ROX-23251: Add base for email sender service

emailsender/.gitignore

@@ -0,0 +1 @@
+/bin/

emailsender/README.md

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+# ACSCS Email Service
+
+The email service which allows sending email notification
+from ACS Central instance without configuring any additional integration.
+
+
+## Quickstart
+
+```sh
+# Start email sender service
+CLUSTER_ID=test go run cmd/app/main.go
+
+...
+main.go:49] Creating api server...
+main.go:65] Application started. Will shut down gracefully on [interrupt terminated].
+```

emailsender/cmd/app/main.go

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+// Package main for email sender service
+package main
+
+import (
+	"context"
+	"flag"
+	"net/http"
+	"os"
+	"os/signal"
+
+	"github.com/gorilla/mux"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/golang/glog"
+	"github.com/stackrox/acs-fleet-manager/emailsender/config"
+)
+
+func main() {
+
+	// This is needed to make `glog` believe that the flags have already been parsed, otherwise
+	// every log messages is prefixed by an error message stating the flags haven't been
+	// parsed.
+	_ = flag.CommandLine.Parse([]string{})
+
+	// Always log to stderr by default, required for glog.
+	if err := flag.Set("logtostderr", "true"); err != nil {
+		glog.Info("unable to set logtostderr to true.")
+	}
+
+	cfg, err := config.GetConfig()
+	if err != nil {
+		glog.Errorf("Failed to load configuration: %v", err)
+		os.Exit(1)
+	}
+
+	ctx := context.Background()
+
+	// base router
+	router := mux.NewRouter()
+
+	// example handler
+	router.HandleFunc("/test", func(rw http.ResponseWriter, req *http.Request) {
+		glog.Info("called /test endpoint")
+	})
+
+	server := http.Server{Addr: cfg.ServerAddress, Handler: router}
+
+	go func() {
+		glog.Info("Creating api server...")
+		var err error
+		if cfg.EnableHTTPS {
+			err = server.ListenAndServeTLS(cfg.HTTPSCertFile, cfg.HTTPSKeyFile)
+		} else {
+			err = server.ListenAndServe()
+		}
+		if err != http.ErrServerClosed {
+			glog.Fatalf("ListenAndServer error: %v", err)
+		}
+	}()
+
+	sigs := make(chan os.Signal, 1)
+	notifySignals := []os.Signal{os.Interrupt, unix.SIGTERM}
+	signal.Notify(sigs, notifySignals...)
+
+	glog.Info("Application started. Will shut down gracefully on interrupt terminated OS signals")
+	sig := <-sigs
+	if err := server.Shutdown(ctx); err != nil {
+		glog.Errorf("API Shutdown error: %v", err)
+	}
+
+	glog.Infof("Caught %s signal", sig)
+	glog.Info("Email sender application has been stopped")
+}

emailsender/config/config.go

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+// Package config for email sender service
+package config
+
+import (
+	"github.com/caarlos0/env/v6"
+
+	"github.com/pkg/errors"
+	"github.com/stackrox/rox/pkg/errorhelpers"
+)
+
+// Config contains this application's runtime configuration.
+type Config struct {
+	ClusterID     string `env:"CLUSTER_ID"`
+	ServerAddress string `env:"SERVER_ADDRESS" envDefault:":8080"`
+	EnableHTTPS   bool   `env:"ENABLE_HTTPS" envDefault:"false"`
+	HTTPSCertFile string `env:"HTTPS_CERT_FILE" envDefault:""`
+	HTTPSKeyFile  string `env:"HTTPS_KEY_FILE" envDefault:""`
+}
+
+// GetConfig retrieves the current runtime configuration from the environment and returns it.
+func GetConfig() (*Config, error) {
+	c := Config{}
+	var configErrors errorhelpers.ErrorList
+
+	if err := env.Parse(&c); err != nil {
+		return nil, errors.Wrap(err, "unable to parse runtime configuration from environment")
+	}
+
+	if c.ClusterID == "" {
+		configErrors.AddError(errors.New("CLUSTER_ID environment variable is not set"))
+	}
+
+	if c.EnableHTTPS {
+		if c.HTTPSCertFile == "" || c.HTTPSKeyFile == "" {
+			configErrors.AddError(errors.New("ENABLE_HTTPS is true but required variables HTTPS_CERT_FILE or HTTPS_KEY_FILE are empty"))
+		}
+	}
+
+	if cfgErr := configErrors.ToError(); cfgErr != nil {
+		return nil, errors.Wrap(cfgErr, "invalid configuration settings")
+	}
+	return &c, nil
+}

emailsender/config/config_test.go

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+package config
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetConfigSuccess(t *testing.T) {
+	t.Setenv("CLUSTER_ID", "test-1")
+	t.Setenv("SERVER_ADDRESS", ":8888")
+	t.Setenv("ENABLE_HTTPS", "true")
+	t.Setenv("HTTPS_CERT_FILE", "/some/tls.crt")
+	t.Setenv("HTTPS_KEY_FILE", "/some/tls.key")
+
+	cfg, err := GetConfig()
+
+	require.NoError(t, err)
+	assert.Equal(t, cfg.ClusterID, "test-1")
+	assert.Equal(t, cfg.ServerAddress, ":8888")
+	assert.Equal(t, cfg.EnableHTTPS, true)
+	assert.Equal(t, cfg.HTTPSCertFile, "/some/tls.crt")
+	assert.Equal(t, cfg.HTTPSKeyFile, "/some/tls.key")
+}
+
+func TestGetConfigFailureMissingClusterID(t *testing.T) {
+	cfg, err := GetConfig()
+
+	assert.Error(t, err)
+	assert.Nil(t, cfg)
+}
+
+func TestGetConfigFailureEnabledHTTPSMissingCert(t *testing.T) {
+	t.Setenv("CLUSTER_ID", "test-1")
+	t.Setenv("ENABLE_HTTPS", "true")
+	t.Setenv("HTTPS_KEY_FILE", "/some/tls.key")
+
+	cfg, err := GetConfig()
+
+	assert.Error(t, err)
+	assert.Nil(t, cfg)
+}
+
+func TestGetConfigFailureEnabledHTTPSMissingKey(t *testing.T) {
+	t.Setenv("CLUSTER_ID", "test-1")
+	t.Setenv("ENABLE_HTTPS", "true")
+	t.Setenv("HTTPS_CERT_FILE", "/some/tls.crt")
+
+	cfg, err := GetConfig()
+
+	assert.Error(t, err)
+	assert.Nil(t, cfg)
+}
+
+func TestGetConfigFailureEnabledHTTPSOnly(t *testing.T) {
+	t.Setenv("CLUSTER_ID", "test-1")
+	t.Setenv("ENABLE_HTTPS", "true")
+
+	cfg, err := GetConfig()
+
+	assert.Error(t, err)
+	assert.Nil(t, cfg)
+}