Convert PEM String to tls.Certificate

util.go

// Convert PEM string to tls.Certificate
// Based on https://medium.com/@prateeknischal25/using-encrypted-private-keys-with-golang-server-379919955854
func X509Pem(b []byte) (tls.Certificate, error) {
	var pemBlocks []*pem.Block
	var v *pem.Block
	var pkey []byte
	for {
		v, b = pem.Decode(b)
		if v == nil {
			break
		}
		if v.Type == "RSA PRIVATE KEY" || v.Type == "PRIVATE KEY" {
			pkey = pem.EncodeToMemory(v)
		} else {
			pemBlocks = append(pemBlocks, v)
		}
	}

	if len(pemBlocks) == 0 {
		return tls.Certificate{}, fmt.Errorf("no certificate found")
	}

	// Combine all certificate blocks into a single PEM-encoded byte slice
	var certPEM []byte
	for _, block := range pemBlocks {
		certPEM = append(certPEM, pem.EncodeToMemory(block)...)
	}

	return tls.X509KeyPair(certPEM, pkey)
}