Nrp

content/NRP/basic_kubernetes.md

++++
+title = "Basic Kubernetes"
+description = "Basic Kubernetes"
+weight=20
++++
+
+### Setup
+
+This section assumes you've completed the [Quick Start]({{< ref "quick_start.md">}}) section.
+
+If you are in multiple namespaces, you need to be aware of which namespace you’re working in, and either set it with `kubectl config set-context nautilus --namespace=the_namespace` or specify in each `kubectl` command by adding `-n namespace`.
+
+### Explore the system
+
+To get the list of cluster nodes (although you may not have access to all of them), type:
+
+```
+kubectl get nodes
+```
+
+Right now you probably don't have anything running in the namespace, and these commands will return `No resources found in ... namespace.`. There are three categories we will examine: pods, deployments and services. Later these commands will be useful to see what's running:
+
+List all the pods in your namespace
+
+```
+kubectl get pods
+```
+
+List all the deployments in your namespace
+
+```
+kubectl get deployments
+```
+
+List all the services in your namespace
+
+```
+kubectl get services
+```
+
+### Launch a simple pod
+
+Let’s create a simple generic pod, and login into it.
+
+You can copy-and-paste the lines below. Create the `pod1.yaml` file with the following content:
+
+```yaml
+apiVersion: v1
+kind: Pod
+metadata:
+  name: test-pod
+spec:
+  containers:
+  - name: mypod
+    image: ubuntu
+    resources:
+      limits:
+        memory: 100Mi
+        cpu: 100m
+      requests:
+        memory: 100Mi
+        cpu: 100m
+    command: ["sh", "-c", "echo 'Im a new pod' && sleep infinity"]
+```
+
+Reminder, indentation is important in YAML, just like in Python.
+
+*If you don't want to create the file and are using Mac or Linux, you can create yaml's dynamically like this:*
+
+```
+kubectl create -f - << EOF
+<contents you want to deploy>
+EOF
+```
+
+Now let’s start the pod:
+
+```
+kubectl create -f pod1.yaml
+```
+
+See if you can find it:
+
+```
+kubectl get pods
+```
+
+Note: You may see the other pods too.
+
+If it is not yet in Running state, you can check what is going on with
+
+```
+kubectl get events --sort-by=.metadata.creationTimestamp
+```
+
+Events and other useful information about the pod can be seen in `describe`:
+
+```
+kubectl describe pod test-pod
+```
+
+If the pod is in Running state, we can check its logs
+
+```
+kubectl logs test-pod
+```
+
+Let’s log into it
+
+```
+kubectl exec -it test-pod -- /bin/bash
+```
+
+You are now inside the (container in the) pod!
+
+Does it feel any different than a regular, dedicated node?
+
+Try to create some directories and some files with content.
+
+(Hello world will do, but feel free to be creative)
+
+We will want to check the status of the networking.
+
+But ifconfig is not available in the image we are using; so let’s install it.
+
+First, let's make sure our installation tools are updated.
+
+```
+apt update
+```
+Now, we can use apt to install the necessary network tools.
+
+```
+apt install net-tools
+```
+Now check the networking:
+
+```
+ifconfig -a
+```
+
+Get out of the Pod (with either Control-D or exit).
+
+You should see the same IP displayed with kubectl
+
+```
+kubectl get pod -o wide test-pod
+```
+
+We can now destroy the pod
+
+```
+kubectl delete -f pod1.yaml
+```
+
+Check that it is actually gone:
+
+```
+kubectl get pods
+```
+
+Now, let’s create it again:
+
+```
+kubectl create -f pod1.yaml
+```
+
+Does it have the same IP?
+
+```
+kubectl get pod -o wide test-pod
+```
+
+Log back into the pod:
+
+```
+kubectl exec -it test-pod -- /bin/bash
+```
+
+What does the network look like now?
+
+What is the status of the files your created?
+
+Finally, let’s delete the pod explicitly:
+
+```
+kubectl delete pod test-pod
+```
+
+### Let’s make it a deployment
+
+You saw that when a pod was terminated, it was gone.
+
+While above we did it by ourselves, the result would have been the same if a node died or was restarted.
+
+In order to gain a higher availability, the use of Deployments is recommended. So, that’s what we will do next.
+
+You can copy-and-paste the lines below.
+
+###### dep1.yaml:
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test-dep
+  labels:
+    k8s-app: test-dep
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      k8s-app: test-dep
+  template:
+    metadata: 
+      labels:
+        k8s-app: test-dep
+    spec:
+      containers:
+      - name: mypod
+        image: ubuntu
+        resources:
+           limits:
+             memory: 500Mi
+             cpu: 500m
+           requests:
+             memory: 100Mi
+             cpu: 50m
+        command: ["sh", "-c", "sleep infinity"]
+```
+
+Now let’s start the deployment:
+
+```
+kubectl create -f dep1.yaml
+```
+
+See if you can find it:
+
+```
+kubectl get deployments
+```
+
+The Deployment is just a conceptual service, though.
+
+See if you can find the associated pod:
+
+```
+kubectl get pods
+```
+
+Once you have found its name, let’s log into it
+
+```
+kubectl get pod -o wide test-dep-<hash>
+kubectl exec -it test-dep-<hash> -- /bin/bash
+```
+
+You are now inside the (container in the) pod!
+
+Create directories and files as before.
+
+Try various commands as before.
+
+Let’s now delete the pod!
+
+```
+kubectl delete pod test-dep-<hash>
+```
+
+Is it really gone?
+
+```
+kubectl get pods 
+```
+
+What happened to the deployment?
+
+```
+kubectl get deployments
+```
+
+Get into the new pod
+
+```
+kubectl get pod -o wide test-dep-<hash>
+kubectl exec -it test-dep-<hash> -- /bin/bash
+```
+
+Was anything preserved?
+
+Let’s now delete the deployment:
+
+```
+kubectl delete -f dep1.yaml
+```
+
+Verify everything is gone:
+
+```
+kubectl get deployments
+kubectl get pods
+```
+
+### More tutorials are available at [Nautilus Documentation - Tutorials](https://docs.pacificresearchplatform.org)
+