mysql-replica-healthcheck-agent

mysql-replica-healthcheck-agent is a HTTP daemon to show an information of "SHOW REPLICA STATUS" in JSON format.

This is useful for HAProxy's health check access instead of option mysql-check.

Usage

$ mysql-replica-healthcheck-agent
2024/08/04 17:09:42 Starting healthchecker for replica1 on port 5000
2024/08/04 17:09:42 Starting healthchecker for replica2 on port 5001

# Check the status of replica1
$ curl localhost:5000/ | jq .
{
  "Connect_Retry": 60,
  "Exec_Source_Log_Pos": 1048,
  "Last_Errno": 0,
  "Last_Error": "",
  "Source_Host": "db-master",
  "Source_Log_File": "mysql-bin.000006",
  "Source_Port": 3306,
  ...
  "Until_Log_File": "",
  "Until_Log_Pos": 0
}

# Check the status of replica2
$ curl localhost:5001/ | jq .
{
  "Connect_Retry": 60,
  "Exec_Source_Log_Pos": 1048,
  "Last_Errno": 0,
  "Last_Error": "",
  "Source_Host": "db-master",
  "Source_Log_File": "mysql-bin.000006",
  "Source_Port": 3306,
  ...
  "Until_Log_File": "",
  "Until_Log_Pos": 0
}

• The query "SHOW REPLICA STATUS" was successful, returning HTTP status 200 and JSON.
• If the agent could not connect to MySQL or if MySQL is not a replica, it returns HTTP status 500.
• If Seconds_Behind_Source exceeds the specified max_seconds_behind_source, it returns HTTP status 500. This allows monitoring of replica lag.

Options

• --config : Path to the configuration file. Default is "/etc/mysql-replica-healthcheck-agent/replicas.yml".

The configuration file is a YAML file that defines multiple replica configurations. Example:

# /etc/mysql-replica-healthcheck-agent/replicas.yml
---
replica1:
  host: 127.0.0.1
  port: 3307
  user: root
  password: rootpassword
  max_seconds_behind_source: 300
  fail_replica_not_running: true
  healthcheck_config:
    port: 5000
    path: /

replica2:
  host: 127.0.0.1
  port: 3308
  user: root
  password: rootpassword
  max_seconds_behind_source: 300
  fail_replica_not_running: true
  healthcheck_config:
    port: 5001
    path: /

Start a separate health checker for each replica.

If the replica is not running, it returns HTTP status 500. When the option fail_replica_not_running: false is specified, it returns 200.

License

Apache License 2.0