CKAD試験無料問題集「Linux Foundation Certified Kubernetes Application Developer 認定」

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Create a Service:
- Create a Service resource that defines how the pods of your application will be accessed externallv
- Specify a unique name for the Service and define the port mapping-
- Example:

2. Set Selector: - Use the 'selector field to specify the label that the Service should use to identify the pods it should target - Ensure that the pods of your Deployment are labeled with the specified 'app: myapp' label. 3. Configure Load Balancing: - The default load balancing strategy for Kubernetes Services is round-robin, which distributes traffic evenly across the available pods. - No additional configuration is needed for this strategyc 4. Deploy and Test: - Apply the Service YAML file. - Test the Service by accessing it from outside the cluster. - Ensure that the traffic is distributed evenly across the pods using the round-robin strategy. 5. Optional: External Access: - If you want to expose the Service to the internet, you can set the Service 'type' to 'Load8alancer'. This will create a LoadBalancer resource (often an external IP address) that routes traffic to the Service.

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Define the CRD:
- Create a YAML file named 'database.crd.yaml' to define the "Database' resource:

2. the CRD: - Apply tre 'database.cre.yaml' using 'kubectl "ply -f database.crd.ya'mr 3. Create A Database Instance: - 'eate YAML file 'd:tabaseyarnl' to define a database instance

4. Apply the Database Instance: - Apply the 'database.yaml' using 'kubectl apply -f database.yamr 5. IJpdate the Deployment - Update the Amy-app-deployment.yaml' to use the 'Database' resource:

6. Apply the Updated Deployment: - Apply the updated 'my-app-deployment.yamr using 'kubectl apply -f my-app-deployment.yamr 7. Verify the Configuration: - Use 'kubectl get databases to check the database instance. - Use 'kubectl describe pod -l app=my-app' to verify that the pods are using the values from the 'Database' resource tor connecting to the PostgreSQL database. This approach demonstrates how to utilize CRDs to define custom resources in Kubernetes and how to connect applications dynamically to these resources. The CRO ensures proper definition of the database resource, while the deployment utilizes the 'fieldRef mechanism to access and retrieve database connection details directly from the CRD, enabling dynamic configuration and simplification of application setup.,

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. IJPdate the Deployment YAMLI
- Update the 'replicas to 2.
- Define 'maxunavailable: 2 and 'maxSurge: O' in the 'strategy.rollingupdate' section to control the rolling update process.
- Configure a 'strategy-type' to 'RollinglJpdate' to trigger a rolling update when the deployment is updated.
- Add a 'spec-template-spec-imagePullPolicy: Always" to ensure that the new image is pulled even if it exists in the pod's local cache.

2. Create the Deployment - Apply the updated YAML file using 'kubectl apply -f wordpress-deploymentyamr 3. Verify the Deployment: - Check the status of the deployment using 'kubectl get deployments wordpress-deployment to confirm the rollout and updated replica count. 4. Trigger the Automatic Update: - Push a new image to the 'wordpress/wordpress:latest' Docker Hub repository. 5. Monitor the Deployment: - Use 'kubectl get pods -l app=wordpress' to monitor the pod updates during the rolling update process. You will observe that two pods are terminated at a time, while two new pods with the updated image are created. 6. Check for Successful Update: - Once the deployment is complete, use 'kubectl describe deployment wordpress-deployment' to see that the 'updatedReplicas' field matches the 'replicas' field, indicating a successful update.

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Create a Kubernetes Secret for Docker Hub Credentials:
- You'll need a Secret to securely store your Docker Hub credentials for pulling images. Create a Secret with the following YAML:

- Replace with the base64 encoded content of your Docker Hub credentials file. This file is typically named '~/.docker/config.json' and contains your Docker Hub username and password. You can create this file or update it manually. To encode the file, use a command like 'base64 ~/.docker/config .jsons 2. Create a ConfigMap for Deployment Configuratiom - Create a ConfigMap to hold the image name and any other deployment-specific configuration:

3. Define a Deployment with a Blue-Green Strategy: - Create a Deployment named swordpress-deployment that incorporates the blue-green deployment strategy. This Deployment will have a 'strategy' section with a 'type' of 'Recreate' (for initial deployment) and a 'blueGreenDeploymentStrategy' section: 4. Create a Service.

- Create a Kubernetes Service that exposes your WordPress application. This service will automatically route traffic to the active replica set.

5. Automate the Blue-Green Deployment - Use a 'DeploymentConfig' resource to configure the automatic deployment

6. Apply the resources: - Apply all the YAML files using 'kubectl apply -f' to create the necessary resources. 7. Trigger the Blue-Green Deployment - Push a new image to the Docker Hub repository 'example/wordpress:latest' The 'Deploymentconfig' will automatically trigger the blue-green deployment: -A new replica set with the updated image will be created, and traffic will be shifted to the new replica set gradually - Once the traffic has been shifted, the old replica set will be deleted. Note: This implementation assumes that you are using OpenShift. If you are using a different Kubernetes distribution, the configuration may need to be adjusted SligntlY. ,

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Create a Service for Each Environment:
- Define services for both 'staging' and 'production' environments, ensuring that the services for each environment are named appropriately. For example, 'staging-service' and .

2. Create an Ingress Resource: - Define an Ingress resource that maps the hostnames to the corresponding services.

3. Apply the Configuration: - Apply the service and ingress definitions using 'kubectl apply -f services.yaml' and 'kubectl apply -f ingress.yaml' respectively. 4. Test the Configuration: - Access 'staging.example.com' and 'example.com' in your browser to ensure that the traffic is directed to the correct services and environments. ,

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Define the Pod YAMI-: Create a Pod definition that includes two containers: one tor the web server and one for the database.

2. Configure Networking: The key to allowing the web server to connect to the database is to use the pod's internal network. Since containers Within a pod share the same network namespace, you can configure the webserver to connect to the database using the name "db". 3. Environment Variables: Set an environment variable CDB HOST') within the webserver container to point to the database container by its name. This ensures the web server can correctly connect to the database within the pod. 4. Pod Deployment: Apply the YAML to create the pod using 'kubectl apply -f web-db-pod.yamr. 5. Verification: To check the pod's status: - Run 'kubectl get pods' - Check the logs of the web server container to confirm it can connect to the database. 6. Important Note: In this example, we're using the default pod networking within Kubernetes. For more complex applications, consider using a service to expose the database container This will allow access to the database from outside the pod.,

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Create the ConfigMap: Define the ConfigMap with your desired environment variables.

2. Update the Deployment: Modify your Deployment YAML file to: - Use a 'volumeMount' to mount the ConfigMap into the container. - Specify a 'volume' using a 'configMap' source, referencing tne 'app-config' ConfigMap. - Set 'imagePullPolicy: Always' to ensure the pod always pulls the latest container image.

3. Apply the changes: Use 'kubectl apply -f deployment-yamp to update the Deployment 4. Llpdate the ConfigMap: Whenever you need to update the configuration, modify the Sapp-config' ConfigMap using 'kubectl apply -f configmap-yamr 5. Verify changes: Observe the pods for the 'web-app' Deployment. They should automatically restart and pick up the new environment variables from the updated ConfigMap. By setting 'imagePullPolicy: AlwayS , your pods will always pull the latest container image- This ensures that the pod's container always uses the latest code. Additionally, the 'volumeMount' and 'volume detinitions mount tne Sapp-config' ConfigMap into the containers 'letc/config' directory, making the environment variables accessible within the container When you update the ConfigMap, the pod will detect the change and automatically restart, loading the new configuration from the updated ConfigMap. ,

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1. Create the Service YAMI-:
- Define the service type as 'LoadBalancer' to expose it via a public IP
- Set the 'targetPort' to the port that the web server listens on inside the pods (let's assume it's 8080)-
- Set the 'port' to 8080, which will be the port used to access the service from outside the cluster.

2. Apply the Service: - Use 'kubectl apply -f web-app-service.yaml' to create the service- 3. Get the External IP: - Once the service iS created, use 'kubectl get services web-app-services to get the external IP address. This will be assigned by the cloud provider and will be available for users to access the application. 4. Test the Service: - Access the application using the external IP address and port 8080. For example, if the external IP is '123.45.67.89' , you would access the application through 'http://123.45.67.89:8080' ,

See the solution below with Step by Step Explanation.
Explanation:
Solution (Step by Step) :
1 . Create a CRD for Secret Validation:
- Define a Custom Resource Definition (CRD) named 'SecretValidator' to specify the required secret for the deployment.
- This CRD will have a 'spec' section containing the name of the secret.

2. Create a Validation Webhook Configuration: - Create a ValidatingWebhookConfiguration resource. - Define the 'rules' to match the 'SecretValidatoo CRD and ensure that the webhook is triggered for all operations on the CRD. - Specify the 'failurePolicy' as 'Fail' to prevent pod deployment if the validation fails. - Provide the 'admissionReviewVersions' to indicate the supported API versions. - Set the 'sideEffects' to 'None' as the webhook only performs validation and does not modify the object.

3. Create the Secret Validation Service: - Create a Deployment for a service that will handle the validation webhook requests. - The service should have a container with a code that checks if the required secret exists in the namespace.

4. Implement the Validation Logic in the Service: - In the code of the secret validation service container, you will need to: - Receive the request from the Kubernetes API server. - Retrieve the 'secretName' from the 'SecretValidator' CRD. - Check if a secret with that name exists in the namespace. - If the secret exists, allow the pod deployment. - If the secret does not exist, deny the pod deployment and return an error message. package main import ( "context" "encoding/json" "fmt" "io/ioutil" "net/http" metavl "k8s.io/apimachinery/pkg/apis/meta/v1" "k8s.io/apimachinery/pkg/runtime" "k8s.io/apimachinery/pkg/runtime/serializer" "k8s.io/apimachinery/pkg/types" "k8s.io/client-go/kubernetes" "k8s.io/client-go/rest" func main() { // Create a Kubernetes clientset config, err := rest. InClusterConfig() if err != nil { panic(err) clientset, err := kubernetes.NewForConfig(config) if err != nil { panic(err) // Create a scheme for decoding the CRD scheme := runtime.NewScheme() codecs := serializer.NewCodecFactory(scheme) deserializer := codecs.UniversalDeserializer() // Start the HTTP server http.HandleFunc("/validate", func(w http.ResponseWriter, r http.Request) { // Read the admission review request body body, err := ioutil.ReadAll(r.Body) if err != nil { http.Error(w, fmt.Sprintf("Error reading body: %v" err), http.StatuslnternalServerError) return } // Unmarshal the admission review request var admissionReview metavl .AdmissionReview , err = deserializer.Decode(body, nil, &admissionReview) if err != nil { http.Error(w, fmt.Sprintf("Error decoding admission review: %v", err), http.StatuslnternalServerError) return } // Unmarshal the admission review request var admissionReview metavl .AdmissionReview , err = deserializer.Decode(body, nil, &admissionReview) if err != nil { http.Error(w, fmt.Sprintf("Error decoding admission review: %v", err), http.StatuslnternalServerError) return } // Check if the secret exists , err = clientset.CoreV1 ().Secrets(admissionReview.Request.Namespace).Get(context.TODO(), secretValidator.Spec.SecretName, metavl .GetOptions{}) if err nil { // Secret does not exist, deny the request admissionReview.Response = &metavl .AdmissionResponse{ IJID: admissionReview.Request.UlD, Allowed: false, Result: &metavl .Status{ Status: metavl .StatusFailure, Message: fmt.Sprintf("Secret %s not found in namespace %s", secretValidator.Spec.SecretName, admissionReview.Request.Namespace), } } } else { // Secret exists, allow the request admissionReview.Response = &metavl .AdmissionResponse{ UID: admissionReview.Request.UlD, Allowed: true, Result: &metavl .Status{ Status: metavl .StatusSuccess, // Marshal the admission review response response, err := json.Marshal(admissionReview) if err nil { http.Error(w, fmt.Sprintf("Error marshaling admission review: %v", err), http.StatuslnternalServerError) return } // Write the response to the client w.WriteHeader(http.StatusOK) w.Write(response) }) // Start the HTTP server on port 8443 http.ListenAndServeTLS(":8443", "/path/to/cert.pem", "/path/to/key.pem", nil) } // Define the SecretValidator CRD type SecretValidator struct { metav1 .TypeMeta metav1 .ObjectMeta Spec SecretValidatorSpec } type SecretValidatorSpec struct {

} 5. Create a SecretValidator Resource: - Create a 'SecretValidator' resource in the same namespace as the deployment. - Set the 'spec.secretName' to the name of the required secret.

6. Deploy the Application with the Validation: - Ensure that the deployment for the application is in the same namespace as the 'SecretValidator' resource. - The deployment should reference the 'SecretValidator' resource in its annotations to trigger the validation webhook.

Note: This setup will only work for deployment creation. For other operations (e.g., updates), you need to update the 'rules' in the 'ValidatingWebhookConfiguration'. You can also extend this solution to validate other resources or create more specific validation policies.]