Microservice platforms are getting popular as it is helping in scale development. It helps in replacing the legacy system. SAP BTP is a Platform as a Service (Paas) provides microservice platforms
SAP BTP, Kubernetes
It was originally developed by Google. It can run any Docker container, means it helps to manage applications that are made up of multiple containers and manage them in different environments.
Functionalities it offers
High Availability - no downtime
High performance – Loads fast and users get high speed response
Backup and restore – Run from the latest state after recovery
In SAP BTP when the Kyma Environment is activated and, in the dashboard, below components of Kubernetes can be found. The below explanation will help to get an overview understanding of components of Kubernetes
It is the smallest unit of Kubernetes. It creates a running environment on top of the container. It is usually meant to run one application each POD. Each POD gets IP and communicate each other with IP address. The IP address is internal not public. If POD dies IP address stay and new POD gets attached. POD communicate with each other using component Service.
Blueprint of pods. In deployments it can specify how many replicas are needed. It is an abstraction of POD and it would be mostly working on deployment. It is abstraction over POD. If one of replica of POD would die the SERVICE would forward the request the another one. So, the application would be still accessible.
It is a static IP address that can be attached to each POD. Each POD will have its own SERVICE. When a POD dies the SERVICE and its IP address will stay.
When POD Dies.
The application will be replicated to another node avoid downtime. SERVICE is persistence permanent IP with DNS name does not need to adjust end point. Also, SERVICE act like load balance which helps to access App from the node which is available.
In cases where it needs the Apps along with database to be replicated, it cannot use DEPLOYMENT. STATEFULSET helps in replicating PODS avoid inconsistency of data.
Application as external service. The IP and port of the application is masked. Ingress does forward to SERVICE.
Each application will have its database endpoint. CONFIGMAP component would contain external configuration of application. So that in future it can change the configuration using this component. CONFIGMAP is connected to POD.
CONFIGAMP store credentials in plain text. To overcome this Secret component helps to store the confidential data.
If POD gets restarted the data will be lost. VOLUMES help in retain the data. Attach storage with DB POD.
Kubernetes doesn’t manage data persistence.
These are the main components that are created and configured in Kubernetes that help the application run in POD. With all these components running perfectly User can access the application using URL through browser.