I'm trying to expose some of the container info as env variables reading the values from the pod's spec.template.spec.containers[0].name which seems to be not working. What would be the apiSpec for referencing the container fields inside the deployment template.The deployment template is as follows:
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx
spec:
replicas: 2
selector:
matchLabels:
run: nginx
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
run: nginx
spec:
containers:
- image: nginx
name: nginx
ports:
- containerPort: 8000
resources: {}
env:
- name: MY_CONTAINER_NAME
valueFrom:
fieldRef:
fieldPath: spec.template.spec.containers[0].nameTwo things: first, the container name is fixed -- it's defined by the PodSpec template -- are you perhaps thinking of the docker container's name (which will be a long generated name composed of the namespace, container name, pod UID, and restart count)? Because the docker container's name will for sure not be present in .spec.containers[0].name
Second, while I agree with David that I doubt kubernetes will let you run arbitrary fieldPath: selectors, if you're open to being flexible with your command: you can actually use the Pod's own ServiceAccount to query the kubernetes API at launch time to retrieve all of the Pod's info, including its status: structure which likely has a ton of the information you're after.
The Downward API enables you to expose the pod’s own metadata to the processes running inside that pod.
Currently, it allows you to pass the following information to your containers:
And that's it. As you can see the container port is not part of this list.
In general, the metadata available through the Downward API is fairly limited. If you need more, you’ll need to obtain it from the Kubernetes API server directly which you can do either by using client libraries or by using an ambassador container.