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https://github.com/hombit/scoop-on-docker-swarm

Run Python SCOOP on docker swarm cluster
https://github.com/hombit/scoop-on-docker-swarm

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Run Python SCOOP on docker swarm cluster

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README 

        
Docker swarm for Python SCOOP

=============================



The project shows how to run [SCOOP](http://scoop.readthedocs.io/) program with

[Docker swarm mode](https://docs.docker.com/engine/swarm/)



Architecture of the project

---------------------------



The project has only one Docker Swarm manager host and numerical Docker Swarm

worker hosts. Docker Swarm manager host runs two containers: `SCOOP` broker and

`SCOOP` root worker. Each of Docker Swarm worker hosts runs one `SCOOP` worker

container. `SCOOP` broker connects to each worker (including root worker) and

asks them to perform calculations. Root worker does one more thing: it runs

simple web-server (based on [bottle](http://bottlepy.org)) on port 8000 and

shows the result of computation there.



### Diagrams



Architecture of the `SCOOP` project from [its

website](http://scoop.readthedocs.io/en/0.7/usage.html)



![](http://scoop.readthedocs.io/en/0.7/_images/architecture.png)



Architecture of the Docker Swarm from [Docker

website](https://docs.docker.com/engine/swarm/how-swarm-mode-works/nodes/)



![](https://docs.docker.com/engine/swarm/images/swarm-diagram.png)



Install Docker

--------------



You can install docker to each future docker swarm host manually or using

`docker-machine`.



### Docker-machine way (preferred)



Install Docker onto your computer using instructions on

[docker.com](http://docker.com). Remember that you need all staff: Docker

Engine, Docker Machine and Docker Compose. Modern installation packages for

Windows and Mac include all of them.



You need ssh access to each of your hosts without password. Generate pair of

private and public ssh keys if you haven’t them yet (keep the default location):



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ssh-keygen -t rsa

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Copy them to each host. Here and further I use capitals to indicate words that

you should replace.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ssh-copy-id USER@HOST_NAME

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Be sure that you can execute sudo commands on each host without password. If you

cannot then run `visudo` and add line `USER ALL=(ALL)NOPASSWD:ALL` (replace

`USER` with your username).



Than install Docker on each host using `docker-machine` (in the terms of Docker

create Docker machine):



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docker-machine create --driver generic --generic-ip-address=HOST_NAME --generic-ssh-key=/Users/hombit/.ssh/id_rsa --generic-ssh-user=USER DOCKER_MACHINE_NAME

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Now if you want to perform some `docker` or `docker-compose` command on

particular host you need to activate it and perform your command.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Check status of the machine

docker-machine status DOCKER_MACHINE_NAME

# If it isn't running:

docker-machine start DOCKER_MACHINE_NAME

# Update environment

eval "$(docker-machine env DOCKER_MACHINE_NAME)"

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Now do what you need, you don’t need to ssh to your host.



### Manual way



Ssh to each your host and install Docker manually. Use instructions from

[docker.com](http://docker.com). When you need to perform some `docker` or

`docker-compose` command on the host, you should ssh to it. Don’t forget to add

your user to `docker` group or use `sudo` for every Docker command.



Create swarm

------------



See [Docker swarm mode

tutorial](https://docs.docker.com/engine/swarm/swarm-tutorial/)



One of your Docker hosts will be a Leader. Ssh to this host or activate related

Docker machine. Than initialise swarm:



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docker swarm --advertise-addr LEADER_IP_VISIBLE_FOR_SWARM_NODES

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Remember output and type it on every host that will be a member of the swarm:



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docker swarm join --token TOKEN LEADER_IP_VISIBLE_FOR_SWARM_NODES:2377

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Return to the leader and check your swarm:



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docker node ls

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Generate ssh keys

-----------------



We need secret ssh keys to connect broker with workers. Generate pairs of ssh

keys for `SCOOP` broker (ssh client) and workers (ssh hosts):



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

mkdir secrets

yes | ssh-keygen -f secrets/ssh_client_rsa_key -N '' -C '' -t rsa

yes | ssh-keygen -f secrets/ssh_host_rsa_key -N '' -C '' -t rsa

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Build Docker services

---------------------



On each host do:



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docker-compose build

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Deploy stack of services

------------------------



Do on manager host:



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# In the future versions of Docker command will be replaced with docker deploy

docker stack deploy --compose-file=docker-compose.yml scoop

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



`scoop` is the name of stack and it is hardcoded in the project, please don’t

change it.



Now you can check that all services have started:



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docker stack ps scoop

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Check

-----



Go to http://YOUR_MANAGER_ADDRESS:8000 and check that it responds.



Limitations and what to do next

-------------------------------



`docker-compose.yml` can be split into three parts: for building images, for

running on one host for debug purposes and for Docker swarm mode.



It is bad idea to build images on each host. It is much better to use [Docker

registry](https://docs.docker.com/registry/) for building and storing images.