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227 votes
14 answers
300k views

How can I debug "ImagePullBackOff"?

All of a sudden, I cannot deploy some images which could be deployed before. I got the following pod status: [root@webdev2 origin]# oc get pods NAME READY STATUS ...
Devs love ZenUML's user avatar
146 votes
11 answers
73k views

What is the difference between persistent volume (PV) and persistent volume claim (PVC) in simple terms?

What is the difference between persistent volume (PV) and persistent volume claim (PVC) in Kubernetes/ Openshift by referring to documentation? What is the difference between both in simple terms?
smc's user avatar
  • 2,225
47 votes
1 answer
41k views

Can I connect one service account to multiple namespaces in Kubernetes?

I have couple of namespaces - assume NS1 and NS2. I have serviceaccounts created in those - sa1 in NS1 and sa2 in NS2. I have created roles and rolebindings for sa1 to do stuff within NS1 and sa2 ...
rahul's user avatar
  • 3,068
43 votes
2 answers
29k views

What is the different between openshift deploymentconfig and kubernetes deployment

After far as I know: deploymentconfig → replicationcontroller → pod vs. deployment → replicaset → pod Otherwise, do these two resources have additional differences? The more ...
Weiwei Jiang's user avatar
32 votes
2 answers
89k views

How to include script and run it into kubernetes yaml?

It is how to run simple batch in kubernetes yaml (helloworld.yaml): ... image: "ubuntu:14.04" command: ["/bin/echo", "hello", "world"] ... In Kubernetes i can deploy that like this: $ kubectl ...
smftr's user avatar
  • 955
31 votes
3 answers
39k views

Share persistent volume claims amongst containers in Kubernetes/OpenShift

This may be a dumb question but I haven't found much online and want to clarify this. Given two deployments A and B, both with different container images: They're deployed in two different pods(...
Donovan Muller's user avatar
27 votes
3 answers
38k views

Kubernetes ConfigMap size limitation

Though resourceQuotas may limit the number of configmaps in a namespace, is there any such option to limit the size of the individual configmap? I will not like some user to start uploading large text ...
Ijaz Ahmad's user avatar
  • 11.6k
25 votes
4 answers
25k views

Difference between API versions v2beta1 and v2beta2 in Horizontal Pod Autoscaler?

The Kubernetes Horizontal Pod Autoscaler walkthrough in https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/ explains that we can perform autoscaling on custom ...
Ajay Maity's user avatar
25 votes
2 answers
13k views

what's the difference between openshift route and k8s ingress?

I'm new to openshift and k8s. I'm not sure what's the difference between these two terms, openshift route vs k8s ingress ?
Feng Xi's user avatar
  • 1,025
22 votes
2 answers
27k views

What is the "kube-system" namespace for?

In a default openshift install, there is an unused project titled kube-system. It seems like openshift-infra is for things like metrics, default is for the router and registry, and openshift is for ...
thisguy123's user avatar
22 votes
5 answers
28k views

How to solve liquibase waiting for changelog lock problem in several pods in OpenShift cluster?

We are supporting several microservices written in Java using Spring Boot and deployed in OpenShift. Some microservices communicate with databases. We often run a single microservice in multiple pods ...
Alex Crazy's user avatar
19 votes
6 answers
14k views

How to obtain the enable admission controller list in kubernetes?

AFAIK, the admission controller is the last pass before the submission to the database. However I cannot know which one is enabled, Is there a way to know which one is taking effect? Thanks.
Weiwei Jiang's user avatar
18 votes
3 answers
24k views

Cannot determine if job needs to be started: Too many missed start time (> 100). Set or decrease .spec.startingDeadlineSeconds or check clock skew

I've created and pushed a cron job to deployment, but when I see it running in OpenShift, I get the following error message: Cannot determine if job needs to be started: Too many missed start time (&...
nelion's user avatar
  • 1,832
17 votes
3 answers
17k views

OpenShift oc create fails with "already exists"

Attempting to create a set of resources based on a file via oc create fails if they already exist. According to the docs here oc create should: Parse a configuration file and create one or more ...
Tom Manterfield's user avatar
15 votes
4 answers
18k views

Kubernetes - Liveness and Readiness probe implementation

I'm developing a service using Spring and deploying it on OpenShift. Currently I'm using Spring Actuator health endpoint to serve as a liveness and readiness probe for Kubernetes. However, I will ...
dplesa's user avatar
  • 1,395
14 votes
1 answer
19k views

Request vs limit cpu in kubernetes/openshift

I have some dilemma to choose what should be the right request and limit setting for a pod in Openshift. Some data: during start up, the application requires at least 600 millicores to be able to ...
bLaXjack's user avatar
  • 830
12 votes
4 answers
22k views

Oc get pods - Command to just print pod names

I want to get a list of just the pod names and the Result should not include the status, number of instances etc. I am using the command oc get pods It prints Pod1-qawer Running ...
lr-pal's user avatar
  • 359
12 votes
4 answers
21k views

Restart Pod when secrets gets updated

We are using secret as environment variables on pod, but every time we have updated on secrets, we are redeploying the pods to take changes effect. We are looking for a mechanism where Pods get ...
ramesh reddy's user avatar
12 votes
1 answer
8k views

How to use image stream in deploy configuration for OpenShift

I want my deploy configuration to use an image that was the output of a build configuration. I am currently using something like this: - apiVersion: v1 kind: DeploymentConfig metadata: ...
Zhao Li's user avatar
  • 5,336
11 votes
4 answers
13k views

Differences between OpenShift and Kubernetes

What's the difference between OpenShift and Kubernetes and when should you use each? I understand that OpenShift is running Kubernetes under the hood but am looking to determine when running OpenShift ...
bbodenmiller's user avatar
  • 3,131
10 votes
1 answer
11k views

Openshift vs Rancher, what are the differences? [closed]

I am totally new to this two technologies (I know docker and kubernetes btw). Haven't find much an the web about this comparison topic. I have read that Openshift is used by more companies,but a ...
beatrice's user avatar
  • 4,067
10 votes
1 answer
19k views

How to update Secrets (Without Deleting and Creating) in Openshift?

I have a folder in my server that I want to update inside a cointaier in a pod. How do I do that without deleting the Secret? I know that the following creates my secret: oc create secret generic ...
zeh's user avatar
  • 1,277
10 votes
3 answers
17k views

ArgoCD tracking subdirectories in a specified path

I'm using ArgoCD and I want to track files under different subdirectories. I've setted the path as ./root_directory, but I would like to track also files in the subdirectories of root_directory. For ...
Stewe's user avatar
  • 129
10 votes
1 answer
4k views

Openshift: No nodes are available that match all of the following predicates:: Insufficient cpu (173), MatchNodeSelector (5)

I have a project in west-1 on Openshift v3. In it I have an app that worked fine and one that stopped working following a GitHub committing something very downstream within the code. The issue is with ...
Matteo Ferla's user avatar
  • 2,228
9 votes
1 answer
15k views

How do you remove the deploymentConfig, image streams, etc using Openshift OC?

After creating a new app using oc new-app location/nameofapp, many things are created: a deploymentConfig, an imagestream, a service, etc. I know you can run oc delete <label>. I would like to ...
womplefrog's user avatar
9 votes
2 answers
6k views

Get name of most recently created pod

In OpenShift, is there a more elegant way of obtaining the name of the most recently created pod in application my_app than this one? name=$(oc get pods -l app=my_app -o=jsonpath='{range.items[*]}{....
rookie099's user avatar
  • 2,431
9 votes
3 answers
10k views

How to get access-logs from OpenShift router (HAProxy)?

How to get access-logs from openshift router (HAproxy). I tried to use this command: $ oc project default $ oc logs router-1-g... I got output: I0129 09:47:17.125616 1 router.go:554] Router ...
Slavik  Muz's user avatar
  • 1,187
8 votes
1 answer
8k views

Kubernetes: How to pass pipe character in readiness probe command

I am having an issue with passing a pipe character | in readiness probe command. I want to have a probe command: curl --silent http://localhost:8080/actuator/health | grep --quiet -e '^{\"status\"\:\...
Michal Foksa's user avatar
  • 11.7k
8 votes
4 answers
26k views

Ansible K8s module: Failed to import the required Python library (openshift) on Python /usr/bin/python3

The env Ansible 2.9.6 (python3) Tried to run a simple playbook - hosts: master gather_facts: no become: yes tasks: - name: create name space k8s: name: testing ...
Hua's user avatar
  • 93
8 votes
1 answer
26k views

Openshift: unable to validate against any security > context constraint

I try to create the following statefulSet: apiVersion: apps/v1 kind: StatefulSet metadata: name: es-cluster namespace: efk spec: serviceName: elasticsearch replicas: 3 selector: ...
Trace's user avatar
  • 18.6k
8 votes
1 answer
17k views

How to use environment variables in init container args in kubernetes/openshift?

This is an excerpt of my deployment config: ... spec: containers: - env: - name: GIT_USERNAME valueFrom: secretKeyRef: key: username ...
wederer's user avatar
  • 550
8 votes
1 answer
30k views

Configure restart policy of pod from deployment config

We're using Openshift (a managed version of Kubernetes) and I'm struggling to set the pod restart policy from 'Always' to 'Never' for all pods created by our deployment config, but I'm not sure where ...
b15's user avatar
  • 2,201
8 votes
2 answers
3k views

Docker Inside Docker oom_score_adj: invalid argument

On Kubernetes, to build docker images, we use Docker Inside Docker (dind) where a docker daemon will be running as a privileged user But some times times we have observed that the docker image ...
Rajiv's user avatar
  • 402
8 votes
2 answers
7k views

Docker: Insert certificate into ketstore

I'm trying to add a certificate into $JAVA_HOME/jre/lib/security/cacerts truststore on my Dockerfile: FROM frolvlad/alpine-oraclejdk8:slim VOLUME /tmp RUN keytool -import -alias vault -storepass ...
user10063942's user avatar
7 votes
3 answers
22k views

Retrieve secret value from openshift

I created a key/value secret in openshift. I want to retrieve the value of that key/value pair. i tried using oc describe secret ashish -n my-project but it gave the value as shown below but i dont ...
ashish's user avatar
  • 293
7 votes
3 answers
3k views

kubernetes vs openshift (routes and services)

I'm new to kubernetes and openshift (came from docker swarm world) and I'm having trouble with some of kubernetes and openshift documentation especially related to route and services. I was looking ...
tkyass's user avatar
  • 3,098
7 votes
2 answers
17k views

how to modify pod memory limit of a running pod

I am using YML to create pod and have specified the resource request and limit. Now I am not aware of how to modify the resource limits of a running pod. For example memory-demo.yml apiVersion: v1 ...
Casey's user avatar
  • 97
7 votes
1 answer
3k views

List pods that are servicing a service

I am trying to get the list of pods that are servicing a particular service There are 3 pods associated with my service. I tried to execute the below command oc describe svc my-svc-1 I am expecting to ...
lr-pal's user avatar
  • 359
7 votes
2 answers
8k views

Kubernetes - Readiness Probe execution after container started

Is there a way to prevent readiness probe from execution once container has successfully started? I suppose that liveness probe should be enough to monitor container health.
dplesa's user avatar
  • 1,395
7 votes
2 answers
2k views

Service mesh and Async services

I am planning to introduce K8s/Istio into my infra. Right now I have plenty of services which communicate with each other using RabbitMQ. Service mesh concept seems to assume all services should be ...
arkadiy kraportov's user avatar
7 votes
3 answers
4k views

How to access from one container to another container stdout and stderr inside Kubernetes pod

I have a Pod with two containers. apiVersion: v1 kind: Pod metadata: name: test spec: containers: - name: my-container image: google/my-container:v1 - name: third-party image: google/...
nassi.harel's user avatar
7 votes
2 answers
3k views

Ingress route - path based routing to different React app

I have different react apps and its backend-service deployed independently inside the Openshift. There is one app among them where users login and navigate to othes apps using links provided in this ...
vvra's user avatar
  • 2,882
6 votes
4 answers
15k views

Openshift Route is not load balancing from Service pods

I have tried before on Openshift Origin 3.9 and Online. I have deployed a simple hello world php app on Openshift. It has a Service and a Route. When I call the route, I am getting expected output ...
John Seen's user avatar
  • 719
6 votes
3 answers
11k views

How to have multiple object types in a single openshift yaml template?

Here is the sample template for single PersistentVolumeClaim with name : claim1 apiVersion: "v1" kind: "PersistentVolumeClaim" metadata: name: "claim1" spec: accessModes: - "ReadWriteOnce" ...
rakesh kotian's user avatar
6 votes
3 answers
4k views

Pod unable to install packages(apt-get update or apt-get install )

I have observed that the pods in my cluster is not able to install the packages when exec to the pod . While debugging i have realized that its due to /etc/resolv.conf entries. The /etc/resolv.conf ...
Rakesh Kotian's user avatar
6 votes
1 answer
9k views

fsGroup vs supplementalGroups

I'm running my deployment on OpenShift, and found that I need to have a GID of 2121 to have write access. I still don't seem to have write access when I try this: security: podSecurityContext: ...
Kun Hwi Ko's user avatar
6 votes
2 answers
14k views

Declarative Jenkins Pipeline use existing Kubernetes Pod Template

I am using the OpenShift Jenkins image within an OpenShift Cluster. This default Jenkins image results in a Jenkins container that is preconfigured to point to my Kubernetes cluster. Additionally, the ...
ssc327's user avatar
  • 700
6 votes
1 answer
1k views

How to specify values for parent Helm chart

I am trying to configure Prometheus, which is included in the Gitlab Helm chart according to https://gitlab.com/charts/gitlab/blob/master/requirements.yaml My main issue is how to configure ...
djuarezg's user avatar
  • 2,415
6 votes
1 answer
18k views

Zookeeper: Hostname resolution fails

I am running Zookeeper in an OpenShift/Kubernetes environment. I have setup zookeeper as a StatefulSet in order to reliably persist config data. I configured three servers in my zoo.cfg by hostname, ...
Franz Wimmer's user avatar
  • 1,478
6 votes
1 answer
1k views

How to set node ip as nameserver in dnsConfig?

Im overriding the the dns policy of a pod since I'm facing a issue with default /etc/resolv.conf of the pod. Another issue is that the pod is not able to connect to smtp server server due to default /...
Rakesh Kotian's user avatar

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