Improve docker healthcheck (#2110)

The new docker health check respects the jetty configuration and uses the configured port and context path.
It supports ssl listeners and follows redirects.

Co-authored-by: Sebastian Sdorra <sebastian.sdorra@cloudogu.com>

scm-server/src/main/java/sonia/scm/server/ServerConfiguration.java

@@ -0,0 +1,129 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.server;
+
+import org.eclipse.jetty.server.Connector;
+import org.eclipse.jetty.server.Handler;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.server.handler.HandlerCollection;
+import org.eclipse.jetty.util.resource.Resource;
+import org.eclipse.jetty.webapp.WebAppContext;
+import org.eclipse.jetty.xml.XmlConfiguration;
+import org.xml.sax.SAXException;
+
+import java.io.IOException;
+import java.net.URL;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+public final class ServerConfiguration {
+
+  private static final String CONFIGURATION = "/server-config.xml";
+  @SuppressWarnings("java:S1075") // not a real uri
+  private static final String DEFAULT_CONTEXT_PATH = "/scm";
+
+  private final XmlConfiguration jettyConfiguration;
+
+  public ServerConfiguration() {
+    this(CONFIGURATION);
+  }
+
+  public ServerConfiguration(String configurationUrl) {
+    this.jettyConfiguration = read(configurationUrl);
+  }
+
+  public ServerConfiguration(Path configurationPath) {
+    this.jettyConfiguration = parse(Resource.newResource(configurationPath));
+  }
+
+  public void configure(Server server) {
+    try {
+      jettyConfiguration.configure(server);
+    } catch (Exception ex) {
+      throw new ScmServerException("error during server configuration", ex);
+    }
+  }
+
+  public List<Listener> getListeners() {
+    List<Listener> listeners = new ArrayList<>();
+
+    Server server = new Server();
+    configure(server);
+
+    String contextPath = findContextPath(server.getHandlers());
+    if (contextPath == null) {
+      contextPath = DEFAULT_CONTEXT_PATH;
+    }
+
+    for (Connector connector : server.getConnectors()) {
+      if (connector instanceof ServerConnector) {
+        ServerConnector serverConnector = (ServerConnector) connector;
+        String scheme = "http";
+        String protocol = serverConnector.getDefaultProtocol();
+        if ("SSL".equalsIgnoreCase(protocol) || "TLS".equalsIgnoreCase(protocol)) {
+          scheme = "https";
+        }
+        listeners.add(new Listener(scheme, serverConnector.getPort(), contextPath));
+      }
+    }
+
+    return listeners;
+  }
+
+  private String findContextPath(Handler[] handlers) {
+    for (Handler handler : handlers) {
+      if (handler instanceof WebAppContext) {
+        return ((WebAppContext) handler).getContextPath();
+      } else if (handler instanceof HandlerCollection) {
+        String contextPath = findContextPath(((HandlerCollection) handler).getHandlers());
+        if (contextPath != null) {
+          return contextPath;
+        }
+      }
+    }
+    return null;
+  }
+
+  private static XmlConfiguration read(String configurationUrl) {
+    URL configURL = ScmServer.class.getResource(configurationUrl);
+
+    if (configURL == null) {
+      throw new ScmServerException("could not find server-config.xml");
+    }
+
+    return parse(Resource.newResource(configURL));
+  }
+
+  private static XmlConfiguration parse(Resource resource) {
+    try {
+      return new XmlConfiguration(resource);
+    } catch (IOException | SAXException ex) {
+      throw new ScmServerException("could not read server configuration", ex);
+    }
+  }
+
+}