Document how plugin can be used with vendored and GOPATH OPA dependency.

README.md

@@ -101,6 +101,20 @@ IP/port of the Istio Ingress gateway.
     curl --user bob:password -i http://$GATEWAY_URL/api/v1/products
     ```
 
+## How to use the OPA-Istio plugin
+
+### Option 1: Using `vendored` OPA dependency
+
+In this option, the shared object file `opa_istio_plugin.so` generated by running `make build-plugin` can only be loaded using the `opa_istio` binary generated by running `make build`.
+
+Step-by-step instructions to use this option can be found [here](./docs/plugin_vendor.md).
+
+### Option 2: Using `GOPATH` OPA dependency
+
+In this option, the shared object file `opa_istio_plugin.so` generated by running `make build-plugin` can be loaded by a OPA binary built from source by cloning the OPA repo.
+
+Step-by-step instructions to use this option can be found [here](./docs/plugin.md).
+
 ## Configuration
 
 To deploy OPA-Istio include the following container in your Kubernetes Deployments:

docs/plugin.md

@@ -1,4 +1,4 @@
-##  Instructions to build the OPA-Istio plugin as a Go plugin:
+##  Instructions to load the OPA-Istio plugin using `GOPATH` OPA:
 
 1. Clone OPA in your `GOPATH`.
 

docs/plugin_vendor.md

@@ -0,0 +1,28 @@
+##  Instructions to load the OPA-Istio plugin using `vendored` OPA:
+
+1. Build the OPA-Istio binary.
+
+   ```bash
+   make build
+   ```
+
+2. Build the OPA-Istio plugin.
+
+    ```bash
+    make build-plugin
+    ```
+
+3. Create a configuration file.
+
+    ```yaml
+    plugins:
+        envoy.ext_authz.grpc:
+            addr: :9191
+            query: data.istio.authz.allow
+    ```
+
+4. Run OPA-Istio
+
+    ```bash
+    opa_istio --plugin-dir=. run --server --config-file=config.yaml
+    ```