This commit is a breaking change:
1. `role` in DCS is written as "primary" instead of "master".
2. `role` in REST API responses is also written as "primary".
3. REST API no longer accepts role=master in requests (for example switchover/failover/restart endpoints).
4. `/metrics` REST API endpoint will no longer report `patroni_master`.
5. `patronictl` no longer accepts `--master` argument.
6. `no_master` option in declarative configuration of custom replica creation methods is no longer treated as a special option, please use `no_leader` instead.
7. `patroni_wale_restore` doesn't accept `--no_master` anymore.
8. `patroni_barman` doesn't accept `--role=master` anymore.
9. callback scripts will be executed with role=primary instead of role=master
10. On Kubernetes Patroni by default will set role label to primary. In case if you want to keep old behavior and avoid downtime or lengthy complex migrations you can configure `kubernetes.leader_label_value` and `kubernetes.standby_leader_label_value` to `master`.
However, a few exceptions regarding master are still in place:
1. `GET /master` REST API endpoint will continue to work.
2. `master_start_timeout` and `master_stop_timeout` in global configuration are still accepted.
3. `master` tag is still preserved in Consul services in addition to `primary`.
Rationale for these exceptions: DBA doesn't always 100% control the infrastructure and can't adjust the configuration.
We currently have a script named `patroni_barman_recover` in Patroni, which is intended to be used as a custom bootstrap method, or as a custom replica creation method.
Now there is need of one more Barman related script in Patroni to handle switching of config models in Barman upon `on_role_change` events.
However, instead of creating another Patroni script, let's say `patroni_barman_config_switch`, and duplicating a lot of logic in the code, we decided to refactor the code so:
* Instead of two separate scripts (`patroni_barman_recover` and `patroni_barman_config_switch`), we have a single script (`patroni_barman`) with 2 sub-commands (`recover` and `config-switch`)
This is the overview of changes that have been performed:
* File `patroni.scripts.barman_recover` has been removed, and its logic has been split into a few files:
* `patroni.scripts.barman.cli`: handles the entrypoint of the new `patroni_barman` command, exposing the argument parser and calling the appropriate functions depending on the sub-command
* `patroni.scripts.barman.utils`: implements utilitary enums, functions and classes wich can be used by `cli` and by sub-commands implementation:
* retry mechanism
* logging set up
* communication with pg-backup-api
* `patroni.scripts.barman.recover`: implements the `recover` sub-command only
* File `patroni.tests.test_barman_recover` has been renamed as `patroni.tests.test_barman`
* File `patroni.scripts.barman.config_switch` was created to implement the `config-switch` sub-command only
* `setup.py` has been changed so it generates a `patroni_barman` application instead of `patroni_barman_recover`
* Docs and unit tests were updated accordingly
References: PAT-154.
