I did a small deployment in K8s using Docker image but it is not showing in deployment but only showing in pods. Reason: It is not creating any default namespace in deployments.
Please suggest:
Following are the commands I used.
$ kubectl run hello-node --image=gcr.io/$DEVSHELL_PROJECT_ID/hello-node:1.0 --port=8080 --namespace=default
pod/hello-node created
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-node 1/1 Running 0 12s
$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
default hello-node 1/1 Running 0 9m9s
kube-system event-exporter-v0.2.5-599d65f456-4dnqw 2/2 Running 0 23m
kube-system kube-proxy-gke-hello-world-default-pool-c09f603f-3hq6 1/1 Running 0 23m
$ kubectl get deployments
**No resources found in default namespace.**
$ kubectl get deployments --all-namespaces
NAMESPACE NAME READY UP-TO-DATE AVAILABLE AGE
kube-system event-exporter-v0.2.5 1/1 1 1 170m
kube-system fluentd-gcp-scaler 1/1 1 1 170m
kube-system heapster-gke 1/1 1 1 170m
kube-system kube-dns 2/2 2 2 170m
kube-system kube-dns-autoscaler 1/1 1 1 170m
kube-system l7-default-backend 1/1 1 1 170m
kube-system metrics-server-v0.3.1 1/1 1 1 170m
Arghya Sadhu's answer is correct. In the past kubectl run command indeed created by default a Deployment instead of a Pod. Actually in the past you could use it with so called generators and you were able to specify exactly what kind of resource you want to create by providing --generator flag followed by corresponding value. Currently --generator flag is deprecated and has no effect.
Note that you've got quite clear message after running your kubectl run command:
$ kubectl run hello-node --image=gcr.io/$DEVSHELL_PROJECT_ID/hello-node:1.0 --port=8080 --namespace=default
pod/hello-node created
It clearly says that the Pod hello-node was created. It doesn't mention about a Deployment anywhere.
As an alternative to using imperative commands for creating either Deployments or Pods you can use declarative approach:
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello-node
namespace: default
labels:
app: hello-node
spec:
replicas: 3
selector:
matchLabels:
app: hello-node
template:
metadata:
labels:
app: hello-node
spec:
containers:
- name: hello-node-container
image: gcr.io/$DEVSHELL_PROJECT_ID/hello-node:1.0
ports:
- containerPort: 8080
Declaration of namespace can be ommitted in this case as by default all resources are deployed into the default namespace.
After saving the file e.g. as nginx-deployment.yaml you just need to run:
kubectl apply -f nginx-deployment.yaml
Expansion of the environment variables within the yaml manifest actually doesn't work so the following line from the above deployment example cannot be used:
image: gcr.io/$DEVSHELL_PROJECT_ID/hello-node:1.0
The simplest workaround is a fairly simple sed "trick".
First we need to change a bit our project id's placeholder in our deployment definition yaml. It may look like this:
image: gcr.io/{{DEVSHELL_PROJECT_ID}}/hello-node:1.0
Then when applying the deployment definition instead of simple kubectl apply -f deployment.yaml run this one-liner:
sed "s/{{DEVSHELL_PROJECT_ID}}/$DEVSHELL_PROJECT_ID/g" deployment.yaml | kubectl apply -f -
The above command tells sed to search through deployment.yaml document for {{DEVSHELL_PROJECT_ID}} string and each time this string occurs, to substitute it with the actual value of $DEVSHELL_PROJECT_ID environment variable.