httpwsrep

HTTP status codes for galera cluster

This helps to check the galera cluster using HAProxy - option httpchk which queries the galera node and gets its current state from: SHOW STATUS LIKE 'wsrep_local_state';

if wsrep_local_state == 4 it will return HTTP 200 OK, otherwise HTTP 503 Service Unavailable

The posible values for wsrep_local_state are:

HAProxy example

backend galera
    mode tcp
    option httpchk
    default-server check port 9200
    server node0 10.0.0.1:3306
    server node1 10.0.0.2:3306
    server node2 10.0.0.3:3306

httpwsrep

You need to run httpwsrep in each galera node preferably using a supervisor, for example if using immortal you could create /usr/local/etc/immortal/httpwsrep.yml with something like this:

cmd: /path/to/httpwsrep
env:
    DSN: mysql://haproxy@tcp(10.0.0.1:3306)/
log:
    file: /var/log/httpwsrep.log

a valid mysql user needs to be created, in this case the user is haproxy

By default port 9200 is used but if required can change it using option --port

metrics

You can use Prometheus and query the endpoint: /metrics