lightning: support dynamically modifying the log level

go.sum

@@ -117,6 +117,7 @@ github.com/cznic/sortutil v0.0.0-20181122101858-f5f958428db8 h1:LpMLYGyy67BoAFGd
 github.com/cznic/sortutil v0.0.0-20181122101858-f5f958428db8/go.mod h1:q2w6Bg5jeox1B+QkJ6Wp/+Vn0G/bo3f1uY7Fn3vivIQ=
 github.com/cznic/strutil v0.0.0-20171016134553-529a34b1c186/go.mod h1:AHHPPPXTw0h6pVabbcbyGRK1DckRn7r/STdZEeIDzZc=
 github.com/cznic/y v0.0.0-20170802143616-045f81c6662a/go.mod h1:1rk5VM7oSnA4vjp+hrLQ3HWHa+Y4yPCa3/CsJrcNnvs=
+github.com/danjacques/gofslock v0.0.0-20191023191349-0a45f885bc37 h1:X6mKGhCFOxrKeeHAjv/3UvT6e5RRxW6wRdlqlV6/H4w=
 github.com/danjacques/gofslock v0.0.0-20191023191349-0a45f885bc37/go.mod h1:DC3JtzuG7kxMvJ6dZmf2ymjNyoXwgtklr7FN+Um2B0U=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=

lightning/lightning.go

@@ -35,6 +35,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/shurcooL/httpgzip"
 	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
 	"golang.org/x/net/http/httpproxy"
 
 	"github.com/pingcap/tidb-lightning/lightning/backend"
@@ -108,6 +109,7 @@ func (l *Lightning) GoServe() error {
 	mux.HandleFunc("/progress/table", handleProgressTable)
 	mux.HandleFunc("/pause", handlePause)
 	mux.HandleFunc("/resume", handleResume)
+	mux.HandleFunc("/loglevel", handleLogLevel)
 
 	mux.Handle("/web/", http.StripPrefix("/web", httpgzip.FileServer(web.Res, httpgzip.FileServerOptions{
 		IndexHTML: true,
@@ -554,6 +556,36 @@ func handleResume(w http.ResponseWriter, req *http.Request) {
 	}
 }
 
+func handleLogLevel(w http.ResponseWriter, req *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+
+	var logLevel struct {
+		Level zapcore.Level `json:"level"`
+	}
+
+	switch req.Method {
+	case http.MethodGet:
+		logLevel.Level = log.Level()
+		w.WriteHeader(http.StatusOK)
+		json.NewEncoder(w).Encode(logLevel)
+
+	case http.MethodPut, http.MethodPost:
+		if err := json.NewDecoder(req.Body).Decode(&logLevel); err != nil {
+			writeJSONError(w, http.StatusBadRequest, "invalid log level", err)
+			return
+		}
+		oldLevel := log.SetLevel(zapcore.InfoLevel)
+		log.L().Info("changed log level", zap.Stringer("old", oldLevel), zap.Stringer("new", logLevel.Level))
+		log.SetLevel(logLevel.Level)
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("{}"))
+
+	default:
+		w.Header().Set("Allow", http.MethodGet+", "+http.MethodPut+", "+http.MethodPost)
+		writeJSONError(w, http.StatusMethodNotAllowed, "only GET, PUT and POST are allowed", nil)
+	}
+}
+
 func checkSystemRequirement(cfg *config.Config, dbsMeta []*mydump.MDDatabaseMeta) error {
 	// in local mode, we need to read&write a lot of L0 sst files, so we need to check system max open files limit
 	if cfg.TikvImporter.Backend == config.BackendLocal {

lightning/log/log.go

@@ -106,6 +106,11 @@ func L() Logger {
 	return appLogger
 }
 
+// Level returns the current global log level.
+func Level() zapcore.Level {
+	return appLevel.Level()
+}
+
 // SetLevel modifies the log level of the global logger. Returns the previous
 // level.
 func SetLevel(level zapcore.Level) zapcore.Level {

web/docs/api.yaml

@@ -1,7 +1,7 @@
 openapi: 3.0.2
 info:
   title: TiDB Lightning web interface
-  version: 3.0.0
+  version: 4.0.6
 servers:
   - url: http://127.0.0.1:8289/
 tags:
@@ -11,6 +11,8 @@ tags:
     description: Task progress
   - name: Pause
     description: Pause/resume tasks
+  - name: Log
+    description: Logging
 components:
   schemas:
     Error:
@@ -236,6 +238,23 @@ components:
       properties:
         paused:
           type: boolean
+    LogLevel:
+      type: object
+      required:
+        - level
+      additionalProperties: false
+      properties:
+        level:
+          type: string
+          description: Log level
+          enum:
+            - debug
+            - info
+            - warn
+            - error
+            - dpanic
+            - panic
+            - fatal
   parameters:
     TaskId:
       name: taskId
@@ -255,6 +274,13 @@ components:
           example: |
             [mydumper]
             data-source-dir = '/data/db1'
+    LogLevel:
+      description: Log level
+      required: true
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/LogLevel'
   responses:
     serverModeDisabled:
       description: Server mode disabled
@@ -465,3 +491,31 @@ paths:
       responses:
         200:
           description: The program is resumed
+  /loglevel:
+    get:
+      summary: Get the current log level
+      operationId: GetLogLevel
+      tags: [Log]
+      responses:
+        200:
+          description: Current log level
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/LogLevel'
+    put:
+      summary: Change the current log level
+      operationId: PutLogLevel
+      tags: [Log]
+      requestBody:
+        $ref: '#/components/requestBodies/LogLevel'
+      responses:
+        200:
+          description: Log level is updated
+        400:
+          description: Invalid log level
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+