Blogs

Sidecar pattern is a single-node pattern made up of two containers. It involves co-locating another container in a node/pod along with the main application container. The application container contains the core logic for the application. The role of the sidecar is to augment and improve the application container, often without the application container’s knowledge. In its simplest form, a sidecar container can be used to add functionality to a container that might otherwise be difficult to add. In addition to being co-located on the same machine, the application container and sidecar container share several resources, including parts of the filesystem, hostname and network, and many other namespaces. The sidecar can be plugged and unplugged from the main application, since it is isolated and cannot impact the application in case it starts misbehaving. ...

Transactional Outbox is a pattern to reliably publish messages without the use of distributed transactions. It uses an Outbox and a message dispatcher to reliably persist state and publish messages.

The Idempotent Consumer pattern provides the necessary safeguards to allows logic wrapped by it to be executed only once. It implements an unique identifier for each message and an idempotent repository.

Event driven architecture (EDA) is an architectural paradigm where behavior is composed by reacting to events. In this paradigm events imply a significant change in state.

A single container provides application isolation and mobility. However, a container by itself doesn’t improve the quality of your service—for example, in terms of load balancing or failover. This is where multi-container solutions come into play. However managing a handful of containers is completely different from managing production-scale containers, which may number from hundreds to thousands. To support container management, we need an easy way of deploying and handling these containers at scale. This is where container orchestration. comes into play. ...

An API Gateway provides a single and unified API entry point across one or more internal APIs. It mediates, routes, and invokes a respective endpoint after request verification, content filtering, authentication, and authorization.

Controllers create and manage pods. Controllers respond to pod state and health. Kubernetes lets you assert that resources such as pods are in a certain desired state, with specific versions. Controllers track those resources and attempt to run your software as described. There are a variety of controllers in Kubernetes, primarily ReplicaSets and Deployments. ReplicaSet - A ReplicaSet is responsible for reconciling the desired state at all times. The ReplicaSet is used to define and manage a collection of identical pods that are running on different cluster nodes. A ReplicaSet defines the image are used by the containers in the pod and the number of instances of the pod that will run in the cluster. These properties and the many others are called the desired state. If some Pods in the ReplicaSet crash and terminate, the system will recreate Pods with the original configurations on healthy nodes automatically and keep a certain number of processes continuously running. For e.g if you specified three Pods in a ReplicaSet and one fails, Kubernetes will automatically schedule and run another Pod for you. If elementary conditions are met (for example, enough memory and CPU), Pods associated with a ReplicaSet are guaranteed to run. They provide fault-tolerance, high availability, and self-healing capabilities. ...

Pods are an important feature of Kubernetes. A Pod is the smallest unit of work that Kubernetes manages and is the fundamental unit that the rest of the system is built on. Each pod contains one or more containers. Instead of deploying containers individually, you always deploy and operate on a pod of containers. Pods are always scheduled together (always run on the same machine). A pod is as an atomic unit. Even if a pod does contain multiple containers, they are always run on a single worker node, it never spans multiple worker nodes. All the containers in a pod have the same IP address and port space. They communicate using localhost or standard inter-process communication. All containers in a pod have access to shared local storage on the node hosting the pod. This shared storage is mounted on each container. Pods provide a great solution for managing groups of closely related containers that depend on each other and need to co-operate on the same host to accomplish their purpose. Pods are considered as ephemeral, throwaway entities that can be discarded and replaced at will. Any pod storage is destroyed with its pod. Each pod gets a unique ID (UID), so you can still distinguish between them if necessary. ...

Circuit breakers help to avoid one failing component tearing down other dependent services in a domino effect. The key idea is for a service to fail fast if a dependent resource is not available, as opposed to waiting for a timeout/error for each service invocation during the period in which the dependent resource is down.

The Reactive Manifesto describes how to design and architect Reactive systems according to your needs.Systems built as Reactive Systems are more Reliable, flexible, loosely coupled, scalable and resilient. This makes them easier to develop and amenable to change. Reactive systems are more tolerant of failure and when failure does occur, they meet it with elegance rather than disaster.