tools/etcd-dump-metrics: automate metrics fetch from release binaries

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

tools/etcd-dump-metrics/install_linux.go

@@ -0,0 +1,54 @@
+// Copyright 2018 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build linux
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/coreos/etcd/pkg/fileutil"
+)
+
+const downloadURL = `https://storage.googleapis.com/etcd/%s/etcd-%s-linux-amd64.tar.gz`
+
+func install(ver, dir string) (string, error) {
+	ep := fmt.Sprintf(downloadURL, ver, ver)
+
+	resp, err := http.Get(ep)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	d, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	tarPath := filepath.Join(dir, "etcd.tar.gz")
+	if err = ioutil.WriteFile(tarPath, d, fileutil.PrivateFileMode); err != nil {
+		return "", err
+	}
+
+	if err = exec.Command("bash", "-c", fmt.Sprintf("tar xzvf %s -C %s --strip-components=1", tarPath, dir)).Run(); err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, "etcd"), nil
+}