ImagePullBackOff Error from mongo (Kubernetes) - kubernetes

Question

I am trying to create a Kubernetes pod with the following config file:
apiVersion: apps/v1
kind: Deployment
metadata:
name: mongodb-deployment
labels:
app: mongodb
spec:
replicas: 1
selector:
matchLabels:
app: mongodb
template:
metadata:
labels:
app: mongodb
spec:
containers:
- name: mongodb
image: mongo
ports:
- containerPort: 27017
env:
- name: MONGO_INITDB_ROOT_USERNAME
valueFrom:
secretKeyRef:
name: mongodb-secret
key: mongo-root-username
- name: MONGO_INITDB_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mongodb-secret
key: mongo-root-password
However, I get an ImagePullBackOff, and when I use kubectl describe pod, here's what's shown:
Name: mongodb-deployment-8f6675bc5-jzmvw
Namespace: default
Priority: 0
Node: minikube/192.168.64.2
Start Time: Thu, 10 Dec 2020 16:30:21 +0800
Labels: app=mongodb
pod-template-hash=8f6675bc5
Annotations: <none>
Status: Pending
IP: 172.17.0.3
IPs:
IP: 172.17.0.3
Controlled By: ReplicaSet/mongodb-deployment-8f6675bc5
Containers:
mongodb:
Container ID:
Image: mongo
Image ID:
Port: 27017/TCP
Host Port: 0/TCP
State: Waiting
Reason: ErrImagePull
Ready: False
Restart Count: 0
Environment:
MONGO_INITDB_ROOT_USERNAME: <set to the key 'mongo-root-username' in secret 'mongodb-secret'> Optional: false
MONGO_INITDB_ROOT_PASSWORD: <set to the key 'mongo-root-password' in secret 'mongodb-secret'> Optional: false
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-w5ltt (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
default-token-w5ltt:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-w5ltt
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 115m default-scheduler Successfully assigned default/mongodb-deployment-8f6675bc5-jzmvw to minikube
Normal Pulling 115m kubelet Pulling image "mongo"
Warning Failed 114m kubelet Failed to pull image "mongo": rpc error: code = Unknown desc = Error response from daemon: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
Warning Failed 114m kubelet Error: ErrImagePull
Normal BackOff 114m kubelet Back-off pulling image "mongo"
Warning Failed 114m kubelet Error: ImagePullBackOff
I don't think it's a problem with the image/image name. Is there something wrong with my config file?
Any advice would be greatly appreciated!

Answer 1

There are few reasons for ImagePullBackOff error in Kubernetes, to determine it's cause you should run kubectl describe pod
Failed to pull image "mongo": rpc error: code = Unknown desc = Error response from daemon: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
This error means that image cannot be pulled from your container registry.
You can try to login to docker using docker login command.
If it fails you can try modifying your /etc/resolv.conf and adding nameserver 8.8.8.8 and then restarting docker using sudo systemctl restart docker.
Other cause might be using proxy or VPN connection. You can refer to answers in this question.