Add the ability to customize index.html (#113)

User may provide a custom index.html template file to be used instead
of the built-in version. Changes to this file are watched by laminard
using inotify in order to load and compress the custom file for gzip
delivery, reusing the existing method for serving static assets.

This feature obviates the custom css feature, so remove references from
the manual and add a deprecation warning if it is used.

Add a section to the UserManual describing how to use this feature and
including a link to an example using Semantic UI.

UserManual.md

@@ -616,11 +616,11 @@ DESCRIPTION=Anything here will appear on the job page in the frontend <em>unesca
 
 Change `LAMINAR_TITLE` in `/etc/laminar.conf` to your preferred page title. Laminar must be restarted for this change to take effect.
 
-## Custom stylesheet
+## Custom HTML template
 
-If it exists, the file `/var/lib/laminar/custom/style.css` will be served by laminar and may be used to change the appearance of Laminar's WebUI.
+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, for example adding menu links or adding a custom stylesheet. Any required assets will need to be served directly from your [HTTP reverse proxy](#Service-configuration) or other HTTP server.
 
-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).
+An example customization can be found at [cweagans/semantic-laminar-theme](https://github.com/cweagans/semantic-laminar-theme).
 
 ---
 

src/http.cpp

@@ -297,3 +297,8 @@ void Http::notifyLog(std::string job, uint run, std::string log_chunk, bool eot)
         }
     }
 }
+
+void Http::setHtmlTemplate(std::string tmpl)
+{
+    resources->setHtmlTemplate(tmpl);
+}

src/http.h

@@ -43,6 +43,9 @@ public:
     void notifyEvent(const char* data, std::string job = nullptr);
     void notifyLog(std::string job, uint run, std::string log_chunk, bool eot);
 
+    // Allows supplying a custom HTML template. Pass an empty string to use the default.
+    void setHtmlTemplate(std::string tmpl = std::string());
+
 private:
     virtual kj::Promise<void> request(kj::HttpMethod method, kj::StringPtr url, const kj::HttpHeaders& headers,
                                       kj::AsyncInputStream& requestBody, Response& response) override;

src/laminar.cpp

@@ -113,6 +113,12 @@ Laminar::Laminar(Server &server, Settings settings) :
       .addPath((homePath/"cfg"/"jobs").toString(true).cStr())
       .addPath((homePath/"cfg").toString(true).cStr()); // for groups.conf
 
+    loadCustomizations();
+    srv.watchPaths([this]{
+        LLOG(INFO, "Reloading customizations");
+        loadCustomizations();
+    }).addPath((homePath/"custom").toString(true).cStr());
+
     srv.listenRpc(*rpc, settings.bind_rpc);
     srv.listenHttp(*http, settings.bind_http);
 
@@ -121,6 +127,14 @@ Laminar::Laminar(Server &server, Settings settings) :
     loadConfiguration();
 }
 
+void Laminar::loadCustomizations() {
+    KJ_IF_MAYBE(templ, fsHome->tryOpenFile(kj::Path{"custom","index.html"})) {
+        http->setHtmlTemplate((*templ)->readAllText().cStr());
+    } else {
+        http->setHtmlTemplate();
+    }
+}
+
 uint Laminar::latestRun(std::string job) {
     auto it = activeJobs.byJobName().equal_range(job);
     if(it.first == it.second) {
@@ -789,8 +803,14 @@ R"x(
     return true;
 }
 
+// TODO: deprecate
 std::string Laminar::getCustomCss() {
     KJ_IF_MAYBE(cssFile, fsHome->tryOpenFile(kj::Path{"custom","style.css"})) {
+        static bool warningShown = false;
+        if(!warningShown) {
+            LLOG(WARNING, "Custom CSS has been deprecated and will be removed from a future release. Use a custom HTML template instead.");
+            warningShown = true;
+        }
         return (*cssFile)->readAllText().cStr();
     } else {
         return std::string();

src/laminar.h

@@ -103,6 +103,7 @@ public:
 
 private:
     bool loadConfiguration();
+    void loadCustomizations();
     void assignNewJobs();
     bool tryStartRun(std::shared_ptr<Run> run, int queueIndex);
     void handleRunFinished(Run*);

src/resources.cpp

@@ -37,7 +37,6 @@
 
 Resources::Resources()
 {
-    INIT_RESOURCE("/", index_html, CONTENT_TYPE_HTML);
     INIT_RESOURCE("/favicon.ico", favicon_ico, CONTENT_TYPE_ICO);
     INIT_RESOURCE("/favicon-152.png", favicon_152_png, CONTENT_TYPE_PNG);
     INIT_RESOURCE("/icon.png", icon_png, CONTENT_TYPE_PNG);
@@ -48,14 +47,36 @@ Resources::Resources()
     INIT_RESOURCE("/js/ansi_up.js", js_ansi_up_js, CONTENT_TYPE_JS);
     INIT_RESOURCE("/js/Chart.min.js", js_Chart_min_js, CONTENT_TYPE_JS);
     INIT_RESOURCE("/css/bootstrap.min.css", css_bootstrap_min_css, CONTENT_TYPE_CSS);
+    // Configure the default template
+    setHtmlTemplate(std::string());
+}
 
+void Resources::setHtmlTemplate(std::string tmpl) {
+    extern const char _binary_index_html_z_start[];
+    extern const char _binary_index_html_z_end[];
+
+    z_stream strm;
+    memset(&strm, 0, sizeof(z_stream));
+
+    if(!tmpl.empty()) {
+        // deflate
+        index_html.resize(tmpl.size());
+        deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, MAX_WBITS|GZIP_FORMAT, 8, Z_DEFAULT_STRATEGY);
+        strm.next_in = (unsigned char*) tmpl.data();
+        strm.avail_in = tmpl.size();
+        strm.next_out = (unsigned char*) index_html.data();
+        strm.avail_out = tmpl.size();
+        if(deflate(&strm, Z_FINISH) != Z_STREAM_END) {
+            LLOG(FATAL, "Failed to compress index.html");
+        }
+        index_html.resize(strm.total_out);
+    } else {
+        // use the default template from compile-time asset
         if(const char* baseUrl = getenv("LAMINAR_BASE_URL")) {
             // The administrator needs to customize the <base href>. Unfortunately this seems
             // to be the only thing that needs to be customizable but cannot be done via dynamic
             // DOM manipulation without heavy compromises. So replace the static char array with
             // a modified buffer accordingly.
-        z_stream strm;
-        memset(&strm, 0, sizeof(z_stream));
             std::string tmp;
             tmp.resize(INDEX_HTML_UNCOMPRESSED_SIZE);
             // inflate
@@ -84,10 +105,12 @@ Resources::Resources()
                 LLOG(FATAL, "Failed to compress index.html");
             }
             index_html.resize(strm.total_out);
-        // update resource map
-        resources["/"].start = index_html.data();
-        resources["/"].end = index_html.data() + index_html.size();
+        } else {
+            index_html = std::string(_binary_index_html_z_start, _binary_index_html_z_end);
         }
+    }
+    // update resource map
+    resources["/"] = Resource{index_html.data(), index_html.data() + index_html.size(), CONTENT_TYPE_HTML};
 }
 
 inline bool beginsWith(std::string haystack, const char* needle) {

src/resources.h

@@ -34,6 +34,9 @@ public:
     // type. Function returns false if no resource for the given path exists
     bool handleRequest(std::string path, const char** start, const char** end, const char** content_type);
 
+    // Allows providing a custom HTML template. Pass an empty string to use the default.
+    void setHtmlTemplate(std::string templ = std::string());
+
 private:
     struct Resource {
         const char* start;