If a pod is added to the onap namespace that has a node affinity rule like the rule below then the readiness containers will fail with the error 

2019-06-26 15:41:10,020 - INFO - Checking if message-router-kafka is ready
2019-06-26 15:41:10,774 - ERROR - Exception when calling list_namespaced_pod: Invalid value for `match_expressions`, must not be `None`

...

"spec": {"spec": { "affinity": {          "nodeAffinity": {            "requiredDuringSchedulingIgnoredDuringExecution": {              "nodeSelectorTerms": [                {                  "matchFields": [                   

{                      "key": "metadata.name",                      "operator": "In",                      "values": [                        "node1"                      ]                    }

                  ]                }              ]            }          }        },        "containers": [

...

 

This can be recreated using the attached file and the command 

kubectl -n onap create -f recreatereadinessbug.json

then delete a pod

kubectl -n onap delete po dev-dmaap-message-router-0

then check error

kubectl -n onap logs -f dev-dmaap-message-router-0 message-router-readiness

 

doing 

kubectl -n onap delete -f recreatereadinessbug.json

will remove the problem