List of current implementations and users

[c4milo]

Is there a list somewhere with current implementations? so far I've found https://github.com/google/cel-cpp and https://github.com/google/cel-go.

Also, it will be very useful for newcomers like me to know who is currently using CEL. I'm aware of OpenPolicyAgent's Rego being based on CEL as well as Istio's expression language. Who else?

[ghost]

thanks ! JUst what i was looking for !

[TristonianJones]

You've found all the repos. :) In addition to Istio, here are a few other references you might find useful:

• Our open source project page describes how CEL is used in various Google products.
• knative/eventing has a proposal to integrate CEL for event filtering.
• krakend.io uses CEL for validating JWT contents.

I've heard of a handful of folks experimenting with CEL elsewhere, but haven't gotten official confirmation of an integration yet.

Open Policy Agent executes its linear evaluation paths with the same semantics as CEL, but has not yet integrated it. If there is enough demand, this is a development effort that the OPA and CEL teams are willing to pursue.

I think once there are a few more adopters, we'll create an ADOPTERS.md. In the mean, we should update the current README.md with at least the open source project page link.

[jugaadi]

Is there any python implementation?

[TristonianJones]

We haven't implemented anything for python yet, but you use something like https://github.com/go-python/gopy to create python bindings on top of the go implementation.

[devkanro]

For someone who wants to implement the CEL: I have built an implementation of the filtering, ordering, and CEL DSL for our backend framework (sisyphus).

Those are my ANTLR Grammar file(.g4)

• Filtering https://github.com/ButterCam/sisyphus/blob/master/lib/sisyphus-dsl/src/main/antlr/com/bybutter/sisyphus/dsl/filtering/grammar/Filter.g4
• Ordering https://github.com/ButterCam/sisyphus/blob/master/lib/sisyphus-dsl/src/main/antlr/com/bybutter/sisyphus/dsl/ordering/grammar/Order.g4
• CEL https://github.com/ButterCam/sisyphus/blob/master/lib/sisyphus-dsl/src/main/antlr/com/bybutter/sisyphus/dsl/cel/grammar/Cel.g4

Use the ANTLR can generate lexer and parser for all languages. In our case is Java. Then we just need to visit the AST, you can find some example there (Kotlin):

• CEL https://github.com/ButterCam/sisyphus/blob/master/lib/sisyphus-dsl/src/main/kotlin/com/bybutter/sisyphus/dsl/cel/CelContext.kt

We also built a test framework for test gRPC APIs with cel.

[snazy]

We also have https://github.com/projectnessie/cel-java , which is a pure Java implementation. The newest release 0.2.0 supports "plan Java" (Jackson based) as an alternative to protobuf.

[TristonianJones]

@snazy Nice work! And, I hope to get those rounding issues sorted in the spec for you by end of quarter. @devkanro I'm looking forward to reviewing this more in the coming weeks too :)

[thesayyn]

I started https://github.com/thesayyn/cel-js a year back but never got to finish it. it is partially working but there are missing features such as a type-checker.

recently I started working on a rust implementation that could be embedded via WASM or pure rust. I went this way because it is faster and I don’t have to repeat myself for JS and Rust

https://github.com/thesayyn/cel-rust

[CLOVIS-AI]

Hi! I have started working on a Kotlin implementation. It is extremely early days, and cannot do anything meaningful at the moment, but I plan on improving it little by little. https://gitlab.com/opensavvy/cel

It supports the following platforms:

• JVM
• JS (browser & node)
• Linux, macOS, iOS, watchOS, tvOS (x64, Arm64)
• mingwx64

I plan to add WASM (browser, node, WASI) in the future.