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Extension server tool

This is a tool to apply configuration using ExtensionConfigDiscovery mechanism in Envoy. The tool allows rapid pushes of Wasm modules and Wasm configuration. It accepts two flags:

  • -p for the port to listen on.
  • -c for the directory to watch configuration files for.

An example configuration is provided here. Each extension configuration has the following fields:

  • name is the name of the resource in ECDS.
  • path or url for the Wasm code.
  • sha256 for the Wasm code SHA256 hash. The code is not refetched if the hash matches. The config is rejected if SHA256 is specified but does not match.
  • vm_id and root_id optional settings for the VM and root context.
  • configuration JSON configuration to apply for the extension.

Usage

An experimental build of this server is available as a docker image gcr.io/istio-testing/extensionserver.

  1. Follow instructions to install Istio 1.7 release, and install a demo application bookinfo.

  2. Deploy the extension server and EnvoyFilter in "default" namespace.:

    kubectl apply -f extensionserver.yaml envoyfilter.yaml

    This step deploys the extension server with a configmap extensionserver that contains a simple filter headers_rust.wasm.

  3. Validate the demo application continues to work as before.

  4. The filter should pause the request if server header is set to envoy-wasm-pause. Try:

    curl -H "server:envoy-wasm-pause" http://<GATEWAY_IP>/productpage