kubernetes pod (mssql-tools) failing with CrashLoopBackOff error and restarting - kubernetes

Question

I'm using Rancher Dekstop for K8 in WSL 2 in Windows 11.
I'm trying to create a pod using the simple yaml:
apiVersion: v1
kind: Pod
metadata:
name: mssql-tools
labels:
name: mssql-tools
spec:
containers:
- name: mssql-tools
image: mcr.microsoft.com/mssql-tools:latest
But it is continuously giving CrashLoopBackOff error.
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
mssql-tools 0/1 CrashLoopBackOff 11 (8s ago) 14m
And here is the result of kubectl describe pod mssql-tool:
$ kubectl describe pod mssql-tools
Name: mssql-tools
Namespace: default
Priority: 0
Service Account: default
Node: desktop-2ohsprk/172.22.97.204
Start Time: Mon, 26 Dec 2022 04:34:19 +0500
Labels: name=mssql-tools
Annotations: <none>
Status: Running
IP: 10.42.0.57
IPs:
IP: 10.42.0.57
Containers:
mssql-tools:
Container ID: docker://76343010f4344a5d26fb35f3b0278271d3336e8e10d695cc22e78520262f34bf
Image: mcr.microsoft.com/mssql-tools:latest
Image ID: docker-pullable://mcr.microsoft.com/mssql-tools#sha256:62556500522072535cb3df2bb5965333dded9be47000473e9e0f84118e248642
Port: <none>
Host Port: <none>
State: Terminated
Reason: Completed
Exit Code: 0
Started: Mon, 26 Dec 2022 04:46:20 +0500
Finished: Mon, 26 Dec 2022 04:46:20 +0500
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Mon, 26 Dec 2022 04:45:51 +0500
Finished: Mon, 26 Dec 2022 04:45:51 +0500
Ready: False
Restart Count: 9
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-wkqlg (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
kube-api-access-wkqlg:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
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 12m default-scheduler Successfully assigned default/mssql-tools to desktop-2ohsprk
Normal Pulled 12m kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 1.459473213s
Normal Pulled 12m kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 823.403008ms
Normal Pulled 11m kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 835.697509ms
Normal Pulled 11m kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 873.802598ms
Normal Created 11m (x4 over 12m) kubelet Created container mssql-tools
Normal Started 11m (x4 over 12m) kubelet Started container mssql-tools
Normal Pulling 10m (x5 over 12m) kubelet Pulling image "mcr.microsoft.com/mssql-tools:latest"
Normal Pulled 10m kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 740.64559ms
Warning BackOff 6m56s (x25 over 11m) kubelet Back-off restarting failed container
Normal SandboxChanged 50s kubelet Pod sandbox changed, it will be killed and re-created.
Normal Pulled 48s kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 951.332457ms
Normal Pulled 32s kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 828.839917ms
Normal Pulling 4s (x3 over 49s) kubelet Pulling image "mcr.microsoft.com/mssql-tools:latest"
Normal Pulled 3s kubelet Successfully pulled image "mcr.microsoft.com/mssql-tools:latest" in 713.951656ms
Normal Created 3s (x3 over 48s) kubelet Created container mssql-tools
Normal Started 3s (x3 over 48s) kubelet Started container mssql-tools
Warning BackOff 2s (x5 over 47s) kubelet Back-off restarting failed container
The same container works perfectly if I run it via docker and I can use its shell to execute sqlcmd properly.
I can't figure out any reason for this.
Any help would be really appreciated.
Thanks

Answer 1

Crashloopbackoff is the common error which indicates that pod failed to start and it continued to fail repeatedly when kubernetes tried to restart this.
To troubleshoot this issue follow the below steps:
Check for “Back off Restarting Failed Container” by running the command Run kubectl describe pod [name].
If you get a Liveness probe failed and Back-off restarting failed container messages from the kubelet, this indicates the container is not responding and is in the process of restarting.
Check from the previous container instance. Run kubectl get pods to identify the Kubernetes pod that causes CrashLoopBackOff error. You can run kubectl logs --previous --tail 10command to get the last ten log lines from the pod.
Check deployment logs by running the command: kubectl logs -f deploy/ -n
Refer to this link for more detailed troubleshooting steps.

Answer 2

So after trying and digging through multiple options, finally it worked by executing the command sleep 3600000 i.e. delaying it so that the pod initializes itself properly and then executes the container.
Here is the working yaml:
apiVersion: v1
kind: Pod
metadata:
name: mssql-tools
labels:
name: mssql-tools
spec:
containers:
- name: mssql-tools
image: mcr.microsoft.com/mssql-tools:latest
command: ["sleep"]
args:
- "3600000"
imagePullPolicy: IfNotPresent
The command and argument passing portion can also be mentioned like the following:
apiVersion: v1
...
...
spec:
containers:
- name: mssql-tools
image: mcr.microsoft.com/mssql-tools:latest
command:
- sleep
- "3600000"
...
and btw, you can also deploy a container by passing a command with the kubectl run command line: i.e.
kubectl run mssql --image=mcr.microsoft.com/mssql-tools --command sleep 3600000 -n myNameSpace
Note: You can omit -n myNameSpace if you are not deploying it in a specific namespace or deploying it in the default namespace.