In a world as complex and distributed as the cloud, the need for a central authorization system used among various platforms has never been more significant. Microservices and applications tend to either have their own authorization logic constructed into the code or depend on external authorization systems. This makes introducing new policies or making changes to the existing ones unnecessarily messy and complex. This is where the need for a unified system to enforce policies across the entire cloud native stack is quite pronounced. Open Policy Agent tends to hit the nail right on the head here. Let’s understand how.
What is Open Policy Agent (OPA)?
OPA is an open source policy engine that acts as a unified framework that amalgamates and automates the implementation of policies across the cloud native stack. It is a domain agnostic decision engine that separates policy decisions from enforcement. OPA helps decouple policy from application logic which means that you can extract your policy from regular business or application logic. It runs as a self-contained server binary. OPA enables you to translate written security policies into executable code for every layer of the cloud native stack. It can be used to centralize security, operation, and compliance across CI/CD pipelines, APIs, Kubernetes, and the ilk.
How does OPA function?
OPA is a unified toolset for implementing policies across an entire stack. But, how can OPA service requests for all the diverse services and technologies? The answer behind that is the Policy decision model. When any service needs to make an authorization decision, it makes the decision inquiry to the relevant OPA API. This inquiry is then evaluated against the policies already stored in the OPA and responds with a decision. Both requests and responses are sent in a JSON format and policies are written using a high-level language specifically designed for OPA called Rego.
OPA utilizes a multitude of APIs to make it easy to inject new policies and check the status of existing ones. It should ideally be deployed as close to your service as possible. It offers architectural flexibility as it can be deployed as a standalone daemon, a container, or as a Go library. A crucial design basis of OPA is that policies and service data are both stored in the memory of the relevant host.
OPA’s take on cloud native policy management
When it comes to the cloud native world, systems are increasingly complex and heterogeneous. So, to be able to manage policy in these systems is complicated and painful. The cloud environment has a variety of frameworks, deployment platforms, and programming languages as well as the underlying infrastructure and data that come with their own ways of dealing with policy. Therefore, the goal is to unify policy enforcement where managing, distributing, and logging policy across an entire stack is united. This is where OPA comes in. It fulfills the promise of unifying policy enforcement across the stack.
You can introduce OPA at any level of the stack and in any system as it helps you perform various tasks at various levels:
1. It is integrated with Kubernetes for things like enforcing admission control policies, extending the basic features, and acting as an authorizer. You have to first deploy OPA as a mutating admission controller. Then, you can inject pods with sidecar containers, add particular annotations to your resources, and more.
OPA also helps administrators set simple policies that allow developers to accelerate pipeline production without worrying about operational security. OPA has the ability to reject resources disallowed by the policy as it integrates directly with the Kubernetes API.
2. OPA is integrated with service mesh projects like Istio to enable you to create and add authorization policies right into your service mesh. This decreases lateral movement and enforces compliance regulations.
3. Authorization policy is omnipresent but usually seems like a collage where different developers come out with their own version of code and everything is put together. This is not only messy, but it is also a time consuming process that OPA helps avoid entirely. So, OPA uses a declarative policy language, Rego, that makes the above task fairly simple. This language is essentially focused on two things: logic and data. This means that when you are writing policies, you are only focussing on the logic and data relevant to the policies.
OPA at scale
At scale, OPA reaches out to a few API endpoints for management features like bundles, to fetch policy and data from a centralized location. The decision log API enables OPA instances to report back on any decisions made. These can be used to improve the quality of your policies. The status API allows OPA to send health updates to the management server.
Security breaches have glaringly increased in the past 3 years. And a lack of policy enforcement only adds to the risk of security breaches, downtimes, etc. Therefore, there is a severe need for security frameworks within enterprises. Open Policy Agent (OPA) provides a framework that enables companies to automate a multitude of security checks. It makes it easier to analyze information in a distributed environment. The deal is made sweeter by the fact that OPA can integrate with many modern-day systems and has created a unified approach to create and enforce policies across an entire cloud native stack. As microservices grow, so will the adoption of OPA.
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