How to maintain sticky session(session persistence) with docker swarm?
I have one Java based web application which is deployed in
jboss-10.1.0(wildfly). I am using docker swarm mode(docker version
1.12.1) to scale my application everything works perfectly but the only issue I am facing is session management.
Now let’s take scenario.
I have two instance is running for my application(i.e.
App2).I am using default load balancer provided by docker swarm mode with
nginx to redirect my application from
chintan.test.com:80 so that I don’t need to write down port with my url and I am able to access directly with this URL
Now the default load balancer is using RR(
Round-Robin algorithm) to serve my web request.So first time I visit the
chintan.test.com it goes to
App1 instance and display login page I login with credentials and everything works perfectly after few minutes it’s switch to
App2 and again the login page comes.
Is there any way or tools(should be Open-source) through which I handle sessions ? So at least I login to
App1 and stick to
App1 until I logout.
2 Solutions collect form web for “How to maintain sticky session(session persistence) with docker swarm?”
Docker swarm does not currently support sticky sessions, round robin is the only way to reach services by their exposed ports.
To implement sticky sessions, you would need to implement a reverse proxy inside of docker that supports sticky sessions and communicates directly to the containers by their container id (rather than doing a DNS lookup on the service name which would again go to the round robin load balancer). Implementing that load balancer would also require you to implement your own service discovery tool so that it knows which containers are available.
Tried using Nginx and HA-Proxy but none of them seems to be work well in SWARM mode. Then I used Traefik in Docker Swarm and it did the trick for me.The only constraint is that Traefik should run on manager node as it needs to be aware of new worker nodes being added or removed. It doesn’t require restart also even if you scale up service, add nodes etc.
I have tested the configuration with Docker compose version 3 which is the latest and deployed using Docker stack deploy.Step by step instructions are over here
To start off you need to create a docker-compose.yml (version 3) and add the load balancer Traefik Image. This is how it looks like
loadbalancer: image: traefik command: --docker \ --docker.swarmmode \ --docker.watch \ --web \ --loglevel=DEBUG ports: - 80:80 - 9090:8080 volumes: - /var/run/docker.sock:/var/run/docker.sock deploy: restart_policy: condition: any mode: replicated replicas: 1 update_config: delay: 2s placement: constraints: [node.role == manager]
and then the Image for which you need session stickiness
whoami: image: tutum/hello-world networks: - net ports: - "80" deploy: restart_policy: condition: any mode: replicated replicas: 5 placement: constraints: [node.role == worker] update_config: delay: 2s labels: - "traefik.docker.network=test_net" - "traefik.port=80" - "traefik.frontend.rule=PathPrefix:/hello;" - "traefik.backend.loadbalancer.sticky=true"
You can follow this link for a detailed explanation.