This blog is part of my Docker series. This is a continuation from my previous blog on Docker Networking. In this blog, I will cover current Docker networking limitations, Pipework overview and a sample Docker application where I have linked containers in 2 different hosts.

There are 4 networking options that Docker provides when creating containers:

1. –net=bridge. This is the default option that Docker provides where containers connect to the linux “docker” bridge.
2. –net=host. In this option, there is no new network namespace created for the container and the container shares the same network namespace as host machine.
3. –net=(container name or id). In this option, the new container shares the same network namespace as the specified container in the ‘net’ option. (Example:  “sudo docker run -ti –name=ubuntu2 –net=container:ubuntu1 ubuntu:14.04 /bin/bash”. Here, ubuntu2 container shares same network namespace as ubuntu1 container)
4. –net=none. In this option, container does not get allocated a new network namespace. Only the loopback interface is created in this case. This option is useful in scenarios where we want to create our own networking options for the container.

Currently, Native Docker networking has the following limitations.

Continue reading Docker Networking – Part2 →

This blog is part of my Docker series. In this blog, I will cover basics of Docker Networking that covers the ingress and egress connectivity for containers and how containers are linked together. I will cover advanced networking topics in next blog.

When docker service is started, a linux bridge is created on the host machine. The interfaces on the containers talk to the bridge and the bridge proxies to external world. Multiple containers on the same host can talk to each other through the linux bridge.

Following is the bridge created on host machine seen through ifconfig. The bridge gets allocated IP address 172.17.42.1.

docker0   Link encap:Ethernet  HWaddr 56:84:7a:fe:97:99  
          inet addr:172.17.42.1  Bcast:0.0.0.0  Mask:255.255.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

Now, lets create 2 containers:

Continue reading Docker Networking – Part1 →

This blog is part of my Docker series. In this blog, I will cover some Hands-on stuff that I tried with Docker.

I installed Docker in my Ubuntu 12.04 that is running on Virtualbox using the procedure here. I have also installed Docker in Ubuntu 14.04 using the procedure here. To install a specific version of Docker and not the latest, use the procedure here.

Following is the docker version that got installed. I have seen recently that 1.4.1 is the default version that gets installed.

$ docker --version
Docker version 1.3.1, build 4e9bbfa
$ sudo docker version
Client version: 1.3.1
Client API version: 1.15
Go version (client): go1.3.3
Git commit (client): 4e9bbfa
OS/Arch (client): linux/amd64
Server version: 1.3.1
Server API version: 1.15
Go version (server): go1.3.3
Git commit (server): 4e9bbfa

To test the basic container functionality, try the following:

$ sudo docker run -t -i ubuntu:14.04 /bin/bash
root@ce1b5eff4e71:/#

Continue reading Docker Hands-on →