Charmed PostgreSQL K8s

Channel Revision Published Runs on
latest/stable 20 20 Sep 2022
Ubuntu 20.04
14/stable 280 28 Jun 2024
Ubuntu 22.04
14/stable 281 28 Jun 2024
Ubuntu 22.04
14/candidate 281 18 Jun 2024
Ubuntu 22.04
14/candidate 280 18 Jun 2024
Ubuntu 22.04
14/beta 281 18 Jun 2024
Ubuntu 22.04
14/beta 280 18 Jun 2024
Ubuntu 22.04
14/edge 315 Yesterday
Ubuntu 22.04
14/edge 314 Yesterday
Ubuntu 22.04
juju deploy postgresql-k8s --channel 14/stable
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Backup flowcharts

This document contains backups management flowchart, including all major hooks. This sources can be found at src/backups.py.

Hook Handler Flowcharts

These flowcharts detail the control flow of the hooks in this program. Unless otherwise stated, a hook deferral is always followed by a return.

On S3 Credentials Changed Hook

Click to navigate the mermaid diagram on GitHub.

flowchart TD
  hook_fired([s3-credentials-changed Hook]) --> has_cluster_initialised{Has cluster\n initialised?}
  has_cluster_initialised -- no --> defer>defer]
  defer --> rtn([return])
  has_cluster_initialised -- yes --> are_all_required_settings_provided{Are all required\nS3 settings provided?}
  are_all_required_settings_provided -- no --> rtn
  are_all_required_settings_provided -- yes --> render_pgbackrest_config[Update backup settings]
  render_pgbackrest_config --> is_leader{Is current\nunit leader?}
  is_leader -- no --> rtn
  is_leader -- yes -->  is_blocked{Is unit in\nblocked state?}
  is_blocked -- yes --> rtn
  is_blocked -- no --> could_initialise_stanza{Could initialise\npgBackRest Stanza?}
  could_initialise_stanza -- no --> set_blocked[Set Blocked\nstatus]
  set_blocked --> rtn
  could_initialise_stanza -- yes --> is_wal_archiving_to_s3_working{Is WAL archiving\nto S3 working?}
  is_wal_archiving_to_s3_working -- no --> set_blocked
  is_wal_archiving_to_s3_working -- yes --> is_tls_disabled_or_single_unit_cluster{Is TLS disabled or\nsingle unit cluster}
  is_tls_disabled_or_single_unit_cluster -- yes --> stop_pgbackrest_tls_server[Stop pgBackRest\nTLS server]
  is_tls_disabled_or_single_unit_cluster -- no --> is_replica_and_tls_server_not_running_on_primary{Is current\nunit a replica\nand TLS server isn't\nrunning on primary?}
  is_replica_and_tls_server_not_running_on_primary -- yes --> rtn
  stop_pgbackrest_tls_server --> rtn
  is_replica_and_tls_server_not_running_on_primary -- no --> start_pgbackrest_tls_server[Start pgBackRest\nTLS server]
  start_pgbackrest_tls_server --> rtn

When certificates are received from TLS certificates operator through the certificates relation (or the relation is removed) the steps starting from Is TLS disabled or single unit cluster are also executed.

On Create Backup Hook

Click to navigate the mermaid diagram on GitHub.

flowchart TD
  hook_fired([create-backup Hook]) --> is_blocked{Is unit in\nblocked state?}
  is_blocked -- yes --> fail_action([fail action])
  is_blocked -- no --> is_primary_tls_enabled_multiple_unit_cluster{Is primary in\na TLS enabled\nmultiple units cluster?}
  is_primary_tls_enabled_multiple_unit_cluster -- yes --> fail_action
  is_primary_tls_enabled_multiple_unit_cluster -- no --> is_replica_tls_disabled{Is replica and\nwith TLS disabled?}
  is_replica_tls_disabled -- yes --> fail_action
  is_replica_tls_disabled -- no --> has_stanza_been_initialises{Has stanza been initialised?}
  has_stanza_been_initialises -- no --> fail_action
  has_stanza_been_initialises -- yes --> is_s3_relation_established{Is S3 relation\nestablished?}
  is_s3_relation_established -- no --> fail_action
  is_s3_relation_established -- yes --> has_missing_s3_parameters{Has missing S3 parameters?}
  has_missing_s3_parameters -- yes --> fail_action
  has_missing_s3_parameters -- no --> was_possible_upload_metadata_file_test_connectivity_s3{Was it possible\nto upload metadata file\nto test connectivity to S3?}
  was_possible_upload_metadata_file_test_connectivity_s3 -- no --> fail_action
  was_possible_upload_metadata_file_test_connectivity_s3 -- yes --> is_replica{Is current\nunit a replica?}
  is_replica -- no --> set_maintenance[Set Maintenance Status]
  is_replica -- yes --> block_new_connections[Block new\nconnections to this\nunit's database]
  block_new_connections --> set_maintenance
  set_maintenance --> has_backup_creation_succeeded{Has backup creation succeeded?}
  has_backup_creation_succeeded -- no --> upload_error_logs_s3[Upload error\nlogs to S3]
  upload_error_logs_s3 --> fail_action2([fail action])
  fail_action2 --> is_replica2{Is current\nunit a replica?}
  is_replica2 -- no --> set_active[Set Active Status]
  is_replica2 -- yes --> allow_new_connections[Allow new\nconnections to this\nunit's database]
  has_backup_creation_succeeded -- yes --> were_backup_logs_uploaded_s3{Were backup logs\nuploaded to S3?}
  were_backup_logs_uploaded_s3 -- no --> fail_action2
  were_backup_logs_uploaded_s3 -- yes --> finish_action[backup created]
  finish_action --> is_replica2

On List Backups Hook

Click to navigate the mermaid diagram on GitHub.

flowchart TD
  hook_fired([list-backups Hook]) --> is_s3_relation_established{Is S3 relation\nestablished?}
  is_s3_relation_established -- no --> fail_action([fail action])
  is_s3_relation_established -- yes --> has_missing_s3_parameters{Has missing S3 parameters?}
  has_missing_s3_parameters -- yes --> fail_action
  has_missing_s3_parameters -- no --> does_pgbackrest_returned_backups_list{Does pgBackRest\nreturned the\nbackups list?}
  does_pgbackrest_returned_backups_list -- no --> fail_action
  does_pgbackrest_returned_backups_list -- yes --> return_formatted_backup_list[Return formatted\nbackup list]

On Restore Hook

Click to navigate the mermaid diagram on GitHub.

flowchart TD
  hook_fired([restore Hook]) --> has_user_provided_backup_id{Has user provided\na backup id?}
  has_user_provided_backup_id -- no --> fail_action([fail action])
  has_user_provided_backup_id -- yes --> is_workload_container_accessible{Is workload\ncontainer accessible?}
  is_workload_container_accessible -- no --> fail_action
  is_workload_container_accessible -- yes --> is_blocked{Is unit in\nblocked state?}
  is_blocked -- yes --> fail_action
  is_blocked -- no --> is_single_unit_cluster{Is single\nunit cluster?}
  is_single_unit_cluster -- no --> fail_action
  is_single_unit_cluster -- yes --> is_leader{Is current\nunit leader?} 
  is_leader -- no --> fail_action
  is_leader -- yes -->  is_backup_id_valid{Is backup id\nvalid?}
  is_backup_id_valid -- no --> fail_action
  is_backup_id_valid -- yes --> set_maintenance[Set Maintenance Status]
  set_maintenance --> has_database_stopped{Has database\nstopped?}
  has_database_stopped -- no --> fail_action
  has_database_stopped -- yes --> was_previous_cluster_info_removed{Was previous cluster\ninfo removed?}
  was_previous_cluster_info_removed -- no --> start_database_again[Start database again]
  start_database_again --> fail_action
  was_previous_cluster_info_removed -- yes --> was_data_directory_emptied{Was the data\ndirectory emptied?}
  was_data_directory_emptied --> no --> start_database_again
  was_data_directory_emptied --> yes --> configure_restore[Configure Patroni to restore the backup]
  configure_restore --> start_database[Start the database]
  start_database --> finish_action[restore started]

The unit status becomes Active or Blocked after a, respectively, successful or failed restore is detected in the update status hook.


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