Adding a new service to an application

As your application grows in complexity and popularity, you may need to add new components. For example you may add a cache like Varnish or a new data store like MongoDB.

This guide walks you through the process of adding a standard (“off the shelf”) component to an existing application using a public repository.

What you’ll need

Before you start, please check you have the following:

Sample project

In this example we’re using the same simple "hello world" project that we used in our Getting Started guides.

Overview

In this example you have decided to make your Hello World application dynamic by adding a Redis service. To do this, we need to do four things:

  1. We need to add a standard Redis service to the application using a pre-built image from a public repository
  2. We need to add a new service.yml Stencil to our existing Formations to define the Kubernetes service
  3. We need to add a new deployment.yml Stencil to the same Formation to define the deployment of this new service
  4. We need to deploy our updated application to see it working

Adding a new component (service) to your application

  1. Open your Cloud 66 dashboard and click on the name of the application to which you want to add a new service (“Hello World” in our case)

  2. Click on the edit icon in the top left-hand corner of the application detail panel to open the Service Editor.

  3. Click on the + Add Service button and then give the new service a name (redis would be sensible)

  4. Next change the service image dropdown to “It’s in a Docker image repository”

  5. Type redis into the Docker image field and click Go (be careful - capitalisation matters)

  6. Once Skycap has successfully analysed the Redis image, click Save Changes

You should now be able to see the Redis service below your original “Hello World” service.

Adding stencils to configure the new service

Simply adding an image to Skycap won’t be enough to get your new service working on your cluster. You need to configure it so that it will be deployed, and will be able to start up and communicate with your existing service.

To do this, we need to add two new Stencils to your existing Formation. Just as we did with our original Hello World application, we need:

  • A service.yml to define the service in Kubernetes
  • A deployment.yml to populate and initialise the new service

Adding a second service.yml

Click on Formations in the right hand panel and then click on the name of the Formation we are going to edit (“Hello World”) Click on the + at the top right of the Stencils panel and select service.yml from the available templates. Select “redis” from the Service dropdown (on the right-hand side) In the Stencil code change both port and targetPort to 6379 (the standard Redis port) Add a commit message and click Save changes

You should now see a new Stencil called redis_service.yml in your Formation. Next, we need to define our Redis deployment.

Adding a second deployment.yml

  1. On the Formation detail page, click on the + at the top right of the Stencils panel and select deployment.yml from the available templates.
  2. Select redis from the Service dropdown (on the right-hand side)
  3. In the Stencil code change containerPort to 6379
  4. Delete the command entirely - we don’t need it for this example
  5. Add a commit message and click Save changes

We are now nearly ready to deploy our updated Hello World app. We just need to create a new Snapshot and render our enlarged Formation.

Deploying the updated application

So far we have:

  • Added a pre-built Redis image to our app
  • Configured that Redis image as a new service to run alongside our Hello World service
  • Configured a deployment for that Redis service to initialise it in our Minikube cluster

To see this new, improved app in action, we need to deploy it to Minikube. To do this we follow the now familiar steps from our Getting started with Skycap Formations guide.

A quick reminder:

  1. Click on the green Snapshot button and choose Snapshot all
  2. Once the build is complete, open the Formation detail page
  3. Click on the *Render Formation” button
  4. Copy the cx command and add | kubectl apply -f -
  5. Paste the resulting command into your terminal (make sure Minikube is running)

Once kubectl has applied all the changes, you will be able to run the minikube service helloworld -n hello-world command. (Bear in mind your command may need to be slightly different depending on what you named your service and namespace.)

This will open up the Hello World web page, as usual, but this version of the page is different. If you have successfully deployed Redis, the page will say “(connected to Redis)” in the sub-headline and will have a green check mark next to it.

If the command fails, double check that the pod has started up completely by using the get pods command. It will take slightly longer to start up than the previous example.

Hello World and Redis

Normally the original application (Hello World) would need to be updated with code to enable it query Redis in this way. However, in order to keep our example simple, we wrote the original Hello World application to work both with and without Redis. If you can read Golang, check out the main.go file to see how we did this.

What’s next?

Next
Deploy your first app with Cloud 66