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https://github.com/kuadrant/wasm-shim

A Proxy-Wasm module allowing communication to Authorino and Limitador.
https://github.com/kuadrant/wasm-shim

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A Proxy-Wasm module allowing communication to Authorino and Limitador.

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# Wasm-shim

[![Rust](https://github.com/Kuadrant/wasm-shim/actions/workflows/rust.yaml/badge.svg)](https://github.com/Kuadrant/wasm-shim/actions/workflows/rust.yaml)
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A Proxy-Wasm module written in Rust, acting as a shim between Envoy and both Rate-limiting and External Auth services.

## Sample configuration

Following is a sample configuration used by the shim.

```yaml
services:
auth-service:
type: auth
endpoint: auth-cluster
failureMode: deny
timeout: 10ms
ratelimit-service:
type: ratelimit
endpoint: ratelimit-cluster
failureMode: allow
actionSets:
- name: rlp-ns-A/rlp-name-A
routeRuleConditions:
hostnames: [ "*.toystore.com" ]
predicates:
- request.url_path.startsWith("/get")
- request.host == "test.toystore.com"
- request.method == "GET"
actions:
- service: auth-service
scope: auth-scope-a
- service: ratelimit-service
scope: ratelimit-scope-a
predicates:
- auth.identity.anonymous == true
data:
- expression:
key: my_header
value: request.headers["my-custom-header"]
```

## Features

### CEL Predicates and Expression

`routeRuleConditions`'s `predicate`s are expressed in [Common Expression Language (CEL)](https://cel.dev). `Predicate`s
evaluating to a `bool` value, while `Expression`, used for passing data to a service, evaluate to some `Value`.

These expression can operate on the data made available to them through the Well Known Attributes, see below

### Well Known Attributes

| Attribute | Description |
|---------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Envoy Attributes](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/advanced/attributes) | Contextual properties provided by Envoy during request and connection processing |
| `source.remote_address` | This attribute evaluates to the `trusted client address` (IP address without port) as it is being defined by [Envoy Doc](https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_conn_man/headers#x-forwarded-for) |
| `auth.*` | Data made available by the authentication service to the `ActionSet`'s pipeline |

## Building

Prerequisites:

* Install `wasm32-unknown-unknown` build target

```
rustup target add wasm32-unknown-unknown
```

Build the WASM module

```
make build
```

Build the WASM module in release mode

```
make build BUILD=release
```

Build the WASM module with features

```
make build FEATURES=debug-host-behaviour
```

## Testing

```
cargo test
```

## Running local development environment (kind)

`docker` is required.

Run local development environment

```sh
make local-setup
```

This deploys a local kubernetes cluster using kind, with the local build of wasm-shim mapped to the envoy container. An
echo API as well as limitador, authorino, and some test policies are configured.

To expose the envoy endpoint run the following:

```sh
kubectl port-forward --namespace kuadrant-system deployment/envoy 8000:8000
```

There is then a single auth action set defined for e2e testing:

* `auth-a` which defines auth is required for requests to `/get` for the `AuthConfig` with `effective-route-1`

```sh
curl -H "Host: test.a.auth.com" http://127.0.0.1:8000/get -i
# HTTP/1.1 401 Unauthorized
```

```sh
curl -H "Host: test.a.auth.com" -H "Authorization: APIKEY IAMALICE" http://127.0.0.1:8000/get -i
# HTTP/1.1 200 OK
```

And some rate limit action sets defined for e2e testing:

* `rlp-a`: Only one data item. Data selector should not generate return any value. Thus, descriptor should be empty and
rate limiting service should **not** be called.

```sh
curl -H "Host: test.a.rlp.com" http://127.0.0.1:8000/get -i
```

* `rlp-b`: Conditions do not match. Hence, rate limiting service should **not** be called.

```sh
curl -H "Host: test.b.rlp.com" http://127.0.0.1:8000/get -i
```

* `rlp-c`: Descriptor entries from multiple data items should be generated. Hence, rate limiting service should be called.

```sh
curl -H "Host: test.c.rlp.com" -H "x-forwarded-for: 50.0.0.1" -H "my-custom-header-01: my-custom-header-value-01" -H "x-dyn-user-id: bob" http://127.0.0.1:8000/get -i
```

Check limitador logs for received descriptor entries.

```sh
kubectl logs -f deployment/limitador-sample -n kuadrant-system
```

The expected descriptor entries:

```
Entry { key: "limit_to_be_activated", value: "1" }
```

```
Entry { key: "source.address", value: "50.0.0.1:0" }
```

```
Entry { key: "request.headers.my-custom-header-01", value: "my-custom-header-value-01" }
```

```
Entry { key: "user_id", value: "bob" }
```

* `multi-a` which defines two actions for authenticated ratelimiting.

```sh
curl -H "Host: test.a.multi.com" http://127.0.0.1:8000/get -i
# HTTP/1.1 401 Unauthorized
```

Alice has 5 requests per 10 seconds:
```sh
while :; do curl --write-out '%{http_code}\n' --silent --output /dev/null -H "Authorization: APIKEY IAMALICE" -H "Host: test.a.multi.com" http://127.0.0.1:8000/get | grep -E --color "\b(429)\b|$"; sleep 1; done
```

Bob has 2 requests per 10 seconds:
```sh
while :; do curl --write-out '%{http_code}\n' --silent --output /dev/null -H "Authorization: APIKEY IAMBOB" -H "Host: test.a.multi.com" http://127.0.0.1:8000/get | grep -E --color "\b(429)\b|$"; sleep 1; done
```

To rebuild and deploy to the cluster:

```sh
make build local-rollout
```

Stop and clean up resources:

```sh
make local-cleanup
```

## License

[Apache 2.0 License](LICENSE)

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