I am new to the Docker swarm. I deployed a Jenkins service on Docker swarm cluster with 3 managers and 2 worker nodes. I can access the service using node port. But, I want to access the service from outside network using an external loadbalancer. If any one have any reference, please help me on this.
You specified an external load balancer, so you would do something like:
deploy hashicorp consul as part of your app stack, or as a swarm service, to your swarm.
integrate your services with hashicorp consul so they publish their external ips and ports to it. The services would be setup with host mode networking rather than using dockers ingress networking.
integrate your external load balancer with consul so it can deliver traffic to the service.
point your external dns as your external load balancer.
Related
I built two docker applications that communicate with each other using the docker network, but when I tried to run those applications using nomad. The problem within nomad is that the container name is not configurable and gives the container a random name. So I can't add those containers to the docker network and have them know each other with their specific names.
So how can I run two or more docker containers in the same docker network using nomad?
I'm aware of few approaches. First one works with nomad only, the others assume that consul is deployed as well.
Place both containers in the same task group. Nomad will locate them always on the same node and you can access address via Nomad env variables NOMAD_IP_<label>, NOMAD_PORT_<label> or NOMAD_ADDR_<label>.
Register the server application (docker container) in the consul service registry with nomad service stanza. You can then use nomad template stanza in "client" application to render config. Example/doc is here.
Setup consul connect (service mesh) in your deployment.
You could use consul DNS interface. Consul can work as a DNS server and every service is resolvable at <service_name>.service.<dc>.consul (doc). But you have to configure your servers to use consul DNS (doc).
Approach 1 is the easiest but has huge limitation (the same node). Approach 2 worked for me well for several years. Nomad is that intelligent that it will reload/restart your client IP should the server IP/port change.
I have created kubernetes cluster with one master node and one slave node and deployed containers.How can I access containers through external IP.
I have tried assigning IP address to the containers using type=Loadbalancer in docker compose file.
I would suggest you go through the tutorials for Kubernetes.
In general, (1) you would need 3 master nodes. (2) Setup a Ingress-controller ( HTTP Load balancer ) as a type=LoadBalancer service and then configure Ingress with domain for routing, instead of using IP to access those containers directly.
https://kubernetes.io/docs/tutorials/
https://medium.com/google-cloud/kubernetes-101-pods-nodes-containers-and-clusters-c1509e409e16
So, I'm starting to play with docker, so far so good, but I got this question on my head.
Having this two statements in mind (please also correct me if I am misunderstanding something):
1) Docker Swarm provides out of the box service discovering, meaning micro services can talk to each other on the same network by service name without actually knowing on which hosts the other services are allocated.
2) Services instances are ephemeral, so a service can be hosted by different machines in a swarm lifespan.
How should I know which ip adress should expose as a central API gateway service, for instance?
You can expose the IP address of any node in the cluster as Docker has a swarm load balancer running on any of the nodes.
When I deploy a new service with 3 containers via docker cloud I get 3 container endpoints and 1 service endpoint.
What I want to know is, how works the traffic forwarding on the service endpoint to the containers? Is there a built in load balancing or is this just a dns round robin?
The service endpoint has a different IP than the containers, so where is this forwarding service running?
Thank you guys for your help.
I could find the answer here: https://docs.docker.com/docker-cloud/apps/ports/#/service-and-container-dns-endpoints
It says about the service endpoint:
This DNS endpoint (multiple A record) resolves to the IPs of the nodes where the containers are running, in a round-robin fashion.
So I've got a Plex server running on my Docker swarm!! If I kill a node magically it'll start Plex somewhere else. This is great! Now comes the fun part...
With old-school containers I would just port forward port 32400 on my router to the server that was running Plex and it would work find. Now that Plex can run in multiple different places I need to figure out how to forward the port to some static resource. I could use HAProxy to bind some bridge interface and run it on every node to provide failover...but I'd like to see if there's an easier way to accomplish this.
What's the best way to forward ports to services in Docker Swarm?
Port forwarding is built into the new swarm mode. There's a section on load balancing in the documentation:
The swarm manager uses ingress load balancing to expose the services
you want to make available externally to the swarm. The swarm manager
can automatically assign the service a PublishedPort or you can
configure a PublishedPort for the service in the 30000-32767 range.
External components, such as cloud load balancers, can access the
service on the PublishedPort of any node in the cluster whether or not
the node is currently running the task for the service. All nodes in
the swarm cluster route ingress connections to a running task
instance.
Swarm mode has an internal DNS component that automatically assigns
each service in the swarm a DNS entry. The swarm manager uses internal
load balancing to distribute requests among services within the
cluster based upon the DNS name of the service.
Update
The following article discusses how to integrate a proxy load balancer into the docker engine
https://technologyconversations.com/2016/08/01/integrating-proxy-with-docker-swarm-tour-around-docker-1-12-series/