Upon start postmaster process performs various safety checks if there is a postmaster.pid file in the data directory. Although Patroni already detected that the running process corresponding to the postmaster.pid is not a postmaster, the new postmaster might fail to start, because it thinks that postmaster.pid is already locked.
Important!!! Unlink of postmaster.pid isn't an option in this case, because it has a lot of nasty race conditions.
Luckily there is a workaround to this problem, we can pass the pid from postmaster.pid in the `PG_GRANDPARENT_PID` environment variable and postmaster will ignore it.
More likely to hit such problem if you run Patroni and postgres in the docker container.
On Kubernetes 1.10.0 I experienced an issue where calls to `patch_or_create` were failing when bootstraping a cluster. The call was failing because `self._leader_observed_subsets` was `None` instead of `[]`.
It didn't affect directly neither failover nor switchover, but in some rare cases it was reporting it as a success too early, when the former leader released the lock: `Failed over to "None" instead of "desired-node"`
In addition to that this commit improves logs and status messages by differentiating between failover and switchover.
Patroni can attach itself to an already running PostgreSQL instance. If that is the first instance "seen" in the given cluster, Patroni for that instance will create the initialize key, grab the leader key and, if the instance is running a replica, promote.
Because of this behavior, when a cluster with a master and one or more replicas gets Patroni for each node, it is imperative to start running Patroni on the master node before getting to the replicas.
This commit changes such weird behavior and will abort Patroni start if there is no initialize key in DCS and postgres is running as a replica.
Closes https://github.com/zalando/patroni/issues/655
Because they are indeed case insensitive.
Most of the parameters have snake_case_name, but there are three exceptions from this rule: DateStyle, IntervalStyle and TimeZone.
In fact, if you specify timezone = 'some/tzn' it still works, but Patroni wasn't able to find 'timezone' in pg_settings and stripping this parameter out.
We will use CaseInsensitiveDict to keep postgresql.parameters. This change affects only "final" configuration. That means if you put some"duplicates" (work_mem vs WORK_MEM) into patroni yaml or into cluster config, it would be resolved only at the last stage and for example you will be able to see both values if you use `patronictl edit-config`.
Fixes https://github.com/zalando/patroni/issues/649
pgBackRest's restore command generates the appropriate recovery.conf based
on the parameters you provide to pgBackRest. When calling pgBackRest's restore command
via Patroni's custom bootstrap, it deletes that recovery.conf. Specifying the recovery.conf
information in the patroni.yml is less than ideal. It prevent's leveraging pgBackRests
work to ensure recovery.conf files are properly generated. It also can lead to transient
config data in the patroni.yml under certain restore cases, such as a PITR restore
of Cluster B to Cluster A, where the restore_commnand in A needs to reference B.
The parameter is optional. The default behavior is to delete the recovery.conf.
Fixes https://github.com/zalando/patroni/issues/637
* `PATRONI_LOGLEVEL` - sets the general logging level
* `PATRONI_REQUESTS_LOGLEVEL` - sets the logging level for all HTTP requests e.g. Kubernetes API calls
Adds 3 resources that will properly setup the RBAC:
1. service account, which is also assigned to the pods of the cluster, so that they use those particular permissions
2. a role, which holds only the necessary permissions that patroni members need to interact with k8s cluster
3. a rolebinding, which connects two two former things together to use.
The role and rolebinding was created using this tool https://github.com/liggitt/audit2rbac which looks at [audit logs](https://kubernetes.io/docs/tasks/debug-application-cluster/audit/#advanced-audit) provided by the api server.
Output exception trace to the logs when http status code == 403, something is wrong with permissions.
When http status code == 409 -- such error could be ignored, because object probably was created or updated by another process.
For all other http status codes it will also produce stack traces.
I hope it will help to debug issues similar to the https://github.com/zalando/patroni/issues/606
It is very easy to get current timeline on the master by executing
```sql
SELECT ('x' || SUBSTR(pg_walfile_name(pg_current_wal_lsn()), 1, 8))::bit(32)::int
```
Unfortunately the same method doesn't work when postgres is_in_recovery. Therefore we will use replication connection for that on the replicas. In order to avoid opening and closing replication connection on every HA loop we will cache the result if its value matches with the timeline of the master.
Also this PR introduces a new key in DCS: `/history`. It will contain a json serialized object with timeline history in a format similar to the usual history files. The differences are:
* Second column is the absolute wal position in bytes, instead of LSN
* Optionally there might be a fourth column - timestamp, (mtime of history file)
Every iteration of HA loop Patroni needs to call pg_is_in_recovery() and calcualte absolute wal_position. It was doing two separate SELECT statements for that. In case of master it was doing even three queries (wal_position two times).
We will issue one SELECT for every HA loop and cache the results.
* Use scope from config file when listing members
* Add version command to patronictl
* Only delete leader on shutdown when we have the lock to avoid exceptions when leader key does not exist
* Add a timestamp option to list command.
* YAML format for patronictl output
* Fix API request to get version
Make it possible to cancel a running task if you want to reinitialize replica.
There are two possible ways to trigger it:
1. patronictl will ask whether you want to cancel already running task if an attempt to trigger reinitialize has failed
2. if you are using `--force` argument with `patronictl reinit`
This list will be used for initial discovery of etcd cluster members.
If for some reason during work this list of hosts has been exhausted (during work), Patroni will return to initial list.
In addition to that improve ipv6 compatibility by using a special function for splitting host and port.
Fixes https://github.com/zalando/patroni/issues/523
* Use ConfigMaps or Endpoins for leader elections and to keep cluster state
* Label pods with a postgres role
* change behavior of pip install. From now on it will not install all dependencies, you have to specify explicitly DCS you want to use Patroni with: `pip install patroni[etcd,zookeeper,kubernetes]`
* Show information about scheduled failover and maintenance mode when showing list of cluster members. Fixes https://github.com/zalando/patroni/issues/557
* Fix postgres version check functions (postgres 10 and above compatibility) and apply pep8 formatting to the tests.
* Bump some configuration parameters to match with postgres 10 defaults.
* Fix name of contributor in release notes.
Introduces a PostmasterProcess object that identifies a running process via pid and start time.
When pid file is parsed and the correct process identified this object is passed around.
When the process goes away we try to find a new one in case somebody restarted postgres behind our back.
