docs: update README.md

README.md

@@ -1,2 +1,56 @@
 # envoy-go-basic-auth
-Basic Auth based on Envoy Golang http filter
+
+This is a simple basic auth filter for envoy written in go. Only requests that pass the configuration authentication will be proxied to the upstream service.
+
+## Status
+
+This is under active development and is not ready for production use.
+
+## Usage
+
+The client set credentials in `Authorization` header in the following format:
+
+```Plaintext
+credentials := Basic base64(username:password)
+```
+
+An example of the `Authorization` header is as follows (`Zm9vOmJhcg==`, which is the base64-encoded value of `foo:bar`):
+
+```Plaintext
+Authorization: Basic Zm9vOmJhcg==
+```
+
+Configure your envoy.yaml to set pairs of username and password.
+
+```yaml
+http_filters:
+- name: envoy.filters.http.golang
+typed_config:
+  "@type": type.googleapis.com/envoy.extensions.filters.http.golang.v3alpha.Config
+  library_id: example
+  library_path: /etc/envoy/libgolang.so
+  plugin_name: basic-auth
+  plugin_config:
+    "@type": type.googleapis.com/xds.type.v3.TypedStruct
+    value:
+      users:
+        - username: "foo"
+          password: "bar"
+        - username: "lobby"
+          password: "niu"
+```
+
+Then, you can start your filter.
+
+```bash
+make build
+make run 
+```
+
+## Test
+
+This test case is based on a local Envoy. Run it with the example config file.
+
+```bash
+go test test/e2e_authorized_test.go test/common.go
+```