kubernetes jobs init container

Question

I've created a JOB pod with 2 INIT containers At pod creation, my job completed successfully but no sign of the init containers

To me, the job should have wait for the completion of the 2 init containers before starting

My job blueprint (taken from Kubernetes documentation) in case you'd like to reproduce the problem

apiVersion: batch/v1
kind: Job
metadata:
  name: pi
annotations:
  pod.beta.kubernetes.io/init-containers: '[
    {
      "name": "init-myservice",
      "image": "busybox",
      "command": ["sh", "-c", "until nslookup myservice; do echo waiting for myservice; sleep 2; done;"]
    },
    {
      "name": "init-mydb",
      "image": "busybox",
      "command": ["sh", "-c", "until nslookup mydb; do echo waiting for mydb; sleep 2; done;"]
    }
    ]'
spec:
  template:
    metadata:
      name: pi
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never

When checking my job pod

$ kubectl describe pod pi-v2dn9
Name: pi-v2dn9
Namespace: default
Security Policy: anyuid
Node: 192.168.111.4/192.168.111.4
Start Time: Thu, 19 Oct 2017 08:58:39 +0000
Labels: controller-uid=b3091c77-b4ab-11e7-a3ea-fa163ea1c70b
job-name=pi
Status: Succeeded
IP: 10.131.0.46
Controllers: Job/pi
Containers:
pi:
Container ID: docker://4bc5bb4c9fc65c1aa1999c3bdc09b01e54043dcdd464410edd0c9cad334c9c67
Image: perl
Image ID: docker-pullable://docker.io/perl@sha256:80bd8136a0f3e2c7d202236fc5d8f1192dbfa9ec661ecdd5e96a446e9c7913a8
Port:
Command:
perl
-Mbignum=bpi
-wle
print bpi(2000)
State: Terminated
Reason: Completed
Exit Code: 0
Started: Thu, 19 Oct 2017 08:58:53 +0000
Finished: Thu, 19 Oct 2017 08:58:58 +0000
Ready: False
Restart Count: 0
Volume Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-fxdf1 (ro)
Environment Variables: 
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
Volumes:
default-token-fxdf1:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-fxdf1
QoS Class: BestEffort
Tolerations: 
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message

26s 26s 1 {default-scheduler } Normal Scheduled Successfully assigned pi-v2dn9 to 192.168.111.4
25s 25s 1 {kubelet 192.168.111.4} spec.containers{pi} Normal Pulling pulling image "perl"
12s 12s 1 {kubelet 192.168.111.4} spec.containers{pi} Normal Pulled Successfully pulled image "perl"
12s 12s 1 {kubelet 192.168.111.4} spec.containers{pi} Normal Created Created container with docker id 4bc5bb4c9fc6; Security:[seccomp=unconfined]
12s 12s 1 {kubelet 192.168.111.4} spec.containers{pi} Normal Started Started container with docker id 4bc5bb4c9fc6

NO SIGN OF THE INIT CONTAINERS !!!

My Environment: --- Kubernetes version (use kubectl version): Client Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2+43a9be4", GitCommit:"43a9be4", GitTreeState:"clean", BuildDate:"2017-04-20T15:38:11Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"} Server Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2+43a9be4", GitCommit:"43a9be4", GitTreeState:"clean", BuildDate:"2017-04-20T15:38:11Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}

I'm working in a Cluster from OpenStack

OS is Red Hat Enterprise Linux Server 7.3 (Maipo)

Thanks in advance for any help.

score 2 · Answer 1 · answered Oct 19 '17 at 11:18

2

Try adding the annotation to the spec template rather than the Job object:

apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  template:
    metadata:
      name: pi
    annotations:
      pod.beta.kubernetes.io/init-containers: '[
        {
          "name": "init-myservice",
          "image": "busybox",
          "command": ["sh", "-c", "until nslookup myservice; do echo waiting for myservice; sleep 2; done;"]
        },
        {
          "name": "init-mydb",
          "image": "busybox",
          "command": ["sh", "-c", "until nslookup mydb; do echo waiting for mydb; sleep 2; done;"]
        }
        ]'
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never

answered Oct 19 '17 at 11:18

vascop

4,972
4
37
50

Hi Vascop, Thanks for your interest. – Paul Pozicheun Oct 19 '17 at 11:55
Unfortunately, I've already tried this but I'm afraid that with Kube 1.5 the annotation field must be added in the metadata part of the job. I've seen that in documentation https://v1-5.docs.kubernetes.io/docs/concepts/workloads/pods/init-containers/. I've also tried to modify the API version, but jobs need the batch/v1 and it may not fit with init containers. Thanks again for your help. Regards, PP – Paul Pozicheun Oct 19 '17 at 11:56
1

What is proposed by Vascop is working at least for kubernetes v1.7 The indentation inside the example is wrong but the proposed solution is ok. – dbenque Oct 19 '17 at 13:56

score 2 · Answer 2 · answered Oct 22 '17 at 11:25

Your annotations are in the wrong place. Specifically for init containers, they should be defined in the pod metadata, whereas you have added it to the job metadata.

apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  template:
    metadata:
      name: pi
      annotations:
        pod.beta.kubernetes.io/init-containers: '[
          {
            "name": "init-myservice",
            "image": "busybox",
            "command": ["sh", "-c", "until nslookup myservice; do echo waiting for myservice; sleep 2; done;"]
          },
          {
            "name": "init-mydb",
            "image": "busybox",
            "command": ["sh", "-c", "until nslookup mydb; do echo waiting for mydb; sleep 2; done;"]
          }
        ]'
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never

Hi everybody and thank you for all you answers. You are right that the annotations are in the wrong place (but not for Kube 1.5 as they must be placed as I did). Real problem is that INIT containers for JOB don't work before Kube 1.6 (I tried with this version and 1.7 and it worked). — Paul Pozicheun, Oct 30 '17 at 09:35

score 1 · Answer 3 · answered Feb 19 '19 at 11:42

1

Init containers in jobs don't work before 1.6 version. You will have to upgrade to 1.6+ version to make it work

answered Feb 19 '19 at 11:42

Vikas Tawniya

1,323
1
13
22

kubernetes jobs init container

3 Answers3