Move etcd, logger, crypto into their own packages (#8366)

- Deprecates _MINIO_PROFILER, `mc admin profile` does the job
- Move ENVs to common location in cmd/config/

cmd/config/etcd/etcd.go

@@ -0,0 +1,96 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * 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.
+ */
+
+package etcd
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"strings"
+	"time"
+
+	"github.com/coreos/etcd/clientv3"
+	"github.com/minio/minio/cmd/config"
+	"github.com/minio/minio/pkg/env"
+	xnet "github.com/minio/minio/pkg/net"
+)
+
+const (
+	// Default values used while communicating with etcd.
+	defaultDialTimeout   = 30 * time.Second
+	defaultDialKeepAlive = 30 * time.Second
+)
+
+// etcd environment values
+const (
+	EnvEtcdEndpoints     = "MINIO_ETCD_ENDPOINTS"
+	EnvEtcdClientCert    = "MINIO_ETCD_CLIENT_CERT"
+	EnvEtcdClientCertKey = "MINIO_ETCD_CLIENT_CERT_KEY"
+)
+
+// New - Initialize new etcd client
+func New(rootCAs *x509.CertPool) (*clientv3.Client, error) {
+	envEndpoints := env.Get(EnvEtcdEndpoints, "")
+	if envEndpoints == "" {
+		// etcd is not configured, nothing to do.
+		return nil, nil
+	}
+
+	etcdEndpoints := strings.Split(envEndpoints, config.ValueSeparator)
+
+	var etcdSecure bool
+	for _, endpoint := range etcdEndpoints {
+		u, err := xnet.ParseURL(endpoint)
+		if err != nil {
+			return nil, err
+		}
+		// If one of the endpoint is https, we will use https directly.
+		etcdSecure = etcdSecure || u.Scheme == "https"
+	}
+
+	var err error
+	var etcdClnt *clientv3.Client
+	if etcdSecure {
+		// This is only to support client side certificate authentication
+		// https://coreos.com/etcd/docs/latest/op-guide/security.html
+		etcdClientCertFile, ok1 := env.Lookup(EnvEtcdClientCert)
+		etcdClientCertKey, ok2 := env.Lookup(EnvEtcdClientCertKey)
+		var getClientCertificate func(*tls.CertificateRequestInfo) (*tls.Certificate, error)
+		if ok1 && ok2 {
+			getClientCertificate = func(unused *tls.CertificateRequestInfo) (*tls.Certificate, error) {
+				cert, terr := tls.LoadX509KeyPair(etcdClientCertFile, etcdClientCertKey)
+				return &cert, terr
+			}
+		}
+
+		etcdClnt, err = clientv3.New(clientv3.Config{
+			Endpoints:         etcdEndpoints,
+			DialTimeout:       defaultDialTimeout,
+			DialKeepAliveTime: defaultDialKeepAlive,
+			TLS: &tls.Config{
+				RootCAs:              rootCAs,
+				GetClientCertificate: getClientCertificate,
+			},
+		})
+	} else {
+		etcdClnt, err = clientv3.New(clientv3.Config{
+			Endpoints:         etcdEndpoints,
+			DialTimeout:       defaultDialTimeout,
+			DialKeepAliveTime: defaultDialKeepAlive,
+		})
+	}
+	return etcdClnt, err
+}