Now that your Docker images are built, deploy them using a Kubernetes resource definition.
A Kubernetes resource definition is a yaml file that contains a description of all your deployments, services, or any other resources that you want to deploy. All resources can also be deleted from the cluster by using the same yaml file that you used to deploy them.
Create the Kubernetes configuration file.
kubernetes.yaml
1apiVersion: apps/v1
2kind: Deployment
3metadata:
4 name: system-deployment
5 labels:
6 app: system
7spec:
8 selector:
9 matchLabels:
10 app: system
11 template:
12 metadata:
13 labels:
14 app: system
15 spec:
16 containers:
17 - name: system-container
18 image: system:1.0-SNAPSHOT
19 ports:
20 - containerPort: 9080
21---
22apiVersion: apps/v1
23kind: Deployment
24metadata:
25 name: inventory-deployment
26 labels:
27 app: inventory
28spec:
29 selector:
30 matchLabels:
31 app: inventory
32 template:
33 metadata:
34 labels:
35 app: inventory
36 spec:
37 containers:
38 - name: inventory-container
39 image: inventory:1.0-SNAPSHOT
40 ports:
41 - containerPort: 9080
42---
43apiVersion: v1
44kind: Service
45metadata:
46 name: system-service
47spec:
48 type: NodePort
49 selector:
50 app: system
51 ports:
52 - protocol: TCP
53 port: 9080
54 targetPort: 9080
55 nodePort: 31000
56---
57apiVersion: v1
58kind: Service
59metadata:
60 name: inventory-service
61spec:
62 type: NodePort
63 selector:
64 app: inventory
65 ports:
66 - protocol: TCP
67 port: 9080
68 targetPort: 9080
69 nodePort: 32000
This file defines four Kubernetes resources. It defines two deployments and two services. A Kubernetes deployment is a resource responsible for controlling the creation and management of pods. A service exposes your deployment so that you can make requests to your containers. Three key items to look at when creating the deployments are the label, image, and containerPort fields. The label is a way for a Kubernetes service to reference specific deployments. The image is the name and tag of the docker image that you want to use for this container. Finally, the containerPort is the port that your container exposes for purposes of accessing your application. For the services, the key point to understand is that they expose your deployments. The binding between deployments and services is specified by the use of labels — in this case the app label. You will also notice the service has a type of NodePort. This means you can access these services from outside of your cluster via a specific port. In this case, the ports will be 31000 and 32000, but it can also be randomized if the nodePort field is not used.
Run the following commands to deploy the resources as defined in kubernetes.yaml:
kubectl apply -f kubernetes.yaml
When the apps are deployed, run the following command to check the status of your pods:
You’ll see an output similar to the following if all the pods are healthy and running:
NAME READY STATUS RESTARTS AGE
system-deployment-6bd97d9bf6-4ccds 1/1 Running 0 15s
inventory-deployment-645767664f-nbtd9 1/1 Running 0 15s
You can also inspect individual pods in more detail by running the following command:
You can also issue the kubectl get and kubectl describe commands on other Kubernetes resources, so feel free to inspect all other resources.
Next you will make requests to your services.
Then curl or visit the following URLs to access your microservices, substituting the appropriate host name:
The first URL returns system properties and the name of the pod in an HTTP header called X-Pod-Name. To view the header, you may use the -I option in the curl when making a request to http://[hostname]:31000/system/properties. The second URL adds properties from system-service to the inventory. Kubernetes Service. Visiting http://[hostname]:32000/inventory/systems/[kube-service] in general adds to the inventory depending on whether kube-service is a valid Kubernetes Service that can be accessed.
