background-api: Add Healthchecks.io ping

internal/healthchecksio/healthchecks.go

@@ -0,0 +1,44 @@
+// Package healthchecksio is a wrapper for API calls to HealthChecks.io
+package healthchecksio
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/carlmjohnson/errorx"
+	"github.com/carlmjohnson/requests"
+)
+
+// Client is a convenient way to ping HealthChecks.io
+type Client struct {
+	rb *requests.Builder
+}
+
+// New returns a configured client. If c is nil, http.DefaultClient is used.
+func New(uuid string, c *http.Client) Client {
+	return Client{
+		requests.
+			URL("https://hc-ping.com").
+			Path(uuid).
+			Client(c),
+	}
+}
+
+// Start calls the start HealthChecks.io endpoint
+func (cl Client) Start(ctx context.Context) (err error) {
+	defer errorx.Trace(&err)
+
+	return cl.rb.Clone().
+		Path("start").
+		Fetch(ctx)
+}
+
+// Status calls the HealthChecks.io status endpoint
+func (cl Client) Status(ctx context.Context, code int, msg []byte) (err error) {
+	defer errorx.Trace(&err)
+
+	return cl.rb.Clone().
+		Pathf("%d", code).
+		BodyBytes(msg).
+		Fetch(ctx)
+}

pkg/almanack/flags.go

@@ -11,6 +11,7 @@ import (
 	"github.com/spotlightpa/almanack/internal/db"
 	"github.com/spotlightpa/almanack/internal/github"
 	"github.com/spotlightpa/almanack/internal/google"
+	"github.com/spotlightpa/almanack/internal/healthchecksio"
 	"github.com/spotlightpa/almanack/internal/index"
 	"github.com/spotlightpa/almanack/internal/mailchimp"
 	"github.com/spotlightpa/almanack/internal/plausible"
@@ -35,6 +36,7 @@ func AddFlags(fl *flag.FlagSet) func() (svc Services, err error) {
 	gsvc.AddFlags(fl)
 	mailServiceAPIKey := fl.String("mc-api-key", "", "API `key` for MailChimp v2")
 	mailServiceListID := fl.String("mc-list-id", "", "List `ID` MailChimp v2 campaign")
+	hc := fl.String("healthchecks-uuid", "", "`UUID` for Healthchecks.io alert")
 	var pl plausible.API
 	pl.AddFlags(fl)
 
@@ -67,6 +69,7 @@ func AddFlags(fl *flag.FlagSet) func() (svc Services, err error) {
 			Gsvc:                 &gsvc,
 			EmailService:         mc,
 			Plausible:            pl,
+			HC:                   healthchecksio.New(*hc, &client),
 		}, nil
 	}
 }

pkg/almanack/service.go

@@ -8,6 +8,7 @@ import (
 	"github.com/spotlightpa/almanack/internal/db"
 	"github.com/spotlightpa/almanack/internal/github"
 	"github.com/spotlightpa/almanack/internal/google"
+	"github.com/spotlightpa/almanack/internal/healthchecksio"
 	"github.com/spotlightpa/almanack/internal/index"
 	"github.com/spotlightpa/almanack/internal/mailchimp"
 	"github.com/spotlightpa/almanack/internal/plausible"
@@ -30,4 +31,5 @@ type Services struct {
 	Gsvc             *google.Service
 	mailchimp.EmailService
 	Plausible plausible.API
+	HC        healthchecksio.Client
 }

pkg/api/routes-background.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 	"errors"
+	"fmt"
 	"net/http"
 	"strings"
 	"time"
@@ -38,6 +39,13 @@ func (app *appEnv) backgroundSleep(w http.ResponseWriter, r *http.Request) http.
 func (app *appEnv) backgroundCron(w http.ResponseWriter, r *http.Request) http.Handler {
 	app.logStart(r)
 
+	if err := app.svc.HC.Start(r.Context()); err != nil {
+		app.logErr(r.Context(), err)
+		l := almlog.FromContext(r.Context())
+		l.ErrorContext(r.Context(), "could not contact Healthchecks.io with start; continuing")
+		// fallthrough and keep trying…
+	}
+
 	if err := flowmatic.Do(
 		func() error {
 			var errs []error
@@ -114,10 +122,25 @@ func (app *appEnv) backgroundCron(w http.ResponseWriter, r *http.Request) http.H
 			)
 		},
 	); err != nil {
+		msg := fmt.Appendf(nil, "error: %v", err)
+		if suberr := app.svc.HC.Status(r.Context(), 500, msg); suberr != nil {
+			app.logErr(r.Context(), suberr)
+			l := almlog.FromContext(r.Context())
+			l.ErrorContext(r.Context(), "could not contact Healthchecks.io with error")
+			// fallthrough to reply
+		}
+
 		// reply shows up in dev only
 		return app.jsonErr(err)
 	}
 
+	if suberr := app.svc.HC.Status(r.Context(), 200, []byte("OK")); suberr != nil {
+		app.logErr(r.Context(), suberr)
+		l := almlog.FromContext(r.Context())
+		l.ErrorContext(r.Context(), "could not contact Healthchecks.io with success")
+		// fallthrough to reply
+	}
+
 	return app.jsonAccepted("OK")
 }