Code change:
This is a... [x] Bug Report Problem: The documentation mentions "optional" in the restrictions for configmap, but doesn't explain how to use it anywhere else in the documentation. You must create a ConfigMap before referencing it in a Pod specification (unless you mark the ConfigMap as “optional”). If you reference a ConfigMap that doesn’t exist, the Pod won’t start. Likewise, references to keys that don’t exist in the ConfigMap will prevent the pod from starting. Please see for the feature. It appears it got lost in the 1.5-1.6 upgrade. Proposed Solution: Restore the copy from that wrote. Page to Update:
For clarity, the copy from got removed here:
Issues go stale after 90d of inactivity. Mark the issue as fresh with . Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle stale
/remove-lifecycle stale
Issues go stale after 90d of inactivity. Mark the issue as fresh with . Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle stale
/language en /remove-lifecycle stale /assign
Issues go stale after 90d of inactivity. Mark the issue as fresh with . Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle stale
/remove-lifecycle stale
/priority backlog
Issues go stale after 90d of inactivity. Mark the issue as fresh with . Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle stale
/remove-lifecycle stale
Stale issues rot after 30d of inactivity. Mark the issue as fresh with . Rotten issues close after an additional 30d of inactivity. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle rotten
/remove-lifecycle stale
/remove-lifecycle rotten
Issues go stale after 90d of inactivity. Mark the issue as fresh with . Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle stale
Relevant to /remove-lifecycle stale
Issues go stale after 90d of inactivity. Mark the issue as fresh with . Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with . Send feedback to sig-testing, kubernetes/test-infra and/or . /lifecycle stale
This awesome feature is still missing in the documentation, Can someone please add it ?
were you thinking of opening a pull request? We'd be happy to help you with that.
/remove-lifecycle stale
/lifecycle frozen
/triage accepted
I don't see any updates; so unassigning you. Please feel free to assign, if you come back here again and are willing to work on it. Thank you! /unassign
/assign

Related discussion:
text: - You can't use ConfigMaps for {{< glossary_tooltip text="static pods" term_id="static-pod" >}}, because the Kubelet does not support this. <ins> ### Optional ConfigMaps In a Pod, or pod template, you can mark a reference to a ConfigMap as _optional_. If the ConfigMap is non-existent, the configuration for which it provides data in the Pod (e.g. environment variable, mounted volume) will be empty. If the ConfigMap exists, but the referenced key is non-existent the data is also empty. #### Optional ConfigMap in environment variables There might be situations where environment variables are not always required. You can mark an environment variables for a container as optional, like this: ```yaml apiVersion: v1 kind: Pod metadata: name: dapi-test-pod spec: containers: - name: test-container image: gcr.io/google_containers/busybox command: [ "/bin/sh", "-c", "env" ] env: - name: SPECIAL_LEVEL_KEY valueFrom: configMapKeyRef: name: a-config key: akey optional: true # mark the variable as optional restartPolicy: Never ``` If you run this pod, and there is no ConfigMap named `a-config`, the output is empty. If you run this pod, and there is a ConfigMap named `a-config` but that ConfigMap doesn't have a key named `akey`, the output is also empty. If you do set a value for `akey` in the `a-config` ConfigMap, this pod prints that value and then terminates. #### Optional ConfigMap via volume plugin Volumes and files provided by a ConfigMap can be also be marked as optional. The ConfigMap or the key specified does not have to exist. The mount path for such items will always be created. ```yaml apiVersion: v1 kind: Pod metadata: name: dapi-test-pod spec: containers: - name: test-container image: gcr.io/google_containers/busybox command: [ "/bin/sh", "-c", "ls /etc/config" ] volumeMounts: - name: config-volume mountPath: /etc/config volumes: - name: config-volume configMap: name: no-config optional: true # mark the source ConfigMap as optional restartPolicy: Never ``` If you run this pod, and there is no ConfigMap named `no-config`, the mounted volume will be empty. ### Mounted ConfigMaps are updated automatically When a mounted ConfigMap is updated, the projected content is eventually updated too.  This applies in the case where an optionally referenced ConfigMap comes into existence after a pod has started. The kubelet checks whether the mounted ConfigMap is fresh on every periodic sync. However, it uses its local TTL-based cache for getting the current value of the ConfigMap. As a result, the total delay from the moment when the ConfigMap is updated to the moment when new keys are projected to the pod can be as long as kubelet sync period (1 minute by default) + TTL of ConfigMaps cache (1 minute by default) in kubelet. {{< note >}} A container using a ConfigMap as a [subPath](/docs/concepts/storage/volumes/#using-subpath) volume will not receive ConfigMap updates. {{< /note >}} </ins> ## {{% heading "whatsnext" %}}