feat(coderd): add webpush package (#17091)

* Adds `codersdk.ExperimentWebPush` (`web-push`)
* Adds a `coderd/webpush` package that allows sending native push
notifications via `github.com/SherClockHolmes/webpush-go`
* Adds database tables to store push notification subscriptions.
* Adds an API endpoint that allows users to subscribe/unsubscribe, and
send a test notification (404 without experiment, excluded from API docs)
* Adds server CLI command to regenerate VAPID keys (note: regenerating
the VAPID keypair requires deleting all existing subscriptions)

---------

Co-authored-by: Kyle Carberry <kyle@carberry.com>

coderd/webpush_test.go

@@ -0,0 +1,82 @@
+package coderd_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/v2/coderd/coderdtest"
+	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/testutil"
+)
+
+const (
+	// These are valid keys for a web push subscription.
+	// DO NOT REUSE THESE IN ANY REAL CODE.
+	validEndpointAuthKey   = "zqbxT6JKstKSY9JKibZLSQ=="
+	validEndpointP256dhKey = "BNNL5ZaTfK81qhXOx23+wewhigUeFb632jN6LvRWCFH1ubQr77FE/9qV1FuojuRmHP42zmf34rXgW80OvUVDgTk="
+)
+
+func TestWebpushSubscribeUnsubscribe(t *testing.T) {
+	t.Parallel()
+
+	ctx := testutil.Context(t, testutil.WaitShort)
+
+	dv := coderdtest.DeploymentValues(t)
+	dv.Experiments = []string{string(codersdk.ExperimentWebPush)}
+	client := coderdtest.New(t, &coderdtest.Options{
+		DeploymentValues: dv,
+	})
+	owner := coderdtest.CreateFirstUser(t, client)
+	memberClient, _ := coderdtest.CreateAnotherUser(t, client, owner.OrganizationID)
+	_, anotherMember := coderdtest.CreateAnotherUser(t, client, owner.OrganizationID)
+
+	handlerCalled := make(chan bool, 1)
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusCreated)
+		handlerCalled <- true
+	}))
+	defer server.Close()
+
+	err := memberClient.PostWebpushSubscription(ctx, "me", codersdk.WebpushSubscription{
+		Endpoint:  server.URL,
+		AuthKey:   validEndpointAuthKey,
+		P256DHKey: validEndpointP256dhKey,
+	})
+	require.NoError(t, err, "create webpush subscription")
+	require.True(t, <-handlerCalled, "handler should have been called")
+
+	err = memberClient.PostTestWebpushMessage(ctx)
+	require.NoError(t, err, "test webpush message")
+	require.True(t, <-handlerCalled, "handler should have been called again")
+
+	err = memberClient.DeleteWebpushSubscription(ctx, "me", codersdk.DeleteWebpushSubscription{
+		Endpoint: server.URL,
+	})
+	require.NoError(t, err, "delete webpush subscription")
+
+	// Deleting the subscription for a non-existent endpoint should return a 404
+	err = memberClient.DeleteWebpushSubscription(ctx, "me", codersdk.DeleteWebpushSubscription{
+		Endpoint: server.URL,
+	})
+	var sdkError *codersdk.Error
+	require.Error(t, err)
+	require.ErrorAsf(t, err, &sdkError, "error should be of type *codersdk.Error")
+	require.Equal(t, http.StatusNotFound, sdkError.StatusCode())
+
+	// Creating a subscription for another user should not be allowed.
+	err = memberClient.PostWebpushSubscription(ctx, anotherMember.ID.String(), codersdk.WebpushSubscription{
+		Endpoint:  server.URL,
+		AuthKey:   validEndpointAuthKey,
+		P256DHKey: validEndpointP256dhKey,
+	})
+	require.Error(t, err, "create webpush subscription for another user")
+
+	// Deleting a subscription for another user should not be allowed.
+	err = memberClient.DeleteWebpushSubscription(ctx, anotherMember.ID.String(), codersdk.DeleteWebpushSubscription{
+		Endpoint: server.URL,
+	})
+	require.Error(t, err, "delete webpush subscription for another user")
+}