Move admin APIs to new path and add redesigned heal APIs (#5351)

- Changes related to moving admin APIs
   - admin APIs now have an endpoint under /minio/admin
   - admin APIs are now versioned - a new API to server the version is
     added at "GET /minio/admin/version" and all API operations have the
     path prefix /minio/admin/v1/<operation>
   - new service stop API added
   - credentials change API is moved to /minio/admin/v1/config/credential
   - credentials change API and configuration get/set API now require TLS
     so that credentials are protected
   - all API requests now receive JSON
   - heal APIs are disabled as they will be changed substantially

- Heal API changes
   Heal API is now provided at a single endpoint with the ability for a
   client to start a heal sequence on all the data in the server, a
   single bucket, or under a prefix within a bucket.

   When a heal sequence is started, the server returns a unique token
   that needs to be used for subsequent 'status' requests to fetch heal
   results.

   On each status request from the client, the server returns heal result
   records that it has accumulated since the previous status request. The
   server accumulates upto 1000 records and pauses healing further
   objects until the client requests for status. If the client does not
   request any further records for a long time, the server aborts the
   heal sequence automatically.

   A heal result record is returned for each entity healed on the server,
   such as system metadata, object metadata, buckets and objects, and has
   information about the before and after states on each disk.

   A client may request to force restart a heal sequence - this causes
   the running heal sequence to be aborted at the next safe spot and
   starts a new heal sequence.

cmd/api-response.go

@@ -166,13 +166,12 @@ type ListBucketsResponse struct {
 
 // Upload container for in progress multipart upload
 type Upload struct {
-	Key            string
-	UploadID       string `xml:"UploadId"`
-	Initiator      Initiator
-	Owner          Owner
-	StorageClass   string
-	Initiated      string
-	HealUploadInfo *HealObjectInfo `xml:"HealObjectInfo,omitempty"`
+	Key          string
+	UploadID     string `xml:"UploadId"`
+	Initiator    Initiator
+	Owner        Owner
+	StorageClass string
+	Initiated    string
 }
 
 // CommonPrefix container for prefix response in ListObjectsResponse
@@ -182,9 +181,8 @@ type CommonPrefix struct {
 
 // Bucket container for bucket metadata
 type Bucket struct {
-	Name           string
-	CreationDate   string          // time string of format "2006-01-02T15:04:05.000Z"
-	HealBucketInfo *HealBucketInfo `xml:"HealBucketInfo,omitempty"`
+	Name         string
+	CreationDate string // time string of format "2006-01-02T15:04:05.000Z"
 }
 
 // Object container for object metadata
@@ -198,8 +196,7 @@ type Object struct {
 	Owner Owner
 
 	// The class of storage used to store the object.
-	StorageClass   string
-	HealObjectInfo *HealObjectInfo `xml:"HealObjectInfo,omitempty"`
+	StorageClass string
 }
 
 // CopyObjectResponse container returns ETag and LastModified of the successfully copied object
@@ -308,7 +305,6 @@ func generateListBucketsResponse(buckets []BucketInfo) ListBucketsResponse {
 		var listbucket = Bucket{}
 		listbucket.Name = bucket.Name
 		listbucket.CreationDate = bucket.Created.UTC().Format(timeFormatAMZLong)
-		listbucket.HealBucketInfo = bucket.HealBucketInfo
 		listbuckets = append(listbuckets, listbucket)
 	}
 
@@ -339,8 +335,6 @@ func generateListObjectsV1Response(bucket, prefix, marker, delimiter string, max
 		content.Size = object.Size
 		content.StorageClass = globalMinioDefaultStorageClass
 		content.Owner = owner
-		// object.HealObjectInfo is non-empty only when resp is constructed in ListObjectsHeal.
-		content.HealObjectInfo = object.HealObjectInfo
 		contents = append(contents, content)
 	}
 	// TODO - support EncodingType in xml decoding
@@ -498,7 +492,6 @@ func generateListMultipartUploadsResponse(bucket string, multipartsInfo ListMult
 		newUpload.UploadID = upload.UploadID
 		newUpload.Key = upload.Object
 		newUpload.Initiated = upload.Initiated.UTC().Format(timeFormatAMZLong)
-		newUpload.HealUploadInfo = upload.HealUploadInfo
 		listMultipartUploadsResponse.Uploads[index] = newUpload
 	}
 	return listMultipartUploadsResponse
@@ -584,3 +577,31 @@ func writeErrorResponseHeadersOnly(w http.ResponseWriter, errorCode APIErrorCode
 	apiError := getAPIError(errorCode)
 	writeResponse(w, apiError.HTTPStatusCode, nil, mimeNone)
 }
+
+// writeErrorResponseJSON - writes error response in JSON format;
+// useful for admin APIs.
+func writeErrorResponseJSON(w http.ResponseWriter, errorCode APIErrorCode, reqURL *url.URL) {
+	apiError := getAPIError(errorCode)
+	// Generate error response.
+	errorResponse := getAPIErrorResponse(apiError, reqURL.Path)
+	encodedErrorResponse := encodeResponseJSON(errorResponse)
+	writeResponse(w, apiError.HTTPStatusCode, encodedErrorResponse, mimeJSON)
+}
+
+// writeCustomErrorResponseJSON - similar to writeErrorResponseJSON,
+// but accepts the error message directly (this allows messages to be
+// dynamically generated.)
+func writeCustomErrorResponseJSON(w http.ResponseWriter, errorCode APIErrorCode,
+	errBody string, reqURL *url.URL) {
+
+	apiError := getAPIError(errorCode)
+	errorResponse := APIErrorResponse{
+		Code:      apiError.Code,
+		Message:   errBody,
+		Resource:  reqURL.Path,
+		RequestID: "3L137",
+		HostID:    "3L137",
+	}
+	encodedErrorResponse := encodeResponseJSON(errorResponse)
+	writeResponse(w, apiError.HTTPStatusCode, encodedErrorResponse, mimeJSON)
+}