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package main
import (
"bytes"
cryptorand "crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
log "github.com/sirupsen/logrus"
"math/big"
"os"
"time"
)
func main() {
var caPEM, serverCertPEM, serverPrivKeyPEM *bytes.Buffer
// CA config
ca := &x509.Certificate{
SerialNumber: big.NewInt(2020),
Subject: pkix.Name{
Organization: []string{"velotio.com"},
},
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(1, 0, 0),
IsCA: true,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
KeyUsage: x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
BasicConstraintsValid: true,
}
// CA private key
caPrivKey, err := rsa.GenerateKey(cryptorand.Reader, 4096)
if err != nil {
fmt.Println(err)
}
// Self signed CA certificate
caBytes, err := x509.CreateCertificate(cryptorand.Reader, ca, ca, &caPrivKey.PublicKey, caPrivKey)
if err != nil {
fmt.Println(err)
}
// PEM encode CA cert
caPEM = new(bytes.Buffer)
_ = pem.Encode(caPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: caBytes,
})
dnsNames := []string{"webhook-service",
"webhook-service.default", "webhook-service.default.svc"}
commonName := "webhook-service.default.svc"
// server cert config
cert := &x509.Certificate{
DNSNames: dnsNames,
SerialNumber: big.NewInt(1658),
Subject: pkix.Name{
CommonName: commonName,
Organization: []string{"velotio.com"},
},
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(1, 0, 0),
SubjectKeyId: []byte{1, 2, 3, 4, 6},
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
KeyUsage: x509.KeyUsageDigitalSignature,
}
// server private key
serverPrivKey, err := rsa.GenerateKey(cryptorand.Reader, 4096)
if err != nil {
fmt.Println(err)
}
// sign the server cert
serverCertBytes, err := x509.CreateCertificate(cryptorand.Reader, cert, ca, &serverPrivKey.PublicKey, caPrivKey)
if err != nil {
fmt.Println(err)
}
// PEM encode the server cert and key
serverCertPEM = new(bytes.Buffer)
_ = pem.Encode(serverCertPEM, &pem.Block{
Type: "CERTIFICATE",
Bytes: serverCertBytes,
})
serverPrivKeyPEM = new(bytes.Buffer)
_ = pem.Encode(serverPrivKeyPEM, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(serverPrivKey),
})
err = os.MkdirAll("/etc/webhook/certs/", 0666)
if err != nil {
log.Panic(err)
}
err = WriteFile("/etc/webhook/certs/tls.crt", serverCertPEM)
if err != nil {
log.Panic(err)
}
err = WriteFile("/etc/webhook/certs/tls.key", serverPrivKeyPEM)
if err != nil {
log.Panic(err)
}
}
// WriteFile writes data in the file at the given path
func WriteFile(filepath string, sCert *bytes.Buffer) error {
f, err := os.Create(filepath)
if err != nil {
return err
}
defer f.Close()
_, err = f.Write(sCert.Bytes())
if err != nil {
return err
}
return nil
}
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