_install, :<, cron_enable
+      assert_operator cron_enable, :<, cron_check
+      refute_includes calls, [:sudo, 'systemctl', 'restart', 'postgresql']
+    end
+  end
+end

test/components/pgbackrest_test.rb

@@ -288,6 +288,7 @@ def test_install_on_standby_removes_stale_backup_schedules
 
     ssh_executor = Minitest::Mock.new
     ssh_executor.expect(:execute_on_host, nil, ['standby.example.com'])
+    ssh_executor.expect(:execute_on_host, nil, ['standby.example.com'])
     secrets = ActivePostgres::Secrets.new(config)
     pgbackrest = ActivePostgres::Components::PgBackRest.new(config, ssh_executor, secrets)
     calls = []