Add mirror page and top banner regarding primary mirror outage

lib/MetaCPAN/Web/Controller/About.pm

@@ -38,6 +38,8 @@ sub meta_hack : Local : Args(0) {
     my ( $self, $c ) = @_;
 }
 
+sub mirror : Local : Args(0) { }
+
 sub sponsors : Local : Args(0) {
     my ( $self, $c ) = @_;
 }

root/about/mirror.tx

@@ -0,0 +1,44 @@
+%%  cascade base::about::markdown {
+%%      title => $title || 'Using MetaCPAN as a mirror',
+%%  }
+%%  override about -> {
+## MetaCPAN Mirror
+
+MetaCPAN provides an alternate mirror for CPAN, which is also a BackPAN (it
+includes deleted releases). It can be used if there are issues with the primary
+mirror, or you want to access older deleted releases via the `cpan` client.
+
+The address for the mirror is https://cpan.metacpan.org/
+
+### Configuring the Mirror
+
+#### `cpanm`
+
+`cpanm` can use the MetaCPAN mirror using the `-M` option:
+
+    cpanm -M https://cpan.metacpan.org/ Module::To::Install
+
+When using the MetaCPAN mirror, it may also be useful to use MetaCPAN's index.
+This can be done using the `--metacpan` option.
+
+    cpanm -M https://cpan.metacpan.org/ --metacpan Module::To::Install
+
+These options can be set more permanantly using the `PERL_CPANM_OPT` environment variable.
+
+    export PERL_CPANM_OPT='-M https://cpan.metacpan.org/ --metacpan'
+    cpanm Module::To::Install
+
+#### `cpan`
+
+`CPAN.pm` can be configured to use an alternate mirror using the `urllist`
+configuration setting. It also must be configured to use the `urllist` option
+by disabling the `pushy_https` option.
+
+    cpan
+    o conf urllist https://cpan.metacpan.org/
+    o conf pushy_https 0
+    o conf commit
+    install Module::To::Install
+    exit
+
+%%  }

root/base.tx

@@ -22,7 +22,6 @@
         <link rel="shortcut icon" href="/static/icons/favicon.ico">
         <link rel="apple-touch-icon" sizes="152x152" href="/static/icons/apple-touch-icon.png">
         <link rel="search" href="/static/opensearch.xml" type="application/opensearchdescription+xml" title="MetaCPAN">
-        <script async src="https://perl-ads.perlhacks.com/perl-ads.js"></script>
         <script async src="https://www.googletagmanager.com/gtag/js?id=G-6B2JCQSHJE"></script>
         %%  block opengraph -> { }
     </head>
@@ -118,7 +117,13 @@
             </ul>
         </nav>
         <div class="page-content [% block page_content_class -> { } %]">
-          <div id="perl-ad-target" class="top-notify-banner perl-ad-target">
+          <div class="top-notify-banner alert-banner">
+            <p>
+              <i class="fa-solid fa-triangle-exclamation"></i>
+              There is an ongoing outage on the primary CPAN mirror. It is
+              possible to work around the issue by <a href="/about/mirror">using
+              MetaCPAN as a mirror</a>.
+            </p>
           </div>
           <nav class="sidebar">
             %%  block left_nav -> {

root/base/about.tx

@@ -12,6 +12,7 @@ for [
   [ 'FAQ',                    '/about/faq' ],
   [ 'Contributors',           '/about/contributors' ],
   [ 'meta::hack',             '/about/meta_hack' ],
+  [ 'CPAN Mirror',            '/about/mirror' ],
   [ 'Missing Modules',        '/about/missing_modules' ],
   [ 'Distribution Metadata',  '/about/metadata' ],
 ] -> $l {

root/static/less/nav.less

@@ -28,6 +28,14 @@
         color: #c0d2e4;
         text-decoration: underline;
     }
+
+    p:last-child {
+        margin-bottom: 0;
+    }
+
+    &.alert-banner {
+        background-color: #c00;
+    }
 }
 
 .navbar {