Using the Docker Embedded DNS

this is an easy way I just discovered and am noting it here so I don't forget.

to leverage docker's embedded dns, you can setup a custom network and then each container can resolve to each other via the 'name' attribute.

for example;

1. docker network create internaldns
2. docker run --name rmq -p 15672:15672 --net=internaldns -d rabbitmq:management
3. docker run --name httpcontainer -p 8080:8080 --net=internaldns -d scbs/http-rmq

this gives you;
- ability to connect to the host network via bridge
- ability to have httpcontainer look up the rabbitmq container using the dns entry 'rmq'

i love weave.works and think weave net is particularly awesome, but if you're just doing dns lookup on 1 docker host, this seems pretty light and easy

weave + marathon - network

weave + marathon - network

quick note, if you're using weave on marathon with docker, make sure NETWORK is set to BRIDGE ("network":"bridge")

trick for marathon for running docker + weave

weave DNS trick

a little trick with weave and marathon is the specification of the hostname.  unlike raw docker+weave, the hostname in weave DNS can be picked up by --name or --hostname.  But with the marathon json, hostname must have .weave.local as a suffix.  so, to deploy postgres via marathon and give it a weave DNS entry of postgres-server, the entry needs to be postures-server.weave.local

mesos + marathon + docker + weave

mesos + marathon + docker + weave

so here's a little configuration set of links for standing up a PaaS leveraging mesos, marathon, docker and weave (am using centos 7 on a VM);

1. follow the install of the base platform here --> https://open.mesosphere.com/getting-started/install/
2. install docker from here --> https://docs.docker.com/engine/installation/centos/
3. use this weave script from here --> https://github.com/weaveworks/guides/blob/master/mesos-marathon/centos/weave
4. use these service scripts in here --> https://github.com/weaveworks/guides/tree/master/mesos-marathon/centos
5. but most importantly, add the following to /usr/lib/systemd/system/mesos-slave.service

Environment=MESOS_CONTAINERIZERS=docker,mesos
Environment=MESOS_DOCKER_SOCKET=/var/run/weave/weave.sock

now you can deploy normally with marathon and have your containers picked up in weave (and mapped)

docker & weave & photon

Putting Docker, Weave and Photon together

1. appcatalyst vm create [your vm name]
2. appcatalyst vmpower on [your vm name]
3. (wait... 10 seconds or so)
4. appcatalyst guest getip [your vm name]
5. ssh -i /opt/vmware/appcatalyst/etc/appcatalyst_insecure_ssh_key photon@[ip_address]

now you're in the VM, let's get weave

1. sudo curl -L git.io/weave -O /usr/local/bin/weave
2. sudo chmod a+x /usr/local/bin/weave
3. sudo -s
4. /usr/local/bin/weave launch
5. /usr/local/bin/weave launch-dns
6. /usr/local/bin/weave launch-proxy
7. eval $(/usr/local/bin/weave proxy-env)

now you can run docker commands have weave play "nice" (dynamic mapping of --name to weaveDNS, etc.)

https://github.com/weaveworks/weave#readme

https://communities.vmware.com/community/vmtn/devops/vmware-appcatalyst