Add documentation

Author: fbernard

README.md

@@ -1 +1,49 @@
-# elastic-keycloak-security
+# Keycloak security plugin for Elasticsearch
+
+A Simple xpack security plugin to secure [Elasticsearch](https://www.elastic.co/fr/products/elasticsearch) with [Keycloak](https://www.keycloak.org/) 
+
+## Installation 
+
+- Install plugin 
+```
+<ES_HOME>/bin/elasticsearch-plugin install https://github.com/fb64/elastic-keycloak-security/releases/download/0.1_es6.4.3/keycloak-security-0.1_es6.4.3.zip
+```
+
+- Accept permissions to finish installation
+
+- Permissions details
+  - java.lang.RuntimePermission accessDeclaredMembers &rarr; used by keycloak-adapter
+  - java.lang.RuntimePermission getClassLoader &rarr; used by keycloak-adapter
+  - java.lang.reflect.ReflectPermission suppressAccessChecks &rarr; used by keycloak-adapter
+  - java.net.SocketPermission * connect,resolve &rarr; use to communicate with keycloak server
+
+
+### Configuration
+
+- Get client configuration file from keycloak : (Your Realm)  &rarr; Clients &rarr; (Your client) &rarr; Installation
+
+<img src="doc/assets/img/keycloak-client-installation.jpg"> 
+
+- Copy keycloak client configuration in <ES_HOME>/config/keycloak.config
+
+- Add and configure keycloak realm in <ES_HOME>/config/elasticsearch.yml file :
+```YAML
+xpack.security.authc.realms.keycloak.order: 0
+xpack.security.authc.realms.keycloak.type: keycloak
+xpack.security.authc.realms.keycloak.config: keycloak.config
+xpack.security.enabled: true
+```
+
+- Test integration
+
+```Bash
+curl -X GET http://<ES_HOST>:<ES_PORT>/ -H 'Authorization: Bearer <KEYCLOAK TOKEN>'
+```
+
+## Development
+
+For development and test you can run a keycloak instance with pre-configured realm by using docker (from repository root directory) :
+
+```Bash
+docker run -d -e KEYCLOAK_USER=admin -e KEYCLOAK_PASSWORD=admin -e KEYCLOAK_IMPORT=/tmp/elastic-realm-export.json -v "$(pwd)"/src/test/resources/config/elastic-realm-export.json:/tmp/elastic-realm-export.json -p 8080:8080 jboss/keycloak
+```