refactor!: Refactor for better maintainability

[anurag-rajawat]

Description

Part of #26

This PR introduces a significant change to the access-log observability implementation:

• Replaces istio telemetry with envoy wasm plugin:

  • This PR replaces the existing Istio telemetry object-based approach with the envoy wasm plugin for access-log observability.
  • This enables deployment of SentryFlow without sidecar configuration injection via annotation, configmap creation containing the wasm filter binary, telemetry object creation, or workload restarts (assuming an existing Istio sidecar mesh).
  • This enables SentryFlow to gain visibility into the Layer 7 behaviour of sidecar-injected K8s workloads within the cluster, without requiring the creation of any Istio telemetry objects.

• Configurable Knobs:

  • Adds configuration options to configure functionalities within receivers, exporter or SentryFlow itself.

• New APIEvent Protobuf Message:

  • Introduces a new protobuf message APIEvent for structured API call event data.

• Exposes API Event Collection Endpoints:
  Out of the box, SentryFlow exposes two endpoints for receiving API events from external sources:

  • HTTP Endpoint: An HTTP POST endpoint at /api/v1/events on port 8081 allows external sources to send API events in the defined APIEvent structure.
  • gRPC Endpoint: A gRPC service method SendAPIEvent (running on the configured .exporter.grpc.port) provides another option for sending API events.

Does this PR introduce a breaking change?

Yes, this PR introduces a breaking change due to the shift from istio telemetry objects to the Wasm plugin for access log observability.

Additional Information for Reviewers

Docs and test cases will be incorporated after core functionalities are reviewed and approved.

To try it locally

1. Install Istio
2. Build image and deploy it by applying deployments/sentryflow.yaml manifest file:
   Execute following from project's root directory:

REGISTRY=<your-registry> DOCKER_TAG=<some-tag> make -C sentryflow image push

kubectl apply -f deployments/sentryflow.yaml

4. Enable the envoy proxy injection by labelling the namespace in which you'll deploy workload:

kubectl label ns <namespace_name> istio-injection=enabled

5. Deploy some workload and generate traffic by calling APIs.
6. Forward sentryflow's gRPC port 8080 to get the logs for called APIs:

kubectl -n sentryflow port-forward svc/sentryflow 8080:8080

7. Extract and use the following client to get the logs:
   client.tgz

tar xf client.tgz
./sf-client

[nandhued]

@daemon1024 Can you review?

[daemon1024]

Initial Review, PTAL

[daemon1024]

Small nits! Rest LGTM 👌🏽

[daemon1024]

We have added the Labels in WASM and Envoy Filter as well, Nice 👌🏽

LGTM 🙌🏽

[PrimalPimmy]

LGTM except for a comment.