Tell admin that automated check failed when necessary

This keeps track when automated update check fails, and displays a
relevant message to the admin on /admin/updates

Ref T572

admin.go

@@ -612,6 +612,7 @@ func handleViewAdminUpdates(app *App, u *User, w http.ResponseWriter, r *http.Re
 		LatestVersion         string
 		LatestReleaseURL      string
 		LatestReleaseNotesURL string
+		CheckFailed           bool
 	}{
 		UserPage:  NewUserPage(app, r, u, "Updates", nil),
 		AdminPage: NewAdminPage(app),
@@ -624,6 +625,7 @@ func handleViewAdminUpdates(app *App, u *User, w http.ResponseWriter, r *http.Re
 		p.LatestReleaseURL = app.updates.ReleaseURL()
 		p.LatestReleaseNotesURL = app.updates.ReleaseNotesURL()
 		p.UpdateAvailable = app.updates.AreAvailable()
+		p.CheckFailed = app.updates.checkError != nil
 	}
 
 	showUserPage(w, "app-updates", p)

less/core.less

@@ -1350,6 +1350,11 @@ div.row {
 	color: #71D571;
 }
 
+.ex.failure {
+	font-weight: bold;
+	color: @dangerCol;
+}
+
 @media all and (max-width: 450px) {
 	body#post {
 		header {

templates/user/admin/app-updates.tmpl

@@ -15,7 +15,11 @@
 	{{template "admin-header" .}}
 
 {{ if .UpdateChecks }}
-	{{if not .UpdateAvailable}}
+	{{if .CheckFailed}}
+		<p class="intro"><span class="ex failure">&times;</span> Automated update check failed.</p>
+		<p>Installed version: <strong>{{.Version}}</strong> (<a href="{{.CurReleaseNotesURL}}" target="changelog-wf">release notes</a>).</p>
+		<p>Learn about latest releases on the <a href="https://blog.writefreely.org/tag:release" target="changelog-wf">WriteFreely blog</a> or <a href="https://discuss.write.as/c/writefreely/updates" target="forum-wf">forum</a>.</p>
+	{{else if not .UpdateAvailable}}
 		<p class="intro"><span class="check">&check;</span> WriteFreely is <strong>up to date</strong>.</p>
 		<p>Installed version: <strong>{{.Version}}</strong> (<a href="{{.LatestReleaseNotesURL}}" target="changelog-wf">release notes</a>).</p>
     {{else}}

updates.go

@@ -30,6 +30,7 @@ type updatesCache struct {
 	lastCheck      time.Time
 	latestVersion  string
 	currentVersion string
+	checkError     error
 }
 
 // CheckNow asks for the latest released version of writefreely and updates
@@ -38,11 +39,12 @@ type updatesCache struct {
 func (uc *updatesCache) CheckNow() error {
 	uc.mu.Lock()
 	defer uc.mu.Unlock()
+	uc.lastCheck = time.Now()
 	latestRemote, err := newVersionCheck()
 	if err != nil {
+		uc.checkError = err
 		return err
 	}
-	uc.lastCheck = time.Now()
 	if CompareSemver(latestRemote, uc.latestVersion) == 1 {
 		uc.latestVersion = latestRemote
 	}