1. Go überden Wolken

4. Go App Engine Cold Start
Up and running in 500ms! 🚀

6. Hello Gopher
package main
import "fmt"
func main() {
fmt.Println("Hello Gopher!")
}
Ausführen
go build hellogopher.go // 1. Code kompilieren
./hellogopher // 2. Binary ausführen
go run hellogopher.go // Code kompilieren und ausführen

7. Entwicklung
JetBrains
GoLand
Visual
Studio Code Vim Go

8. 5 Fakten zu Go
1. statisches Typsystem
2. Garbage Collection
3. keine Vererbung
4. Concurrency eingebaut
5. native Ausführung
Linux, Win, z/OS, 386, amd64, ARM, wasm, ...

9. Was ist
cloud-native?

10. Cloud Native Technologien befähigen
skalierbare Anwendungen
zu entwickeln und betreiben,
in modernen, dynamischen Umgebungen.
Cloud Native Computing Foundation

11. Skalierbarheisst ...
Last wird auf 2, 3, ... Instanzen verteilt
eine Instanz kann mehrCPU und Speicher
bekommen
ist nichts los, läuft auch nichts
#
#
#

12. Moderne, dynamische Umgebung
heißt ...
Instanzen sind flüchtig
Adressen sind flüchtig
Hostnamen sind flüchtig
kein Dateisystem
#
#
#
#

13. 12 FactorApp
1. Codebasis
2. Abhängigkeiten
3. Konfiguration
4. Unterstützende Dienste
5. Build, Release, Run
6. Prozesse
7. Bindung an Ports
8. Nebenläufigkeit und Skalierung
9. Einweggebrauch
10. Dev-Prod-Vergleichbarkeit
11. Logs
12. Admin-Prozesse
✅
✅
✅

14. TarifrechnerDogOP

15. TarifrechnerDogOp v0.1
TarifrechnerfürHunde OPVersicherung
#
REST API die einen Tarif berechnet
#
Bereitstellung als Container
#
Konfiguration überUmgebungsvariablen
#

16. TarifrechnerDogOp v0.2
Angebote in PostgreSQL DB speichern
#
Migration DatenbankSchema
#
Bereitstellung als Container
#
CRUD Operationen in REST API
#

17. Fallschirm und Rettungsgurt
Problem Details
#
Health Check
#
Logging und Tracing
#

18. Tarifrechner
DogOp v0.1

19. Projekt DogOPaufsetzen
go mod init crossnative/dogop // Go Modul initialisieren
go get github.com/go-chi/chi/v5 // Chi Dependency einbinden
Projektstruktur
go.mod // Modul Deskriptor mit Dependencies
go.sum // Checksummen der Dependencies

20. Projekt DogOPaufsetzen
package main
import (
"net/http"
"github.com/go-chi/chi/v5"
)
func main() {
}
1
2
3
4
5
6
7
8
r := chi.NewRouter()
9
r.Get("/", func(w http.ResponseWriter, req *http.Request
10
w.Write([]byte("Hello DogOp!"))
11
})
12
http.ListenAndServe(":8080", r)
13
14
r := chi.NewRouter()
package main
1
2
import (
3
"net/http"
4
"github.com/go-chi/chi/v5"
5
)
6
7
func main() {
8
9
r.Get("/", func(w http.ResponseWriter, req *http.Request
10
w.Write([]byte("Hello DogOp!"))
11
})
12
http.ListenAndServe(":8080", r)
13
}
14
r.Get("/", func(w http.ResponseWriter, req *http.Request
w.Write([]byte("Hello DogOp!"))
})
package main
1
2
import (
3
"net/http"
4
"github.com/go-chi/chi/v5"
5
)
6
7
func main() {
8
r := chi.NewRouter()
9
10
11
12
http.ListenAndServe(":8080", r)
13
}
14
http.ListenAndServe(":8080", r)
package main
1
2
import (
3
"net/http"
4
"github.com/go-chi/chi/v5"
5
)
6
7
func main() {
8
r := chi.NewRouter()
9
r.Get("/", func(w http.ResponseWriter, req *http.Request
10
w.Write([]byte("Hello DogOp!"))
11
})
12
13
}
14
package main
import (
"net/http"
"github.com/go-chi/chi/v5"
)
func main() {
r := chi.NewRouter()
r.Get("/", func(w http.ResponseWriter, req *http.Request
w.Write([]byte("Hello DogOp!"))
})
http.ListenAndServe(":8080", r)
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14

21. Bauen und Ausführen
// 1. Compilieren in Binary
go build -o build/dogop .
// 2. Binary ausführen
./build/dogop

22. Bauen und Ausführen

23. REST API fürRechner
Request
POST /api/quote
content-type: application/json
{
"age": 8,
"breed": "chow"
}
Response
HTTP/1.1 200 OK
Content-Type: application/json
{
"age": 8,
"breed": "chow",
"tariffs": [
{
"name": "Dog OP _ Basic",
"rate": 12.4
}
]
}

24. REST API fürRechner
func main() {
r.Post("/api/quote", HandleQuote)
}
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
// 1. JSON Request lesen
2
var q Quote
3
json.NewDecoder(r.Body).Decode(&q)
4
5
// 2. Tarif berechnen
6
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
7
quote.Tariffs = []Tariff{tariff}
8
9
// 3. JSON Response schreiben
10
json.NewEncoder(w).Encode(quote)
11
}
12
13
14
r := chi.NewRouter()
15
16
17
18
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
19
w.Write([]byte("Hello DogOp!"))
20
})
21
22
http.ListenAndServe(":8080", r)
23
24
func HandleQuote(w http.ResponseWriter, r *http.Request) {
}
1
// 1. JSON Request lesen
2
var q Quote
3
json.NewDecoder(r.Body).Decode(&q)
4
5
// 2. Tarif berechnen
6
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
7
quote.Tariffs = []Tariff{tariff}
8
9
// 3. JSON Response schreiben
10
json.NewEncoder(w).Encode(quote)
11
12
13
func main() {
14
r := chi.NewRouter()
15
16
r.Post("/api/quote", HandleQuote)
17
18
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
19
w.Write([]byte("Hello DogOp!"))
20
})
21
22
http.ListenAndServe(":8080", r)
23
}
24
// 1. JSON Request lesen
var q Quote
json.NewDecoder(r.Body).Decode(&q)
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
2
3
4
5
// 2. Tarif berechnen
6
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
7
quote.Tariffs = []Tariff{tariff}
8
9
// 3. JSON Response schreiben
10
json.NewEncoder(w).Encode(quote)
11
}
12
13
func main() {
14
r := chi.NewRouter()
15
16
r.Post("/api/quote", HandleQuote)
17
18
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
19
w.Write([]byte("Hello DogOp!"))
20
})
21
22
http.ListenAndServe(":8080", r)
23
}
24
// 2. Tarif berechnen
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
quote.Tariffs = []Tariff{tariff}
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
// 1. JSON Request lesen
2
var q Quote
3
json.NewDecoder(r.Body).Decode(&q)
4
5
6
7
8
9
// 3. JSON Response schreiben
10
json.NewEncoder(w).Encode(quote)
11
}
12
13
func main() {
14
r := chi.NewRouter()
15
16
r.Post("/api/quote", HandleQuote)
17
18
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
19
w.Write([]byte("Hello DogOp!"))
20
})
21
22
http.ListenAndServe(":8080", r)
23
}
24
// 3. JSON Response schreiben
json.NewEncoder(w).Encode(quote)
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
// 1. JSON Request lesen
2
var q Quote
3
json.NewDecoder(r.Body).Decode(&q)
4
5
// 2. Tarif berechnen
6
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
7
quote.Tariffs = []Tariff{tariff}
8
9
10
11
}
12
13
func main() {
14
r := chi.NewRouter()
15
16
r.Post("/api/quote", HandleQuote)
17
18
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
19
w.Write([]byte("Hello DogOp!"))
20
})
21
22
http.ListenAndServe(":8080", r)
23
}
24
func HandleQuote(w http.ResponseWriter, r *http.Request) {
// 1. JSON Request lesen
var q Quote
json.NewDecoder(r.Body).Decode(&q)
// 2. Tarif berechnen
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
quote.Tariffs = []Tariff{tariff}
// 3. JSON Response schreiben
json.NewEncoder(w).Encode(quote)
}
func main() {
r := chi.NewRouter()
r.Post("/api/quote", HandleQuote)
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Hello DogOp!"))
})
http.ListenAndServe(":8080", r)
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Achtung, noch ohne Fehlerhandling! 💣

26. Struct statt Klasse
// Structs definieren
type Tariff struct {
Name string `json:"name"`
Rate float64 `json:"rate"`
}
1
2
3
4
5
6
7
type Quote struct {
8
Age int `json:"age"`
9
Breed string `json:"breed"`
10
Tariffs []Tariff `json:"tariffs"`
11
}
12
type Quote struct {
Age int `json:"age"`
Breed string `json:"breed"`
Tariffs []Tariff `json:"tariffs"`
}
// Structs definieren
1
2
type Tariff struct {
3
Name string `json:"name"`
4
Rate float64 `json:"rate"`
5
}
6
7
8
9
10
11
12
// Structs definieren
type Tariff struct {
Name string `json:"name"`
Rate float64 `json:"rate"`
}
type Quote struct {
Age int `json:"age"`
Breed string `json:"breed"`
Tariffs []Tariff `json:"tariffs"`
}
1
2
3
4
5
6
7
8
9
10
11
12
// Struct erzeugen
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}

27. Fehler💣
func HandleQuote(w http.ResponseWriter, r *http.Request) {
}
1
// 1. JSON Request lesen
2
var q Quote
3
json.NewDecoder(r.Body).Decode(&q) // 💣 Fehler möglich!
4
5
// 2. Tarif berechnen
6
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
7
quote.Tariffs = []Tariff{tariff}
8
9
// 3. JSON Response schreiben
10
json.NewEncoder(w).Encode(quote) // 💣 Fehler möglich!
11
12
json.NewDecoder(r.Body).Decode(&q) // 💣 Fehler möglich!
json.NewEncoder(w).Encode(quote) // 💣 Fehler möglich!
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
// 1. JSON Request lesen
2
var q Quote
3
4
5
// 2. Tarif berechnen
6
tariff := Tariff{Name: "Dog OP _ Basic", Rate: 12.4}
7
quote.Tariffs = []Tariff{tariff}
8
9
// 3. JSON Response schreiben
10
11
}
12

29. Fehler💣
Go kennt kein spezielles Konstrukt zur
Fehlerbehandlung
#
Fehlersind normale Rückgabewerte
#

30. Fehler💣
func HandleQuote(w http.ResponseWriter, r *http.Request) {
}
1
// 1. JSON Request lesen
2
var q Quote
3
4
// Potentieller Fehler
5
err := json.NewDecoder(r.Body).Decode(&q)
6
7
// Auf Fehler prüfen
8
if err != nil {
9
// Fehler behandeln
10
http.Error(w, "Could not decode quote.😔", http.StatusBadRequest)
11
return
12
}
13
14
// ...
15
16
// Potentieller Fehler
err := json.NewDecoder(r.Body).Decode(&q)
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
// 1. JSON Request lesen
2
var q Quote
3
4
5
6
7
// Auf Fehler prüfen
8
if err != nil {
9
// Fehler behandeln
10
http.Error(w, "Could not decode quote.😔", http.StatusBadRequest)
11
return
12
}
13
14
// ...
15
}
16
// Auf Fehler prüfen
if err != nil {
}
func HandleQuote(w http.ResponseWriter, r *http.Request) {
1
// 1. JSON Request lesen
2
var q Quote
3
4
// Potentieller Fehler
5
err := json.NewDecoder(r.Body).Decode(&q)
6
7
8
9
// Fehler behandeln
10
http.Error(w, "Could not decode quote.😔", http.StatusBadRequest)
11
return
12
13
14
// ...
15
}
16
func HandleQuote(w http.ResponseWriter, r *http.Request) {
// 1. JSON Request lesen
var q Quote
// Potentieller Fehler
err := json.NewDecoder(r.Body).Decode(&q)
// Auf Fehler prüfen
if err != nil {
// Fehler behandeln
http.Error(w, "Could not decode quote.😔", http.StatusBadRequest)
return
}
// ...
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

31. HTTPHandlertesten
Unit Tests in Standardlib enthalten
#
Tests in Datei main_test.go
#

32. HTTPHandlertesten
func TestHandleQuote(t *testing.T) {
}
1
// 1. HTTP Recorder erstellen
2
recorder := httptest.NewRecorder()
3
4
// 2. Request erstellen (mit Body)
5
body := `
6
{
7
"age": 8,
8
"breed": "chow"
9
}
10
`
11
req, _ := http.NewRequest("GET", "/api/quote", strings.NewReader(body))
12
13
// 3. Handler Funktion aufrufen
14
HandleQuote(recorder, req)
15
16
// 4. Return Code prüfen
17
if recorder.Code != http.StatusOK {
18
t.Errorf("Wrong status: got %v expected %v", recorder.Code, http.StatusOK)
19
}
20
21
// 1. HTTP Recorder erstellen
recorder := httptest.NewRecorder()
func TestHandleQuote(t *testing.T) {
1
2
3
4
// 2. Request erstellen (mit Body)
5
body := `
6
{
7
"age": 8,
8
"breed": "chow"
9
}
10
`
11
req, _ := http.NewRequest("GET", "/api/quote", strings.NewReader(body))
12
13
// 3. Handler Funktion aufrufen
14
HandleQuote(recorder, req)
15
16
// 4. Return Code prüfen
17
if recorder.Code != http.StatusOK {
18
t.Errorf("Wrong status: got %v expected %v", recorder.Code, http.StatusOK)
19
}
20
}
21
// 2. Request erstellen (mit Body)
body := `
{
"age": 8,
"breed": "chow"
}
`
req, _ := http.NewRequest("GET", "/api/quote", strings.NewReader(body))
func TestHandleQuote(t *testing.T) {
1
// 1. HTTP Recorder erstellen
2
recorder := httptest.NewRecorder()
3
4
5
6
7
8
9
10
11
12
13
// 3. Handler Funktion aufrufen
14
HandleQuote(recorder, req)
15
16
// 4. Return Code prüfen
17
if recorder.Code != http.StatusOK {
18
t.Errorf("Wrong status: got %v expected %v", recorder.Code, http.StatusOK)
19
}
20
}
21
// 3. Handler Funktion aufrufen
HandleQuote(recorder, req)
func TestHandleQuote(t *testing.T) {
1
// 1. HTTP Recorder erstellen
2
recorder := httptest.NewRecorder()
3
4
// 2. Request erstellen (mit Body)
5
body := `
6
{
7
"age": 8,
8
"breed": "chow"
9
}
10
`
11
req, _ := http.NewRequest("GET", "/api/quote", strings.NewReader(body))
12
13
14
15
16
// 4. Return Code prüfen
17
if recorder.Code != http.StatusOK {
18
t.Errorf("Wrong status: got %v expected %v", recorder.Code, http.StatusOK)
19
}
20
}
21
// 4. Return Code prüfen
if recorder.Code != http.StatusOK {
t.Errorf("Wrong status: got %v expected %v", recorder.Code, http.StatusOK)
}
func TestHandleQuote(t *testing.T) {
1
// 1. HTTP Recorder erstellen
2
recorder := httptest.NewRecorder()
3
4
// 2. Request erstellen (mit Body)
5
body := `
6
{
7
"age": 8,
8
"breed": "chow"
9
}
10
`
11
req, _ := http.NewRequest("GET", "/api/quote", strings.NewReader(body))
12
13
// 3. Handler Funktion aufrufen
14
HandleQuote(recorder, req)
15
16
17
18
19
20
}
21
func TestHandleQuote(t *testing.T) {
// 1. HTTP Recorder erstellen
recorder := httptest.NewRecorder()
// 2. Request erstellen (mit Body)
body := `
{
"age": 8,
"breed": "chow"
}
`
req, _ := http.NewRequest("GET", "/api/quote", strings.NewReader(body))
// 3. Handler Funktion aufrufen
HandleQuote(recorder, req)
// 4. Return Code prüfen
if recorder.Code != http.StatusOK {
t.Errorf("Wrong status: got %v expected %v", recorder.Code, http.StatusOK)
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

33. HTTPHandlertesten
go test -v ./...
=== RUN TestHandleQuote
--- PASS: TestHandleQuote (0.00s)
PASS
ok crossnative/dogop 0.228s

34. HTTPHandlertesten

35. Port perUmgebungsvariable
konfigurieren
// Einfach per Standardlib
function main() {
port := os.Getenv("DOGOP_PORT")
http.ListenAndServe(fmt.Sprintf(":%v", config.Port), r)
}

36. Port perUmgebungsvariable
konfigurieren
// Oder mit envconfig von Kelsey Hightower
type Config struct {
Port string `default:"8080"`
}
function main() {
var config Config
err := envconfig.Process("dogop", &config)
if err != nil {
log.Fatal(err.Error())
}
http.ListenAndServe(fmt.Sprintf(":%v", config.Port), r)
}

37. Dockerfile fürDogOP
# 1. DogOp Builder
FROM golang as builder
WORKDIR /app
ADD . /app
RUN CGO_ENABLED=0 go build -ldflags="-w -s" -o build/dogop .
1
2
3
4
5
6
# 2. DogOp Container
7
FROM alpine
8
COPY --from=builder /app/build/dogop /usr/bin/
9
EXPOSE 8080
10
ENTRYPOINT ["/usr/bin/dogop"]
11
# 2. DogOp Container
FROM alpine
COPY --from=builder /app/build/dogop /usr/bin/
EXPOSE 8080
ENTRYPOINT ["/usr/bin/dogop"]
# 1. DogOp Builder
1
FROM golang as builder
2
WORKDIR /app
3
ADD . /app
4
RUN CGO_ENABLED=0 go build -ldflags="-w -s" -o build/dogop .
5
6
7
8
9
10
11
# 1. DogOp Builder
FROM golang as builder
WORKDIR /app
ADD . /app
RUN CGO_ENABLED=0 go build -ldflags="-w -s" -o build/dogop .
# 2. DogOp Container
FROM alpine
COPY --from=builder /app/build/dogop /usr/bin/
EXPOSE 8080
ENTRYPOINT ["/usr/bin/dogop"]
1
2
3
4
5
6
7
8
9
10
11

38. >_ Demo

39. Zusammenfassung DogOPv0.1
1. Go Projekt aufsetzen
2. einfache Rest API Handler
3. Konfiguration perUmgebungsvariable
4. Structs
5. Fehlerbehandeln
6. Unit Tests
7. DockerContainerbauen

40. 12 FactorApp DogOPv0.1
1. Codebasis
2. Abhängigkeiten
3. Konfiguration
4. Unterstützende Dienste
5. Build, Release, Run
6. Prozesse
7. Bindung an Ports
8. Nebenläufigkeit und Skalierung
9. Einweggebrauch
10. Dev-Prod-Vergleichbarkeit
11. Logs
12. Admin-Prozesse
✅
✅
✅
✅
✅

41. Tarifrechner
DogOp v0.2

42. CRUD API fürAngebote
Create Request
POST /api/offer
content-type: application/json
{
"name": "Rollo",
"age": 8,
"breed": "chow",
"customer": "jan"
}
Create Response
HTTP/1.1 200 OK
Content-Type: application/json
{
"id": "427ed4de",
"customer": "jan",
"age": 8,
"breed": "chow",
"name": "Rollo"
}
Read Request
GET /api/offer/427ed4de
Read Response
HTTP/1.1 200 OK
Content-Type: application/json
{
"id": "e8b948c6-28f6-40b5-9d51-dc14a6c1
"customer": "jan",
"age": 8,
"breed": "chow",
"name": "Rollo"
}

43. CRUD API fürAngebote
r.Route("/api/offer", func(sr chi.Router) {
sr.Post("/", HandleCreateOffer(offerRepository))
sr.Get("/{ID}", HandleReadOffer(offerRepository))
})

44. Create Request mit HandlerFunction
func HandleCreateOffer(offerRepository *OfferRepository) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
}
}
1
2
// 1. JSON Request lesen
3
var offer Offer
4
json.NewDecoder(req.Body).Decode(&offer)
5
6
// 2. Offer speichern
7
createdOffer, _ := offerRepository.Insert(req.Context(), &offer)
8
9
// 3. JSON Response schreiben
10
json.NewEncoder(w).Encode(createdOffer)
11
12
13
// 1. JSON Request lesen
var offer Offer
json.NewDecoder(req.Body).Decode(&offer)
// 2. Offer speichern
createdOffer, _ := offerRepository.Insert(req.Context(), &offer)
// 3. JSON Response schreiben
json.NewEncoder(w).Encode(createdOffer)
func HandleCreateOffer(offerRepository *OfferRepository) http.HandlerFunc {
1
return func(w http.ResponseWriter, req *http.Request) {
2
3
4
5
6
7
8
9
10
11
}
12
}
13
func HandleCreateOffer(offerRepository *OfferRepository) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
// 1. JSON Request lesen
var offer Offer
json.NewDecoder(req.Body).Decode(&offer)
// 2. Offer speichern
createdOffer, _ := offerRepository.Insert(req.Context(), &offer)
// 3. JSON Response schreiben
json.NewEncoder(w).Encode(createdOffer)
}
}
1
2
3
4
5
6
7
8
9
10
11
12
13

45. Angebote speichern in PostgreSQL
pgx als PostgreSQL Driverund Toolkit
#
Interface database/sql in Go Standardlib
#

46. Angebote speichern in PostgreSQL
type OfferRepository struct {
connPool *pgxpool.Pool
1
2
}
3
4
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer)
5
// ...
6
}
7
}
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer)
// ...
}
type OfferRepository struct {
1
connPool *pgxpool.Pool
2
3
4
5
6
7
type OfferRepository struct {
connPool *pgxpool.Pool
}
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer)
// ...
}
1
2
3
4
5
6
7

47. Angebote speichern in PostgreSQL
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
}
1
// 1. ID generieren
2
offer.ID = uuid.New().String()
3
4
// 2. Transaktion beginnen
5
tx, _ := r.connPool.Begin(ctx)
6
defer tx.Rollback(ctx)
7
8
// 3. Offer per Insert speichern
9
_, err := tx.Exec(
10
ctx,
11
`INSERT INTO offers
12
(id, customer, age, breed, name)
13
VALUES
14
($1, $2, $3, $4, $5)`,
15
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
16
)
17
if err != nil {
18
return nil, err
19
}
20
21
// 4. Transaktion commiten
22
tx.Commit(ctx)
23
24
// 5. Gespeicherte Offer zurückgeben
25
return offer, nil
26
27
// 1. ID generieren
offer.ID = uuid.New().String()
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
1
2
3
4
// 2. Transaktion beginnen
5
tx, _ := r.connPool.Begin(ctx)
6
defer tx.Rollback(ctx)
7
8
// 3. Offer per Insert speichern
9
_, err := tx.Exec(
10
ctx,
11
`INSERT INTO offers
12
(id, customer, age, breed, name)
13
VALUES
14
($1, $2, $3, $4, $5)`,
15
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
16
)
17
if err != nil {
18
return nil, err
19
}
20
21
// 4. Transaktion commiten
22
tx.Commit(ctx)
23
24
// 5. Gespeicherte Offer zurückgeben
25
return offer, nil
26
}
27
// 2. Transaktion beginnen
tx, _ := r.connPool.Begin(ctx)
defer tx.Rollback(ctx)
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
1
// 1. ID generieren
2
offer.ID = uuid.New().String()
3
4
5
6
7
8
// 3. Offer per Insert speichern
9
_, err := tx.Exec(
10
ctx,
11
`INSERT INTO offers
12
(id, customer, age, breed, name)
13
VALUES
14
($1, $2, $3, $4, $5)`,
15
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
16
)
17
if err != nil {
18
return nil, err
19
}
20
21
// 4. Transaktion commiten
22
tx.Commit(ctx)
23
24
// 5. Gespeicherte Offer zurückgeben
25
return offer, nil
26
}
27
// 3. Offer per Insert speichern
_, err := tx.Exec(
ctx,
`INSERT INTO offers
(id, customer, age, breed, name)
VALUES
($1, $2, $3, $4, $5)`,
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
)
if err != nil {
return nil, err
}
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
1
// 1. ID generieren
2
offer.ID = uuid.New().String()
3
4
// 2. Transaktion beginnen
5
tx, _ := r.connPool.Begin(ctx)
6
defer tx.Rollback(ctx)
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
// 4. Transaktion commiten
22
tx.Commit(ctx)
23
24
// 5. Gespeicherte Offer zurückgeben
25
return offer, nil
26
}
27
// 4. Transaktion commiten
tx.Commit(ctx)
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
1
// 1. ID generieren
2
offer.ID = uuid.New().String()
3
4
// 2. Transaktion beginnen
5
tx, _ := r.connPool.Begin(ctx)
6
defer tx.Rollback(ctx)
7
8
// 3. Offer per Insert speichern
9
_, err := tx.Exec(
10
ctx,
11
`INSERT INTO offers
12
(id, customer, age, breed, name)
13
VALUES
14
($1, $2, $3, $4, $5)`,
15
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
16
)
17
if err != nil {
18
return nil, err
19
}
20
21
22
23
24
// 5. Gespeicherte Offer zurückgeben
25
return offer, nil
26
}
27
// 5. Gespeicherte Offer zurückgeben
return offer, nil
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
1
// 1. ID generieren
2
offer.ID = uuid.New().String()
3
4
// 2. Transaktion beginnen
5
tx, _ := r.connPool.Begin(ctx)
6
defer tx.Rollback(ctx)
7
8
// 3. Offer per Insert speichern
9
_, err := tx.Exec(
10
ctx,
11
`INSERT INTO offers
12
(id, customer, age, breed, name)
13
VALUES
14
($1, $2, $3, $4, $5)`,
15
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
16
)
17
if err != nil {
18
return nil, err
19
}
20
21
// 4. Transaktion commiten
22
tx.Commit(ctx)
23
24
25
26
}
27
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
// 1. ID generieren
offer.ID = uuid.New().String()
// 2. Transaktion beginnen
tx, _ := r.connPool.Begin(ctx)
defer tx.Rollback(ctx)
// 3. Offer per Insert speichern
_, err := tx.Exec(
ctx,
`INSERT INTO offers
(id, customer, age, breed, name)
VALUES
($1, $2, $3, $4, $5)`,
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
)
if err != nil {
return nil, err
}
// 4. Transaktion commiten
tx.Commit(ctx)
// 5. Gespeicherte Offer zurückgeben
return offer, nil
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

48. Aus dem Context gerissen
createdOffer, _ := offerRepository.Insert(req.Context(), &offer)
tx, _ := r.connPool.Begin(ctx)
defer tx.Rollback(ctx)
_, err := tx.Exec(
ctx,
)
tx.Commit(ctx)
return func(w http.ResponseWriter, req *http.Request) {
1
// ...
2
3
// 2. Offer speichern
4
5
6
// ...
7
}
8
9
func (r *OfferRepository) Insert(ctx context.Context, offer *Offer) (*Offer, error) {
10
// ..
11
12
// 2. Transaktion beginnen
13
14
15
16
// 3. Offer per Insert speichern
17
18
19
`INSERT INTO offers
20
(id, customer, age, breed, name)
21
VALUES
22
($1, $2, $3, $4, $5)`,
23
offer.ID, offer.Customer, offer.Age, offer.Breed, offer.Name,
24
25
// ...
26
27
// 4. Transaktion commiten
28
29
30
// ...
31
}
32

49. Connection Pool nutzen
connPool, err := pgxpool.New(context.Background(), config.Db)
offerRepository := &OfferRepository{connPool: connPool}
type Config struct {
1
Port string `default:"8080"`
2
Db string `default:"postgres://postgres:postgres@localhost:5432/dogop"`
3
}
4
5
func main() {
6
7
8
9
10
// ...
11
}
12
type Config struct {
Port string `default:"8080"`
Db string `default:"postgres://postgres:postgres@localhost:5432/dogop"`
}
1
2
3
4
5
func main() {
6
connPool, err := pgxpool.New(context.Background(), config.Db)
7
8
offerRepository := &OfferRepository{connPool: connPool}
9
10
// ...
11
}
12
type Config struct {
Port string `default:"8080"`
Db string `default:"postgres://postgres:postgres@localhost:5432/dogop"`
}
func main() {
connPool, err := pgxpool.New(context.Background(), config.Db)
offerRepository := &OfferRepository{connPool: connPool}
// ...
}
1
2
3
4
5
6
7
8
9
10
11
12

50. DatenbankSchema migrieren
DB Schema Update beim Start derAnwendung
#
DB Schema migrieren mit golang-migrate
#
SQL Migrations Skripte Teil des Binary
#

51. DatenbankSchema migrieren
//go:embed migrations
var migrations embed.FS
1
2
3
func main() {
4
// IO Filesystem erstellen
5
source, err := iofs.New(migrations, "migrations")
6
7
// Connection String für Migration anpassen
8
dbMigrateURL := strings.Replace(config.Db, "postgres://", "pgx://", 1)
9
10
// Golang Migrate intialisieren
11
m, _ := migrate.NewWithSourceInstance("iofs", source, dbMigrateURL)
12
13
// Datenbank Schema aktualisieren
14
m.Up()
15
16
// ...
17
}
18
// IO Filesystem erstellen
source, err := iofs.New(migrations, "migrations")
//go:embed migrations
1
var migrations embed.FS
2
3
func main() {
4
5
6
7
// Connection String für Migration anpassen
8
dbMigrateURL := strings.Replace(config.Db, "postgres://", "pgx://", 1)
9
10
// Golang Migrate intialisieren
11
m, _ := migrate.NewWithSourceInstance("iofs", source, dbMigrateURL)
12
13
// Datenbank Schema aktualisieren
14
m.Up()
15
16
// ...
17
}
18
// Connection String für Migration anpassen
dbMigrateURL := strings.Replace(config.Db, "postgres://", "pgx://", 1)
//go:embed migrations
1
var migrations embed.FS
2
3
func main() {
4
// IO Filesystem erstellen
5
source, err := iofs.New(migrations, "migrations")
6
7
8
9
10
// Golang Migrate intialisieren
11
m, _ := migrate.NewWithSourceInstance("iofs", source, dbMigrateURL)
12
13
// Datenbank Schema aktualisieren
14
m.Up()
15
16
// ...
17
}
18
// Golang Migrate intialisieren
m, _ := migrate.NewWithSourceInstance("iofs", source, dbMigrateURL)
//go:embed migrations
1
var migrations embed.FS
2
3
func main() {
4
// IO Filesystem erstellen
5
source, err := iofs.New(migrations, "migrations")
6
7
// Connection String für Migration anpassen
8
dbMigrateURL := strings.Replace(config.Db, "postgres://", "pgx://", 1)
9
10
11
12
13
// Datenbank Schema aktualisieren
14
m.Up()
15
16
// ...
17
}
18
// Datenbank Schema aktualisieren
m.Up()
//go:embed migrations
1
var migrations embed.FS
2
3
func main() {
4
// IO Filesystem erstellen
5
source, err := iofs.New(migrations, "migrations")
6
7
// Connection String für Migration anpassen
8
dbMigrateURL := strings.Replace(config.Db, "postgres://", "pgx://", 1)
9
10
// Golang Migrate intialisieren
11
m, _ := migrate.NewWithSourceInstance("iofs", source, dbMigrateURL)
12
13
14
15
16
// ...
17
}
18
//go:embed migrations
var migrations embed.FS
func main() {
// IO Filesystem erstellen
source, err := iofs.New(migrations, "migrations")
// Connection String für Migration anpassen
dbMigrateURL := strings.Replace(config.Db, "postgres://", "pgx://", 1)
// Golang Migrate intialisieren
m, _ := migrate.NewWithSourceInstance("iofs", source, dbMigrateURL)
// Datenbank Schema aktualisieren
m.Up()
// ...
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

52. >_ Demo

53. Zusammenfassung DogOPv0.2
1. CRUD API fürAngebote
2. Angebote in PostgreSQL speichern
3. Context
4. Connection Pool nutzen
5. DatenbankSchema migrieren

54. 12 FactorApp DogOPv0.2
1. Codebasis
2. Abhängigkeiten
3. Konfiguration
4. Unterstützende Dienste
5. Build, Release, Run
6. Prozesse
7. Bindung an Ports
8. Nebenläufigkeit und Skalierung
9. Einweggebrauch
10. Dev-Prod-Vergleichbarkeit
11. Logs
12. Admin-Prozesse
✅
✅
✅
✅
✅
✅

55. Fallschirm und
Rettungsgurt

56. Fallschirm und Rettungsgurt
Problem Details
Health Check
Logging und Tracing
#
#
#

57. Health Check
Nutzung von health-go (hellofresh)
Integration des Checks fürpgx
#
#

58. Health Check
// Register Health Check
h, _ := health.New(health.WithChecks(
health.Config{
Name: "db",
Timeout: time.Second * 2,
SkipOnErr: false,
Check: healthPgx.New(healthPgx.Config{
DSN: config.Db,
}),
},
))
1
2
3
4
5
6
7
8
9
10
11
12
// Register Handler Function
13
r.Get("/health", h.HandlerFunc)
14
// Register Handler Function
r.Get("/health", h.HandlerFunc)
// Register Health Check
1
h, _ := health.New(health.WithChecks(
2
health.Config{
3
Name: "db",
4
Timeout: time.Second * 2,
5
SkipOnErr: false,
6
Check: healthPgx.New(healthPgx.Config{
7
DSN: config.Db,
8
}),
9
},
10
))
11
12
13
14
// Register Health Check
h, _ := health.New(health.WithChecks(
health.Config{
Name: "db",
Timeout: time.Second * 2,
SkipOnErr: false,
Check: healthPgx.New(healthPgx.Config{
DSN: config.Db,
}),
},
))
// Register Handler Function
r.Get("/health", h.HandlerFunc)
1
2
3
4
5
6
7
8
9
10
11
12
13
14

59. Problem Details

61. Problem Details
UngültigerRequest
GET /api/offer/-invalid-
Response mit Problem Details
HTTP/1.1 400 Bad Request
Content-Type: application/problem+json
{
"reason": "invalid UUID format",
"status": 400,
"title": "invalid request"
}

62. Problem Details
id, err := uuid.Parse(chi.URLParam(r, "ID"))
return func(w http.ResponseWriter, r *http.Request) {
1
// 1. Offer lesen
2
3
if err != nil {
4
problem.New(
5
problem.Title("invalid request"),
6
problem.Wrap(err),
7
problem.Status(http.StatusBadRequest),
8
).WriteTo(w)
9
return
10
}
11
}
12
id, err := uuid.Parse(chi.URLParam(r, "ID"))
if err != nil {
problem.New(
problem.Title("invalid request"),
problem.Wrap(err),
problem.Status(http.StatusBadRequest),
).WriteTo(w)
return
return func(w http.ResponseWriter, r *http.Request) {
1
// 1. Offer lesen
2
3
4
5
6
7
8
9
10
}
11
}
12
id, err := uuid.Parse(chi.URLParam(r, "ID"))
if err != nil {
problem.New(
problem.Title("invalid request"),
problem.Wrap(err),
problem.Status(http.StatusBadRequest),
).WriteTo(w)
return
return func(w http.ResponseWriter, r *http.Request) {
1
// 1. Offer lesen
2
3
4
5
6
7
8
9
10
}
11
}
12

63. Middleware
cross-cutting Features füralle Requests
(z.B. Logging, Authentifizierung)
#
erzeugen eine Kette von Handlern
router=> middleware handler=> application handler
#
implementieren das Interface http.Handler
#

64. Middleware loggt Requests
func loggingMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log.Printf("%v requested URL %v", r.Host, r.URL)
next.ServeHTTP(w, r)
})
}
1
2
3
4
5
6
7
func main() {
8
r := chi.NewRouter()
9
10
// Nutze Logging Middleware
11
r.Use(loggingMiddleware)
12
13
http.ListenAndServe(":8080", r)
14
}
15
// Nutze Logging Middleware
r.Use(loggingMiddleware)
func loggingMiddleware(next http.Handler) http.Handler {
1
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
2
log.Printf("%v requested URL %v", r.Host, r.URL)
3
next.ServeHTTP(w, r)
4
})
5
}
6
7
func main() {
8
r := chi.NewRouter()
9
10
11
12
13
http.ListenAndServe(":8080", r)
14
}
15
func loggingMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log.Printf("%v requested URL %v", r.Host, r.URL)
next.ServeHTTP(w, r)
})
}
func main() {
r := chi.NewRouter()
// Nutze Logging Middleware
r.Use(loggingMiddleware)
http.ListenAndServe(":8080", r)
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

65. Middlewares nutzen
// Basis Middlewares
r.Use(middleware.RequestID)
r.Use(middleware.RealIP)
r.Use(middleware.Logger)
r.Use(middleware.Recoverer)
func main() {
1
r := chi.NewRouter()
2
3
4
5
6
7
8
9
// Timeout über Request Context setzen
10
r.Use(middleware.Timeout(60 * time.Second))
11
12
http.ListenAndServe(":8080", r)
13
}
14
// Timeout über Request Context setzen
r.Use(middleware.Timeout(60 * time.Second))
func main() {
1
r := chi.NewRouter()
2
3
// Basis Middlewares
4
r.Use(middleware.RequestID)
5
r.Use(middleware.RealIP)
6
r.Use(middleware.Logger)
7
r.Use(middleware.Recoverer)
8
9
10
11
12
http.ListenAndServe(":8080", r)
13
}
14
// Basis Middlewares
r.Use(middleware.RequestID)
r.Use(middleware.RealIP)
r.Use(middleware.Logger)
r.Use(middleware.Recoverer)
// Timeout über Request Context setzen
r.Use(middleware.Timeout(60 * time.Second))
func main() {
1
r := chi.NewRouter()
2
3
4
5
6
7
8
9
10
11
12
http.ListenAndServe(":8080", r)
13
}
14

66. Zusammenfassung DogOP
v0.1
1. Go Projekt aufsetzen
2. einfache Rest API Handler
3. Konfiguration per
Umgebungsvariable
4. Structs
5. Fehlerbehandeln
6. Unit Tests
7. DockerContainerbauen
v0.2
1. CRUD API fürAngebote
2. Angebote in PostgreSQL
speichern
3. Context
4. Connection Pool nutzen
5. DatenbankSchema migrieren

67. 3 Gründe fürGo
1. Einfach
2. Mächtig
3. Langweilig

68. Jan Stamer
jan.stamer@crossnative.com

69. Backup