👌 Applied suggestions

.env

@@ -0,0 +1,6 @@
+WEB3_PROVIDER=
+PRIVATE_KEY=
+KEYSTORE=
+ERC20_TOKEN_ADDRESS=
+HCAPTCHA_SITEKEY=
+HCAPTCHA_SECRET=

Makefile

@@ -1,11 +1,18 @@
 
+include .env
+
 APP_NAME = lsk-faucet
 PKGS=$(shell go list ./... | grep -v "/vendor/")
 BLUE = \033[1;34m
 GREEN = \033[1;32m
 COLOR_END = \033[0;39m
 BINDING_OUTPUT_DIR=$(realpath ./internal/bindings)
 
+validate-env: # Validates if the necessary environment variables are set
+ifndef ERC20_CONTRACT_FILE_PATH
+	$(error `ERC20_CONTRACT_FILE_PATH` environment variable is undefined)
+endif
+
 build: build-frontend build-backend
 
 build-backend: # Builds the application and create a binary at ./bin/
@@ -21,7 +28,7 @@ build-frontend: # Builds the frontned application
 run: # Runs the application, use `make run FLAGS="--help"`
 	./bin/${APP_NAME} ${FLAGS}
 
-generate-abi:
+generate-abi: validate-env
 	@echo "$(BLUE)Generating abi file... $(COLOR_END)"
 	solc --overwrite --abi $(ERC20_CONTRACT_FILE_PATH) -o $(BINDING_OUTPUT_DIR)
 	@echo "$(GREEN)ABI file generated successfully$(COLOR_END)"
@@ -49,9 +56,9 @@ build-image: # Builds docker image
 docker-start: # Runs docker image
 	@echo "$(BLUE)Starting docker container $(APP_NAME)...$(COLOR_END)"
 ifdef PRIVATE_KEY
-	docker run --name $(APP_NAME) -p 8080:8080 -d -e WEB3_PROVIDER=$(WEB3_PROVIDER) -e PRIVATE_KEY=$(PRIVATE_KEY) $(APP_NAME)
+	docker run --name $(APP_NAME) -p 8080:8080 -d --env-file .env $(APP_NAME)
 else ifdef KEYSTORE
-	docker run --name $(APP_NAME) -p 8080:8080 -d -e WEB3_PROVIDER=$(WEB3_PROVIDER) -e KEYSTORE=$(KEYSTORE) -v $(KEYSTORE)/keystore:/app/keystore -v $(KEYSTORE)/password.txt:/app/password.txt $(APP_NAME)
+	docker run --name $(APP_NAME) -p 8080:8080 -d --env-file .env -v $(KEYSTORE)/keystore:/app/keystore -v $(KEYSTORE)/password.txt:/app/password.txt $(APP_NAME)
 endif
 
 docker-stop:

README.md

@@ -22,7 +22,7 @@ LSK faucet is a web application that can be configured and deployed to get ETH a
 
 * Go (1.22 or later)
 * Node.js
-* Solidity compiler (Solc)
+* Solidity compiler (solc)
 * Abigen
 
 ### Installation
@@ -113,25 +113,16 @@ The following are the available command-line flags(excluding above wallet flags)
 #### Build docker image
 Run the following command to build docker image:
 ```bash
-make build
+make build-image
 ```
 
 #### Run faucet
-Run the following command to start the application:
+Set the appropriate configuration in `.env` file and run the following command to start the application:
 
 ```bash
-make docker-start WEB3_PROVIDER=<rpc-endpoint> PRIVATE_KEY=<hex-private-key>
+make docker-start
 
 ```
-**NOTE**: Please replace `<rpc-endpoint>` and `<hex-private-key>` with appropriate values.
-
-or
-
-```bash
-make docker-start WEB3_PROVIDER=<rpc-endpoint> KEYSTORE=<keystore-path>
-```
-
-**NOTE**: Please replace `<rpc-endpoint>` and `<keystore-path>` with appropriate values.
 
 ## License
 

go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/jellydator/ttlcache/v2 v2.11.1
 	github.com/kataras/hcaptcha v0.0.2
 	github.com/sirupsen/logrus v1.9.3
+	github.com/stretchr/testify v1.8.4
 	github.com/urfave/negroni v1.0.0
 	golang.org/x/crypto v0.22.0
 )
@@ -68,6 +69,7 @@ require (
 	github.com/mmcloughlin/addchain v0.4.0 // indirect
 	github.com/olekukonko/tablewriter v0.0.5 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/prometheus/client_golang v1.12.0 // indirect
 	github.com/prometheus/client_model v0.2.1-0.20210607210712-147c58e9608a // indirect
 	github.com/prometheus/common v0.32.1 // indirect
@@ -92,5 +94,6 @@ require (
 	golang.org/x/time v0.5.0 // indirect
 	google.golang.org/protobuf v1.33.0 // indirect
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 	rsc.io/tmplfunc v0.0.3 // indirect
 )

internal/chain/transaction.go

@@ -18,6 +18,11 @@ import (
 	"golang.org/x/crypto/sha3"
 )
 
+var (
+	gasLimitInitializedAccount    uint64 = 35000
+	gasLimitNonInitializedAccount uint64 = 55000
+)
+
 type TxBuilder interface {
 	Sender() common.Address
 	GetContractInstance() *bindings.Token
@@ -145,9 +150,9 @@ func (b *TxBuild) TransferERC20(ctx context.Context, to string, value *big.Int,
 
 	var gasLimit uint64
 	if balance.BitLen() == 0 {
-		gasLimit = 55000
+		gasLimit = gasLimitNonInitializedAccount
 	} else {
-		gasLimit = 35000
+		gasLimit = gasLimitInitializedAccount
 	}
 
 	tx := types.NewTransaction(nonce, tokenAddress, big.NewInt(0), gasLimit, gasPrice, data)

internal/chain/transaction_test.go

@@ -12,6 +12,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethclient/simulated"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestTxBuilder_TransferETH(t *testing.T) {
@@ -89,7 +90,9 @@ func TestTxBuilder_TransferERC20(t *testing.T) {
 	bgCtx := context.Background()
 	toAddress := common.HexToAddress("0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B")
 	value := big.NewInt(1000)
-	txHash, err := txBuilder.TransferERC20(bgCtx, toAddress.Hex(), value, big.NewInt(30000))
+
+	// Transaction when recipient is initialized
+	txHashInitAcc, err := txBuilder.TransferERC20(bgCtx, toAddress.Hex(), value, big.NewInt(30000))
 	if err != nil {
 		t.Errorf("could not add tx to pending block: %v", err)
 	}
@@ -99,9 +102,40 @@ func TestTxBuilder_TransferERC20(t *testing.T) {
 	if err != nil {
 		t.Errorf("could not get block at height 1: %v", err)
 	}
-	if txHash != block.Transactions()[0].Hash() {
-		t.Errorf("did not commit sent transaction. expected hash %v got hash %v", block.Transactions()[0].Hash(), txHash)
+	if txHashInitAcc != block.Transactions()[0].Hash() {
+		t.Errorf("did not commit sent transaction. expected hash %v got hash %v", block.Transactions()[0].Hash(), txHashInitAcc)
+	}
+
+	txInitAcc, _, err := simBackend.Client().TransactionByHash(bgCtx, txHashInitAcc)
+	if err != nil {
+		t.Errorf("could not get transaction by hash: %v", err)
+	}
+
+	gasLimit := txInitAcc.Gas()
+	assert.Equal(t, gasLimit, gasLimitInitializedAccount)
+
+	// Transaction when recipient is not initialized
+	txHashNonInitAcc, err := txBuilder.TransferERC20(bgCtx, toAddress.Hex(), value, big.NewInt(0))
+	if err != nil {
+		t.Errorf("could not add tx to pending block: %v", err)
 	}
+	simBackend.Commit()
+
+	block, err = simBackend.Client().BlockByNumber(bgCtx, big.NewInt(2))
+	if err != nil {
+		t.Errorf("could not get block at height 1: %v", err)
+	}
+	if txHashNonInitAcc != block.Transactions()[0].Hash() {
+		t.Errorf("did not commit sent transaction. expected hash %v got hash %v", block.Transactions()[0].Hash(), txHashNonInitAcc)
+	}
+
+	txNonInitAcc, _, err := simBackend.Client().TransactionByHash(bgCtx, txHashNonInitAcc)
+	if err != nil {
+		t.Errorf("could not get transaction by hash: %v", err)
+	}
+
+	gasLimit = txNonInitAcc.Gas()
+	assert.Equal(t, gasLimit, gasLimitNonInitializedAccount)
 
 	// TODO: Verify ERC20 token balance of recipient if possible in future with the simulator
 }

internal/server/server.go

@@ -3,6 +3,7 @@ package server
 import (
 	"context"
 	"fmt"
+	"math/big"
 	"net/http"
 	"strconv"
 	"time"
@@ -60,7 +61,7 @@ func (s *Server) handleClaim() http.HandlerFunc {
 		currBalance, err := s.GetContractInstance().BalanceOf(&bind.CallOpts{}, common.HexToAddress(address))
 		if err != nil {
 			log.WithError(err).Error("Failed to fetch recipient balance")
-			return
+			currBalance = big.NewInt(0)
 		}
 
 		txHash, err := s.TransferERC20(ctx, address, chain.LSKToWei(int64(s.cfg.payout)), currBalance)