VEO is a docker container scheduler with built in DNS.
This is a masterless cluster which syncs via Erlang OTP node connections and syncs data using Mnesia.
The makefile is the best way to get started with VEO.
make start : Starts a single instance of VEO on your local machine.
make multiple : Starts two instances of VEO in separate docker containers.
make three : Starts three instances of VEO in separate docker containers.
The default cluster.yml (in apps/veo/priv) defines two nodes (uno and dos) which both have the role of master.
It also defines two services (using the nginx container) one in host network mode and other in bridge mode.
If you use start or three with the makefile you should edit the cluster.yml to either remove one host or add the third.
This guide assumes you started with make multiple so you now have two containers running VEO (uno and dos).
Start two separate shells and exec into the containers:
docker exec -it uno bashdocker exec -it dos bashNow you need to get the nginx image into both containers via docker, so in both run:
docker pull nginxChange the resolv.conf to point to localhost:
echo "nameserver 127.0.0.1" > /etc/resolv.conf
You are now ready to attach to the shell of VEO in each container:
./_build/default/rel/veo/bin/veo attachinside the shell type the following:
[H|[T]] = settings:get_applications().You now have the parsed definitions of the two nginx containers specified in the cluster.yml.
To start a container type
container_sup:add_service(T).You will see one of the nodes starting an nginx container in host mode.
Now that you have a container running we can verify that it is actually there and registered with the DNS in both nodes.
Exit the attached shells in both nodes (CTRL+d) * NOTE: CTRL+c will stop the node) *
In the shell of both of the nodes type
dig ngnix.veo'This should return an A record with the IP of the node that is running the nginx service.
The default configuration file specifies two ports for the nginx service, one is 500 and called port1 and the other one is randomly assigned and bound to nginx port 80 (called website).
You can verify this as well with the DNS:
dig _website._tcp.nginx.veo SRVwill show you the port assigned to the nginx container.
curl website.nginx.veo:<PORT FROM SRV QUERY>Should show `Welcome to ngnix!'.
Testing of various options is not done yet.
- HealthChecks
These need to be tested for parsing correctly to a docker acceptable JSON.
- Define actions to take on unhealthy containers (kill/restart/leave).
Activate and define the websocket subscriptions for different state changes.
- Subscribe to state changes for a specific container
- Subscribe to state changes for all containers (multi-node??).
- Subscribe to events (service started, ready, restarted, killed) per container/node/cluster.
Define the API to interact with the cluster.
- Add service
- Delete service
- Add node
- Remove node
- Get container info (all/single)
- Add commands for the REST API.