Merge pull request #113 from cybertec-postgresql/93-add-support-for-m…

…etric-endpoint

[+] add `/metric` endpoint, closes #93

src/api.go

@@ -8,6 +8,54 @@ type uiapihandler struct{}
 
 var uiapi uiapihandler
 
+// GetMetrics returns the list of monitored databases
+func (uiapi uiapihandler) GetMetrics() (res string, err error) {
+	sql := `select coalesce(jsonb_agg(to_jsonb(m)), '[]') from metric m`
+	err = configDb.Get(&res, sql)
+	return
+}
+
+// DeleteMetric removes the database from the list of monitored databases
+func (uiapi uiapihandler) DeleteMetric(id int) error {
+	_, err := configDb.Exec("DELETE FROM pgwatch3.metric WHERE m_id = $1", id)
+	return err
+}
+
+// AddMetric adds the metric to the list of stored metrics
+func (uiapi uiapihandler) AddMetric(params []byte) error {
+	sql := `INSERT INTO pgwatch3.metric(
+m_name, m_pg_version_from, m_sql, m_comment, m_is_active, m_is_helper, 
+m_master_only, m_standby_only, m_column_attrs, m_sql_su)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)`
+	var m map[string]any
+	err := json.Unmarshal(params, &m)
+	if err == nil {
+		_, err = configDb.Exec(sql, m["m_name"], m["m_pg_version_from"],
+			m["m_sql"], m["m_comment"], m["m_is_active"],
+			m["m_is_helper"], m["m_master_only"], m["m_standby_only"],
+			m["m_column_attrs"], m["m_sql_su"])
+	}
+	return err
+}
+
+// UpdateMetric updates the stored metric information
+func (uiapi uiapihandler) UpdateMetric(id int, params []byte) error {
+	sql := `UPDATE pgwatch3.metric(
+m_name, m_pg_version_from, m_sql, m_comment, m_is_active, m_is_helper, 
+m_master_only, m_standby_only, m_column_attrs, m_sql_su)
+= ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
+WHERE m_id = $11`
+	var m map[string]any
+	err := json.Unmarshal(params, &m)
+	if err == nil {
+		_, err = configDb.Exec(sql, m["m_name"], m["m_pg_version_from"],
+			m["m_sql"], m["m_comment"], m["m_is_active"],
+			m["m_is_helper"], m["m_master_only"], m["m_standby_only"],
+			m["m_column_attrs"], m["m_sql_su"], id)
+	}
+	return err
+}
+
 // GetDatabases returns the list of monitored databases
 func (uiapi uiapihandler) GetDatabases() (res string, err error) {
 	sql := `select coalesce(jsonb_agg(to_jsonb(db)), '[]') from monitored_db db`

src/webserver/restapi.go

@@ -3,8 +3,65 @@ package webserver
 import (
 	"io"
 	"net/http"
+	"strconv"
 )
 
+func (Server *WebUIServer) handleMetrics(w http.ResponseWriter, r *http.Request) {
+	var (
+		err    error
+		params []byte
+		res    string
+		id     int
+	)
+
+	defer func() {
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+		}
+	}()
+
+	switch r.Method {
+	case http.MethodGet:
+		// return stored metrics
+		if res, err = Server.api.GetMetrics(); err != nil {
+			return
+		}
+		_, err = w.Write([]byte(res))
+
+	case http.MethodPost:
+		// add new stored metric
+		if params, err = io.ReadAll(r.Body); err != nil {
+			return
+		}
+		err = Server.api.AddMetric(params)
+
+	case http.MethodPatch:
+		// update monitored database
+		if params, err = io.ReadAll(r.Body); err != nil {
+			return
+		}
+		if id, err = strconv.Atoi(r.URL.Query().Get("id")); err != nil {
+			return
+		}
+		err = Server.api.UpdateMetric(id, params)
+
+	case http.MethodDelete:
+		// delete stored metric
+		if id, err = strconv.Atoi(r.URL.Query().Get("id")); err != nil {
+			return
+		}
+		err = Server.api.DeleteMetric(id)
+
+	case http.MethodOptions:
+		w.Header().Set("Allow", "GET, POST, PATCH, DELETE, OPTIONS")
+		w.WriteHeader(http.StatusNoContent)
+
+	default:
+		w.Header().Set("Allow", "GET, POST, PATCH, DELETE, OPTIONS")
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
 func (Server *WebUIServer) handleDBs(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case http.MethodGet:
@@ -21,6 +78,7 @@ func (Server *WebUIServer) handleDBs(w http.ResponseWriter, r *http.Request) {
 		p, err := io.ReadAll(r.Body)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
 		}
 		if err := Server.api.AddDatabase(p); err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)
@@ -30,6 +88,7 @@ func (Server *WebUIServer) handleDBs(w http.ResponseWriter, r *http.Request) {
 		p, err := io.ReadAll(r.Body)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
 		}
 		if err := Server.api.UpdateDatabase(r.URL.Query().Get("id"), p); err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)

src/webserver/server.go

@@ -19,6 +19,10 @@ type apiHandler interface {
 	AddDatabase(params []byte) error
 	DeleteDatabase(id string) error
 	UpdateDatabase(id string, params []byte) error
+	GetMetrics() (res string, err error)
+	AddMetric(params []byte) error
+	DeleteMetric(id int) error
+	UpdateMetric(id int, params []byte) error
 }
 
 type WebUIServer struct {
@@ -50,6 +54,7 @@ func Init(addr string, webuifs fs.FS, api apiHandler) *WebUIServer {
 
 	mux.HandleFunc("/health", s.handleHealth)
 	mux.HandleFunc("/db", s.handleDBs)
+	mux.HandleFunc("/metric", s.handleMetrics)
 	mux.HandleFunc("/", s.handleStatic)
 
 	if 8080 != 0 {