Add the ability to customize index.html

UserManual.md

@@ -622,6 +622,10 @@ If it exists, the file `/var/lib/laminar/custom/style.css` will be served by lam
 
 This directory is also a good place to add any extra assets needed for this customization, but note that in this case you will need to serve this directory directly from your [HTTP reverse proxy](#Service-configuration) (highly recommended).
 
+## Custom HTML template
+
+If it exists, the file `/var/lib/laminar/custom/index.html` will be served by laminar instead of the default markup that is bundled into the Laminar binary. This file can be used to change any aspect of Laminar's WebUI, including adding custom menu links, stylesheets, or anything else. Any additional assets that are needed will need to be served directly from your [HTTP reverse proxy](#Service-configuration) (highly recommended). 
+
 ---
 
 # Badges

src/http.cpp

@@ -211,14 +211,16 @@ kj::Promise<void> Http::request(kj::HttpMethod method, kj::StringPtr url, const
                 return writeEvents(p,s);
             }).attach(kj::mv(stream)).attach(kj::mv(peer));
         }
-    } else if(url.startsWith("/archive/")) {
+    }
+    if(url.startsWith("/archive/")) {
         KJ_IF_MAYBE(file, laminar.getArtefact(url.slice(strlen("/archive/")))) {
             auto array = (*file)->mmap(0, (*file)->stat().size);
             responseHeaders.add("Content-Transfer-Encoding", "binary");
             auto stream = response.send(200, "OK", responseHeaders, array.size());
             return stream->write(array.begin(), array.size()).attach(kj::mv(array)).attach(kj::mv(file)).attach(kj::mv(stream));
         }
-    } else if(parseLogEndpoint(url, name, num)) {
+    }
+    if(parseLogEndpoint(url, name, num)) {
         auto lw = kj::heap<WithSetRef<LogWatcher>>(logWatchers);
         lw->job = name;
         lw->run = num;
@@ -236,19 +238,33 @@ kj::Promise<void> Http::request(kj::HttpMethod method, kj::StringPtr url, const
                 return writeLogChunk(c, s);
             }).attach(kj::mv(output)).attach(kj::mv(stream)).attach(kj::mv(lw));
         }
-    } else if(url == "/custom/style.css") {
+    }
+    if(url == "/custom/style.css") {
         responseHeaders.set(kj::HttpHeaderId::CONTENT_TYPE, "text/css; charset=utf-8");
         responseHeaders.add("Content-Transfer-Encoding", "binary");
         std::string css = laminar.getCustomCss();
         auto stream = response.send(200, "OK", responseHeaders, css.size());
         return stream->write(css.data(), css.size()).attach(kj::mv(css)).attach(kj::mv(stream));
-    } else if(resources->handleRequest(url.cStr(), &start, &end, &content_type)) {
+    }
+    // If there is custom html defined, serve it. Otherwise, the default html
+    // will be served by the next block.
+    if(url == "/index.html" || url == "/") {
+        responseHeaders.set(kj::HttpHeaderId::CONTENT_TYPE, "text/html; charset=utf-8");
+        responseHeaders.add("Content-Transfer-Encoding", "binary");
+        std::string html = laminar.getCustomIndexHtml();
+        if (!html.empty()) {
+            auto stream = response.send(200, "OK", responseHeaders, html.size());
+            return stream->write(html.data(), html.size()).attach(kj::mv(html)).attach(kj::mv(stream));
+        }
+    }
+    if(resources->handleRequest(url.cStr(), &start, &end, &content_type)) {
         responseHeaders.set(kj::HttpHeaderId::CONTENT_TYPE, content_type);
         responseHeaders.add("Content-Encoding", "gzip");
         responseHeaders.add("Content-Transfer-Encoding", "binary");
         auto stream = response.send(200, "OK", responseHeaders, end-start);
         return stream->write(start, end-start).attach(kj::mv(stream));
-    } else if(url.startsWith("/badge/") && url.endsWith(".svg") && laminar.handleBadgeRequest(std::string(url.begin()+7, url.size()-11), badge)) {
+    }
+    if(url.startsWith("/badge/") && url.endsWith(".svg") && laminar.handleBadgeRequest(std::string(url.begin()+7, url.size()-11), badge)) {
         responseHeaders.set(kj::HttpHeaderId::CONTENT_TYPE, "image/svg+xml");
         responseHeaders.add("Cache-Control", "no-cache");
         auto stream = response.send(200, "OK", responseHeaders, badge.size());

src/laminar.cpp

@@ -796,3 +796,11 @@ std::string Laminar::getCustomCss() {
         return std::string();
     }
 }
+
+std::string Laminar::getCustomIndexHtml() {
+    KJ_IF_MAYBE(htmlFile, fsHome->tryOpenFile(kj::Path{"custom","index.html"})) {
+        return (*htmlFile)->readAllText().cStr();
+    } else {
+        return std::string();
+    }
+}

src/laminar.h

@@ -95,6 +95,10 @@ public:
     // which handles this url.
     std::string getCustomCss();
 
+    // Fetches the content of $LAMINAR_HOME/custom/index.html or an empty
+    // string. This is used for custom template overrides.
+    std::string getCustomIndexHtml();
+
     // Aborts a single job
     bool abort(std::string job, uint buildNum);