Merge pull request #124 from orange-cloudfoundry/use-nats-instead-of-…

…gorouter

use nats instead of gorouters to manage a routing table

.github/workflows/goreleaser.yml

@@ -22,7 +22,7 @@ jobs:
       - name: set up go
         uses: actions/setup-go@v5
         with:
-          go-version: "1.21"
+          go-version: "1.22"
 
       - name: cache go modules
         uses: actions/cache@v4

.github/workflows/unit-tests.yml

@@ -16,7 +16,7 @@ jobs:
       - name: set up go
         uses: actions/setup-go@v5
         with:
-          go-version: "1.21"
+          go-version: "1.22"
 
       - name: cache go modules
         uses: actions/cache@v4

README.md

@@ -73,13 +73,11 @@ This is useful for authentication purpose, for example:
 
 ### How does it work?
 
-Promfetcher only needs [gorouter] and will read route table from it.
+Promfetcher only needs [NATS](https://nats.io/) an infrastructure that allows data exchange, segmented in the form of messages (We call this a "message oriented middleware"). Promfetcher subscribes to NATS in order to receive messages about routes and then manages its own routing table in memory.
 
 When asking metrics for an App, Promfetcher will asynchronously call all App instances
 (provided by the gorouter routing table) metrics endpoint and merge them together with new labels.
 
-[gorouter]: https://github.com/cloudfoundry/gorouter
-
 Example, given an App with metrics from instance 0:
 
 ```

config/config.go

@@ -20,11 +20,26 @@ import (
 	"github.com/orange-cloudfoundry/promfetcher/models"
 )
 
-type GorouterConfig struct {
-	Host string `yaml:"host"`
-	Port uint16 `yaml:"port"`
-	User string `yaml:"user"`
-	Pass string `yaml:"pass"`
+type NatsConfig struct {
+	Hosts                 []NatsHost       `yaml:"hosts"`
+	User                  string           `yaml:"user"`
+	Pass                  string           `yaml:"pass"`
+	TLSEnabled            bool             `yaml:"tls_enabled"`
+	CACerts               string           `yaml:"ca_certs"`
+	CAPool                *x509.CertPool   `yaml:"-"`
+	ClientAuthCertificate tls.Certificate  `yaml:"-"`
+	TLSPem                `yaml:",inline"` // embed to get cert_chain and private_key for client authentication
+}
+
+type NatsHost struct {
+	Hostname string
+	Port     uint16
+}
+
+var defaultNatsConfig = NatsConfig{
+	Hosts: []NatsHost{{Hostname: "localhost", Port: 4222}},
+	User:  "",
+	Pass:  "",
 }
 
 type BackendConfig struct {
@@ -34,15 +49,6 @@ type BackendConfig struct {
 	TLSPem `yaml:",inline"` // embed to get cert_chain and private_key for client authentication
 }
 
-var defaultGoroutersConfig = []GorouterConfig{
-	{
-		Host: "localhost",
-		Port: 8080,
-		User: "",
-		Pass: "",
-	},
-}
-
 type BrokerConfig struct {
 	BrokerServiceID string `yaml:"broker_service_id"`
 	BrokerPlanID    string `yaml:"broker_plan_id"`
@@ -92,16 +98,22 @@ type TLSPem struct {
 }
 
 type Config struct {
-	Gorouters         []GorouterConfig `yaml:"gorouters,omitempty"`
-	Logging           Log              `yaml:"logging,omitempty"`
-	Port              uint16           `yaml:"port,omitempty"`
-	HealthCheckPort   uint16           `yaml:"health_check_port,omitempty"`
-	EnableSSL         bool             `yaml:"enable_ssl,omitempty"`
-	SSLCertificate    tls.Certificate  `yaml:"-"`
-	TLSPEM            TLSPem           `yaml:"tls_pem,omitempty"`
-	CACerts           string           `yaml:"ca_certs,omitempty"`
-	CAPool            *x509.CertPool   `yaml:"-"`
-	SkipSSLValidation bool             `yaml:"skip_ssl_validation,omitempty"`
+	Nats                        NatsConfig      `yaml:"nats,omitempty"`
+	NatsClientPingInterval      time.Duration   `yaml:"nats_client_ping_interval,omitempty"`
+	NatsClientMessageBufferSize int             `yaml:"-"`
+	EnableHTTP2                 bool            `yaml:"enable_http2"`
+	DropletStaleThreshold       time.Duration   `yaml:"droplet_stale_threshold,omitempty"`
+	StartResponseDelayInterval  time.Duration   `yaml:"start_response_delay_interval,omitempty"`
+	Index                       uint            `yaml:"index,omitempty"`
+	Logging                     Log             `yaml:"logging,omitempty"`
+	Port                        uint16          `yaml:"port,omitempty"`
+	HealthCheckPort             uint16          `yaml:"health_check_port,omitempty"`
+	EnableSSL                   bool            `yaml:"enable_ssl,omitempty"`
+	SSLCertificate              tls.Certificate `yaml:"-"`
+	TLSPEM                      TLSPem          `yaml:"tls_pem,omitempty"`
+	CACerts                     string          `yaml:"ca_certs,omitempty"`
+	CAPool                      *x509.CertPool  `yaml:"-"`
+	SkipSSLValidation           bool            `yaml:"skip_ssl_validation,omitempty"`
 
 	Backends BackendConfig `yaml:"backends,omitempty"`
 
@@ -124,18 +136,23 @@ type Config struct {
 }
 
 var defaultConfig = Config{
-	Gorouters:           defaultGoroutersConfig,
-	Logging:             Log{},
-	Port:                8085,
-	HealthCheckPort:     8080,
-	DisableKeepAlives:   true,
-	MaxIdleConns:        100,
-	MaxIdleConnsPerHost: 2,
-	SQLCnxMaxIdle:       5,
-	SQLCnxMaxOpen:       10,
-	SQLCnxMaxLife:       "1h",
-	Broker:              defaultBrokerConfig,
-	BaseURL:             "http://localhost:8085",
+	Nats:                       defaultNatsConfig,
+	NatsClientPingInterval:     time.Duration(20 * float64(time.Second)),
+	DropletStaleThreshold:      120 * time.Second,
+	StartResponseDelayInterval: 5 * time.Second,
+	EnableHTTP2:                true,
+	Index:                      0,
+	Logging:                    Log{},
+	Port:                       8085,
+	HealthCheckPort:            8080,
+	DisableKeepAlives:          true,
+	MaxIdleConns:               100,
+	MaxIdleConnsPerHost:        2,
+	SQLCnxMaxIdle:              5,
+	SQLCnxMaxOpen:              10,
+	SQLCnxMaxLife:              "1h",
+	Broker:                     defaultBrokerConfig,
+	BaseURL:                    "http://localhost:8085",
 }
 
 func DefaultConfig() (*Config, error) {
@@ -154,6 +171,21 @@ func (c *Config) Process() error {
 		c.Backends.ClientAuthCertificate = certificate
 	}
 
+	if c.Nats.TLSEnabled {
+		certificate, err := tls.X509KeyPair([]byte(c.Nats.CertChain), []byte(c.Nats.PrivateKey))
+		if err != nil {
+			errMsg := fmt.Sprintf("Error loading NATS key pair: %s", err.Error())
+			return fmt.Errorf(errMsg)
+		}
+		c.Nats.ClientAuthCertificate = certificate
+
+		certPool := x509.NewCertPool()
+		if ok := certPool.AppendCertsFromPEM([]byte(c.Nats.CACerts)); !ok {
+			return fmt.Errorf("Error while adding CACerts to gorouter's routing-api cert pool: \n%s\n", c.Nats.CACerts)
+		}
+		c.Nats.CAPool = certPool
+	}
+
 	if c.EnableSSL {
 		if c.TLSPEM.PrivateKey == "" || c.TLSPEM.CertChain == "" {
 			return fmt.Errorf("Error parsing PEM blocks of router.tls_pem, missing cert or key.")
@@ -245,7 +277,6 @@ func (c *Config) buildCertPool() error {
 }
 
 func (c *Config) Initialize(configYAML []byte) error {
-	c.Gorouters = make([]GorouterConfig, 0)
 	return yaml.Unmarshal(configYAML, &c)
 }
 
@@ -272,3 +303,17 @@ func InitConfigFromFile(file *os.File) (*Config, error) {
 
 	return c, nil
 }
+
+func (c *Config) NatsServers() []string {
+	var natsServers []string
+	for _, host := range c.Nats.Hosts {
+		uri := url.URL{
+			Scheme: "nats",
+			User:   url.UserPassword(c.Nats.User, c.Nats.Pass),
+			Host:   fmt.Sprintf("%s:%d", host.Hostname, host.Port),
+		}
+		natsServers = append(natsServers, uri.String())
+	}
+
+	return natsServers
+}