I have this script. A Pod will have two containers, one for the main application and the other for logging. I want the logging container to sleep to help me debug an issue.
apiVersion: apps/v1
kind: Deployment
metadata:
name: codingjediweb
spec:
replicas: 2
selector:
matchLabels:
app: codingjediweb
template:
metadata:
labels:
app: codingjediweb
spec:
volumes:
- name: shared-logs
emptyDir: {}
containers:
- name: codingjediweb
image: docker.io/manuchadha25/codingjediweb:03072020v2
volumeMounts:
- name: shared-logs
mountPath: /deploy/codingjediweb-1.0/logs/
env:
- name: db.cassandraUri
value: cassandra://xx.yy.xxx.yyy:9042
- name: db.password
value: 9__
- name: db.keyspaceName
value: somei
- name: db.username
value: supserawesome
ports:
- containerPort: 9000
- name: logging
image: busybox
volumeMounts:
- name: shared-logs
mountPath: /deploy/codingjediweb-1.0/logs/
command: ["tail -f /deploy/codingjediweb-1.0/logs/*.log"]
Before running tail -f ..., I want to add a sleep/delay to avoid a race condition (the application takes sometime before logging and tail -f fails in the meanwhile because the log file doesn't exist. Alternatively, I am ok to run a script like this - while true; do sleep 86400; done .
How can I do that?
got it - had to do command: ['sh', '-c', "while true; do sleep 86400; done"]
Related
Pod is running state but logging inside the container and and running capsh --print, give error as:
sh: capsh: not found
Running same image with --cap-add SYS_ADMIN or --privileged as docker container gives desired output.
What changes in deployment or extra permissions are needed for it to work inside k8s container?
Deployment :
kind: Deployment
apiVersion: apps/v1
metadata:
name: sample-deployment
namespace: sample
labels:
app: sample
spec:
replicas: 1
selector:
matchLabels:
app: sample
template:
metadata:
labels:
app: sample
spec:
containers:
- name: sample
image: alpine:3.17
command:
- sh
- -c
- while true; do echo Hello World; sleep 10; done
env:
- name: NFS_EXPORT_0
value: /var/opt/backup
- name: NFS_LOG_LEVEL
value: DEBUG
volumeMounts:
- name: backup
mountPath: /var/opt/backup
securityContext:
capabilities:
add: ["SYS_ADMIN"]
volumes:
- name: backup
persistentVolumeClaim:
claimName: sample-pvc
I am trying to use git-sync image as a side car in kubernetes that runs git-pull periodically and mounts cloned data to shared volume.
Everything is working fine when I configure it for sync one time. I want to run it periodically like every 10 mins. Somehow when I configure it to run periodically pod initializing is failing.
I read documentation but couldn't find proper answer. Would be nice if you help me to figure out what I am missing in my configuration.
Here is my configuration that failing.
Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx-helloworld
image: nginx
ports:
- containerPort: 80
volumeMounts:
- mountPath: "/usr/share/nginx/html"
name: www-data
initContainers:
- name: git-sync
image: k8s.gcr.io/git-sync:v3.1.3
volumeMounts:
- name: www-data
mountPath: /data
env:
- name: GIT_SYNC_REPO
value: "https://github.com/musaalp/design-patterns.git" ##repo-path-you-want-to-clone
- name: GIT_SYNC_BRANCH
value: "master" ##repo-branch
- name: GIT_SYNC_ROOT
value: /data
- name: GIT_SYNC_DEST
value: "hello" ##path-where-you-want-to-clone
- name: GIT_SYNC_PERIOD
value: "10"
- name: GIT_SYNC_ONE_TIME
value: "false"
securityContext:
runAsUser: 0
volumes:
- name: www-data
emptyDir: {}
Pod
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: nginx-helloworld
name: nginx-helloworld
spec:
containers:
- image: nginx
name: nginx-helloworld
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Never
status: {}
you are using the git-sync as an initContainers, which run only during init (once in lifecycle)
A Pod can have multiple containers running apps within it, but it can also have one or more init containers, which are run before the app containers are started.
Init containers are exactly like regular containers, except:
Init containers always run to completion.
Each init container must complete successfully before the next one starts.
init-containers
So use this as a regular container
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: git-sync
image: k8s.gcr.io/git-sync:v3.1.3
volumeMounts:
- name: www-data
mountPath: /data
env:
- name: GIT_SYNC_REPO
value: "https://github.com/musaalp/design-patterns.git" ##repo-path-you-want-to-clone
- name: GIT_SYNC_BRANCH
value: "master" ##repo-branch
- name: GIT_SYNC_ROOT
value: /data
- name: GIT_SYNC_DEST
value: "hello" ##path-where-you-want-to-clone
- name: GIT_SYNC_PERIOD
value: "20"
- name: GIT_SYNC_ONE_TIME
value: "false"
securityContext:
runAsUser: 0
- name: nginx-helloworld
image: nginx
ports:
- containerPort: 80
volumeMounts:
- mountPath: "/usr/share/nginx/html"
name: www-data
volumes:
- name: www-data
emptyDir: {}
I am trying to execute some scripts as part of statefulset deployment kind. This script I have added as configmap and I use this as volumeMount inside the pod definition. I use the lifecycle poststart exec command to execute this script. It fails with the permission issue.
based on certain articles, I found that we should copy this file as part of InitContainer and then use that (I am not sure why should we do and what will make a difference)
Still, I tried it and that also gives the same error.
Here is my ConfigMap:
apiVersion: v1
kind: ConfigMap
metadata:
name: postgres-configmap-initscripts
data:
poststart.sh: |
#!/bin/bash
echo "It`s done"
Here is my StatefulSet:
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: postgres-statefulset
spec:
....
serviceName: postgres-service
replicas: 1
template:
...
spec:
initContainers:
- name: "postgres-ghost"
image: alpine
volumeMounts:
- mountPath: /scripts
name: postgres-scripts
containers:
- name: postgres
image: postgres
lifecycle:
postStart:
exec:
command: ["/bin/sh", "-c", "/scripts/poststart.sh" ]
ports:
- containerPort: 5432
name: dbport
....
volumeMounts:
- mountPath: /scripts
name: postgres-scripts
volumes:
- name: postgres-scripts
configMap:
name: postgres-configmap-initscripts
items:
- key: poststart.sh
path: poststart.sh
The error I am getting:
postStart hook will be call at least once but may be call more than once, this is not a good place to run script.
The poststart.sh file that mounted as ConfigMap will not have execute mode hence the permission error.
It is better to run script in initContainers, here's an quick example that do a simple chmod; while in your case you can execute the script instead:
cat << EOF | kubectl apply -f -
apiVersion: v1
kind: ConfigMap
metadata:
name: busybox
data:
test.sh: |
#!/bin/bash
echo "It's done"
---
apiVersion: v1
kind: Pod
metadata:
name: busybox
labels:
run: busybox
spec:
volumes:
- name: scripts
configMap:
name: busybox
items:
- key: test.sh
path: test.sh
- name: runnable
emptyDir: {}
initContainers:
- name: prepare
image: busybox
imagePullPolicy: IfNotPresent
command: ["ash","-c"]
args: ["cp /scripts/test.sh /runnable/test.sh && chmod +x /runnable/test.sh"]
volumeMounts:
- name: scripts
mountPath: /scripts
- name: runnable
mountPath: /runnable
containers:
- name: busybox
image: busybox
imagePullPolicy: IfNotPresent
command: ["ash","-c"]
args: ["while :; do . /runnable/test.sh; sleep 1; done"]
volumeMounts:
- name: scripts
mountPath: /scripts
- name: runnable
mountPath: /runnable
EOF
I'm currently setting up a kubernetes cluster with 3 nodes on 3 differents vm and each node is composed of 1 pod witch run the following docker image: ethereum/client-go:stable
The problem is that I want to do a health check test using a bash script (because I have to test a lot of things) but I don't understand how I can export this file to each container that are deployed with my yaml deployment file.
I've tried to add wget command in the yaml file to download my health check script from my github repo but it wasn't very clean from my point of view, maybe there is an other way ?
My current deployment file:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: goerli
name: goerli-deploy
spec:
replicas: 3
selector:
matchLabels:
app: goerli
template:
metadata:
labels:
app: goerli
spec:
containers:
- image: ethereum/client-go:stable
name: goerli-geth
args: ["--goerli", "--datadir", "/test2"]
env:
- name: LASTBLOCK
value: "0"
- name: FAILCOUNTER
value: "0"
ports:
- containerPort: 30303
name: geth
livenessProbe:
exec:
command:
- /bin/sh
- /test/health.sh
initialDelaySeconds: 60
periodSeconds: 100
volumeMounts:
- name: test
mountPath: /test
restartPolicy: Always
volumes:
- name: test
hostPath:
path: /test
I expect to put health check script in /test/health.sh
Any ideas ?
This could be a perfect usecase for the init container, As there could be different images for the init container and the Application container thus they have different file system inside the pods, therefore we need to use Emptydir in order to share the state.
for further detail follow the link init-containers
Thanks to Suresh Vishnoi:
A way to resolve my problem is to use init container this way:
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: goerli
name: goerli-deploy
spec:
replicas: 3
selector:
matchLabels:
app: goerli
template:
metadata:
labels:
app: goerli
spec:
containers:
- image: ethereum/client-go:stable
name: goerli-geth
args: ["--goerli", "--datadir", "/test2"]
env:
- name: LASTBLOCK
value: "0"
- name: FAILCOUNTER
value: "0"
ports:
- containerPort: 30303
name: geth
livenessProbe:
exec:
command:
- /bin/sh
- /test/health.sh
initialDelaySeconds: 60
periodSeconds: 100
volumeMounts:
- name: test
mountPath: /test
initContainers:
- name: healthcheck
image: ethereum/client-go:stable
command: ["wget", "-O", "/test2/health.sh", "https://My-script-bash"]
volumeMounts:
- name: test
mountPath: "/test"
restartPolicy: Always
volumes:
- name: test
emptyDir: {}
The downloaded file will be visible in /test/health.sh
If you're using helm look at chart tests: https://github.com/helm/helm/blob/master/docs/chart_tests.md. This covers readinessProbe tho, not liveness.
For advanced liveness probe, I'd run some kind of healthcheck sidecar which does all the advanced tests continiosly via localhost, and exposes a single /healthcheck endpoint. Then use the endpoint in a liveness probe.
Trying to mount config files from a hostPath to a kubernetes container. This works using minikube and VirtualBox shared folder, but I am unable to make this work on Linux.
I making use of AWS EKS and the following architecture https://aws.amazon.com/quickstart/architecture/amazon-eks/. I think my problem is that the files need to live on each of the EKS Node instances.
Here is the architecture diagram:
Below is the Deployment file.
apiVersion: apps/v1
kind: Deployment
metadata:
name: openhim-core-deployment
spec:
replicas: 1
selector:
matchLabels:
component: openhim-core
template:
metadata:
labels:
component: openhim-core
spec:
volumes:
- name: core-config
hostPath:
path: /var/config/openhim-core
containers:
- name: openhim-core
image: jembi/openhim-core:5.rc
ports:
- containerPort: 8080
- containerPort: 5000
- containerPort: 5001
volumeMounts:
- name: core-config
mountPath: /usr/src/app/config
env:
- name: NODE_ENV
value: development
After much pain I found that I am trying to place the configuration on the Linux Bastion host where I have access to kubectl but in fact this configuration will have to be on each of the EC2 instances in every availability zone.
The solution for me was to make use of a initContainer.
apiVersion: apps/v1
kind: Deployment
metadata:
name: openhim-core-deployment
spec:
replicas: 1
selector:
matchLabels:
component: openhim-core
template:
metadata:
labels:
component: openhim-core
spec:
volumes:
- name: core-config
hostPath:
path: /var/config/openhim-core
containers:
- name: openhim-core
image: jembi/openhim-core:5
ports:
- containerPort: 8080
- containerPort: 5000
- containerPort: 5001
volumeMounts:
- name: core-config
mountPath: /usr/src/app/config
env:
- name: NODE_ENV
value: development
initContainers:
- name: install
image: busybox
command:
- wget
- "-O"
- "/usr/src/app/config/development.json"
- https://s3.eu-central-1.amazonaws.com/../development.json
volumeMounts:
- name: core-config
mountPath: "/usr/src/app/config"
volumes:
- name: core-config
emptyDir: {}