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/crypto/parse.go

@@ -0,0 +1,42 @@
+// MinIO Cloud Storage, (C) 2017-2019 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 crypto
+
+import (
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// ParseMasterKey parses the value of the environment variable
+// `EnvKMSMasterKey` and returns a key-ID and a master-key KMS on success.
+func ParseMasterKey(envArg string) (KMS, error) {
+	values := strings.SplitN(envArg, ":", 2)
+	if len(values) != 2 {
+		return nil, fmt.Errorf("Invalid KMS master key: %s does not contain a ':'", envArg)
+	}
+	var (
+		keyID  = values[0]
+		hexKey = values[1]
+	)
+	if len(hexKey) != 64 { // 2 hex bytes = 1 byte
+		return nil, fmt.Errorf("Invalid KMS master key: %s not a 32 bytes long HEX value", hexKey)
+	}
+	var masterKey [32]byte
+	if _, err := hex.Decode(masterKey[:], []byte(hexKey)); err != nil {
+		return nil, err
+	}
+	return NewMasterKey(keyID, masterKey), nil
+}