chore(heartbeat): Refactor heartbeat. (#344)

This is mostly an enablement PR for future follow-ups (e.g. TCP healthcheck).

Signed-off-by: Lennard Eijsackers <[email protected]>

Author: Blokje5

heartbeat.go

@@ -0,0 +1,123 @@
+package heartbeat
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/contentsquare/chproxy/config"
+)
+
+var errUnexpectedResponse = fmt.Errorf("unexpected response")
+
+type HeartBeat interface {
+	IsHealthy(ctx context.Context, addr string) error
+	Interval() time.Duration
+}
+
+type heartBeatOpts struct {
+	defaultUser     string
+	defaultPassword string
+}
+
+type Option interface {
+	apply(*heartBeatOpts)
+}
+
+type defaultUser struct {
+	defaultUser     string
+	defaultPassword string
+}
+
+func (o defaultUser) apply(opts *heartBeatOpts) {
+	opts.defaultUser = o.defaultUser
+	opts.defaultPassword = o.defaultPassword
+}
+
+func WithDefaultUser(user, password string) Option {
+	return defaultUser{
+		defaultUser:     user,
+		defaultPassword: password,
+	}
+}
+
+type heartBeat struct {
+	interval time.Duration
+	timeout  time.Duration
+	request  string
+	response string
+	user     string
+	password string
+}
+
+// User credentials are not needed
+const defaultEndpoint string = "/ping"
+
+func NewHeartbeat(c config.HeartBeat, options ...Option) HeartBeat {
+	opts := &heartBeatOpts{}
+	for _, o := range options {
+		o.apply(opts)
+	}
+
+	newHB := &heartBeat{
+		interval: time.Duration(c.Interval),
+		timeout:  time.Duration(c.Timeout),
+		request:  c.Request,
+		response: c.Response,
+	}
+
+	if c.Request != defaultEndpoint {
+		if c.User != "" {
+			newHB.user = c.User
+			newHB.password = c.Password
+		} else {
+			newHB.user = opts.defaultUser
+			newHB.password = opts.defaultPassword
+		}
+	}
+
+	if newHB.request != defaultEndpoint && newHB.user == "" {
+		panic("BUG: user is empty, no default user provided")
+	}
+
+	return newHB
+}
+
+func (hb *heartBeat) IsHealthy(ctx context.Context, addr string) error {
+	req, err := http.NewRequest("GET", addr+hb.request, nil)
+	if err != nil {
+		return err
+	}
+	if hb.request != defaultEndpoint {
+		req.SetBasicAuth(hb.user, hb.password)
+	}
+	ctx, cancel := context.WithTimeout(ctx, hb.timeout)
+	defer cancel()
+	req = req.WithContext(ctx)
+
+	startTime := time.Now()
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("cannot send request in %s: %w", time.Since(startTime), err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("non-200 status code: %s", resp.Status)
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("cannot read response in %s: %w", time.Since(startTime), err)
+	}
+	r := string(body)
+	if r != hb.response {
+		return fmt.Errorf("%w: %s", errUnexpectedResponse, r)
+	}
+	return nil
+}
+
+func (hb *heartBeat) Interval() time.Duration {
+	return hb.interval
+}