CKAD Exam Tips & Tricks

I recently passed the CKAD exam and wanted to write up a few tips and tricks that I think other folk might find useful. The exam consists of a number of hands on questions or problems that have to be solved on the command line. This is the first practical certification exam I'd taken and it was significantly different to the multiple choice style certifications I've done in the past. To prepare you'll need to spend lots of time on the command line and be very familiar with both kubectl and vi editor (more on this later). Watch the Time You'll have 2 hours to [...]

By |2021-09-21T23:17:00+01:00September 21st, 2021|Kubernetes|0 Comments

CKAD Part17 – Volumes, PersistentVolumes & PersistentVolumeClaims

Kubernetes Volumes Internal container storage is ephemeral, which means that it exits only for the lifetime of the container. When the container is stopped any data written inside the container is lost. Volumes provide a means of storing data beyond the life of the container. The Pod definition below contains an emptyDir Volume  An emptyDir is an empty directory that is created when a Pod is assigned to a Node. All containers in a Pod can read and write in the emptyDir Volume which makes useful for multi container Pod use cases. apiVersion: v1 kind: Pod metadata: name: pod-volume-1 spec: containers: - name: volume-container-1 image: [...]

By |2021-07-01T15:33:34+01:00July 1st, 2021|Kubernetes|0 Comments

CKAD Prep Part 16 – Network Policies

Network Policies By default, a Pod can communicate with any other Pod in the same cluster. NetworkPolicies allow you to limit the network traffic allowed to and from Pods in the cluster. A sample NetworkPolicy is shown below. apiVersion: kind: NetworkPolicy metadata: name: sample-network-policy spec: podSelector: matchLabels: app: secure-app policyTypes: - Ingress - Egress ingress: # traffic coming into the Pod - from: - podSelector: matchLabels: allow-access: "true" # allow inbound traffic from Pods that have this label ports: - protocol: TCP port: 6379 egress: # traffic coming into the Pod - to: - podSelector: matchLabels: allow-access: "true" # allow outbound traffic to Pods [...]

By |2021-06-22T22:49:04+01:00June 22nd, 2021|Kubernetes|0 Comments

CKAD Prep Part 15 – Services

Kubernetes Services A Kubernetes Service object is an abstraction that provides network access to a dynamic set of Pod replicas. Rather than access Pods directly via their IPs, you can use a Service to proxy requests and deal with service discovery and load balancing. A Service usually uses a selector to decide which Pods will receive traffic. As Pods are dynamically added and removed, the Service will maintain a list of active Pods that are eligible to receive traffic. Defining a Service Below is a sample Service definition. apiVersion: v1 kind: Service metadata: name: my-service spec: type: ClusterIP selector: app: nginx ports: - protocol: TCP [...]

By |2021-06-22T22:51:23+01:00June 15th, 2021|Kubernetes|0 Comments

CKAD Prep Part 14 – Jobs & Cronjobs

Jobs & Cronjobs Jobs A Job is a Kubernetes object that executes a workload and then terminates once the workload is complete. When a Job finishes, the containers involved are terminated and the Pod transitions to the Completed state. Jobs and Pods are similar in that they're both used to run containers. However, Pods typically run containers continuously, whereas Jobs run containers to do a discrete piece of work and then terminate. The sample Job below is taken from the Kubernetes documentation and uses Perl to compute π to 2000 decimal places. apiVersion: batch/v1 kind: Job metadata: name: pi spec: template: spec: containers: - name: [...]

By |2021-06-22T22:56:08+01:00June 13th, 2021|Kubernetes|0 Comments

CKAD Prep Part 13 – Rolling Updates & Rollbacks

Rolling Updates & Rollbacks Rolling updates provide a mechanism for updating containers in a cluster without downtime. This powerful Kubernetes feature allows you to update containers while maintaining high availability. To see this in action we'll create a Deployment consisting of 3 nginx Pods using the definition below. Note that the container image we're going to run is library/nginx:1.20.0. apiVersion: apps/v1 kind: Deployment metadata: name: rolling-update-deployment spec: replicas: 3 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: library/nginx:1.20.0 imagePullPolicy: IfNotPresent Run kubectl apply -f rolling-update-deployment.yaml to create the Deployment.  A quick listing will show 3 Pods running as [...]

By |2021-06-22T23:34:01+01:00June 10th, 2021|Kubernetes|0 Comments
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