On debian, the configuration files (postgresql.conf, pg_hba.conf, etc) are not stored in the data directory. It would be great to be able to configure the location of this separate directory. Patroni could override existing configuration files where they are used to be.
The default is to store configuration files in the data directory. This setting is targeting custom installations like debian and any others moving configuration files out of the data directory.
Fixes#465
So far Patroni was populating pg_hba.conf only when running bootstrap code and after that it was not very handy to manage it's content, because it was necessary to login to every node, change pg_hba.conf manually and run pg_ctl reload.
This commit intends to fix it and give Patroni control over pg_hba.conf. It is possible to define pg_hba.conf content via `postgresql.pg_hba` in the patroni configuration file or in the `DCS/config` (dynamic configuration).
If the `hba_file` is defined in the `postgresql.parameters`, Patroni will ignore `postgresql.pg_hba`.
For backward compatibility this feature is not enabled by default. To enable it you have to set `postgresql.use_unix_socket: true`.
If feature is enable, and `unix_socket_directories` is defined and non empty, Patroni will use the first suitable value from it to connect to the local postgres cluster.
If the `unix_socket_directories` is not defined, Patroni will assume that default value should be used and will not pass `host` to command line arguments and omit it from connection url.
Solves: https://github.com/zalando/patroni/issues/61
In addition to mentioned above, this commit solves couple of bugs:
* manual failover with pg_rewind in a pause state was broken
* psycopg2 (or libpq, I am not really sure what exactly) doesn't mark cursors connection as closed when we use unix socket and there is an `OperationalError` occurs. We will close such connection on our own.
Previously pg_ctl waited for a timeout and then happily trodded on considering PostgreSQL to be running. This caused PostgreSQL to show up in listings as running when it was actually not and caused a race condition that resulted in either a failover or a crash recovery or a crash recovery interrupted by failover and a missed rewind.
This change adds a master_start_timeout parameter and introduces a new state for the main run_cycle loop: starting. When master_start_timeout is zero we will fail over as soon as there is a failover candidate. Otherwise PostgreSQL will be started, but once master_start_timeout expires we will stop and release leader lock if failover is possible. Once failover succeeds or fails (no leader and no one to take the role) we continue with normal processing. While we are waiting for the master timeout we handle manual failover requests.
* Introduce timeout parameter to restart.
When restart timeout is set master becomes eligible for failover after that timeout expires regardless of master_start_time. Immediate restart calls will wait for this timeout to pass, even when node is a standby.
* Add https and auth support for etcd
Also implement support of PATRONI_ETCD_URL and PATRONI_ETCD_SRV
environment variables
* Implement etcd.proxy etcd.cacert, etcd.cert and etcd.key support
Now it should be possible to set up fully encrypted connection to etcd
with authorization.
Adds a new configuration variable synchronous_mode. When enabled Patroni will manage synchronous_standby_names to enable synchronous replication whenever there are healthy standbys available. With synchronous mode enabled Patroni will automatically fail over only to a standby that was synchronously replicating at the time of master failure. This effectively means zero lost user visible transactions.
To enforce the synchronous failover guarantee Patroni stores current synchronous replication state in the DCS, using strict ordering, first enable synchronous replication, then publish the information. Standby can use this to verify that it was indeed a synchronous standby before master failed and is allowed to fail over.
We can't enable multiple standbys as synchronous, allowing PostreSQL to pick one because we can't know which one was actually set to be synchronous on the master when it failed. This means that on standby failure commits will be blocked on the master until next run_cycle iteration. TODO: figure out a way to poke Patroni to run sooner or allow for PostgreSQL to pick one without the possibility of lost transactions.
On graceful shutdown standbys will disable themselves by setting a nosync tag for themselves and waiting for the master to notice and pick another standby. This adds a new mechanism for Ha to publish dynamic tags to the DCS.
When the synchronous standby goes away or disconnects a new one is picked and Patroni switches master over to the new one. If no synchronous standby exists Patroni disables synchronous replication (synchronous_standby_names=''), but not synchronous_mode. In this case, only the node that was previously master is allowed to acquire the leader lock.
Added acceptance tests and documentation.
Implementation by @ants with extensive review by @CyberDem0n.
- fix the false claim that Patroni in a paused mode may promote a master.
- merge all allowed API actions together.
- describe the payload of the API pause request as JSON.
In addition for that make pg_ctl --timeout option configurable.
If the stop or start didn't succeeded during given timeout when demoting
master, role will be forcibly changed to 'unknown' and all needed
callbacks executed.
