Running a ROS node as a Kubernetes deployment

Estimated time: 10 min

The following instructions describe how to setup a Kubernetes cluster on a robot running Ubuntu 20.04 and run a ROS node on it.

The installation script installs and configures:

• Docker
• A single-node Kubernetes cluster (packages: kubectl, kubeadm, kubelet)

Once you’ve done this, you can use Kubernetes to:

• Reduce downtime during updates with Kubernetes deployments
• Apply CPU, disk or memory quotas to individual processes
• Add additional compute nodes to the cluster, such as an Nvidia Jetson
• Use a network plugin to apply network access control
• Manage project configuration or sensitive secrets such as account credentials

For more details, refer to the Kubernetes documentation.

Installing the cluster on the robot

See https://github.com/googlecloudrobotics/core/blob/main/docs/how-to/connecting-robot.md#installing-the-cluster-on-the-robot.

Run a ROS node with Kubernetes

If you’re already using ROS on your robot, you can run a ROS node inside Kubernetes that will communicate with other nodes on the robot. If not, you can follow the ROS tutorials to get started.

First, make sure you’re running roscore. In another terminal, please run:

roscore

Caution: If you have a more complicated ROS setup, such as a ROS master running on another machine, you might need to change ROS_MASTER_URI or ROS_IP in rostopic-echo.yaml.

You can run a ROS node by creating a Kubernetes Deployment object, and you can describe a Deployment in a YAML file. For example, this YAML file describes a Deployment that runs rostopic echo. Create file called rostopic-echo.yaml with the following contents:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: rostopic-echo
spec:
  selector:
    matchLabels:
      app: rostopic-echo
  template:
    metadata:
      labels:
        app: rostopic-echo
    spec:
      containers:
      - name: rostopic-echo
        image: ros:melodic-ros-core
        args:
        - rostopic
        - echo
        - chatter
        env:
        - name: ROS_MASTER_URI
          value: http://192.168.9.1:11311
        - name: ROS_IP
          value: 192.168.9.1
      hostNetwork: true

Note: For simplicity, this example uses hostNetwork: true to disable network isolation. Advanced users can disable host networking to improve security. For more information, see the networking documentation for Docker, Kubernetes and ROS.

After creating rostopic-echo.yaml, use kubectl to apply it to your cluster:

kubectl apply -f rostopic-echo.yaml

Depending on your internet connection, it will take a minute or so to download the Docker image. Wait until you see Running:

$ watch kubectl get pods -l app=rostopic-echo
NAMESPACE     NAME                                        READY   STATUS      RESTARTS   AGE
default       rostopic-echo-576cbf47c7-dtlc6              1/1     Running     0          1m

Now, publish a ROS message and check that it was received inside Kubernetes:

$ rostopic pub -1 chatter std_msgs/String "Hello, world"
$ kubectl logs -l app=rostopic-echo
data: "Hello, world"
---

Kubernetes will keep this node running until you delete the deployment:

kubectl delete -f rostopic-echo.yaml