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I have been trying to create an overlay network between two hosts with no success. I keep getting the error message:
mavungu@mavungu-Aspire-5250:~$ sudo docker -H tcp://192.168.0.18:2380 network create -d overlay myapp
Error response from daemon: 500 Internal Server Error: failed to parse pool request for address space "GlobalDefault" pool "" subpool "": cannot find address space GlobalDefault (most likely the backing datastore is not configured)
mavungu@mavungu-Aspire-5250:~$ sudo docker network create -d overlay myapp
[sudo] password for mavungu:
Error response from daemon: failed to parse pool request for address space "GlobalDefault" pool "" subpool "": cannot find address space GlobalDefault (most likely the backing datastore is not configured)
My environment details:
mavungu@mavungu-Aspire-5250:~$ sudo docker info Containers: 1
Images: 364 Server Version: 1.9.1 Storage Driver: aufs Root Dir:
/var/lib/docker/aufs Backing Filesystem: extfs Dirs: 368 Dirperm1
Supported: true Execution Driver: native-0.2 Logging Driver:
json-file Kernel Version: 3.19.0-26-generic Operating System: Ubuntu
15.04 CPUs: 2 Total Memory: 3.593 GiB Name: mavungu-Aspire-5250 Registry: https://index.docker.io/v1/ WARNING: No swap limit support
I have a swarm cluster working well with consul as the discovery mechanism:
mavungu@mavungu-Aspire-5250:~$ sudo docker -H tcp://192.168.0.18:2380 info
Containers: 4
Images: 51
Role: primary
Strategy: spread
Filters: health, port, dependency, affinity, constraint
Nodes: 2
mavungu-Aspire-5250: 192.168.0.36:2375
└ Containers: 1
└ Reserved CPUs: 0 / 2
└ Reserved Memory: 0 B / 3.773 GiB
└ Labels: executiondriver=native-0.2, kernelversion=3.19.0-26-generic, operatingsystem=Ubuntu 15.04, storagedriver=aufs
mavungu-HP-Pavilion-15-Notebook-PC: 192.168.0.18:2375
└ Containers: 3
└ Reserved CPUs: 0 / 4
└ Reserved Memory: 0 B / 3.942 GiB
└ Labels: executiondriver=native-0.2, kernelversion=4.2.0-19-generic, operatingsystem=Ubuntu 15.10, storagedriver=aufs
CPUs: 6
Total Memory: 7.715 GiB
Name: bb47f4e57436
My consul is available at 192.168.0.18:8500 and it works well with the swarm cluster.
I would like to be able to create an overlay network across the two hosts. I have configured the docker engines on both hosts with this additional settings:
DOCKER_OPTS="-D --cluster-store-consul://192.168.0.18:8500 --cluster-advertise=192.168.0.18:0"
DOCKER_OPTS="-D --cluster-store-consul://192.168.0.18:8500 --cluster-advertise=192.168.0.36:0"
I had to stop and restart the engines and reset the swarm cluster... After failing to create the overlay network, I changed the --cluster-advertise setting to this :
DOCKER_OPTS="-D --cluster-store-consul://192.168.0.18:8500 --cluster-advertise=192.168.0.18:2375"
DOCKER_OPTS="-D --cluster-store-consul://192.168.0.18:8500 --cluster-advertise=192.168.0.36:2375"
But still it did not work. I am not sure of what ip:port should be set for the --cluster-advertise= . Docs, discussions and tutorials are not clear on this advertise thing.
There is something that I am getting wrong here. Please help.
I think the options that you specify should use
cluster-store=consulinstead ofcluster-store-consul. Try to reset and restart the engine and swarm and check if it works. It should work after that. The getting started doc clearly explains how to configure docker overlay networks using consul as backing data-store.When you execute the
docker runcommand, be sure to add--net myapp. Here is a full step-by-step tutorial (online version):How to deploy swarm on a cluster with multi-hosts network
TL;DR: step-by-step tutorial to deploy a multi-hosts network using Swarm. I wanted to put online this tutorial ASAP so I didn't even take time for the presentation. The markdown file is available on the github of my website. Feel free to adapt and share it, it is licensed under a Creative Commons Attribution 4.0 International License.
Prerequisites
EnvironmentSwarm manager and consul master will be run on the machine named bugs20. Other nodes, bugs19, bugs18, bugs17 and bugs16, will be swarm agents and consul members.
Before we startConsul is used for the multihost networking, any other key-value store can be used -- note that the engine supports Consul Etcd, and ZooKeeper. Token (or static file) are used for the swarm agents discovery. Tokens use REST API, a static file is preferred.
The networkThe network is range 192.168.196.0/25. The host named bugsN has the IP address 192.168.196.N.
The docker daemonAll nodes are running docker daemon as follow:
Options details:Binds the daemon to an interface to allow be part of the swarm cluster. An IP address can obviously be specificied, it is a better solution if you have several NIC.
Defines the interface and the port of the docker daemon should use to advertise itself.
Defines the URL of the distributed storage backend. In our case we use consul, though there are other discovery tools that can be used, if you want to make up your mind you should be interested in reading this service discovery comparison.
As consul is distributed, the URL can be local (remember, swarm agents are also consul members) and this is more flexible as you don't have to specify the IP address of the consul master and be selected after the docker daemon has been started.
The aliases usedIn the following commands these two aliases are used:
Be sure to have the path of the consul binary in your
$PATH. Once you are in the directory just typeexport PATH=$PATH:$(pwd)will do the trick.It is also assumed that the variable
$IPhas been properly set and exported. It can be done, thanks to.bashrcor.zshrcor else, with something like this:Consul
Let's start to deploy all consul members and master as needed.
Consul master (bugs20)
Options details:Start the consul agent as a server.
We expect only one master.
This consul server/master will be named "master20".
Specifies the IP address on which it should be bound. Optional if you have only one NIC.
Specifies the RPC IP address on which the server should be bound. By default it is localhost. Note that I am unsure about the necessity of this option, and this force to add
-rpc-addr=192.168.196.20:8400for local request such asconsul members -rpc-addr=192.168.196.20:8400orconsul join -rpc-addr=192.168.196.20:8400 192.168.196.9to join the consul member that has the IP address192.168.196.9.Consul members (bugs{16..19})
It is suggested to use tmux, or similar, with the option
:setw synchronize-panes onso this one command:consul -d agent -data-dir /tmp/consul -node=$HOST -bind=$IPstarts all consul members.Join consul members
A one line command can be used too. If you are using zsh, then
consul join -rpc-addr=192.168.196.20:8400 192.168.196.{16..19}is enough, or a foor loop:for i in $(seq 16 1 19); do consul join -rpc-addr=192.168.196.20:8400 192.168.196.$i;done. You can verify if your members are part of your consul deployment with the command:Consul members and master are deployed and working. The focus will now be on docker and swarm.
Swarm
In the following the creation of swarm manager and swarm members discovery are detailed using two different methods: token and static file. Tokens use a hosted discovery service with Docker Hub while static file is just local and does not use the network (nor any server). Static file solution should be preferred (and is actually easier).
[static file] Start the swarm manager while joining swarm members
Create a file named
/tmp/cluster.discowith the contentswarm_agent_ip:2375.Then just start the swarm manager as follow:
And you're done !
[token] Create and start the swarm manager
On the swarm master (bugs20), create a swarm:
This create a swarm and save the token ID in the file
swarm_idof the current directory. Once created, the swarm manager need to be run as a daemon:To verify if it is started you can run:
[token] Join swarm members into the swarm cluster
Then the swarm manager will need some swarm agent to join.
std[in|out] will be busy, these commands need to be ran on different terminals. Adding
-dabefore thejoinshould solve this and enables a for-loop to be used for the joins.After the join of the swarm members:
After the discovery of the swarm members
To verify if the members are well discovered, you can execute
swarm-docker info:At this point swarm is deployed and all containers run will be run over different nodes. By executing several:
and then a:
As shown, the containers are disseminated over bugs{16...19}.
Multi-hosts network
A network overlay is needed so all the containers can be "plugged in" this overlay. To create this network overlay, execute:
And voilà !
Once this overlay is created, add
--net netto the commandswarm-docker run --rm -it ubuntu bashand all your containers will be able to communicate natively as if they were on the same LAN. The default network is 10.0.0.0/24.Enabling Multicast
Multicast is not support by the default overlay. Another driver is required to be able to use multicast. The docker plugin weave net does support multicast.
To use this driver, once installed, you will need to run
$weave launchon all Swarm agents and Swarm manager. Then you'll need to connect the weave together, this is done by running$weave connect $SWARM_MANAGER_IP. It is not obviously the IP address of the Swarm manager but it is cleaner to do so (or use another node than the Swarm agents).At this point the weave cluster is deployed, but no weave network has been created. Running
$swarm-docker network create --driver weave weave-netwill create the weave network namedweave-net. Starting containers with the--net weave-netwill enable them to share the same LAN and use multicast. Example of a full command to start such containers is:$swarm-docker run --rm -it --privileged --net=weave-net ubuntu bash.For anyone coming to this since Docker 1.12 was released, this is now trivially easy - Swarm Mode is built into the engine and you don't need Consul or any other extra components.
Assuming you have two hosts with Docker installed, intitialize the Swarm on the first machine:
That host becomes the first manager node in the swarm, and it writes out the command you use to join other nodes to the swarm - the secret token, and the IP address where the manager is listening.
On the second host:
Now you have a secure 2-node swarm which has service discovery, rolling updates and service scaling.
Create your overlay network on the manager node with:
And you now have a multi-host overlay network with built-in DNS, so services can resolve each other based on service name.