Explanation
Overviewof Functions:
The serverless and elastic architecture of Oracle Functions means there's no infrastructure administration or software administration for you to perform. You don't provision or maintain compute instances, and operating system softwarepatches and upgrades are applied automatically. Oracle Functions simply ensures your app is highly-available, scalable, secure, and monitored. With Oracle Functions, you can write code in Java, Python, Node, Go, and Ruby (and for advanced use cases, bringyour own Dockerfile, and Graal VM). You can then deploy your code, call it directly or trigger it in response to events, and get billed only for the resources consumed during the execution.
References:
https://docs.cloud.oracle.com/en-us/iaas/Content/Functions/Concepts/functionsoverview.htm

Explanation
Oracle Functions: Using Key Management To Encrypt And Decrypt Configuration Variables Since this process involves multiple steps, I thought it would be helpful to give you an outline of the steps that we're going to take:
Create a KMS vault
Create a Master Encryption Key
Generate a Data Encryption Key
Use the DEK plaintext return value to encrypt the sensitive value (offline) Store the encrypted sensitive value as a config variable in the serverless application Store the DEK ciphertext and the initVector used to encrypt the sensitive value as Function config variables Within the function, decrypt theDEK ciphertext back into plaintext using the OCID and Cryptographic Endpoint by invoking the OCI KMS SDK Decrypt the sensitive value using the decrypted DEK plaintext and the initVector


References:
https://blogs.oracle.com/developers/oracle-functions-using-key-management-to-encrypt-and-decrypt-configuratio
https://docs.oracle.com/en/database/other-databases/essbase/19.3/essad/encrypt-values-using-kms.html

Explanation
microservice is larger and can do more than a function. A function is a relatively small bit of code that performs only one action in response to an event.
Many microservices can run on several servers, and different instances of a specific microservice can run on several servers.
In many cases, microservices can be decomposed into a number of smaller stateless functions. The difference between microservices and functions is not simply the size. Functions are stateless, and they require no knowledge about or configuration of the underlying server-hence, the term serverless.
Microservices are best suited for long-running, complex applications that have significant resource and management requirements. You can migrate an existing monolithic application to microservices, which makes it easier to modularly develop features for the application and deploy it in the cloud. Microservices are also a good choice for building e-commerce sites, as they can retain information throughout a transaction and meet the needs of a 24/7 customer base.
On the other hand, serverless functions only execute when needed. Once the execution is over, the computing instance that runs the code decommissions itself. Serverless aligns with applications that are event driven, especially when the events are sporadic and the event processingis not resource-intensive. Serverless is a good choice when developers need to deploy fast and there are minimal application scaling concerns. For example, a good use of serverless computing is a scheduled task that needs to perform some data aggregation and will execute for just a few seconds.

References:
https://www.cloudflare.com/learning/serverless/glossary/serverless-microservice/
https://developer.oracle.com/java/fn-project-introduction.html
https://searchapparchitecture.techtarget.com/answer/When-should-I-choose-between-serverless-and-microservice

Explanation
Kubernetes cluster is a group of nodes. The nodes are the machines running applications. Each node can be a physical machine or a virtual machine. The node'scapacity (its number of CPUs and amount of memory) is defined when the node is created. A cluster comprises:
- one or more master nodes (for high availability, typically there will be a number of master nodes)
- one or more worker nodes (sometimes known asminions)
Connecting to Worker Nodes Using SSH
If you provided a public SSH key when creating the node pool in a cluster, the public key is installed on all worker nodes in the cluster. On UNIX and UNIX-like platforms (including Solaris and Linux), you canthen connect through SSH to the worker nodes using the ssh utility (an SSH client) to perform administrative tasks.
Note the following instructions assume the UNIX machine you use to connect to the worker node:
Has the ssh utility installed.
Has access tothe SSH private key file paired with the SSH public key that was specified when the cluster was created.
How to connect to worker nodes using SSH depends on whether you specified public or private subnets for the worker nodes when defining the node poolsin the cluster.
Connecting to Worker Nodes in Public Subnets Using SSH
Before you can connect to a worker node in a public subnet using SSH, you must define an ingress rule in the subnet's security list to allow SSH access. The ingress rule must allow access to port 22 on worker nodes from source 0.0.0.0/0 and any source port To connect to a worker node in a public subnet through SSH from a UNIX machine using the ssh utility:
1- Find out the IP address of the worker node to which you want to connect. You can do this in a number of ways:
Using kubectl. If you haven't already done so, follow the steps to set up the cluster's kubeconfig configuration file and (if necessary) set the KUBECONFIG environment variable to point to the file. Note that you must set upyour own kubeconfig file. You cannot access a cluster using a kubeconfig file that a different user set up.
See Setting Up Cluster Access. Then in a terminal window, enter kubectl get nodes to see the public IP addresses of worker nodes in node pools in the cluster.
Using the Console. In the Console, display the Cluster List page and then select the cluster to which the worker node belongs. On the Node Pools tab, click the name of the node pool to which the worker node belongs. On the Nodes tab, you see the public IP address of every worker node in the node pool.
Using the REST API. Use the ListNodePools operation to see the public IP addresses of worker nodes in a node pool.
2- In the terminal window, enter ssh opc@<node_ip_address> to connect to the worker node, where <node_ip_address> isthe IP address of the worker node that you made a note of earlier. For example, you might enter ssh [email protected].
Note that if the SSH private key is not stored in the file or in the path that the ssh utility expects (for example, the ssh utility mightexpect the private key to be stored in ~/.ssh/id_rsa), you must explicitly specify the private key filename and location in one of two ways:
Use the -i option to specify the filename and location of the private key. For example, ssh -i
~/.ssh/my_keys/my_host_key_filename [email protected]
Add the private key filename and location to an SSH configuration file, either the client configuration file (~/.ssh/config) if it exists, or the system-wide client configuration file (/etc/ssh/ssh_config). For example, youmight add the following:
Host 192.0.2.254 IdentityFile ~/.ssh/my_keys/my_host_key_filename
For more about the ssh utility's configuration file, enter man ssh_config Note also that permissions on the private key file must allow you read/write/execute access, but prevent other users from accessing the file. For example, to set appropriate permissions, you might enter chmod 600
~/.ssh/my_keys/my_host_key_filename. If permissions are not set correctly and the private key file is accessible to other users, thessh utility will simply ignore the private key file.
References:
https://docs.cloud.oracle.com/en-us/iaas/Content/ContEng/Tasks/contengconnectingworkernodesusingssh.htm

Explanation
https://docs.cloud.oracle.com/en-us/iaas/Content/API/Concepts/sdks.htm