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 always synchronous and 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, a long 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. Queues implement an asynchronous, point-to-point messaging pattern.
Events
Message queuing is an effective way to implement communication where a producer can asynchronously send 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

Troubleshooting Oracle Functions:
There are common issues related to Oracle Functions and how you can address them.
Invoking a function returns a FunctionInvokeSubnetNotAvailable message and a 502 error (due to a DHCP Options issue) When you invoke a function that you've deployed to Oracle Functions, you might see the following error message:
{"code":"FunctionInvokeSubnetNotAvailable","message":"dhcp options ocid1.dhcpoptions........ does not exist or Oracle Functions is not authorized to use it"} Fn: Error invoking function. status: 502 message: dhcp options ocid1.dhcpoptions........ does not exist or Oracle Functions is not authorized to use it If you see this error:
Double-check that a policy has been created to give Oracle Functions access to network resources.
Create Policies to Control Access to Network and Function-Related Resources:
Service Access to Network Resources
When Oracle Functions users create a function or application, they have to specify a VCN and a subnet in which to create them. To enable the Oracle Functions service to create the function or application in the specified VCN and subnet, you must create an identity policy to grant the Oracle Functions service access to the compartment to which the network resources belong.
To create a policy to give the Oracle Functions service access to network resources:
Log in to the Console as a tenancy administrator.
Create a new policy in the root compartment:
Open the navigation menu. Under Governance and Administration, go to Identity and click Policies.
Follow the instructions in To create a policy, and give the policy a name (for example, functions-service-network-access).
Specify a policy statement to give the Oracle Functions service access to the network resources in the compartment:
Allow service FaaS to use virtual-network-family in compartment <compartment-name> For example:
Allow service FaaS to use virtual-network-family in compartment acme-network Click Create.
Double-check that the set of DHCP Options in the VCN specified for the application still exists.
References:
https://docs.cloud.oracle.com/en-us/iaas/Content/Functions/Tasks/functionstroubleshooting.htm
https://docs.cloud.oracle.com/en-us/iaas/Content/Functions/Tasks/functionscreatingpolicies.htm

When a function you've deployed to Oracle Functions is running, it can access other Oracle Cloud Infrastructure resources. For example:
- You might want a function to get a list of VCNs from the Networking service.
- You might want a function to read data from an Object Storage bucket, perform some operation on the data, and then write the modified data back to the Object Storage bucket.
To enable a function to access another Oracle Cloud Infrastructure resource, you have to include the function in a dynamic group, and then create a policy to grant the dynamic group access to that resource.
https://docs.cloud.oracle.com/en-us/iaas/Content/Functions/Tasks/functionsaccessingociresources.htm

Setting up ExternalDNS for Oracle Cloud Infrastructure (OCI):
Inspired by Kubernetes 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 the Kubernetes API to determine a desired list of DNS records.
In a broader sense, ExternalDNS allows you to control DNS records dynamically via Kubernetes resources in a DNS provider-agnostic way Deploy ExternalDNS Connect your kubectl client 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

If you are running your Kubernetes cluster on Oracle Container Engine for Kubernetes (commonly known as OKE), you can have OCI automatically provision load balancers for you by creating a Service of type LoadBalancer instead of (or in addition to) installing an ingress controller like Traefik or Voyage YAML file

When you apply this YAML file to your cluster, you will see the new service is created. After a short time (typically less than a minute) the OCI Load Balancer will be provisioned.

https://oracle.github.io/weblogic-kubernetes-operator/faq/oci-lb/