Install opa with Homebrew

Project links

• Homepage
• Repository

Commands and aliases

• opa

Project history

OPA was created to provide a unified policy decision point across the stack. The official docs describe it as an open-source, general-purpose policy engine with simple APIs for offloading policy decisions and a high-level declarative language, Rego, for writing policies against structured data.

OPA entered the Cloud Native Computing Foundation on March 29, 2018, moved to Incubating on April 2, 2019, and reached Graduated maturity on January 29, 2021. CNCF's graduation announcement emphasized open governance, feature maturity, sustainability, and production use across cloud-native environments.

Adoption history

By the 2021 CNCF graduation announcement, OPA had more than 90 contributors from roughly 30 organizations, maintainers from Google, Microsoft, VMware, and Styra, and production adoption at organizations including Goldman Sachs, Netflix, Pinterest, and T-Mobile. CNCF also reported survey data from more than 150 organizations, with 91% using OPA in some stage from QA to production.

OPA's ecosystem expanded through Kubernetes admission control, Envoy authorization, CI/CD checks, API gateways, service meshes, and infrastructure-as-code validation. Gatekeeper became the Kubernetes-native policy-controller companion, while related tools such as Conftest and OPA's official ecosystem entries made the opa binary useful both in clusters and in developer workflows.

How it is used

Developers write Rego policies and feed OPA JSON-like input and data. The opa CLI is used to run policies locally, test Rego, build bundles, evaluate decisions, and support CI checks; services can call OPA over APIs or embed policy evaluation into a broader control plane.

Platform and security teams use OPA to enforce Kubernetes admission rules, API authorization, deployment guardrails, configuration rules, and audit policies without hard-coding every rule in each application. The same policy language can be reused from local command-line checks to production admission controllers.

Why package nerds care

OPA is one of the canonical examples of a single CLI package representing a much larger cloud-native control-plane concept. The Homebrew formula is just opa, but the binary brings a policy language, evaluator, test runner, bundle format, server mode, WebAssembly targets, and a CNCF ecosystem with it.

Timeline

• 2018-03-29: OPA was accepted into the CNCF.
• 2019-04-02: OPA moved to CNCF Incubating maturity.
• 2019: Kubernetes Gatekeeper work helped make OPA a common choice for admission control and cluster policy.
• 2021-01-29: OPA reached CNCF Graduated maturity.
• 2021-02-04: CNCF announced OPA's graduation and summarized contributor, maintainer, and adopter data.

Related projects

• Related projects include OPA Gatekeeper, Conftest, Rego Playground, Kubernetes admission webhooks, Envoy external authorization integrations, SPIFFE/SPIRE, Helm, CoreDNS, and other policy-as-code tooling.

Sources

• https://formulae.brew.sh/formula/opa
• https://kubernetes.io/blog/2019/08/06/opa-gatekeeper-policy-and-governance-for-kubernetes/
• https://openpolicyagent.org/ecosystem/entry/gatekeeper
• https://www.cncf.io/announcements/2021/02/04/cloud-native-computing-foundation-announces-open-policy-agent-graduation/
• https://www.cncf.io/projects/open-policy-agent-opa/
• https://www.openpolicyagent.org/docs
• https://www.openpolicyagent.org/docs/policy-language