Kubernetes Container Timezone Management


I want to show how to change the container’s timezone which runs on the Kubernetes cluster. Basically, when you push a docker image from the docker hub you can easily check which timezone already defined for the image. I just defined a basic YAML file, creates a container that sleeps “100000” seconds. We used BusyBox image.

BusyBox combines tiny versions of many common UNIX utilities into a single small executable. It provides replacements for most of the utilities you usually find in GNU fileutils, shellutils, etc.

Default TimeZone:

Step 1: Create a test  POD definition file 

#cat /tmp/defaulttz.yaml
apiVersion: v1
kind: Pod
metadata:
  labels:
    run: defaulttz
  name: defaulttz
spec:
  containers:
  - image: busybox
    name: defaulttz
    args:
    - sleep
    - "100000"
#kubectl  create  -f  /tmp/defaulttz.yaml
pod/defaulttz created
#kubectl  get  pods
NAME        READY   STATUS    RESTARTS   AGE
defaulttz   1/1     Running   0          13s

Step 2: Deploy new POD without change 

When you create a new Pod with a POD definition file, it performs some steps like pull image, create container and start container etc.

#kubectl describe  pod defaulttz
.........
.........
  Type    Reason     Age        From               Message
  ----    ------     ----       ----               -------
  Normal  Scheduled  <unknown>  default-scheduler  Successfully assigned default/defaulttz to node01
  Normal  Pulling    2m30s      kubelet, node01    Pulling image "busybox"
  Normal  Pulled     2m24s      kubelet, node01    Successfully pulled image "busybox"
  Normal  Created    2m24s      kubelet, node01    Created container defaulttz
  Normal  Started    2m23s      kubelet, node01    Started container defaulttz

Now we can check the timezone variable for BusyBox image. First, you need to get a shell to the running container then run “date” command.

#kubectl exec  defaulttz  -it  --  /bin/sh
/ # date
Sat Dec 21 10:01:33 UTC 2019
/ # ls  -ld  /etc/localtime
-rw-r--r--    1 root     root           127 Sep 17 20:51 /etc/localtime
/ # strings  /etc/localtime
TZif2
TZif2
UTC0
/ #

New TimeZone:

Step 1: Create new POD definition file with spesific timezone.

Let’s try to change this timezone variable from UTC to GMT+3. We defined two variables that “volumeMounts” and “volumes”. A hostPath volume mounts a file or directory from the host node’s filesystem into your Pod. So we defined a new volume that shares the Timezone variable to the Pod. And we attached this volume to the container with volumeMounts method.

Connect one of the worker nodes that the container will schedule. You can define any timezone under this directory.

node01 $ ls  -ld /usr/share/zoneinfo/*
#cat /tmp/tzistanbul
apiVersion: v1
kind: Pod
metadata:
  name: tzistanbul
spec:
  containers:
  - name: tzistanbul
    image: busybox
    args:
    - sleep
    - "1000000"
    volumeMounts:
    - name: tz-istanbul
      mountPath: /etc/localtime
  volumes:
    - name: tz-istanbul
      hostPath:
        path: /usr/share/zoneinfo/Europe/Istanbul

Step 2: Deploy new POD

Now it’s time to create POD.

#kubectl create  -f  /tmp/tzistanbul
pod/tzistanbul created
#kubectl get  pods
NAME         READY   STATUS    RESTARTS   AGE
defaulttz    1/1     Running   0          13m
tzistanbul   1/1     Running   0          4s

Get a shell to the running Container:

#kubectl exec  tzistanbul  -it  --  /bin/sh

Step 3: Check TimeZone

Check if the container gets the timezone as you need.
/ # df -h /etc/localtime
Filesystem                Size      Used Available Use% Mounted on
/dev/vda1                44.1G     21.8G     20.0G  52% /etc/localtime
/ # ls  -ld  /etc/localtime
-rw-r--r--    1 root     root          1956 Oct  3 00:06 /etc/localtime
/ # date
Sat Dec 21 13:17:04 +03 2019
/ # strings  /etc/localtime
TZif2
EEST
TZif2
EEST
<+03>-3
/ #

I'm a IT Infrastructure and Operations Architect with extensive experience and administration skills and works for Interbank Card Center Of Turkey(BKM). I provide hardware and software support for the IT Infrastructure and Operations tasks.

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