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:
A Cloud 66 Account — If you don't already have one sign up for a Cloud 66 account. You'll get free unlimited access to all products for 4 weeks.
An existing application set up in Skycap
An existing Formation defined in Skycap — You can learn how to do that with our Getting started with Skycap Formations guide.
In this example we’re using the same simple "hello world" project that we used in our Getting Started guides.
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:
- We need to add a standard Redis service to the application using a pre-built image from a public repository
- We need to add a new
service.ymlStencil to our existing Formations to define the Kubernetes service
- We need to add a new
deployment.ymlStencil to the same Formation to define the deployment of this new service
- We need to deploy our updated application to see it working
Adding a new component (service) to your application
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)
Click on the edit icon in the top left-hand corner of the application detail panel to open the Service Editor.
Click on the + Add Service button and then give the new service a name (
rediswould be sensible)
Next change the service image dropdown to “It’s in a Docker image repository”
redisinto the Docker image field and click Go (be careful - capitalisation matters)
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:
service.ymlto define the service in Kubernetes
deployment.ymlto 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
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
- On the Formation detail page, click on the + at the top right of the Stencils panel and select
deployment.ymlfrom the available templates.
- Select redis from the Service dropdown (on the right-hand side)
- In the Stencil code change
- Delete the
commandentirely - we don’t need it for this example
- 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:
- Click on the green Snapshot button and choose Snapshot all
- Once the build is complete, open the Formation detail page
- Click on the *Render Formation” button
- Copy the
cxcommand and add
| kubectl apply -f -
- Paste the resulting command into your terminal (make sure Minikube is running)
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.
- Learn how to update an existing service in Skycap.
- Learn how to roll back to an older version of your application using Snapshots.
- Learn how to add custom environment variables to your application.
- Learn how to set up access control and permissions on your Formations and Stencils
- Learn how to use your Habitus build flow within Skycap.
- Learn how to use validation policies to ensure your Stencils adhere to your standards and conventions.