add more readme

README.md

@@ -1,48 +1,106 @@
 # Overview
 
 Nebula Agent is an daemon service in each machine of [nebula](https://github.com/vesoft-inc/nebula) cluster. It helps to keep track of nebula metad/storaged/graphd, start/stop them, call local rpc of them.
+It is only used for [backup and restore](https://github.com/vesoft-inc/nebula-br) tools for now.
+
+# Quick Start
+
+## Download directly
+
+If you are in linux amd64 environment, you could download it directly.
+
+1. Download the agent.
+  ```bash
+  $ wget https://github.com/vesoft-inc/nebula-agent/releases/download/v0.1.1/agent-v0.1.1
+  ```
+2. Change the agent name.
+  ```bash
+  $ mv agent-v0.1.1 agent
+  ```
+3. Add execute permission to agent.
+  ```bash
+  $ chmod +x agent
+  ```
+
+## Download repo and build
+
+If you are in other environments, you should first install (golang)[https://go.dev/] 1.16+ and git.
+Then you could download the repo and build agent binary yourself.
+1. Clone repo.
+```bash
+$ git clone [email protected]:vesoft-inc/nebula-agent.git
+```
+
+2. Change directory to nebula-agent.
+```bash
+$ cd nebula-agent
+```
+
+3. Compile with `make`.
+```bash
+$ make
+```
+
+4. Add execute permission to agent.
+```bash
+$ cd bin
+$ chmod +x agent
+```
+
+## Usage
+
+If you want to use nebula-agent, you should start one and **only one** nebula-agent service in each nebula cluster machine which contains metad/storaged/metad services.
+It should be given an agent daemon address and the metad address. If you have multi-metad in one nebula cluster, any address of them will be OK.
+
+```bash
+Usage of agent:
+  --agent string
+        The agent server address
+  --meta string
+        The nebula metad service address, any metad address will be ok
+  --debug
+        Open debug will output more detail info
+  --hbs int
+        Agent heartbeat interval to nebula meta, in seconds (default 60)
+```
+
+An example:
+
+```bash
+./agent --agent="127.0.0.1:8888" --meta="127.0.0.1:9559"
+```
+
 
 # Features
 
+Nebula Agent provide two type of services now: file management in nebula machines and agent service. 
+
 ## File Management
 
-```proto
+```C++
 // UploadFile upload file from agent machine to external storage
 rpc UploadFile(UploadFileRequest) returns (UploadFileResponse);
 // DownloadFile download file from external storage to agent machine
 rpc DownloadFile(DownloadFileRequest) returns (DownloadFileResponse);
+
 // MoveDir rename dir in agent machine
 rpc MoveDir(MoveDirRequest) returns (MoveDirResponse);
 // RemoveDir delete dir in agent machine
 rpc RemoveDir(RemoveDirRequest) returns (RemoveDirResponse);
+// ExistDir check if dir in agent machine exist
+rpc ExistDir(ExistDirRequest) returns (ExistDirResponse);
 ```
 
 ## Agent Service
 
-```proto
-// start/stop metad/storaged/graphd service
+```C++
+// start/stop/get status of metad/storaged/graphd service
 rpc StartService(StartServiceRequest) returns (StartServiceResponse);
 rpc StopService(StopServiceRequest) returns (StopServiceResponse);
+rpc ServiceStatus(ServiceStatusRequest) returns (ServiceStatusResponse);
 
 // ban read/write by call graphd's api
 rpc BanReadWrite(BanReadWriteRequest) returns (BanReadWriteResponse);
 rpc AllowReadWrite(AllowReadWriteRequest) returns (AllowReadWriteResponse);
 ```
 
-# Usage
-
-Agent will be started in each machine automatically, with it's listen address and metad's address given.
-
-```
-Usage of bin/agent:
-  --agent string
-        The agent server address
-  --meta string
-        The nebula metad service address, any metad address will be ok
-  --debug
-        Open debug will output more detail info
-  --hbs int
-        Agent heartbeat interval to nebula meta, in seconds (default 60)
-```
-
-An example: `agent --agent="127.0.0.1:8888" --meta="127.0.0.1:9559"`