integration: add cluster setup and configuration and a few tests

integration/internal/httputil/httputil.go

@@ -0,0 +1,44 @@
+package httputil
+
+import (
+	"context"
+	"net"
+	"net/http"
+)
+
+type localRoundTripper struct {
+	underlying http.RoundTripper
+	portToAddr map[string]string
+}
+
+func NewLocalRoundTripper(underlying http.RoundTripper, portToAddr map[string]string) http.RoundTripper {
+	lrt := &localRoundTripper{underlying: underlying, portToAddr: portToAddr}
+	return lrt
+}
+
+func (lrt *localRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	req = req.Clone(req.Context())
+	req.URL.Host = lrt.remapHost(req.Context(), req.Host)
+	return lrt.underlying.RoundTrip(req)
+}
+
+func (lrt *localRoundTripper) remapHost(ctx context.Context, hostport string) string {
+	host, port, err := net.SplitHostPort(hostport)
+	if err != nil {
+		host = hostport
+		port = "443"
+	}
+
+	dst, ok := lrt.portToAddr[port]
+	if !ok {
+		return hostport
+	}
+
+	ips, err := net.DefaultResolver.LookupIPAddr(ctx, host)
+	if err != nil || len(ips) == 0 || ips[0].String() != "127.0.0.1" {
+		return hostport
+	}
+
+	return dst
+
+}