![](https://hackernoon.com/hn-images/1*h9iJ9whjCQ-ovuSGOCOVcA.png)

This post will show you how to setup a **Swarm Cluster**, deploy a couple of microservices, and create a Reverse Proxy Service (with [**Traefik**](https://traefik.io/)) in charge of routing requests on their base URLs.

![](https://hackernoon.com/hn-images/0*4bVQigaoHVORG5jK.)

If you haven’t already, create a Swarm cluster, you could use the shell script below to setup a cluster with 3 nodes (1 Manager & 2 Workers)

Issue the following command to execute the script:

> chmod +x setup.sh

> ./setup.sh

The output of the above command is as follows:

![](https://hackernoon.com/hn-images/0*JGIZdKmzUqatk94i.)

At this moment, we have 3 nodes:

![](https://hackernoon.com/hn-images/0*m089OwIWHjyY3z68.)

Our example microservice application consists of two parts. The **Books API** and the **Movies API**. For both parts I have prepared images for you that can be pulled from the [DockerHub](https://hub.docker.com/u/mlabouardy/).

The **Dockerfiles** for both images can be found on my [Github](https://github.com/mlabouardy/alb-go).

Create _docker-compose.yml_ file with the following content:

*   We use an **overlay network** named _traefik-net_, on which we add the services we want to expose to **Traefik**.
*   We use _constraints_ to deploy the APIs on workers & Traefik on Swarm manager.
*   Traefik container is configured to listen on port **80** for the standard HTTP traffic, but also exposes port **8080** for a web dashboard.
*   The use of docker socket (**/var/run/docker.sock**) allows Traefik to listen to **Docker Daemon** events, and reconfigure itself when containers are started/stopped.
*   The label _traefik.frontend.rule_ is used by Træfik to determine which container to use for which Request Path.
*   The _configs_ part create a configuration file for Traefik from _config.toml_(it enables the **Docker** backend)

In order to deploy our stack, we should execute the following command:

> docker stack deploy — compose-file docker-compose.yml api

Let’s check the overlay network:

> docker network ls

![](https://hackernoon.com/hn-images/0*G2jzOPQS6OLBPzD9.)

Traefik configuration:

> docker config ls

![](https://hackernoon.com/hn-images/0*_jmU6aURCZCyT3e2.)

To display the configuration content:

> docker config inspect api\_traefik-config — pretty

![](https://hackernoon.com/hn-images/0*Zn0bdMLZ8kaBD98I.)

And finally, to list all the services:

> docker stack ps api

![](https://hackernoon.com/hn-images/0*CfIqyG6UMKnnD460.)

In the list of above, you can see that the 3 containers are being running on **node-1**, **node-2** & **node-3** :

![](https://hackernoon.com/hn-images/0*byQWqrM8ZBrtRw_H.)

If you point your favorite browser (not you IE) to the **Traefik Dashboard URL** (**http://MANAGER\_NODE\_IP:8080**) you should see that the frontends and backends are well defined:

![](https://hackernoon.com/hn-images/0*9hNDn71R43GvrU7r.)

If you check [**http://MANAGER\_NODE\_IP/books**,](http://MANAGER_NODE_IP/books,) you will get a list of books:

![](https://hackernoon.com/hn-images/0*qzj1AO4PTRRkPVhf.)

If you replace the base URL with **/movies**:

![](https://hackernoon.com/hn-images/0*uIAArV6zv5EKN_-L.)

What happens if we want to scale out the books & movies APIs. With the **docker service scale** command:

![](https://hackernoon.com/hn-images/0*_M6lvw_QDZho4Gk1.)

![](https://hackernoon.com/hn-images/0*Q2xrhc_nlpZAZUH1.)

We can confirm that:

![](https://hackernoon.com/hn-images/0*W3R6UKxouLVbfQd1.)

Obviously **Traefik** did recognise that we started more containers and made them available to the right frontend automatically:

![](https://hackernoon.com/hn-images/0*OIE0IZQvexcx_ph-.)

In the diagram below, you will find that the manager has decied to schedule the new containers on **node-2** (3 of them) and **node-3** (4 of them) using the [Round Robin](https://en.wikipedia.org/wiki/Round-robin_scheduling) strategy:

![](https://hackernoon.com/hn-images/0*n_B3wVNIdtnr_kNC.)

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Architecting a Highly Scalable Golang API with Docker Swarm & Traefik

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@mlabouardy

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