feat(add get lastest block number): add get lastest block number

add get lastest block number

Author: yuanyu90221

.gitignore

@@ -0,0 +1,26 @@
+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file
+.env
+bin

Makefile

@@ -0,0 +1,14 @@
+.PHONY=build
+
+build-client:
+	@CGO_ENABLED=0 GOOS=linux go build -o bin/go-client learn/go-client.go
+
+run-client: build-client
+	@./bin/go-client
+
+coverage:
+	@go test -v -cover ./...
+
+test:
+	@go test -v ./...
+

README.md

@@ -0,0 +1,60 @@
+# golang-ethereum-sample
+
+This repository is to demo how to interact with ethereum jsonrpc server by golang
+
+## install dependency
+
+```shell
+go get github.com/ethereum/go-ethereum
+```
+
+## connect to ETH JSONRPC
+
+```golang
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/leetcode-golang-classroom/golang-ethereum-sample/internal/config"
+)
+
+func main() {
+	// setup client connect to jsonprc node
+	client, err := ethclient.DialContext(context.Background(), config.AppConfig.EthJsonRpcURL)
+	if err != nil {
+		log.Fatalf("Error to create a ether client: %v", err)
+	}
+	defer client.Close()
+	block, err := client.BlockByNumber(context.Background(), nil)
+	if err != nil {
+		log.Fatalf("Error to get a block: %v", err)
+	}
+	fmt.Println(block.Number())
+}
+```
+
+## setup local ethereum node with ganache
+
+1. install ganache-cli
+  
+```shell
+pnpm add -g ganache-cli
+```
+
+2. start ganache node
+
+```shell
+ganache-cli
+```
+
+![ganache-node-info](ganache-node-info.png)
+
+## setup ENV for local node
+
+```yaml
+ETH_JSON_RPC_URL=http://localhost:8545
+```

ganache-node-info.png

@@ -0,0 +1,48 @@
+module github.com/leetcode-golang-classroom/golang-ethereum-sample
+
+go 1.22.4
+
+require (
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/StackExchange/wmi v1.2.1 // indirect
+	github.com/bits-and-blooms/bitset v1.10.0 // indirect
+	github.com/btcsuite/btcd/btcec/v2 v2.2.0 // indirect
+	github.com/consensys/bavard v0.1.13 // indirect
+	github.com/consensys/gnark-crypto v0.12.1 // indirect
+	github.com/crate-crypto/go-kzg-4844 v1.0.0 // indirect
+	github.com/deckarep/golang-set/v2 v2.6.0 // indirect
+	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
+	github.com/ethereum/c-kzg-4844 v1.0.0 // indirect
+	github.com/ethereum/go-ethereum v1.14.5 // indirect
+	github.com/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/go-ole/go-ole v1.3.0 // indirect
+	github.com/gorilla/websocket v1.4.2 // indirect
+	github.com/hashicorp/hcl v1.0.0 // indirect
+	github.com/holiman/uint256 v1.2.4 // indirect
+	github.com/magiconair/properties v1.8.7 // indirect
+	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/mmcloughlin/addchain v0.4.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
+	github.com/sagikazarmark/locafero v0.4.0 // indirect
+	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
+	github.com/shirou/gopsutil v3.21.4-0.20210419000835-c7a38de76ee5+incompatible // indirect
+	github.com/sourcegraph/conc v0.3.0 // indirect
+	github.com/spf13/afero v1.11.0 // indirect
+	github.com/spf13/cast v1.6.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/spf13/viper v1.19.0 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
+	github.com/supranational/blst v0.3.11 // indirect
+	github.com/tklauser/go-sysconf v0.3.12 // indirect
+	github.com/tklauser/numcpus v0.6.1 // indirect
+	go.uber.org/atomic v1.9.0 // indirect
+	go.uber.org/multierr v1.9.0 // indirect
+	golang.org/x/crypto v0.22.0 // indirect
+	golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.20.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	rsc.io/tmplfunc v0.0.3 // indirect
+)

go.mod

@@ -0,0 +1,106 @@
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+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+rsc.io/tmplfunc v0.0.3 h1:53XFQh69AfOa8Tw0Jm7t+GV7KZhOi6jzsCzTtKbMvzU=
+rsc.io/tmplfunc v0.0.3/go.mod h1:AG3sTPzElb1Io3Yg4voV9AGZJuleGAwaVRxL9M49PhA=

go.sum

@@ -0,0 +1,37 @@
+package config
+
+import (
+	"log"
+
+	"github.com/spf13/viper"
+)
+
+type Config struct {
+	EthJsonRpcURL string `mapstructure:"ETH_JSON_RPC_URL"`
+}
+
+var AppConfig *Config
+
+func init() {
+	v := viper.New()
+	v.AddConfigPath(".")
+	v.SetConfigName(".env")
+	v.SetConfigType("env")
+	v.AutomaticEnv()
+	failOnError(v.BindEnv("ETH_JSON_RPC_URL"), "fail on Bind ETH_JSON_RPC_URL")
+	err := v.ReadInConfig()
+	if err != nil {
+		log.Println("load from environment variable")
+	}
+	err = v.Unmarshal(&AppConfig)
+	if err != nil {
+		failOnError(err, "Failed to read enivroment")
+	}
+
+}
+
+func failOnError(err error, msg string) {
+	if err != nil {
+		log.Fatalf("%s: %s", msg, err)
+	}
+}

internal/config/config.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/leetcode-golang-classroom/golang-ethereum-sample/internal/config"
+)
+
+func main() {
+	// setup client connect to jsonprc node
+	client, err := ethclient.DialContext(context.Background(), config.AppConfig.EthJsonRpcURL)
+	if err != nil {
+		log.Fatalf("Error to create a ether client: %v", err)
+	}
+	defer client.Close()
+	block, err := client.BlockByNumber(context.Background(), nil)
+	if err != nil {
+		log.Fatalf("Error to get a block: %v", err)
+	}
+	// get latest block number
+	fmt.Println(block.Number())
+}