For managing Patroni clusters, the Patroni api can be used. For many tasks, a command line interface for
this api would be a useful addition. This commit adds patroncli (The name is still under debate).
The command line interface needs access to the DCS; this is required for any operation. For some tasks it is required
to have access to the Patroni api.
A small summary of the additions to get the cli/ctl started:
* Updated Docker image to use 'true' as the archive_command, to ensure disk not filling up during failover
testing.
* The cli currently can list members, failover a master and remove a given cluster from DCS.
* The cli can be configured with a command, for repeated access to the same DCS
* Added some simple tests for the cli, code coverage is very low
Instead of checking that nofailover node should not
be marked as healthiest in one of the _failover
functions, do make it unhealthy in the is_healthiest_node.
The initialize key was checked against the value
of the node name before removal, but it was changed
recently to contain either an empty string, or cluster
sysid. To fix this, the check for the previous value
was simply removed: we can guarantee that the code path
that removes the key is the one that created it.
Tags are labels assigned to individual members in order
to alter its default behavior, i.e. exclude from the
leader election or indicate a possibility to create base
backups from the member.
This commit only adds support for setting tags in the
configuration file, exposes the tags to DCS /member subkey
and returns the tags in a response of the API request. At
the moment the tag names are not validated, nor they are
interpreted in any way.
Support for setting tags via the API is also in the scope
of further work.
If the namespace is not specified in a config file /service/ would be
used.
Also it's possible to use just '/' as a namespace. It means we would
have following structure:
/scope1
/scope2
...
Such situation could happen if we replaced all etcd nodes except one
which was used by patroni. After replacing the last node patroni will
try to execute request on all other nodes from machines_cache but non of
them are available. Michines cache would became empty and patroni will
stick to the latest node which was available in the machines_cache and
will never try to refresh machines_cache from dns for example.
Currently machines cache is refreshed only when one request to the etcd
cluster has failed, but probably it should be done periodically, for
example every minute...
One can use pgpass configuration parameter in the postgres
subsection of Patroni. By default pgpass is written in ~/.
Mock actual writes to pgpass in the tests.
Oleksii Kliukin