Apache Mesos,MESOS-DNS, MARATHON and Docker - mysql

Question

In my environment running mesos-slave, mesos-master marathon and mesos-dns in standalone mode.
I deployed mysql app to marathon to run as docker container.
MySql app configurations as follows.
{
"id": "mysql",
"cpus": 0.5,
"mem": 512,
"instances": 1,
"container": {
"type": "DOCKER",
"docker": {
"image": "mysql:5.6.27",
"network": "BRIDGE",
"portMappings": [
{
"containerPort": 3306,
"hostPort": 32000,
"protocol": "tcp"
}
]
}
},
"constraints": [
[
"hostname",
"UNIQUE"
]],
"env": {
"MYSQL_ROOT_PASSWORD": "password"
},
"minimumHealthCapacity" :0,
"maximumOverCapacity" : 0.0
}
Then I deploy app called mysql client. Mysql client app needs to connect to mysql app.
mysql app config as follows.
{
"id": "mysqlclient",
"cpus": 0.3,
"mem": 512.0,
"cmd": "/scripts/create_mysql_dbs.sh",
"instances": 1,
"container": {
"type": "DOCKER",
"docker": {
"image": "mysqlclient:latest",
"network": "BRIDGE",
"portMappings": [{
"containerPort": 3306,
"hostPort": 0,
"protocol": "tcp"
}]
}
},
"env": {
"MYSQL_ENV_MYSQL_ROOT_PASSWORD": "password",
"MYSQL_PORT_3306_TCP_ADDR": "mysql.marathon.slave.mesos.",
"MYSQL_PORT_3306_TCP_PORT": "32000"
},
"minimumHealthCapacity" :0,
"maximumOverCapacity" : 0.0
}
My mesos-dns config.json. as follows
{
"zk": "zk://127.0.0.1:2181/mesos",
"masters": ["127.0.0.1:5050"],
"refreshSeconds": 60,
"ttl": 60,
"domain": "mesos",
"port": 53,
"resolvers": ["127.0.0.1"],
"timeout": 5,
"httpon": true,
"dnson": true,
"httpport": 8123,
"externalon": true,
"listener": "127.0.0.1",
"SOAMname": "ns1.mesos",
"SOARname": "root.ns1.mesos",
"SOARefresh": 60,
"SOARetry": 600,
"SOAExpire": 86400,
"SOAMinttl": 60,
"IPSources": ["mesos", "host"]
}
I can ping with service name mysql.marathon.slave.mesos. from host machine. But when I try to ping from mysql docker container I get host unreachable. Why docker container cannot resolve hsot name?
I tried with set dns parameter to apps. But its not work.
EDIT:
I can ping mysql.marathon.slave.mesos. from master/slave hosts. But I cannot ping from mysqlclient docker container. It says unreachable. How can I fix this?

Answer 1

Not sure what your actual question is, by guessing I think you want to know how you can resolve a Mesos DNS service name to an actual endpoint the MySQL client.
If so, you can use my mesosdns-resolver bash script to get the endpoint from Mesos DNS:
mesosdns-resolver.sh -sn mysql.marathon.mesos -s <IP_ADDRESS_OF_MESOS_DNS_SERVER>
You can use this in your create_mysql_dbs.sh script (whatever it does) to get the actual IP address and port where your mysql app is running.
You can pass in an environment variable like
"MYSQL_ENV_SERVICE_NAME": "mysql.marathon.mesos"
and then use it like this in the image/script
mesosdns-resolver.sh -sn $MYSQL_ENV_SERVICE_NAME -s <IP_ADDRESS_OF_MESOS_DNS_SERVER>
Also, please note that Marathon is not necessarily the right tool for running one-off operations (I assume you initialize your DBs with the second app). Chronos would be a better choice for this.