I am trying to write a deployment for a k8s pod.
I am having the following in the deploy.yaml file
apiVersion: apps/v1beta1 # for versions before 1.8.0 use apps/v1beta1
kind: Deployment
metadata:
name: __DEPLOY_NAME__-__ENV__
namespace: __RG_NAME__
spec:
replicas: 1
template:
metadata:
labels:
app: __DEPLOY_NAME__-__ENV__
containers:
- name: __DEPLOY_NAME__-__ENV__
image: __CONTAINER_REGISTRY__/__IMAGE_NAME__
env:
- name: NODE_ENV
value: __ENV__
imagePullPolicy: Always
volumeMounts:
- name: config-volume
mountPath: /etc/config
ports:
- containerPort: __PORT__
volumes:
- name: config-volume
configMap:
name: config
configMap:
name: oauth
I trying to use two different config maps named 'config' and 'oauth' as volume mounts in the same pod. When I tried the above code I got the following error.
error validating data: found invalid field volumes for v1.Container; if you choose to ignore these errors, turn validation off with --validate=false
I am not sure if what I want to achieve is feasible and if not then how should I give the volume mounts.
First: fix indentation on your volumes block, it should be two spaces less (not a child of containers: but sibling of it.
Second: you should create two distinct volumes with distinct names and then have a volume mount for each one of them
Third: if you need to merge files from them you might want to try mounting particular files with subPath
Related
I'm trying to play with single pod multi container scenario.
The problem is one of my container (directus) is a node app that run as user 'node' with uid 1000
First try, I use hostpath as storage back end. With this, I need to change the host's directory mode with chmod manualy.
Now, I'm trying using longhorn.
And basicaly I don't want to change a host directory mod/ownership each time i deploy this deployment.
Here is my manifest
apiVersion: apps/v1
kind: Deployment
metadata:
name: lh-directus
namespace: lh-directus
spec:
replicas: 1
selector:
matchLabels:
app: lh-directus
template:
metadata:
labels:
app: lh-directus
spec:
nodeSelector:
kubernetes.io/os: linux
isGeneralDeployment: "true"
volumes:
- name: lh-directus-uploads-volume
persistentVolumeClaim:
claimName: lh-directus-uploads-pvc
- name: lh-directus-dbdata-volume
persistentVolumeClaim:
claimName: lh-directus-dbdata-pvc
containers:
# Redis Cache
- name: redis
image: redis:6
# Database
- name: database
image: postgres:12
volumeMounts:
- name: lh-directus-dbdata-volume
mountPath: /var/lib/postgresql/data
# Directus
- name: directus
image: directus/directus:latest
securityContext:
fsGroup: 1000
volumeMounts:
- name: lh-directus-uploads-volume
mountPath: /directus/uploads
When I Appy the manifest, I got error
error: error validating "lh-directus.yaml": error validating data: ValidationError(Deployment.spec.template.spec.containers[2].securityContext): unknown field "fsGroup" in io.k8s.api.core.v1.SecurityContext; if you choose to ignore these errors, turn validation off with --validate=false
I reads about initContainer ....
But Kindly please tell me how to fix this problem without initContainer and without manualy set/change host's path ownership/mod.
Sincerely
-bino-
I define a Secret:
apiVersion: v1
kind: Secret
metadata:
name: mysecret
type: Opaque
stringData:
config.yaml: |-
apiUrl: "https://my.api.com/api/v1"
username: Administrator
password: NewPasswdTest11
And then creating volume mount in Deployment:
apiVersion: apps/v1
kind: Deployment
metadata:
name: k8s-webapp-test
labels:
name: k8s-webapp-test
version: 1.0.4
spec:
replicas: 2
selector:
matchLabels:
name: k8s-webapp-test
version: 1.0.4
template:
metadata:
labels:
name: k8s-webapp-test
version: 1.0.4
spec:
nodeSelector:
kubernetes.io/os: windows
volumes:
- name: secret-volume
secret:
secretName: string-data-secret
containers:
- name: k8s-webapp-test
image: dockerstore/k8s-webapp-test:1.0.4
ports:
- containerPort: 80
volumeMounts:
- name: secret-volume
mountPath: "/secrets"
readOnly: false
So, after the deployment, I have 2 pods with volume mounts in C:\secrets (I do use Windows nodes). When I try to edit config.yaml that is located in C:\secrets folder, I get following error:
Access to the path 'c:\secrets\config.yaml' is denied.
Although I marked file as readOnly false I cannot write to it. How can I modify the file?
As you can see here it is not possible by intention:
Secret, configMap, downwardAPI and projected volumes will be mounted as read-only volumes. Applications that attempt to write to these volumes will receive read-only filesystem errors. Previously, applications were allowed to make changes to these volumes, but those changes were reverted at an arbitrary interval by the system. Applications should be re-configured to write derived files to another location
You can look into using an init container which maps the secret and then copies it to the desired location where you might be able to modify it.
As an alternative to the init container you might also use a container lifecycle hook i.e. a PostStart-hook which executes immediately after a container is created.
lifecycle:
postStart:
exec:
command:
- "/bin/sh"
- "-c"
- >
cp -r /secrets ~/secrets;
You can create secrets from within a Pod but it seems you need to utilize the Kubernetes REST API to do so:
https://kubernetes.io/docs/concepts/overview/kubernetes-api/
I would like to pass in some of the values in kubernetes yaml files during runtime like reading from config/properties file.
what is the best way to do that?
In the below example, I do not want to hardcode the port value, instead read the port number from config file.
Ex:
logstash.yaml
apiVersion: v1
kind: ReplicationController
metadata:
name: test
namespace: test
spec:
replicas: 1
selector:
app: test
template:
metadata:
labels:
app: test
spec:
containers:
- name: test
image: logstash
ports:
- containerPort: 33044 (looking to read this port from config file)
env:
- name: INPUT_PORT
value: "5044"
config.yaml
logstash_port: 33044
This sounds like a perfect use case for Helm (www.helm.sh).
Helm Charts helps you define, install, and upgrade Kubernetes applications. You can use a pre-defined chart (like Nginx, etc) or create your own chart.
Charts are structured like:
mychart/
Chart.yaml
values.yaml
charts/
templates/
...
In the templates folder, you can include your ReplicationController files (and any others). In the values.yaml file you can specify any variables you wish to share amongst the templates (like port numbers, file paths, etc).
The values file can be as simple or complex as you require. An example of a values file:
myTestService:
containerPort: 33044
image: "logstash"
You can then reference these values in your template file using:
apiVersion: v1
kind: ReplicationController
metadata:
name: test
namespace: test
spec:
replicas: 1
selector:
app: test
template:
metadata:
labels:
app: test
spec:
containers:
- name: test
image: logstash
ports:
- containerPort: {{ .Values.myTestService.containerPort }}
env:
- name: INPUT_PORT
value: "5044"
Once finished you can compile into Helm chart using helm package mychart. To deploy to your Kubernetes cluster you can use helm install mychart-VERSION.tgz. That will then deploy your chart to the cluster. The version number is set within the Chart.yaml file.
You can use Kubernetes ConfigMaps for this. ConfigMaps are introduced to include external configuration files such as property files.
First create a ConfigMap artifact out of your property like follows:
kubectl create configmap my-config --from-file=db.properties
Then in your Deployment yaml you can provide it as a volume binding or environment variables
Volume binding :
apiVersion: v1
kind: ReplicationController
metadata:
name: test
labels:
app: test
spec:
containers:
- name: test
image: test
ports:
- containerPort: 33044
volumeMounts:
- name: config-volume
mountPath: /etc/creds <mount path>
volumes:
- name: config-volume
configMap:
name: my-config
Here under mountPath you need to provide the location of your container where your property file should resides. And underconfigMap name you should define the name of your configMap you created.
Environment variables way :
apiVersion: v1
kind: ReplicationController
metadata:
name: test
labels:
app: test
spec:
containers:
- name: test
image: test
ports:
- containerPort: 33044
env:
- name: DB_PROPERTIES
valueFrom:
configMapKeyRef:
name: my-config
items:
- key: <propert name>
path: <path/to/property>
Here under the configMapKeyRef section under name you should define your config map name you created. e.g. my-config. Under the items you should define the key(s) of your property file and path to each of the key, Kubernetes will automatically resolve the value of the property internally.
You can find more about ConfigMap here.
https://kubernetes-v1-4.github.io/docs/user-guide/configmap/
There are some parameters you can't change once a pod is created. containerPort is one of them.
You can add a new container to a pod though. And open a new port.
The parameters you CAN change, you can do it either by dynamically creating or modifying the original deployment (say with sed) and running kubectl replace -f FILE command, or through kubectl edit DEPLOYMENT command; which automatically applies the changes.
I am trying to "pass" a value from the init container to a container. Since values in a configmap are shared across the namespace, I figured I can use it for this purpose. Here is my job.yaml (with faked-out info):
apiVersion: batch/v1
kind: Job
metadata:
name: installer-test
spec:
template:
spec:
containers:
- name: installer-test
image: installer-test:latest
env:
- name: clusterId
value: "some_cluster_id"
- name: in_artifactoryUrl
valueFrom:
configMapKeyRef:
name: test-config
key: artifactorySnapshotUrl
initContainers:
- name: artifactory-snapshot
image: busybox
command: ['kubectl', 'create configmap test-config --from-literal=artifactorySnapshotUrl=http://artifactory.com/some/url']
restartPolicy: Never
backoffLimit: 0
This does not seem to work (EDIT: although the statements following this edit note may still be correct, this is not working because kubectl is not a recognizable command in the busybox image), and I am assuming that the pod can only read values from a configmap created BEFORE the pod is created. Has anyone else come across the difficulty of passing values between containers, and what did you do to solve this?
Should I deploy the configmap in another pod and wait to deploy this one until the configmap exists?
(I know I can write files to a volume, but I'd rather not go that route unless it's absolutely necessary, since it essentially means our docker images must be coupled to an environment where some specific files exist)
You can create an EmptyDir volume, and mount this volume onto both containers. Unlike persistent volume, EmptyDir has no portability issue.
apiVersion: batch/v1
kind: Job
metadata:
name: installer-test
spec:
template:
spec:
containers:
- name: installer-test
image: installer-test:latest
env:
- name: clusterId
value: "some_cluster_id"
volumeMounts:
- name: tmp
mountPath: /tmp/artifact
initContainers:
- name: artifactory-snapshot
image: busybox
command: ['/bin/sh', '-c', 'cp x /tmp/artifact/x']
volumeMounts:
- name: tmp
mountPath: /tmp/artifact
restartPolicy: Never
volumes:
- name: tmp
emptyDir: {}
backoffLimit: 0
If for various reasons, you don't want to use share volume. And you want to create a configmap or a secret, here is a solution.
First you need to use a docker image which contains kubectl : gcr.io/cloud-builders/kubectl:latest for example. (docker image which contains kubectl manage by Google).
Then this (init)container needs enough rights to create resource on Kubernetes cluster. Ok by default, kubernetes inject a token of default service account named : "default" in container, but I prefer to make more explicit, then add this line :
...
initContainers:
- # Already true by default but if use it, prefer to make it explicit
automountServiceAccountToken: true
name: artifactory-snapshot
And add "edit" role to "default" service account:
kubectl create rolebinding default-edit-rb --clusterrole=edit --serviceaccount=default:myapp --namespace=default
Then complete example :
apiVersion: batch/v1
kind: Job
metadata:
name: installer-test
spec:
template:
spec:
initContainers:
- # Already true by default but if use it, prefer to make it explicit.
automountServiceAccountToken: true
name: artifactory-snapshot
# You need to use docker image which contains kubectl
image: gcr.io/cloud-builders/kubectl:latest
command:
- sh
- -c
# the "--dry-run -o yaml | kubectl apply -f -" is to make command idempotent
- kubectl create configmap test-config --from-literal=artifactorySnapshotUrl=http://artifactory.com/some/url --dry-run -o yaml | kubectl apply -f -
containers:
- name: installer-test
image: installer-test:latest
env:
- name: clusterId
value: "some_cluster_id"
- name: in_artifactoryUrl
valueFrom:
configMapKeyRef:
name: test-config
key: artifactorySnapshotUrl
First of all, kubectl is a binary. It was downloaded in your machine before you could use the command. But, In your POD, the kubectl binary doesn't exist. So, you can't use kubectl command from a busybox image.
Furthermore, kubectl uses some credential that is saved in your machine (probably in ~/.kube path). So, If you try to use kubectl from inside an image, this will fail because of missing credentials.
For your scenario, I will suggest the same as #ccshih, use volume sharing.
Here is the official doc about volume sharing between init-container and container.
The yaml that is used here is ,
apiVersion: v1
kind: Pod
metadata:
name: init-demo
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
volumeMounts:
- name: workdir
mountPath: /usr/share/nginx/html
# These containers are run during pod initialization
initContainers:
- name: install
image: busybox
command:
- wget
- "-O"
- "/work-dir/index.html"
- http://kubernetes.io
volumeMounts:
- name: workdir
mountPath: "/work-dir"
dnsPolicy: Default
volumes:
- name: workdir
emptyDir: {}
Here init-containers saves a file in the volume and later the file was available in inside the container. Try the tutorial by yourself for better understanding.
I am trying to configure hostPath as the volume in kubernetes. I have logged into VM server, from where I usually use kubernetes commands such as kubectl.
Below is the pod yaml:
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: helloworldanilhostpath
spec:
replicas: 1
template:
metadata:
labels:
run: helloworldanilhostpath
spec:
volumes:
- name: task-pv-storage
hostPath:
path: /home/openapianil/samplePV
type: Directory
containers:
- name: helloworldv1
image: ***/helloworldv1:v1
ports:
- containerPort: 9123
volumeMounts:
- name: task-pv-storage
mountPath: /mnt/sample
In VM server, I have created "/home/openapianil/samplePV" folder and I have a file present in it. It has a sample.txt file.
once I try to create this deployment. it does not happen with error -
Warning FailedMount 28s (x7 over 59s) kubelet, aks-nodepool1-39499429-1 MountVolume.SetUp failed for volume "task-pv-storage" : hostPath type check failed: /home/openapianil/samplePV is not a directory.
Can anyone please help me in understanding the problem here.
hostPath type volumes refer to directories on the Node (VM/machine) where your Pod is scheduled for running (aks-nodepool1-39499429-1 in this case). So you'd need to create this directory at least on that Node.
To make sure your Pod is consistently scheduled on that specific Node you need to set spec.nodeSelector in the PodTemplate:
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: helloworldanilhostpath
spec:
replicas: 1
template:
metadata:
labels:
run: helloworldanilhostpath
spec:
nodeSelector:
kubernetes.io/hostname: aks-nodepool1-39499429-1
volumes:
- name: task-pv-storage
hostPath:
path: /home/openapianil/samplePV
type: Directory
containers:
- name: helloworldv1
image: ***/helloworldv1:v1
ports:
- containerPort: 9123
volumeMounts:
- name: task-pv-storage
mountPath: /mnt/sample
In most cases it's a bad idea to use this type of volume; there are some special use cases, but chance are yours is not one them!
If you need local storage for some reason then a slightly better solution is to use local PersistentVolumes.