ImgCred: http://openvswitch.org/, http://socketplane.io/, https://consul.io/, https://docker.com/
Containers have no doubt been a hyped technology in 2014 and now moving into 2015. Containers have been around for a while now (See my other post on a high-level overview of the timeline) and will be a major technology to think about for the developer as well as within the datacenter moving forward.
Today I want to take the time to go over Socketplane.io’s first preview of the technology they have been working on and since announcing their company in mid-october. Socketplane.io is “driving DevOps Defined Networking by enabling distributed security, application services and orchestration for Docker and Linux containers.” and is backed by some great tech talent, Brent Salisbury, Dave Tucker, Madhu Venugopal, John M. Willis who all bring leading edge network and ops skills into one great effort which is socketplane.io. I have had the pleasure to meet up with Brent and Madhu at ONS last year and have done some work with Brent way back when I was working on Floodlight, and am very excited for the future of Socketplane.io.
What’s behind Socketplane.io and What is the current preview technology?
The current tech preview released on github allows you to get a taste of multi-host networking between Dockerhosts using Open vSwitch and Consul as core enablers by building VXLAN tunnels between hosts to connect docker containers on the same virtual(logical) network with no remote/external SDN controller needed. The flows are programmed via OVSDB into the software switch so the user experience and maintenance is smooth with the least amount of moving parts. Users will interact with a wrapper CLI called “socketplane” for docker that also controls how socketplane’s virtual networks are created, deleted and manipulated. Socketplane’s preview uses this wrapper but if your following Docker’s plugin trend then you know they hope to provide virtual network services this way in the future (keep posted on this). I’d also love to see this tech be portable to other container technologies such as LXD or Rocket in the future. Enough text, lets get into the use of Socketplane.io
First lets look at the components of what we will be setting up in this post. Below you will see 2 nodes: socketplane node1 and socketplane node2, we will be setting up these using Vagrant and Virtualbox using Socketplane’s included Vagrantfile. In these two nodes, when socketplane starts up we it will install OVS and Docker and start a socketplane container that runs Consul for managing network state. (one socketplane container will be the master, I’ll show more on this later as well). Then we can create networks, create containers and play with some applications. I will cover this in detail as well as show how the hosts are connected via VXLAN and demo a sample web application across hosts.
Setup Socketplane.io’s preview.
Set an environment variable named SOCKETPLANE_NODES that tells the installation file how many nodes to setup on your local environment. I chose 3. Then run “vagrant up” in the source directory.
After a few or ten minutes you should be all set to test out socketplane thanks to the easy vagrant setup provided by the socketplane guys. (There are also manual install instructions on their github page if you fancy setting this on on bare-metal or something) You should see 3 nodes in virtualbox after this. Or you can run “vagrant status”
Now we can SSH into one of our socketplane nodes. Lets SSH into node1.
Now you SSHed into one of the socketplane nodes. We can issues a “sudo socketplane” command and see the available options the CLI tool gives us.
Some of the commands that are used to run. start, stop, remove etc containers are used via “socketplanerun | start | stop | rm | attach” and these are used just like “docker run | start | stop | rm | attach”
Socketplane sets up a “default” network that (for me) has a 10.1.0.0/16 subnet address and if you run “socketplane network list” you should see this network. To see how we can create virtual networks (vnets) we can issue a command pictures below “socketplane network create foo4 10.6.0.0/16”
This will create a vnet named foo4 along with a vlan for vxlan and default gateway at the .1 address. Now we can see both our default network and our “foo4” network in the list command.
If we look at our Open vSwitch configuration now using the “ovs-vsctl show” command we will also see a new port named foo4 that acts as our gateway so we can talk to the rest of the nodes on this virtual network. You should also see the vxlan endpoints that aligns with your eth1 interfaces on the sockeplane node.
Great, now we are all set up so run some containers that connect over the virtual network we just created. So on socketplane-1 issue a “sudo socketplane run -n foo4 -it ubuntu:14.10 /bin/bash”, this will start a ubuntu container on socketplane-1 and connect it to the foo4 network.
You can Ctrl-Q + Ctrl-P to exit the container and leave the tty open. If you issue a ovs-vsctl show command again you will see a ovs<uuid> port added to the docker0-ovs bridge. This connects the container to the bridge allowing it to communicate over the vnet. Lets create another container, but this time on our socketplane-2 host. So exit out and ssh into socketplane-2 and issue the same command. We should then be able to ping between our two containers on different hosts using ths same vnet.
Awsome, we can ping out first container from our second without having to setup any network information on the second host. This is because the network state it propagated across the cluster so when we reference “foo4” on any of the nodes it will use the same network information. If you Ctrl-Q + Ctrl-P while running ping, we can also see the flows that are in our switch. We just need to use appctl and reference our docker0-ovs integration bridge.
As we can see our flows indicate the VXLAN flows thatheader and forward it to the destination vxlan endpoint and pop (action:pop_vlan) the vlan off the encap in ingress to our containers.
To show a more useful example we can start a simple web application on socketplane-2 and access it over our vnet on socketplane-1 without having to use the Dockerhost IP or NAT. See blow.
First start an image named tutum/hello-world and add it to the foo4 network and expose port 80 at runtime and give it a name “Web”. Use the “web” name with the socketplane info command to get the IP Address.
Next, logout and SSH to socketplane-1 and run an image called tutm/curl (simple curl tool) and run a curl <IP-Address> and you should get back a response from the simple “Web” container we just setup.
This is great! No more accessing pages based on host addresses and NAT. Although a simple use-case, this shows some of the benefit of running a virtual network across many docker hosts.
A little extra
So i mentioned before that socketplane runs Consul in a separate container, you can see the logs of consul by issuing “sudo socketplane agent logs” on any node. But for some more fun and to poke around at some things we are going to use nsenter. First find the socketplane docker container, then follow the commands to get into the socketplane container.
Now your in the socketplane container, we can issue an ip link see that socketplane uses HOST networking to attach consul and get consul running on the host network so the Consul cluster can communicate. We can confirm this by looking at the script used to start the service container.
See line:5 of this snippet, docker runs socketplane with host networking.
You can issue this command on the socketplane-* hosts or in the socketplane container and you should receive a response back from Consul showing you that is listening on 8500.
You can issue “consul members” on the socketplane hosts to see the cluster as well.
You can also play around with consul via the python-consul library to see information stored in Consul.
Overall this a great upgrade to the docker ecosystem, we have seen other software products like Weave, Flannel, Flocker and others i’m probably missing address a clustered Docker setup with some type of networking overlay or communications proxy to connect multi-hosted containers. Socketplane’s preview is completely opensource and is developed on github, if your interested in walking through the code, working on bugs or possibly suggesting or adding features visit the git page. Overall I like the OVS integration a lot mainly because I am a proponent of the software switch and pushing intelligence to the edge. I’d love to see some optional DPDK integration for performance in the near future as well as more features that enable fire-walling between vnets and others. I’m sure its probably on the horizon and am eagerly looking forward to see what Socketplane.io has for containers in the future.