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// author: Gary A. Stafford | |
// site: https://programmaticponderings.com | |
// license: MIT License | |
// purpose: Service F | |
// date: 2021-06-05 | |
package main | |
import ( | |
"bytes" | |
"context" | |
"encoding/json" | |
runtime "github.com/banzaicloud/logrus-runtime-formatter" | |
"net/http" | |
"os" | |
"time" | |
"github.com/google/uuid" | |
"github.com/gorilla/mux" | |
"github.com/prometheus/client_golang/prometheus/promhttp" | |
log "github.com/sirupsen/logrus" | |
"github.com/streadway/amqp" | |
"go.mongodb.org/mongo-driver/mongo" | |
"go.mongodb.org/mongo-driver/mongo/options" | |
) | |
var ( | |
logLevel = getEnv("LOG_LEVEL", "debug") | |
port = getEnv("PORT", ":8080") | |
serviceName = getEnv("SERVICE_NAME", "Service F") | |
message = getEnv("GREETING", "Hola, from Service F!") | |
queueName = getEnv("QUEUE_NAME", "service-d.greeting") | |
mongoConn = getEnv("MONGO_CONN", "mongodb://mongodb:27017/admin") | |
rabbitMQConn = getEnv("RABBITMQ_CONN", "amqp://guest:guest@rabbitmq:5672") | |
) | |
type Greeting struct { | |
ID string `json:"id,omitempty"` | |
ServiceName string `json:"service,omitempty"` | |
Message string `json:"message,omitempty"` | |
CreatedAt time.Time `json:"created,omitempty"` | |
Hostname string `json:"hostname,omitempty"` | |
} | |
var greetings []Greeting | |
// *** HANDLERS *** | |
func GreetingHandler(w http.ResponseWriter, _ *http.Request) { | |
w.Header().Set("Content-Type", "application/json; charset=utf-8") | |
w.WriteHeader(http.StatusOK) | |
greetings = nil | |
tmpGreeting := Greeting{ | |
ID: uuid.New().String(), | |
ServiceName: serviceName, | |
Message: message, | |
CreatedAt: time.Now().Local(), | |
Hostname: getHostname(), | |
} | |
greetings = append(greetings, tmpGreeting) | |
callMongoDB(tmpGreeting, mongoConn) | |
err := json.NewEncoder(w).Encode(greetings) | |
if err != nil { | |
log.Error(err) | |
} | |
} | |
func HealthCheckHandler(w http.ResponseWriter, _ *http.Request) { | |
w.Header().Set("Content-Type", "application/json; charset=utf-8") | |
w.WriteHeader(http.StatusOK) | |
_, err := w.Write([]byte("{\"alive\": true}")) | |
if err != nil { | |
log.Error(err) | |
} | |
} | |
// *** UTILITY FUNCTIONS *** | |
func getHostname() string { | |
hostname, err := os.Hostname() | |
if err != nil { | |
log.Error(err) | |
} | |
return hostname | |
} | |
func callMongoDB(greeting Greeting, mongoConn string) { | |
log.Info(greeting) | |
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) | |
defer cancel() | |
client, err := mongo.Connect(ctx, options.Client().ApplyURI(mongoConn)) | |
if err != nil { | |
log.Error(err) | |
} | |
defer func(client *mongo.Client, ctx context.Context) { | |
err := client.Disconnect(ctx) | |
if err != nil { | |
log.Error(err) | |
} | |
}(client, nil) | |
collection := client.Database("service-f").Collection("messages") | |
ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second) | |
defer cancel() | |
_, err = collection.InsertOne(ctx, greeting) | |
if err != nil { | |
log.Error(err) | |
} | |
} | |
func getMessages(rabbitMQConn string) { | |
conn, err := amqp.Dial(rabbitMQConn) | |
if err != nil { | |
log.Error(err) | |
} | |
defer func(conn *amqp.Connection) { | |
err := conn.Close() | |
if err != nil { | |
log.Error(err) | |
} | |
}(conn) | |
ch, err := conn.Channel() | |
if err != nil { | |
log.Error(err) | |
} | |
defer func(ch *amqp.Channel) { | |
err := ch.Close() | |
if err != nil { | |
log.Error(err) | |
} | |
}(ch) | |
q, err := ch.QueueDeclare( | |
queueName, | |
false, | |
false, | |
false, | |
false, | |
nil, | |
) | |
if err != nil { | |
log.Error(err) | |
} | |
msgs, err := ch.Consume( | |
q.Name, | |
"service-f", | |
true, | |
false, | |
false, | |
false, | |
nil, | |
) | |
if err != nil { | |
log.Error(err) | |
} | |
forever := make(chan bool) | |
go func() { | |
for delivery := range msgs { | |
log.Debug(delivery) | |
callMongoDB(deserialize(delivery.Body), mongoConn) | |
} | |
}() | |
<-forever | |
} | |
func deserialize(b []byte) (t Greeting) { | |
log.Debug(b) | |
var tmpGreeting Greeting | |
buf := bytes.NewBuffer(b) | |
decoder := json.NewDecoder(buf) | |
err := decoder.Decode(&tmpGreeting) | |
if err != nil { | |
log.Error(err) | |
} | |
return tmpGreeting | |
} | |
func getEnv(key, fallback string) string { | |
if value, ok := os.LookupEnv(key); ok { | |
return value | |
} | |
return fallback | |
} | |
func run() error { | |
go getMessages(rabbitMQConn) | |
router := mux.NewRouter() | |
api := router.PathPrefix("/api").Subrouter() | |
api.HandleFunc("/greeting", GreetingHandler).Methods("GET") | |
api.HandleFunc("/health", HealthCheckHandler).Methods("GET") | |
api.Handle("/metrics", promhttp.Handler()) | |
return http.ListenAndServe(port, router) | |
} | |
func init() { | |
formatter := runtime.Formatter{ChildFormatter: &log.JSONFormatter{}} | |
formatter.Line = true | |
log.SetFormatter(&formatter) | |
log.SetOutput(os.Stdout) | |
level, err := log.ParseLevel(logLevel) | |
if err != nil { | |
log.Error(err) | |
} | |
log.SetLevel(level) | |
} | |
func main() { | |
if err := run(); err != nil { | |
log.Fatal(err) | |
os.Exit(1) | |
} | |
} |
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