Add consul config adapter usage example. (#2988)

example/config/consul/boot/boot.go

@@ -0,0 +1,35 @@
+package boot
+
+import (
+	consul "github.com/gogf/gf/contrib/config/consul/v2"
+
+	"github.com/gogf/gf/v2/frame/g"
+	"github.com/gogf/gf/v2/os/gctx"
+	"github.com/hashicorp/consul/api"
+	"github.com/hashicorp/go-cleanhttp"
+)
+
+func init() {
+	var (
+		ctx          = gctx.GetInitCtx()
+		consulConfig = api.Config{
+			Address:    "127.0.0.1:8500",
+			Scheme:     "http",
+			Datacenter: "dc1",
+			Transport:  cleanhttp.DefaultPooledTransport(),
+			Token:      "3f8aeba2-f1f7-42d0-b912-fcb041d4546d",
+		}
+		configPath = "server/message"
+	)
+
+	adapter, err := consul.New(ctx, consul.Config{
+		ConsulConfig: consulConfig,
+		Path:         configPath,
+		Watch:        true,
+	})
+	if err != nil {
+		g.Log().Fatalf(ctx, `New consul adapter error: %+v`, err)
+	}
+
+	g.Cfg().SetAdapter(adapter)
+}

example/config/consul/main.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	_ "github.com/gogf/gf/example/config/consul/boot"
+
+	"github.com/gogf/gf/v2/frame/g"
+	"github.com/gogf/gf/v2/os/gctx"
+)
+
+func main() {
+	var ctx = gctx.GetInitCtx()
+
+	// Available checks.
+	g.Dump(g.Cfg().Available(ctx))
+
+	// All key-value configurations.
+	g.Dump(g.Cfg().Data(ctx))
+
+	// Retrieve certain value by key.
+	g.Dump(g.Cfg().MustGet(ctx, "redis.addr"))
+}