chore: add flag to print version number

Author: iczc

README.md

@@ -7,12 +7,12 @@ The faucet is a web application with the goal of distributing small amounts of E
 
 * Use private key as sender
 ```bash
-docker run -d -p 8080:8080 -e WEB3_PROVIDER="rpc endpoint" -e PRIVATE_KEY="hex private key" chainflag/eth-faucet -httpport 8080
+docker run -d -p 8080:8080 -e WEB3_PROVIDER="rpc endpoint" -e PRIVATE_KEY="hex private key" chainflag/eth-faucet:1.0.0 -httpport 8080
 ```
 
 * Use keystore file as sender
 ```bash
-docker run -d -p 8080:8080 -e WEB3_PROVIDER="rpc endpoint" -e KEYSTORE="keystore path" -v `pwd`/keystore:/app/keystore -v `pwd`/password.txt:/app/password.txt chainflag/eth-faucet -httpport 8080
+docker run -d -p 8080:8080 -e WEB3_PROVIDER="rpc endpoint" -e KEYSTORE="keystore path" -v `pwd`/keystore:/app/keystore -v `pwd`/password.txt:/app/password.txt chainflag/eth-faucet:1.0.0 -httpport 8080
 ```
 
 **Optional Flags**
@@ -65,7 +65,7 @@ _For more details, please refer to the [web readme](https://github.com/chainflag
 
 3. Build binary application to run faucet
 ```bash
-go build -o eth-faucet main.go
+go build
 export WEB3_PROVIDER=https://ropsten.infura.io
 export PRIVATE_KEY=secret
 ./eth-faucet

cmd/server.go

@@ -15,7 +15,10 @@ import (
 	"github.com/chainflag/eth-faucet/internal/server"
 )
 
-const DefaultKeyAuth = "password.txt"
+const (
+	AppVersion     = "v1.0.0"
+	DefaultKeyAuth = "password.txt"
+)
 
 var chainIDMap = map[string]int{"mainnet": 1, "ropsten": 3, "rinkeby": 4, "goerli": 5, "kovan": 42}
 
@@ -26,10 +29,15 @@ var (
 	payoutFlag    = flag.Int("payout", 1, "Number of Ethers to transfer per user request")
 	proxyCntFlag  = flag.Int("proxycount", 0, "Count of reverse proxies in front of the server")
 	queueCapFlag  = flag.Int("queuecap", 100, "Maximum transactions waiting to be sent")
+	versionFlag   = flag.Bool("v", false, "Print version number")
 )
 
 func init() {
 	flag.Parse()
+	if *versionFlag {
+		fmt.Println(AppVersion)
+		os.Exit(0)
+	}
 }
 
 func Execute() {