Oracle 1Z0-1084-22 Exam

Setting up ExternalDNS for Oracle Cloud Infrastructure (OCI):

Inspired byKubernetes DNS, Kubernetes' cluster-internal DNS server, ExternalDNS makes Kubernetes resources discoverable via public DNS servers. Like KubeDNS, it retrieves a list of resources (Services, Ingresses, etc.) from theKubernetes APIto determine a desired list of DNS records.

In a broader sense,ExternalDNSallows you tocontrol DNS records dynamically via Kubernetes resources in a DNS provider-agnostic way

Deploy ExternalDNS

Connect yourkubectlclient to the cluster you want to test ExternalDNS with. We first need to create a config file containing the information needed to connect with the OCI API.

Create a new file (oci.yaml) and modify the contents to match the example below. Be sure to adjust the values to match your own credentials:

auth:

region: us-phoenix-1

tenancy: ocid1.tenancy.oc1...

user: ocid1.user.oc1...

key: |

-----BEGIN RSA PRIVATE KEY-----

-----END RSA PRIVATE KEY-----

fingerprint: af:81:71:8e...

compartment: ocid1.compartment.oc1...

References:

https://github.com/kubernetes-sigs/external-dns/blob/master/README.md

https://github.com/kubernetes-sigs/external-dns/blob/master/docs/tutorials/oracle.md

What Is Cloud Native?

Cloud native technologies are characterized by the use of containers, microservices, serverless functions, development pipelines, infrastructure expressed as code, event-driven applications, and Application Programming Interfaces (APIs). Cloud native enables faster software development and the ability to build applications that are resilient, manageable, observable, and dynamically scalable to global enterprise levels.

When constructing a cloud-native application, you'll want to be sensitive to how back-end services communicate with each other. Ideally, the less inter-service communication, the better. However, avoidance isn't always possible as back-end services often rely on one another to complete an operation.

While direct HTTP calls between microservices are relatively simple to implement, care should be taken to minimize this practice. To start, these calls are alwayssynchronousand will block the operation until a result is returned or the request times outs. What were once self-contained, independent services, able to evolve independently and deploy frequently, now become coupled to each other. As coupling among microservices increase, their architectural benefits diminish.

Executing an infrequent request that makes a single direct HTTP call to another microservice might be acceptable for some systems. However, high-volume calls that invoke direct HTTP calls to multiple microservices aren't advisable. They can increase latency and negatively impact the performance, scalability, and availability of your system. Even worse, along series of direct HTTP communication can lead to deep and complex chains of synchronous microservices calls,shown in Figure 4-9:

A message queue is an intermediary construct through which a producer and consumer pass a message. Queuesimplement an asynchronous, point-to-point messaging pattern.

Events

Message queuingis an effective way to implement communication where a producer canasynchronouslysend a consumer a message.

References:

https://www.xenonstack.com/blog/cloud-native-architecture/

https://www.oracle.com/sa/cloud/cloud-native/

https://www.oracle.com/technetwork/topics/entarch/cloud-native-app-development-wp-3664668.pdf

Serverless computing refers to a concept in which the user does not need to manage any server infrastructure at all. The user does not run any servers, but instead deploys the application code to a service provider's platform. The application logic is executed,scaled, and billed on demand, without any costs to the user when the application is idle.

Benefits of the Serverless or FaaS

So far almost every aspect of Serverless or FaaS is discussed in a brief, so let's talk about the pros and cons of using Serverless or FaaS

Reduced operational and development cost

Serverless or FaaS offers less operational and development cost as it encourages to use third-party services like Auth, Database and etc.

Scaling

Horizontal scaling in Serverless or FaaS is completely automatic, elastic and managed by FaaS provider.If your application needs more requests to be processed in parallel the provider will take of that without you providing any additional configuration.

References:

https://medium.com/@avishwakarma/serverless-or-faas-a-deep-dive-e67908ca69d5

https://qvik.com/news/serverless-faas-computing-costs/

https://pages.awscloud.com/rs/112-TZM-766/images/PTNR_gsc-serverless-ebook_Feb-2019.pdf

What Is Cloud Native?

Cloud native technologies are characterized by the use of containers, microservices, serverless functions, development pipelines, infrastructure expressed as code, event-driven applications, and Application Programming Interfaces (APIs). Cloud native enables faster software development and the ability to build applications that are resilient, manageable, observable, and dynamically scalable to global enterprise levels.

When constructing a cloud-native application, you'll want to be sensitive to how back-end services communicate with each other. Ideally, the less inter-service communication, the better. However, avoidance isn't always possible as back-end services often rely on one another to complete an operation.

While direct HTTP calls between microservices are relatively simple to implement, care should be taken to minimize this practice. To start, these calls are alwayssynchronousand will block the operation until a result is returned or the request times outs. What were once self-contained, independent services, able to evolve independently and deploy frequently, now become coupled to each other. As coupling among microservices increase, their architectural benefits diminish.

Executing an infrequent request that makes a single direct HTTP call to another microservice might be acceptable for some systems. However, high-volume calls that invoke direct HTTP calls to multiple microservices aren't advisable. They can increase latency and negatively impact the performance, scalability, and availability of your system. Even worse, along series of direct HTTP communication can lead to deep and complex chains of synchronous microservices calls,shown in Figure 4-9:

A message queue is an intermediary construct through which a producer and consumer pass a message. Queuesimplement an asynchronous, point-to-point messaging pattern.

Events

Message queuingis an effective way to implement communication where a producer canasynchronouslysend a consumer a message.

References:

https://www.xenonstack.com/blog/cloud-native-architecture/

https://www.oracle.com/sa/cloud/cloud-native/

https://www.oracle.com/technetwork/topics/entarch/cloud-native-app-development-wp-3664668.pdf

Before using Oracle Functions, you must have an Oracle Cloud Infrastructure CLI configuration file that contains the credentials of the user account that you will be using to create and deploy functions. These user account credentials are referred to as a 'profile'.

By default, the Oracle Cloud Infrastructure CLI configuration file is located at~/.oci/config. You might already have a configuration file as a result of installing the Oracle Cloud Infrastructure CLI. However, you don't need to have installed the Oracle Cloud Infrastructure CLI in order to use Oracle Functions.

References:

https://docs.cloud.oracle.com/en-us/iaas/Content/Functions/Tasks/functionsconfigureocicli.htm#:~:text=By%20default%2C%20the%20Oracle%20Cloud,file%20is%20located%20at%20~%2F.

https://docs.cloud.oracle.com/en-us/iaas/Content/API/SDKDocs/cliconfigure.htm