Change master->primary, take two (#3127)

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.

features/basic_replication.feature

@@ -65,7 +65,7 @@ Feature: basic replication
     Then I receive a response returncode 0
     And postgres2 role is the primary after 24 seconds
     And Response on GET http://127.0.0.1:8010/history contains recovery after 10 seconds
-    And there is a postgres2_cb.log with "on_role_change master batman" in postgres2 data directory
+    And there is a postgres2_cb.log with "on_role_change primary batman" in postgres2 data directory
     When I issue a PATCH request to http://127.0.0.1:8010/config with {"synchronous_mode": null, "master_start_timeout": 0}
     Then I receive a response code 200
     When I add the table bar to postgres2

features/citus.feature

@@ -69,7 +69,7 @@ Feature: citus
   Scenario: check that in-flight transaction is rolled back after timeout when other workers need to change pg_dist_node
     Given I start postgres4 in citus group 2
     Then postgres4 is a leader in a group 2 after 10 seconds
-    And "members/postgres4" key in a group 2 in DCS has role=master after 3 seconds
+    And "members/postgres4" key in a group 2 in DCS has role=primary after 3 seconds
     When I run patronictl.py edit-config batman --group 2 -s ttl=20 --force
     Then I receive a response returncode 0
     And I receive a response output "+ttl: 20"

features/ignored_slots.feature

@@ -10,7 +10,7 @@ Feature: ignored slots
     When I shut down postgres1
     And I start postgres1
     Then postgres1 is a leader after 10 seconds
-    And "members/postgres1" key in DCS has role=master after 10 seconds
+    And "members/postgres1" key in DCS has role=primary after 10 seconds
     # Make sure Patroni has finished telling Postgres it should be accepting writes.
     And postgres1 role is the primary after 20 seconds
     # 1. Create our test logical replication slot.
@@ -38,7 +38,7 @@ Feature: ignored slots
     # cycle we don't accidentally rewind to before the slot creation.
     And replication works from postgres1 to postgres0 after 20 seconds
     When I shut down postgres1
-    Then "members/postgres0" key in DCS has role=master after 10 seconds
+    Then "members/postgres0" key in DCS has role=primary after 10 seconds
 
     # 2. After a failover the server (now a replica) still has the slot.
     When I start postgres1
@@ -54,7 +54,7 @@ Feature: ignored slots
 
     # 3. After a failover the server (now a primary) still has the slot.
     When I shut down postgres0
-    Then "members/postgres1" key in DCS has role=master after 10 seconds
+    Then "members/postgres1" key in DCS has role=primary after 10 seconds
     And postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin after 2 seconds
     And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin after 2 seconds
     And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin after 2 seconds

features/patroni_api.feature

@@ -7,7 +7,7 @@ Scenario: check API requests on a stand-alone server
 	When I issue a GET request to http://127.0.0.1:8008/
 	Then I receive a response code 200
 	And I receive a response state running
-	And I receive a response role master
+	And I receive a response role primary
 	When I issue a GET request to http://127.0.0.1:8008/standby_leader
 	Then I receive a response code 503
 	When I issue a GET request to http://127.0.0.1:8008/health
@@ -17,7 +17,7 @@ Scenario: check API requests on a stand-alone server
 	When I issue a POST request to http://127.0.0.1:8008/reinitialize with {"force": true}
 	Then I receive a response code 503
 	And I receive a response text I am the leader, can not reinitialize
-	When I run patronictl.py switchover batman --master postgres0 --force
+	When I run patronictl.py switchover batman --primary postgres0 --force
 	Then I receive a response returncode 1
 	And I receive a response output "Error: No candidates found to switchover to"
 	When I issue a POST request to http://127.0.0.1:8008/switchover with {"leader": "postgres0"}

features/recovery.feature

@@ -12,7 +12,7 @@ Feature: recovery
     Then postgres0 role is the primary after 10 seconds
     When I issue a GET request to http://127.0.0.1:8008/
     Then I receive a response code 200
-    And I receive a response role master
+    And I receive a response role primary
     And I receive a response timeline 1
     And "members/postgres0" key in DCS has state=running after 12 seconds
     And replication works from postgres0 to postgres1 after 15 seconds

features/standby_cluster.feature

@@ -26,7 +26,7 @@ Feature: standby cluster
   Scenario: Detach exiting node from the cluster
     When I shut down postgres1
     Then postgres0 is a leader after 10 seconds
-    And "members/postgres0" key in DCS has role=master after 5 seconds
+    And "members/postgres0" key in DCS has role=primary after 5 seconds
     When I issue a GET request to http://127.0.0.1:8008/
     Then I receive a response code 200
 

features/steps/patroni_api.py

@@ -119,7 +119,7 @@ def check_response(context, component, data):
 @step('I issue a scheduled switchover from {from_host:w} to {to_host:w} in {in_seconds:d} seconds')
 def scheduled_switchover(context, from_host, to_host, in_seconds):
     context.execute_steps(u"""
-        Given I run patronictl.py switchover batman --master {0} --candidate {1} --scheduled "{2}" --force
+        Given I run patronictl.py switchover batman --primary {0} --candidate {1} --scheduled "{2}" --force
     """.format(from_host, to_host, datetime.now(tzutc) + timedelta(seconds=int(in_seconds))))