Docker-Swarm-Loadbalancer/mysql-proxy/README.md

# MySQL Proxy

## Usage with docker-compose

without

```yaml
version: "2"

services:
  db:
    image: mysql:8.0.0
    restart: always
    ports:
      - "3307:3306" #for external connection
    volumes:
      - ../mysql-data/db:/var/lib/mysql #mysql-data
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: dbuser
      MYSQL_USER: dbuser
      MYSQL_PASSWORD: password
```

within

```yaml
version: "2"

services:
  mysql:
    image: mysql:8.0.0
    restart: always
    expose:
      - "3306" #for service mysql-proxy
    ports:
      - "3307:3306" #for external connection
    volumes:
      - ../mysql-data/db:/var/lib/mysql #mysql-data
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: dbuser
      MYSQL_USER: dbuser
      MYSQL_PASSWORD: password
  db:
    image: matthewbaggett/mysql-proxy
    expose:
      - "3306" #for service php
    ports:
      - "3308:3306" #for external connection
    restart: always
    volumes:
      - ../mysql-proxy-conf:/opt/mysql-proxy/conf
    environment:
      PROXY_DB_PORT: 3306
      REMOTE_DB_HOST: mysql
      REMOTE_DB_PORT: 3306
      LUA_SCRIPT: "/opt/mysql-proxy/conf/main.lua"
    depends_on:
      - mysql
```

## Query to stdout

For `docker-compose up` without `-d` (`../mysql-proxy/main.lua`)

```lua
function read_query(packet)
   if string.byte(packet) == proxy.COM_QUERY then
	print(string.sub(packet, 2))
   end
end
```

## Query logging for mysql-proxy

```yaml
volumes:
  - ../mysql-proxy-conf:/opt/mysql-proxy/conf
  - ../mysql-proxy-logs:/opt/mysql-proxy/logs
environment:
  PROXY_DB_PORT: 3306
  REMOTE_DB_HOST: mysql
  REMOTE_DB_PORT: 3306
  LUA_SCRIPT: "/opt/mysql-proxy/conf/log.lua"
  LOG_FILE: "/opt/mysql-proxy/logs/mysql.log"
```

`/mysql-proxy-conf/log.lua` https://gist.github.com/simonw/1039751

```lua
local log_file = os.getenv("LOG_FILE")

local fh = io.open(log_file, "a+")

function read_query( packet )
    if string.byte(packet) == proxy.COM_QUERY then
        local query = string.sub(packet, 2)
        fh:write( string.format("%s %6d -- %s \n",
            os.date('%Y-%m-%d %H:%M:%S'),
            proxy.connection.server["thread_id"],
            query))
        fh:flush()
    end
end
```

## thanks

https://hub.docker.com/r/zwxajh/mysql-proxy
https://hub.docker.com/r/gediminaspuksmys/mysqlproxy/

## logrotate

The image can be expand with `logrotate`
Config file `/etc/logrotate.d/mysql-proxy` (approximate)

```text
/opt/mysql-proxy/mysql.log {
	weekly
	missingok
	rotate 35600
	compress
	delaycompress
	notifempty
	create 666 root root
	postrotate
		/etc/init.d/mysql-proxy reload > /dev/null
	endscript
}
```

## troubleshooting

If you can't create the chain `mysql` -> `mysql-proxy` -> `external client liten 0.0.0.0:3308`
check extends ports on the `mysql` service and/or add `expose` directly

```yaml
expose:
  - "3306" #for service mysql-proxy
```

> note: Log send to file with delay (buffering mechanism). You can restart the container for get the log immediately.