Readiness probe failed: MongoDB shell version v4.0.10

Question

While running monogodb in kubernetes it gives following error:-

I tried to change image of mongodb

Warning  Unhealthy  2m28s  kubelet, minikube  Readiness probe failed: MongoDB 
shell version v4.0.10
connecting to: mongodb://127.0.0.1:27017/?gssapiServiceName=mongodb
2019-06-08T15:25:01.774+0000 E QUERY    [js] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:344:17
@(connect):2:6
exception: connect failed
 Warning  Unhealthy  2m17s  kubelet, minikube  Readiness probe failed: MongoDB shell version v4.0.10
connecting to: mongodb://127.0.0.1:27017/?gssapiServiceName=mongodb
2019-06-08T15:25:12.008+0000 E QUERY    [js] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:344:17
@(connect):2:6
exception: connect failed

Answer 1

I was observing the same error, once I've increased initialDelaySeconds: value to some higher number in Readiness probe spec inside deployment, the issue has gone and mongodb Pod has been spawned without error. Actually, it takes some time for docker to pull up docker.io/bitnami/mongodb image and initialize socket mongodb listener, therefore Readiness probe indicates issue while container process has not ready for network connections.

    readinessProbe:
      exec:
        command:
        - mongo
        - --eval
        - db.adminCommand('ping')
      failureThreshold: 6
      initialDelaySeconds: 360
      periodSeconds: 10
      successThreshold: 1
      timeoutSeconds: 5

Meanwhile, you can check mongodb Pod for any inbound connection statuses or any relevant event.

kubectl logs <mongodb-Pod-name>

I've used stable/mongodb Helm chart to deploy MongoDB and discovered the error similar to yours:

helm install --name mongodb stable/mongodb

Warning Unhealthy 38m kubelet, gke-helm-test-default-pool-efed557c-52tf Readiness probe failed: MongoDB shell version v4.0.9 connecting to: mongodb://127.0.0.1:27017/?gssapiServiceName=mongodb 2019-06-10T12:46:46.054+0000 E QUERY [js] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused : connect@src/mongo/shell/mongo.js:343:13 @(connect):2:6 exception: connect failed

When I made some adjustment and gain readinessProbe.initialDelaySeconds from 5 sec to 360 sec, mongodb container run up without any failures.

helm install --name mongodb stable/mongodb --set readinessProbe.initialDelaySeconds=360