Deploying services to an edge cluster

How to deploy services to an edge cluster

Setting node policy on this edge cluster can cause deployment policies to deploy edge services here. This content shows an example of doing that.

Set some aliases to make it more convenient to run the hzn command. (The hzn command is inside the agent container, but these aliases make it possible to run hzn from this host.)

cat << 'END_ALIASES' >> ~/.bash_aliases
alias getagentpod='kubectl -n openhorizon-agent get pods --selector=app=agent -o jsonpath={.items[].metadata.name}'
alias hzn='kubectl -n openhorizon-agent exec -i $(getagentpod) -- hzn'
END_ALIASES
source ~/.bash_aliases

Verify that your edge node is configured (registered with the Open Horizon management hub):
```
hzn node list
```
To test your edge cluster agent, set your node policy with a property that deploys the example helloworld operator and service to this edge node:
```
cat << 'EOF' > operator-example-node.policy.json
{
  "properties": [
    { "name": "openhorizon.example", "value": "nginx-operator" }
  ]
}
EOF

cat operator-example-node.policy.json | hzn policy update -f-
hzn policy list
```
Note:
- Because the real hzn command is running inside the agent container, for any hzn commands that require an input file, you need to pipe the file into the command so its content will be transferred into the container.
After a minute, check for an agreement and the running edge operator and service containers:
```
hzn agreement list
kubectl -n openhorizon-agent get pods
```

Using the pod IDs from the previous command, view the log of edge operator and service:

kubectl -n openhorizon-agent logs -f <operator-pod-id>
# control-c to get out
kubectl -n openhorizon-agent logs -f <service-pod-id>
# control-c to get out

You can also view the environment variables that the agent passes to the edge service:
```
kubectl -n openhorizon-agent exec -i <service-pod-id> -- env | grep HZN_
```

Changing what services are deployed to your edge cluster

To change what services are deployed to your edge cluster, change the node policy:
```
cat <new-node-policy>.json | hzn policy update -f-
hzn policy list
```
After a minute or two the new services will be deployed to this edge cluster.
Note: On some VMs with microk8s, the service pods that are being stopped (replaced) might stall in the Terminating state. If that happens, run:
```
kubectl delete pod <pod-id> -n openhorizon-agent --force --grace-period=0
pkill -fe <service-process>
```
If you want to use a pattern instead of a policy to run services on your edge cluster:
```
hzn unregister -f
hzn register -n $HZN_EXCHANGE_NODE_AUTH -p <pattern-name>
```