And some other tricks with overriding handle_one_request and finish
methods from the parent class which were necessary only to make OPTIONS
request from haproxy work with python2, but in fact it was still not
working with python3. Instead of doing all the magic we should simply
give to haproxy what it wants to get: HTTP response code and nothing
more.
Mostly this tag is necessary to give a hint to load balancer
auto-configuration tool that node should not be included into
LB configuration.
In addition to that Patroni also should not return status_code=200
for a health check if the tag is present and value is not `False`.
By default, haproxy sens an OPTION request, which we didn't
handle until now. In addition, all haproxy requests that doesn't
examine the request body close the connection as soon as the status
code is obtained. Such behavior breaks BaseHTTPRequestHandler,
namely handle_one_request, which doesn't check for connection reset
by peer and throw this error on a higher level, but since we don't
call this function directly, there is no place in the code to catch
it, therefore, we have to patch this function in the base class.
In addition, patch the StreamRequestHandler finish() function in
order to handle the connection reset error.
Re-read the cluster from DCS right after the failover to supply
the correct new values to the API thread. Fix a typo.
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 value is empty and leader didn't changed, this probably means
that failover failed.
After 15 seconds timeout we will consider failover status = unknown
curl -XPOST --data '{"leader": "leader_name", "member": "member_name"}' http://127.0.0.1:8008/failover
It will execute some preliminary checks and write failover key into DCS.
Afterward it will wait until new leader key will appear in a DCS.
It's better to execute this request on the master node. It will send a
signal to the main HA loop which makes possible to release leader key
immidiately even if you are working with etcd.
1. run touch_member from the main loop
2. move code which takes care about long tasks into separate class
3. change format of data stored in a DCS: use json instead of url
4. change Member class: from now it deserialize everything into data property
5. rework API: from now it takes into account state of the current node in a dcs
POST /restart -- will restart postgres
You you are restartung leader node, lock would be maintained during
restart.
POST /reinitialize -- will reinitialize node from the leader.
It's not possible to reinitialize current leader.
Command will fail when the leader is unknown.
query method in an api.py also needs retry in some cases (for example
when we are running is_healthiest_node check).
In all cases we should retry only when connection is closed or broken.
BUT, the connection status must be checked via cursor.connection (old
implementation was using general connection object for that). For
multi-threaded applications this is not appropriate, because some other
thread might restore connection.
In addition to that I've changed most of the unit tests to use `Mock` and
`patch` where it is possible.
user:passwd pair should be configured in restapi section of main
configuration file in following format:
restapi:
auth: 'username:password'
Plus implemented some simple routing mechanisms:
GET /foo => do_GET_foo()
POST /bar => do_POST_bar()
Server always returns json which contains some status of postgres:
* instance type: master/slave
* xlog location for master
* xlog received_location, replayed_location
This server could be used by haproxy
GET / returns 200 if there is postgres master behind governor.
GET /slave returns 200 is there is postgres slave behind governor
In all other cases it returns 503
Currently server always listening on 0.0.0.0:8080, but it should be
configurable. In the next versions this rest api could also report some
status of etcd and could be used by is_healthiest_node method
Alexander Kukushkin