10 OpenShift Interview Questions and Answers in 2023
1. Describe the process of deploying an application to OpenShift.
Deploying an application to OpenShift involves several steps.
First, you need to create an OpenShift project. This is done by logging into the OpenShift web console and selecting the “Create Project” option. You will then need to provide a name for the project and select the appropriate resources for the project.
Next, you will need to create an application within the project. This is done by selecting the “Create Application” option from the project page. You will then need to select the type of application you want to deploy, such as a web application, a database, or a custom application.
Once the application is created, you will need to configure the application. This includes setting up the environment variables, configuring the application’s resources, and setting up the application’s routes.
Once the application is configured, you will need to deploy the application. This is done by selecting the “Deploy” option from the application page. You will then need to provide the source code for the application, such as a Git repository URL or a Docker image.
Once the application is deployed, you will need to monitor the application. This is done by selecting the “Monitor” option from the application page. You will then be able to view the application’s logs, metrics, and other information.
Finally, you will need to scale the application. This is done by selecting the “Scale” option from the application page. You will then be able to adjust the number of replicas of the application, as well as the resources allocated to the application.
By following these steps, you can successfully deploy an application to OpenShift.
2. What is the difference between a pod and a deployment in OpenShift?
A pod in OpenShift is a group of one or more containers that are deployed together on the same host. It is the smallest deployable unit in OpenShift and is the basic building block for applications. A pod contains the application containers, shared storage, and other resources that are needed to run the application.
A deployment in OpenShift is a higher-level construct that is used to manage the lifecycle of an application. It is responsible for creating, updating, and deleting pods as needed to ensure that the desired state of the application is maintained. A deployment can be used to define the desired state of an application, such as the number of replicas, the image to use, and the resources to allocate to each pod. It can also be used to roll out new versions of an application, roll back to a previous version, or pause and resume deployments.
3. How do you troubleshoot an application running on OpenShift?
When troubleshooting an application running on OpenShift, the first step is to identify the source of the issue. This can be done by examining the application logs, checking the application's environment variables, and running diagnostic tests.
Once the source of the issue has been identified, the next step is to determine the cause of the issue. This can be done by examining the application code, checking the application's configuration, and running additional diagnostic tests.
Once the cause of the issue has been identified, the next step is to determine the best way to resolve the issue. This can be done by examining the application code, checking the application's configuration, and running additional diagnostic tests.
Once the best way to resolve the issue has been identified, the next step is to implement the solution. This can be done by making changes to the application code, updating the application's configuration, and running additional tests to ensure the issue has been resolved.
Finally, once the issue has been resolved, the last step is to monitor the application to ensure the issue does not reoccur. This can be done by examining the application logs, checking the application's environment variables, and running additional tests to ensure the issue has been resolved.
4. What is the purpose of the OpenShift router?
The OpenShift router is an important component of the OpenShift platform that provides a secure and reliable way for external clients to access applications running on OpenShift. It is responsible for routing requests from external clients to the appropriate application running on OpenShift. The router is also responsible for providing TLS termination, load balancing, and other features such as URL rewriting and request routing. The router is also responsible for providing a secure connection between the external client and the application running on OpenShift. This ensures that all requests are routed securely and that the application is not exposed to any malicious requests. The router also provides a way for applications to be scaled up or down depending on the load. This allows applications to be scaled up or down depending on the demand, ensuring that applications are always running optimally.
5. How do you configure persistent storage for an application running on OpenShift?
Configuring persistent storage for an application running on OpenShift requires the use of persistent volumes. A persistent volume is a piece of storage that has been provisioned by an administrator and is available to all nodes in the cluster.
To configure persistent storage for an application running on OpenShift, the first step is to create a persistent volume claim (PVC). A PVC is a request for storage from the cluster that is associated with a specific application. The PVC will specify the size and type of storage that is needed.
Once the PVC has been created, it can be bound to a specific application. This is done by creating a deployment configuration for the application and specifying the PVC as a volume. The deployment configuration will also specify the mount path for the volume, which is the location where the application will access the data stored in the persistent volume.
Once the deployment configuration has been created, the application can be deployed to the cluster. The persistent volume will be mounted to the application and the data stored in the persistent volume will be available to the application.
Finally, the persistent volume can be configured to be backed up on a regular basis. This can be done by creating a backup policy for the persistent volume and specifying the frequency and type of backups that should be performed.
6. What is the difference between a service and a route in OpenShift?
A service in OpenShift is an abstraction layer that provides a way to access a set of pods. It is a logical grouping of pods that can be accessed by a single IP address and port. Services are used to provide a consistent way to access the pods, regardless of the underlying pod IP addresses.
A route in OpenShift is a way to expose a service to external clients. It is a way to map a service to a public URL, allowing external clients to access the service. Routes are used to provide a consistent way to access the service from outside the OpenShift cluster.
7. How do you scale an application running on OpenShift?
Scaling an application running on OpenShift can be done in several ways.
The first way is to use the built-in scaling features of OpenShift. This includes scaling up or down the number of replicas of a deployment configuration, scaling up or down the resources allocated to a deployment configuration, and scaling up or down the number of pods in a deployment configuration.
The second way is to use the OpenShift command line interface (CLI) to manually scale an application. This can be done by using the oc scale command, which allows you to specify the number of replicas, the resources allocated to the deployment configuration, and the number of pods in the deployment configuration.
The third way is to use the OpenShift web console to manually scale an application. This can be done by navigating to the deployment configuration page, selecting the “Scale” tab, and then specifying the number of replicas, the resources allocated to the deployment configuration, and the number of pods in the deployment configuration.
The fourth way is to use the OpenShift API to programmatically scale an application. This can be done by making a POST request to the /oapi/v1/namespaces/{namespace}/deploymentconfigs/{name}/scale endpoint, and then specifying the number of replicas, the resources allocated to the deployment configuration, and the number of pods in the deployment configuration.
Finally, the fifth way is to use the OpenShift webhooks feature to automatically scale an application. This can be done by creating a webhook that triggers when certain conditions are met, and then specifying the number of replicas, the resources allocated to the deployment configuration, and the number of pods in the deployment configuration.
8. What is the purpose of the OpenShift template?
The purpose of an OpenShift template is to provide a way to quickly and easily deploy applications and services on the OpenShift platform. It is a set of instructions that define how to deploy an application or service on OpenShift. It includes all the necessary components such as source code, configuration files, environment variables, and other resources needed to deploy the application or service. Templates can be used to quickly deploy applications and services on OpenShift, as well as to customize the deployment process. Templates can also be used to automate the deployment process, making it easier to deploy applications and services on OpenShift.
9. How do you secure an application running on OpenShift?
Securing an application running on OpenShift requires a multi-faceted approach.
First, it is important to ensure that the application is running in a secure environment. This means that the OpenShift cluster should be configured with the appropriate security settings, such as authentication and authorization, and that the nodes should be regularly patched and updated.
Second, the application itself should be configured to use secure protocols and encryption. This includes using TLS/SSL for communication, and ensuring that all data is encrypted at rest.
Third, the application should be configured to use secure authentication and authorization mechanisms. This includes using strong passwords, two-factor authentication, and other measures to ensure that only authorized users can access the application.
Finally, the application should be regularly monitored for security vulnerabilities. This includes using automated tools to scan for vulnerabilities, and regularly reviewing the application's logs for suspicious activity.
10. What is the difference between a build and a deployment in OpenShift?
The difference between a build and a deployment in OpenShift is that a build is the process of transforming source code into a runnable application, while a deployment is the process of taking the built application and making it available to users.
A build in OpenShift is typically initiated by a user pushing code to a source code repository, such as GitHub. OpenShift will then detect the change and initiate a build process. This process involves transforming the source code into a runnable application, such as a Docker image.
Once the build is complete, OpenShift will then deploy the application. This involves taking the built application and making it available to users. This can involve creating a new instance of the application, or updating an existing instance. The deployment process can also involve configuring the application, such as setting environment variables or configuring access control.
In summary, a build is the process of transforming source code into a runnable application, while a deployment is the process of taking the built application and making it available to users.