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Known errors and solutions

Nginx ingress

308 redirect to HTTPS

Solution

Edit ingress configmap.
kubectl -n ingress-external edit configmaps ingress-controller-leader-nginx
Add the following annotations:
use-forwarded-headers: "true"
force-ssl-redirect: "false"
Restart controller.
kubectl -n ingress-external scale deployment --replicas=0 ingress-external-nginx-ingress-controller
kubectl -n ingress-external scale deployment --replicas=2 ingress-external-nginx-ingress-controller

References

Duplicate location "/healthz"

Complete nginx pod log:
2020/01/27 17:12:12 [emerg] 105#105: duplicate location "/healthz" in /tmp/nginx-cfg568474076:487
nginx: [emerg] duplicate location "/healthz" in /tmp/nginx-cfg568474076:487
nginx: configuration file /tmp/nginx-cfg568474076 test failed
It happens when you have an ingress object conflicting with "/healthz" path.

Solution

Make sure to not have an ingress object overlapping "/healthz".

Pod sandbox changed, it will be killed and re-created

Cause

This error happens when deploying a pod. It is caused most liked because of Docker processes crashed or is unstable on the node due IO peak.

Solution

The solution is to reboot the node.

References

failed to watch file "/var/log/pods/6438eb52-202a-11ea-8dce-e279cb2777e2/my-app/0.log": no space left on device

Symptom

When you run.
kubectl -n my-ns logs -f my-app-659858b967-5hmtz
The command outputs a few lines of log and then breaks.

Cause

The obvious reason is the node's HD is full. Although this error can be caused by other reasons.
This error (ENOSPC) comes from the inotify_add_watch syscall, and actually has multiple meanings (the message comes from golang). Most likely the problem is from exceeding the maximum number of watches, not filling the disk. This can be increased with the fs.inotify.max_user_watches sysctl.

Solution

Increase max_user_watches.
cat /proc/sys/fs/inotify/max_user_watches # default is 8192
sysctl fs.inotify.max_user_watches=1048576 # increase to 1048576
If you do not have SSH connection to the node, apply the following manifest (not recommended for production environments).
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: more-fs-watchers
namespace: kube-system
labels:
app: more-fs-watchers
spec:
template:
metadata:
labels:
name: more-fs-watchers
spec:
hostNetwork: true
hostPID: true
hostIPC: true
initContainers:
- command:
- sh
- -c
- sysctl -w fs.inotify.max_user_watches=524288;
image: alpine:3.6
imagePullPolicy: IfNotPresent
name: sysctl
resources: {}
securityContext:
privileged: true
volumeMounts:
- name: sys
mountPath: /sys
containers:
- resources:
requests:
cpu: 0.01
image: alpine:3.6
name: sleepforever
command: ["tail"]
args: ["-f", "/dev/null"]
volumes:
- name: sys
hostPath:
path: /sys

References