This article describes the comparison of the YAML files that are used to create applications in a Container Service for Swarm cluster and in a Container Service for Kubernetes (ACK) cluster.
Background
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You can use Kompose to convert a YAML file for a Swarm cluster into a YAML file for an ACK cluster. After the YAML file is converted, you must check the content of the file.
You can obtain Kompose from the GitHub website.
You can download Kompose at one of the following URLs:Note Kompose does not support specific custom labels in ACK. These custom labels are listed in Table 1. Alibaba Cloud ACK team will continue its development efforts to add support for all custom labels.Table 1. Labels not supported by Kompose Label Related topic external External dns_options dns_options oom_kill_disable oom_kill_disable affinity:service Service deployment constraints (affinity:service) - You can also manually modify a YAML file.
This topic describes the comparison of the YAML files that are used in Swarm and in ACK clusters. The sample YAML files that are used in this topic can be modified based on your business requirements.
YAML file comparison
Swarm cluster
web: #---1
image: registry.aliyuncs.com/acs-sample/wordpress:4.5 #---2
ports: #---3
- '80'
environment: #---4
WORDPRESS_AUTH_KEY: changeme #---5
WORDPRESS_SECURE_AUTH_KEY: changeme #---5
WORDPRESS_LOGGED_IN_KEY: changeme #---5
WORDPRESS_NONCE_KEY: changeme #---5
WORDPRESS_AUTH_SALT: changeme #---5
WORDPRESS_SECURE_AUTH_SALT: changeme #---5
WORDPRESS_LOGGED_IN_SALT: changeme #---5
WORDPRESS_NONCE_SALT: changeme #---5
WORDPRESS_NONCE_AA: changeme #---5
restart: always #---6
links: #---7
- 'db:mysql'
labels: #---8
aliyun.logs: /var/log #---9
aliyun.probe.url: http://container/license.txt #---10
aliyun.probe.initial_delay_seconds: '10' #---10
aliyun.routing.port_80: http://wordpress #---11
aliyun.scale: '3' #---12
db: #---1
image: registry.aliyuncs.com/acs-sample/mysql:5.7 #---2
environment: #---4
MYSQL_ROOT_PASSWORD: password #---5
restart: always #---6
labels: #---8
aliyun.logs: /var/log/mysql #---9ACK cluster
If you deploy the wordpress-swarm.yaml file in a Swarm cluster, a WordPress application is created. In an ACK cluster, a web application and a database application are required to provide the same services as the WordPress application in the Swarm cluster.
To deploy the web and database applications in an ACK cluster, you must create two Deployments and two Services in the ACK cluster. The Services are created to enable access to the Deployments.
- The following template is an example of the wordpress-kubernetes-web-deployment.yaml file:
apiVersion: apps/v1 # The API version. kind: Deployment # The type of the resource that you want to create. metadata: name: wordpress #---1 labels: #---8 Labels are only used to identify resources in Kubernetes. app: wordpress spec: # The resource details. replicas: 2 #---12 The number of replicas. selector: matchLabels: app: wordpress tier: frontend strategy: type: Recreate template: # The pod details. metadata: labels: # The same as the previous labels field. app: wordpress tier: frontend spec: # The container details. containers: # - image: wordpress:4 #---2 The image and its version. name: wordpress env: #---4 The environment variable. You can reference ConfigMaps and Secrets through env. - name: WORDPRESS_DB_HOST value: wordpress-mysql #---7 The name of the MySQL service that is accessed by the WordPress application. - name: WORDPRESS_DB_PASSWORD #---5 You can use a Secret to store the password. valueFrom: secretKeyRef: name: mysql-pass key: password-wordpress ports: #---3 The application port. - containerPort: 80 name: wordpress livenessProbe: #add health check ---10 Enables the health check feature. httpGet: path: / port: 8080 initialDelaySeconds: 30 timeoutSeconds: 5 periodSeconds: 5 readinessProbe: #add health check ---10 Enables the health check feature. httpGet: path: / port: 8080 initialDelaySeconds: 5 timeoutSeconds: 1 periodSeconds: 5 volumeMounts: # Mounts the volume to the container. - name: wordpress-pvc mountPath: /var/www/html volumes: # Creates a persistent volume (PV) and a persistent volume claim (PVC) to use the volume. - name: wordpress-pvc persistentVolumeClaim: claimName: wordpress-pv-claim - The following template is an example of the wordpress-kubernetes-web-service.yaml file:
apiVersion: v1 # The API version. kind: Service # The type of the resource that you want to create. metadata: name: wordpress labels: app: wordpress spec: ports: - port: 80 # The Service port. selector: # Uses a label to associate the Service with the application. app: wordpress tier: frontend type: LoadBalancer #---11 The method that is used to access the application. In this example, a LoadBalancer Service is used to automatically create a Server Load Balancer (SLB) instance.
- The following template is an example of the wordpress-kubernetes-db-deployment.yaml file:
apiVersion: apps/v1 kind: Deployment metadata: name: wordpress-mysql labels: app: wordpress spec: selector: matchLabels: app: wordpress tier: mysql strategy: type: Recreate template: metadata: labels: app: wordpress tier: mysql spec: containers: - image: mysql:5.6 name: mysql env: - name: MYSQL_ROOT_PASSWORD valueFrom: secretKeyRef: name: mysql-pass key: password-mysql ports: - containerPort: 3306 name: mysql volumeMounts: - name: wordpress-mysql-pvc mountPath: /var/lib/mysql volumes: - name: wordpress-mysql-pvc persistentVolumeClaim: claimName: wordpress-mysql-pv-claim - The following template is an example of the wordpress-kubernetes-db-service.yaml file:
apiVersion: v1 kind: Service metadata: name: wordpress-mysql labels: app: wordpress spec: ports: - port: 3306 selector: app: wordpress tier: mysql clusterIP: None