Docker Cookbook

200 | Chapter 7: The Docker Ecosystem: Tools

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1b2c4634fc6d nginx:1.7 ... 443/tcp, 192.168.33.11:80->80/tcp swarm-1...
8399c544b619 nginx:1.7 ... 443/tcp, 192.168.33.12:80->80/tcp swarm-2...
You just started two Nginx containers. Swarm scheduled them on two of the nodes in
the cluster. You can open your browser at 
http://192.168.33.11
 and 
http://
192.168.33.12
and you will see the default Nginx page.
The 
docker run
command can take some time to return. Swarm
needs to schedule the container on a node in the cluster, and that
node needs to pull the Nginx image.
Discussion
In this setup, the Docker Swarm server is running within a local container on the
Swarm head node. You can see it with 
docker ps
and you can check the logs with
docker logs
. In the logs, you see the requests made to start the Nginx containers. It
is interesting to see that you are using the Docker client on the Swarm head node to
communicate with the local Docker daemon and the Swarm server running in a local
container:
$ docker ps
CONTAINER ID IMAGE COMMAND ... PORTS
72acd5bc00de swarm:latest swarm manage ... 2375/tcp, 0.0.0.0:1234->1234/tcp
$ docker logs 72acd5bc00de
... msg="Listening for HTTP" addr="0.0.0.0:1234" proto=tcp
... msg="HTTP request received" method=GET uri="/v1.17/info"
... msg="HTTP request received" method=GET uri="/v1.17/containers/json"
... msg="HTTP request received" method=POST uri="/v1.17/containers/create"
... msg="HTTP request received" method=POST uri="/v1.17/containers/.../start"
... msg="HTTP request received" method=GET uri="/v1.17/containers/json"
... msg="HTTP request received" method=POST uri="/v1.17/containers/create"
... msg="HTTP request received" method=POST uri="/v1.17/containers/.../start"
... msg="HTTP request received" method=GET uri="/v1.17/containers/json"
In these logs, you clearly see the API calls being made to the Swarm server to launch
the Nginx containers in the cluster.