feat: initial commit

proxy/main.go

@@ -0,0 +1,24 @@
+package proxy
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/go-redis/redis"
+)
+
+type Proxy struct {
+	RedisClient *redis.Client
+	HttpClient  *http.Client
+
+	GetOptions func() (Options, error)
+}
+
+type Options struct {
+	RedisPrefix        string
+	RedisExpireTimeout time.Duration
+
+	UpstreamAddress     string
+	ReplaceAddress      string
+	StaticServerAddress string
+}

proxy/metadata.go

@@ -0,0 +1,68 @@
+package proxy
+
+import (
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// GetMetadata returns NPM response for a given package path
+func (proxy Proxy) GetMetadata(path string, header http.Header) ([]byte, error) {
+	options, err := proxy.GetOptions()
+	if err != nil {
+		return nil, err
+	}
+
+	// get package from redis
+	pkg, err := proxy.RedisClient.Get(options.RedisPrefix + path).Result()
+
+	// either package doesn't exist or there's some other problem
+	if err != nil {
+
+		// check if error is caused by nonexistend package
+		// if no, return error
+		if err.Error() != "redis: nil" {
+			return nil, err
+		}
+
+		// error is caused by nonexistent package
+		// fetch package
+		req, err := http.NewRequest("GET", options.UpstreamAddress+path, nil)
+
+		// inherit headers from request
+		req.Header = header
+		if err != nil {
+			return nil, err
+		}
+
+		res, err := proxy.HttpClient.Do(req)
+		if err != nil {
+			return nil, err
+		}
+
+		defer res.Body.Close()
+		body, err := ioutil.ReadAll(res.Body)
+		if err != nil {
+			return nil, err
+		}
+
+		// convert body to string
+		pkg = string(body)
+
+		// save to redis
+		_, err = proxy.RedisClient.Set(
+			options.RedisPrefix+path,
+			pkg,
+			options.RedisExpireTimeout,
+		).Result()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// replace tarball urls
+	// FIXME: unmarshall and replace only necessary fields
+	convertedPkg := strings.ReplaceAll(string(pkg), options.ReplaceAddress, options.StaticServerAddress)
+
+	return []byte(convertedPkg), nil
+}

proxy/server.go

@@ -0,0 +1,65 @@
+package proxy
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	ginzap "github.com/gin-contrib/zap"
+	gin "github.com/gin-gonic/gin"
+	zap "go.uber.org/zap"
+)
+
+type ServerOptions struct {
+	ListenAddress string
+}
+
+func (proxy Proxy) Server(options ServerOptions) *http.Server {
+	router := gin.New()
+
+	logger, _ := zap.NewProduction()
+	router.Use(ginzap.Ginzap(logger, time.RFC3339, true))
+
+	router.GET("/:scope/:name", proxy.GetPackageHandler)
+	router.GET("/:scope", proxy.GetPackageHandler)
+	router.NoRoute(proxy.NoRouteHandler)
+
+	return &http.Server{
+		Handler: router,
+		Addr:    options.ListenAddress,
+	}
+}
+
+func (proxy Proxy) GetPackageHandler(c *gin.Context) {
+	key := c.Request.URL.Path
+
+	pkg, err := proxy.GetMetadata(key, c.Request.Header)
+
+	if err != nil {
+		c.AbortWithError(500, err)
+	} else {
+		c.Data(200, "application/json", pkg)
+	}
+}
+
+func (proxy Proxy) NoRouteHandler(c *gin.Context) {
+	if strings.Contains(c.Request.URL.Path, ".tgz") {
+		proxy.GetPackageHandler(c)
+	} else if c.Request.URL.Path == "/" {
+		_, err := proxy.RedisClient.Ping().Result()
+
+		if err != nil {
+			c.AbortWithStatusJSON(503, err)
+		} else {
+			c.AbortWithStatusJSON(200, gin.H{"ok": true})
+		}
+	} else {
+		options, err := proxy.GetOptions()
+
+		if err != nil {
+			c.AbortWithStatusJSON(500, err)
+		} else {
+			c.Redirect(http.StatusTemporaryRedirect, options.UpstreamAddress+c.Request.URL.Path)
+		}
+	}
+}