added monitoring database connection test endpoint to the app (knativ…

…e#778)

* added monitoring database connection test endpoint to the skeleton app

* connect to the cloudsql database without using cloudsql proxy

* updated dep to include cloudsql, mysql driver

* read the secrets directly and pass database instance information in flags

tools/monitoring/Makefile

@@ -13,4 +13,6 @@
 # limitations under the License.
 
 all:
+	go get -u github.com/go-sql-driver/mysql
+	go get -u gopkg.in/yaml.v2
 	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build .

tools/monitoring/gke_deployment/monitoring_service.yaml

@@ -41,11 +41,22 @@ spec:
       containers:
       - name: monitoring-app
         image: gcr.io/knative-tests/test-infra/monitoring:latest
+        command: ["/monitoring",
+                  "--database-name=monitoring",
+                  "--database-instance='knative-tests:us-central1:knative-monitoring'"]
         # This setting makes nodes pull the docker image every time before
         # starting the pod. This is useful when debugging, but should be turned
         # off in production.
         # TODO(yt3liu) Turn this off once monitoring is more stable
         imagePullPolicy: Always
         ports:
         - name: http-server
-          containerPort: 8080
+          containerPort: 8080
+        volumeMounts:
+        - name: monitoring-db-credentials
+          mountPath: /secrets/cloudsql/monitoringdb
+          readOnly: true
+      volumes:
+      - name: monitoring-db-credentials
+        secret:
+          secretName: monitoring-db-credentials

tools/monitoring/main.go

@@ -17,15 +17,36 @@ limitations under the License.
 package main
 
 import (
+	"flag"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
+
+	"github.com/knative/test-infra/tools/monitoring/mysql"
 )
 
-const yamlURL = "https://raw.githubusercontent.com/knative/test-infra/master/tools/monitoring/sample.yaml"
+var dbConfig mysql.DBConfig
+
+const (
+	yamlURL              = "https://raw.githubusercontent.com/knative/test-infra/master/tools/monitoring/sample.yaml"
+	dbUserSecretFile     = "/secrets/cloudsql/monitoringdb/username"
+	dbPasswordSecretFile = "/secrets/cloudsql/monitoringdb/password"
+)
 
 func main() {
+	var err error
+
+	dbName := flag.String("database-name", "", "The monitoring database name")
+	dbInst := flag.String("database-instance", "", "The monitoring CloudSQL instance connection name")
+	flag.Parse()
+
+	dbConfig, err = configureMonitoringDatabase(*dbName, *dbInst)
+	if err != nil {
+		log.Fatal(err)
+	}
+
 	// use PORT environment variable, or default to 8080
 	port := "8080"
 	if fromEnv := os.Getenv("PORT"); fromEnv != "" {
@@ -34,11 +55,12 @@ func main() {
 
 	// register hello function to handle all requests
 	server := http.NewServeMux()
-	server.HandleFunc("/", hello)
+	server.HandleFunc("/hello", hello)
+	server.HandleFunc("/test-conn", testCloudSQLConn)
 
 	// start the web server on port and accept requests
 	log.Printf("Server listening on port %s", port)
-	err := http.ListenAndServe(":"+port, server)
+	err = http.ListenAndServe(":"+port, server)
 	log.Fatal(err)
 }
 
@@ -57,3 +79,38 @@ func hello(w http.ResponseWriter, r *http.Request) {
 	errorPatterns := yamlFile.CollectErrorPatterns()
 	fmt.Fprintf(w, "error patterns collected from yaml:%s", errorPatterns)
 }
+
+func testCloudSQLConn(w http.ResponseWriter, r *http.Request) {
+	log.Printf("Serving request: %s", r.URL.Path)
+	log.Println("Testing mysql database connection.")
+
+	err := dbConfig.TestConn()
+	if err != nil {
+		fmt.Fprintf(w, "Failed to ping the database %v", err)
+		return
+	}
+	fmt.Fprintf(w, "Success\n")
+}
+
+func configureMonitoringDatabase(dbName string, dbInst string) (mysql.DBConfig, error) {
+	var config mysql.DBConfig
+
+	user, err := ioutil.ReadFile(dbUserSecretFile)
+	if err != nil {
+		return config, err
+	}
+
+	pass, err := ioutil.ReadFile(dbPasswordSecretFile)
+	if err != nil {
+		return config, err
+	}
+
+	config = mysql.DBConfig{
+		Username:     string(user),
+		Password:     string(pass),
+		DatabaseName: dbName,
+		Instance:     dbInst,
+	}
+
+	return config, nil
+}

tools/monitoring/mysql/db_mysql.go

@@ -0,0 +1,73 @@
+/*
+Copyright 2019 The Knative Authors
+
+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 mysql
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"fmt"
+
+	_ "github.com/go-sql-driver/mysql"
+)
+
+const driverName = "mysql"
+
+// DBConfig is the configuration used to connection to database
+type DBConfig struct {
+	Username     string
+	Password     string
+	Instance     string
+	DatabaseName string
+}
+
+func (c DBConfig) TestConn() error {
+	conn, err := c.getConn()
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	return nil
+}
+
+func (c DBConfig) getConn() (*sql.DB, error) {
+	conn, err := sql.Open(driverName, c.dataStoreName(c.DatabaseName))
+	if err != nil {
+		return nil, fmt.Errorf("could not get a connection: %v", err)
+	}
+
+	if conn.Ping() == driver.ErrBadConn {
+		return nil, fmt.Errorf("could not connect to the datastore. " +
+			"could be bad address, or this address is inaccessible from your host.\n")
+	}
+
+	return conn, nil
+}
+
+func (c DBConfig) dataStoreName(dbName string) string {
+	var cred string
+	// [username[:password]@]
+	if len(c.Username) > 0 {
+		cred = c.Username
+		if len(c.Password) > 0 {
+			cred = cred + ":" + c.Password
+		}
+		cred = cred + "@"
+	}
+
+	return fmt.Sprintf("%sunix(%s)/%s", cred, "/cloudsql/"+c.Instance, dbName)
+}