This is how i done.

1) Adding the cert to stage CAE:

With the cert in the same directory as you are running the oc command:

oc create secret generic mmx-cert --from-file='cert.p12'

2) Add the secret volume:

The next step is to create a volume for the secret. As a test, I was able to use the oc command to create the volume on the apache nodes. Since the apache nodes have a deployment config, it was straight forward. I took that test setup, and manually added it to the app pods. The pieces I added to the deployment yaml were:

- mountPath: /opt/webserver/cert/nonprod/
  name: mmxcert-volume


- name: mmxcert-volume
  secret:
  defaultMode: 420
  secretName: mmx-cert

3) Verify the cert

md5sum cert.p12

Not sure what's the command oc, but if you are talking about kubectl, please make sure you feed the proper parameter

kubectl create configmap mmx-cert --from-env-file=path/to/xyz.p12

Please go through help as well, the parameter --from-file is based on folder, not file.

$ kubectl create configmap --help
...
# Create a new configmap named my-config based on folder bar
kubectl create configmap my-config --from-file=path/to/bar