infoschema: add virtual table cluster config

Signed-off-by: Lonng <heng@lonng.org>

go.mod

@@ -27,6 +27,7 @@ require (
 	github.com/gorilla/websocket v1.4.0 // indirect
 	github.com/grpc-ecosystem/go-grpc-middleware v1.0.1-0.20190118093823-f849b5445de4
 	github.com/grpc-ecosystem/grpc-gateway v1.5.1 // indirect
+	github.com/jeremywohl/flatten v0.0.0-20190921043622-d936035e55cf
 	github.com/json-iterator/go v1.1.6 // indirect
 	github.com/klauspost/cpuid v0.0.0-20170728055534-ae7887de9fa5
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect

go.sum

@@ -109,6 +109,8 @@ github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
+github.com/jeremywohl/flatten v0.0.0-20190921043622-d936035e55cf h1:Ut4tTtPNmInWiEWJRernsWm688R0RN6PFO8sZhwI0sk=
+github.com/jeremywohl/flatten v0.0.0-20190921043622-d936035e55cf/go.mod h1:4AmD/VxjWcI5SRB0n6szE2A6s2fsNHDLO0nAlMHgfLQ=
 github.com/jonboulle/clockwork v0.1.0 h1:VKV+ZcuP6l3yW9doeqz6ziZGgcynBVQO+obU0+0hcPo=
 github.com/jonboulle/clockwork v0.1.0/go.mod h1:Ii8DK3G1RaLaWxj9trq07+26W01tbo22gdxWY5EU2bo=
 github.com/json-iterator/go v1.1.6 h1:MrUvLMLTMxbqFJ9kzlvat/rYZqZnW3u4wkLzWTaFwKs=

infoschema/tables.go

@@ -17,11 +17,13 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"net/http"
 	"sort"
 	"strings"
 	"sync"
 	"time"
 
+	"github.com/jeremywohl/flatten"
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser/charset"
 	"github.com/pingcap/parser/model"
@@ -87,6 +89,7 @@ const (
 	tableTiKVRegionPeers                    = "TIKV_REGION_PEERS"
 	tableTiDBServersInfo                    = "TIDB_SERVERS_INFO"
 	tableTiDBClusterInfo                    = "TIDB_CLUSTER_INFO"
+	tableTiDBClusterConfig                  = "TIDB_CLUSTER_CONFIG"
 )
 
 type columnInfo struct {
@@ -672,6 +675,13 @@ var tableTiDBClusterInfoCols = []columnInfo{
 	{"GIT_HASH", mysql.TypeVarchar, 64, 0, nil, nil},
 }
 
+var tableTiDBClusterConfigCols = []columnInfo{
+	{"SERVER_TYPE", mysql.TypeVarchar, 8, 0, nil, nil},
+	{"INSTANCE", mysql.TypeVarchar, 64, 0, nil, nil},
+	{"NAME", mysql.TypeVarchar, 256, 0, nil, nil},
+	{"VALUE", mysql.TypeVarchar, 128, 0, nil, nil},
+}
+
 func dataForTiKVRegionStatus(ctx sessionctx.Context) (records [][]types.Datum, err error) {
 	tikvStore, ok := ctx.GetStore().(tikv.Storage)
 	if !ok {
@@ -1939,7 +1949,36 @@ func dataForTiDBClusterInfo(ctx sessionctx.Context) ([][]types.Datum, error) {
 		rows = append(rows, row)
 		idx++
 	}
+	return rows, nil
+}
+
+// TODO: poc for config flatten, fetch all servers
+func dataForClusterConfig() ([][]types.Datum, error) {
+	resp, err := http.Get("http://127.0.0.1:49904/config")
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
 
+	var nested map[string]interface{}
+	if err = json.NewDecoder(resp.Body).Decode(&nested); err != nil {
+		return nil, err
+	}
+	data, err := flatten.Flatten(nested, "", flatten.DotStyle)
+	if err != nil {
+		return nil, err
+	}
+	var rows [][]types.Datum
+	instance := types.NewStringDatum("127.0.0.1:49904")
+	serverTp := types.NewStringDatum("TiKV")
+	for key, val := range data {
+		rows = append(rows, []types.Datum{
+			serverTp,
+			instance,
+			types.NewStringDatum(key),
+			types.NewStringDatum(fmt.Sprintf("%v", val)),
+		})
+	}
 	return rows, nil
 }
 
@@ -1985,6 +2024,7 @@ var tableNameToColumns = map[string][]columnInfo{
 	tableTiKVRegionPeers:                    tableTiKVRegionPeersCols,
 	tableTiDBServersInfo:                    tableTiDBServersInfoCols,
 	tableTiDBClusterInfo:                    tableTiDBClusterInfoCols,
+	tableTiDBClusterConfig:                  tableTiDBClusterConfigCols,
 }
 
 func createInfoSchemaTable(handle *Handle, meta *model.TableInfo) *infoschemaTable {
@@ -2092,6 +2132,8 @@ func (it *infoschemaTable) getRows(ctx sessionctx.Context, cols []*table.Column)
 		fullRows, err = dataForServersInfo()
 	case tableTiDBClusterInfo:
 		fullRows, err = dataForTiDBClusterInfo(ctx)
+	case tableTiDBClusterConfig:
+		fullRows, err = dataForClusterConfig()
 	}
 	if err != nil {
 		return nil, err