Deployment

• Runtime dependencies
• Environment variables
• Kubernetes
  • Deployment descriptor
  • Volumes and secrets
• Docker

All Kaa services, including DCX, are distributed as Docker images. You can run these images using software containerization and orchestration tools, such as Docker, Docker Swarm, Docker Compose, Kubernetes, etc. Kubernetes is the recommended system for managing Kaa-based clusters.

Runtime dependencies

DCX has the following runtime dependencies:

• NATS for inter-service communication.

Regardless of the deployment method, always make sure that you have dependency services up and running prior to starting up DCX.

The below instructions where DCX sources its configuration data from a local file.

Environment variables

The table below summarizes the variables supported by the DCX Docker image and provides default values along with descriptions.

Kubernetes

To run DCX on Kubernetes:

1. Install Kubernetes.
2. Set up NATS as a Kubernetes service or a standalone server.
3. Prepare Kubernetes deployment descriptor.
4. (Optional) Configure volumes and secrets.
5. Prepare a config map, or a separate configuration file and save it into a file available to pods under APP_CONFIG_PATH.
6. Start up the pod:

   kubectl create -f <deployment descriptor filename>
   

7. Check that pods are running:

   kubectl get pods
   

Deployment descriptor

Provided below is a sample deployment descriptor file that pulls the DCX version 1.0.0 Docker image from the official KaaIoT repository and runs one service replica (pod) with 150 MB RAM limit. Default environment variables are used in most cases, except the configuration source is file-based. With this deployment descriptor, the configuration file is expected to be located at ~/dcx-config/service-config.yml of the host machine. See spec.template.spec.volumes.hostPath below and the default APP_CONFIG_PATH above.

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: dcx
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: dcx
        tier: backend
    spec:
      containers:
      - name: dcx
        image: hub.kaaiot.net/kaaiot/dcx/dcx:1.0.0
        terminationMessagePolicy: FallbackToLogsOnError
        imagePullPolicy: Always
        livenessProbe:
          httpGet:
            path: /health
            port: management
          initialDelaySeconds: 150
          periodSeconds: 5
        readinessProbe:
          httpGet:
            path: /health
            port: management
          initialDelaySeconds: 1
          periodSeconds: 1
        resources:
          requests:
            memory: 20Mi
          limits:
            memory: 150Mi
        env:
        - name: KAA_LICENSE_CERT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: license.cert.pass
              key: password
        ports:
        - name: management
          containerPort: 8080
        volumeMounts:
        - name: license-volume
          mountPath: /run/license
        - name: dcx-conf-volume
          mountPath: /srv/dcx
      imagePullSecrets:
      - name: kaaid
      volumes:
        - name: dcx-conf-volume
          hostPath: ~/dcx-config
          defaultMode: 444
        - name: license-volume
          secret:
            secretName: license.cert

Below are some notable parameters of the deployment descriptor:

• spec.replicas defines the number of service instance replicas.
• spec.template.spec.containers.image defines the Docker image to be used, while spec.template.spec.containers.imagePullPolicy defines the image update policy.
• spec.template.spec.imagePullSecrets specifies the image pull secret for the official KaaIoT docker registry. To define this secret, use your KaaID credentials:

  $ export HISTCONTROL=ignorespace  # Prevent saving your credentials in the shell history
  $  KAAID_USER=<your KaaID username>; kubectl create secret docker-registry kaaid --docker-server=hub.kaaiot.net --docker-username=$KAAID_USER --docker-email=$KAAID_USER --docker-password=<your KaaID password>
  

• spec.template.spec.volumes.name.license-volume specifies the volume to contain the license certificate file. We recommend that this volume is created from a Kubernetes secret.
• spec.template.spec.containers.name.dcx.env.name.KAA_LICENSE_CERT_PASSWORD defines the license certificate password environment variable, which is also recommended to be set from a Kubernetes secret.
• spec.template.metadata.labels.app defines the application label to map Kubernetes deployment to the service.
• spec.template.spec.containers.resources defines resources available to each replica. See how Kubernetes manages compute resources for containers.
• spec.template.spec.containers.env defines the environment variables that Kubernetes passes to the service replica.
• spec.template.spec.containers.ports defines the exposed ports. See Connecting applications with services.

Volumes and secrets

The above deployment descriptor mounts a host machine directory for the service to load its configuration file from. However, such simple configuration may not be convenient in multi-node deployments and you might want to create other types of volumes. Besides, if you want to pass sensible pieces of information to the service using the environment variables, such as logins and passwords for dependency services, we recommend using Kubernetes Secrets. To learn more about these subjects, refer to Kubernetes documentation:

• Volumes
• Secrets
• Config maps

Docker

To run DCX in Docker:

1. Install Docker.
2. Set up NATS as a Docker container or a standalone server.
3. Prepare a configuration file and save into a file available to the container under APP_CONFIG_PATH.
4. Run Docker container. For example, use the following command to run the DCX version 1.0.0 image:

   $ docker run \
    -v <host_path_to_config_directory>:/srv/dcx \
    hub.kaaiot.net/kaaiot/dcx/dcx:1.0.0