First pass on pow faucet for testnet (#1624)

* first pass on pow faucet for testnet

* delete unused thing

* remove unneeded thing

*  remove other thing

* https & remove a log

* don't force redirect on https, its not working?

* some renaming of stuff

* lint

* lint

* some stablity config

* move protos to proto directory, add generated pb file for go users

* add health probe

* add hpa and request cpu

* handle err

* some more config

tools/faucet/BUILD.bazel

@@ -0,0 +1,56 @@
+# gazelle:ignore
+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
+load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
+load("@io_bazel_rules_docker//go:image.bzl", "go_image")
+load("@io_bazel_rules_docker//container:container.bzl", "container_push")
+
+IMPORT_PATH = "github.com/prysmaticlabs/prysm/tools/faucet"
+SRCS = [
+    "main.go",
+    "server.go",
+]
+DEPS = [
+    "//proto/faucet:faucet_go_proto",
+    "@org_golang_google_grpc//:go_default_library",
+    "@org_golang_google_grpc//peer:go_default_library",
+    "@org_golang_google_grpc//reflection:go_default_library",
+    "@com_github_prestonvanloon_go_recaptcha//:go_default_library",
+]
+
+go_library(
+    name = "go_default_library",
+    srcs = SRCS,  
+    importpath = IMPORT_PATH,
+    visibility = ["//visibility:private"],
+    deps = DEPS,
+)
+
+go_binary(
+    name = "faucet",
+    embed = [":go_default_library"],
+    visibility = ["//visibility:public"],
+)
+
+go_image(
+    name = "image",
+    srcs = SRCS,
+    importpath = IMPORT_PATH,
+    deps = DEPS,
+    pure = "off", # depends on cgo for go-ethereum crypto
+    static = "on",
+    tags = ["manual"],
+    goarch = "amd64",
+    goos = "linux",
+    race = "off",
+)
+
+container_push(
+    name = "push_image",
+    format = "Docker",
+    image = ":image",
+    registry = "gcr.io",
+    repository = "prysmaticlabs/prysm/faucet",
+    tag = "latest",
+    tags = ["manual"],
+    visibility = ["//visibility:private"],
+)

tools/faucet/main.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"net"
+
+	recaptcha "github.com/prestonvanloon/go-recaptcha"
+	faucetpb "github.com/prysmaticlabs/prysm/proto/faucet"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/reflection"
+)
+
+var (
+	port            = flag.Int("port", 8000, "Port to server gRPC service")
+	recaptchaSecret = flag.String("recaptcha_secret", "", "Secret to verify recaptcha")
+)
+
+func main() {
+	flag.Parse()
+
+	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
+	if err != nil {
+		panic(err)
+	}
+	s := grpc.NewServer()
+	fmt.Println("recaptcha = " + *recaptchaSecret)
+	faucetpb.RegisterFaucetServiceServer(s, &faucetServer{
+		r: recaptcha.Recaptcha{RecaptchaPrivateKey: *recaptchaSecret},
+	})
+
+	reflection.Register(s)
+
+	fmt.Printf("Serving gRPC requests on port %d\n", *port)
+	if err := s.Serve(lis); err != nil {
+		fmt.Printf("Error: %v", err)
+	}
+}

tools/faucet/server.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	recaptcha "github.com/prestonvanloon/go-recaptcha"
+	faucetpb "github.com/prysmaticlabs/prysm/proto/faucet"
+	"google.golang.org/grpc/peer"
+)
+
+var minScore = 0.5
+
+type faucetServer struct {
+	r recaptcha.Recaptcha
+}
+
+// RequestFunds from the ethereum 1.x faucet. Requires a valid captcha
+// response.
+func (s *faucetServer) RequestFunds(ctx context.Context, req *faucetpb.FundingRequest) (*faucetpb.FundingResponse, error) {
+	p, ok := peer.FromContext(ctx)
+	if !ok {
+		return nil, errors.New("peer from ctx not ok")
+	}
+	fmt.Printf("Sending captcha request for peer %s\n", p.Addr.String())
+
+	rr, err := s.r.Check(p.Addr.String(), req.RecaptchaResponse)
+	if err != nil {
+		return nil, err
+	}
+	if !rr.Success {
+		fmt.Printf("Unsuccessful recaptcha request. Error codes: %+v\n", rr.ErrorCodes)
+		return &faucetpb.FundingResponse{Error: "Recaptcha failed"}, nil
+	}
+	if rr.Score < minScore {
+		return &faucetpb.FundingResponse{Error: "Recaptcha score too low"}, nil
+	}
+
+	return &faucetpb.FundingResponse{
+		Amount:          "500000000000000000",
+		TransactionHash: "0xfake",
+	}, nil
+}