Project ideas from Hacker News discussions.

Show HN: CEL by Example

📝 Discussion Summary (Click to expand)

Generating summary…


🚀 Project Ideas

Generating project ideas…

CEL Visual Policy Builder

Summary

  • A web‑based drag‑and‑drop editor that lets non‑programmers construct CEL expressions visually, test them against sample JSON, and export the final expression.
  • Provides instant feedback, syntax highlighting, and a library of common predicates (date checks, path prefixes, auto‑expiring grants) to reduce the learning curve.

Details

Key Value
Target Audience DevOps engineers, policy writers, and product managers who need to write CEL for Kubernetes CRDs, admission policies, or IAM rules.
Core Feature Visual composition of CEL expressions, live preview, sample data testing, and export to code snippets.
Tech Stack React + TypeScript, Monaco Editor, Node.js backend for expression validation, Docker for sandboxed evaluation.
Difficulty Medium
Monetization Revenue‑ready: SaaS subscription (tiered by number of policies and API calls).

Notes

  • HN commenters lament the steep learning curve: “I’d love if languages like Scala, Swift or F# had something like Cel but running at compile time.” The visual builder removes that barrier.
  • Practical utility: teams can prototype policies quickly, catch errors before deployment, and onboard new team members without deep CEL knowledge.

CEL Sandbox & Cost Estimator

Summary

  • A runtime library and API that statically analyzes CEL expressions to estimate execution cost, enforces configurable time/memory limits, and guarantees termination within those bounds.
  • Addresses concerns about “CEL is computationally limited” and “no guarantee to terminate” by providing measurable safety guarantees.

Details

Key Value
Target Audience Kubernetes operators, CI/CD pipelines, and security teams that embed CEL in production workloads.
Core Feature Static cost estimation, sandboxed execution with enforced limits, and integration hooks for policy engines (OPA, Kyverno).
Tech Stack Go (native CEL runtime), Rust for sandboxing, gRPC API, Docker for isolated execution.
Difficulty High
Monetization Revenue‑ready: Enterprise licensing with per‑policy usage metrics.

Notes

  • “IshKebab: … you want guaranteed to terminate in finite but possibly arbitrarily large time.” The estimator turns that into a concrete metric.
  • Discussion highlights the need for “safe sandboxed python execution engine” – this library offers a comparable solution for CEL with lower overhead.

Rego‑to‑CEL Converter & Linter

Summary

  • A command‑line tool and library that translates Rego policies into equivalent CEL expressions, and provides linting, best‑practice suggestions, and migration guidance.
  • Helps teams move from OPA/Rego to CEL without rewriting policies from scratch.

Details

Key Value
Target Audience Teams currently using OPA/Rego who want to adopt CEL for Kubernetes validation or IAM.
Core Feature Two‑way conversion (Rego → CEL, CEL → Rego), linting for idiomatic CEL, and a migration checklist.
Tech Stack Python 3, ANTLR for parsing, Jinja2 templates for code generation, GitHub Actions for CI integration.
Difficulty Medium
Monetization Hobby (open source with optional paid support).

Notes

  • “talideon: … Rego (in the form of OPA) gets used quite a bit for complicated access control logic, while CEL gets used in places where we need simpler logic.” The converter bridges that gap.
  • Practical utility: reduces friction for teams that want to experiment with CEL while keeping existing Rego policies intact.

Read Later