Deploy Application

This guide shows you how to use Kusion CLIs to complete the deployment of an application running in Kubernetes. We call the abstraction of application operation and maintenance configuration as AppConfiguration, and its instance as Application. It is essentially an configuration model that describes an application. The complete definition can be seen here.

In production, the application generally includes minimally several k8s resources:

• Namespace
• Deployment
• Service

tip

This guide requires you to have a basic understanding of Kubernetes. If you are not familiar with the relevant concepts, please refer to the links below:

• Learn Kubernetes Basics
• Namespace
• Deployment
• Service

Prerequisites

Before we start, we need to complete the following steps:

1、Install Kusion

We recommend using HomeBrew(Mac), Scoop(Windows), or an installation shell script to download and install Kusion. See Download and Install for more details.

2、Running Kubernetes cluster

There must be a running Kubernetes cluster and a kubectl command line tool. If you don't have a cluster yet, you can use Minikube to start one of your own.

Initializing

This guide is to deploy an app using Kusion, relying on the Kusion CLI and a Kubernetes cluster.

To initialize the application configuration:

kusion init

The kusion init command will prompt you to enter required parameters, such as project name, project description, image address, etc. You can keep pressing Enter all the way to use the default values.

The output is similar to:

✔ single-stack-sample    A minimal kusion project of single stack
This command will walk you through creating a new kusion project.

Enter a value or leave blank to accept the (default), and press <ENTER>.
Press ^C at any time to quit.

Project Config:
✔ Project Name: helloworld
✔ AppName: helloworld
✔ ProjectName: helloworld
Stack Config: dev
✔ Image: gcr.io/google-samples/gb-frontend:v4

Created project 'helloworld'

Now, we have successfully initialized a project helloworld using the single-stack-sample template, which contains a dev stack.

• AppName represents the name of the sample application, which is recorded in the generated main.k as the name of the AppConfiguration instance.
• ProjectName and Project Name represent the name of the sample project, which is used as the generated folder name and then recorded in the generated project.yaml.
• Image represents the image address of the application container.

info

See Project&Stack for more details about Project and Stack.

The directory structure is as follows:

helloworld
  ├── README.md
  ├── dev
  │   ├── main.k
  │   ├── kcl.mod
  │   ├── kcl.mod.lock
  │   └── stack.yaml
  └── project.yaml

1 directory, 6 files

The project directory has the following files that are automatically generated:

• README.md contains the generated README from a template.
• project.yaml represents project-level configurations.
• dev directory stores the customized stack configuration:
  • dev/main.k stores configurations in the dev stack.
  • dev/stack.yaml stores stack-level configurations.
  • dev/kcl.mod stores stack-level dependencies.
  • dev/kcl.mod.lock stores version-sensitive dependencies.

In general, the .k files are the KCL source code that represents the application configuration, and the .yaml is the static configuration file that describes behavior at the project or stack level.

kcl.mod

There should be a kcl.mod file generated automatically under the project directory. The kcl.mod file describes the dependency for the current project or stack. By default, it should contain a reference to the official catalog repository which holds some common model definitions that fits best practices. You can also create your own models library and reference that.

Compiling

At this point, the project has been initialized with the Kusion built-in template. The configuration is written in KCL, not JSON/YAML which Kubernetes recognizes, so it needs to be compiled to get the final output.

Enter stack dir helloworld/dev and compile:

cd helloworld/dev && kusion compile

The output is printed to stdout by default. You can save it to a file using the -o/--output flag when running kusion compile.

The output of kusion compile is the spec format.

tip

For instructions on the kusion command line tool, execute kusion -h, or refer to the tool's online documentation。

Applying

Compilation is now completed. We can apply the configuration as the next step. In the output from kusion compile, you can see 3 resources:

• a Namespace named helloworld
• a Deployment named helloworld-dev-helloworld in the helloworld namespace
• a Service named helloworld-dev-helloworld-private in the helloworld namespace

Execute command:

kusion apply

The output is similar to:

 ✔︎  Generating Spec in the Stack dev...                                                                                                                                                                                                                                         
Stack: dev  ID                                                       Action
* ├─     v1:Namespace:helloworld                                  Create
* ├─     v1:Service:helloworld:helloworld-dev-helloworld-private  Create
* └─     apps/v1:Deployment:helloworld:helloworld-dev-helloworld  Create


? Do you want to apply these diffs? yes
Start applying diffs ...
 SUCCESS  Create v1:Namespace:helloworld success                                                                                                                                                                                                                                
 SUCCESS  Create v1:Service:helloworld:helloworld-dev-helloworld-private success                                                                                                                                                                                                
 SUCCESS  Create apps/v1:Deployment:helloworld:helloworld-dev-helloworld success                                                                                                                                                                                                
Create apps/v1:Deployment:helloworld:helloworld-dev-helloworld success [3/3] █████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████ 100% | 0s
Apply complete! Resources: 3 created, 0 updated, 0 deleted.

After the configuration applying successfully, you can use the kubectl to check the actual status of these resources.

1、 Check Namespace

kubectl get ns

The output is similar to:

NAME                   STATUS   AGE
default                Active   117d
helloworld             Active   63s
kube-system            Active   117d
...

2、Check Deployment

kubectl get deploy -n helloworld

The output is similar to:

NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
helloworld-dev-helloworld   2/2     2            2           111s

3、Check Service

kubectl get svc -n helloworld

The output is similar to:

NAME                                TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
helloworld-dev-helloworld-private   ClusterIP   10.111.183.0   <none>        80/TCP   2m6s

4、Validate app

Using the kubectl tool, forward native port 30000 to the service port 80.

kubectl port-forward svc/helloworld-dev-helloworld-private -n helloworld 30000:80

Open browser and visit http://127.0.0.1:30000：