Add basic auth push gateway (#398)

* Added ability to add authentication logic into pushgateway request. Added Basic Auth. implementation.

Signed-off-by: bitsal <[email protected]>

Author: bitsal

README.md

@@ -568,12 +568,35 @@ void executeBatchJob() throws Exception {
 }
  ```
 
-A separate registry is used, as the default registry may contain other metrics
+A separate registry is used, as the default registry may contain other metrics 
 such as those from the Process Collector. See the 
 [Pushgateway documentation](https://github.com/prometheus/pushgateway/blob/master/README.md)
 for more information.
 
 
+#### with Basic Auth
+```java
+PushGateway pushgateway = new PushGateway("127.0.0.1:9091");
+pushgateway.setConnectionFactory(new BasicAuthHttpConnectionFactory("my_user", "my_password"));
+```
+
+#### with Custom Connection Preparation Logic
+```java
+PushGateway pushgateway = new PushGateway("127.0.0.1:9091");
+pushgateway.setConnectionFactory(new MyHttpConnectionFactory());
+```
+where
+```java
+class MyHttpConnectionFactory implements HttpConnectionFactory {
+    @Override
+    public HttpURLConnection create(String url) throws IOException {
+        HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
+        // add any connection preparation logic you need
+        return connection;
+    }    
+}
+```
+
 ## Bridges
 
 It is also possible to expose metrics to systems other than Prometheus.

simpleclient_pushgateway/src/main/java/io/prometheus/client/exporter/BasicAuthHttpConnectionFactory.java

@@ -0,0 +1,37 @@
+package io.prometheus.client.exporter;
+
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.net.HttpURLConnection;
+import javax.xml.bind.DatatypeConverter;
+
+public class BasicAuthHttpConnectionFactory implements HttpConnectionFactory {
+    private final HttpConnectionFactory originConnectionFactory;
+    private final String basicAuthHeader;
+
+    public BasicAuthHttpConnectionFactory(HttpConnectionFactory connectionFactory, String user, String password) {
+        this.originConnectionFactory = connectionFactory;
+        this.basicAuthHeader = encode(user, password);
+    }
+
+    public BasicAuthHttpConnectionFactory(String user, String password) {
+        this(new DefaultHttpConnectionFactory(), user, password);
+    }
+
+    @Override
+    public HttpURLConnection create(String url) throws IOException {
+        HttpURLConnection connection = originConnectionFactory.create(url);
+        connection.setRequestProperty("Authorization", basicAuthHeader);
+        return connection;
+    }
+
+    private String encode(String user, String password) {
+        try {
+            byte[] credentialsBytes = (user + ":" + password).getBytes("UTF-8");
+            String encoded = DatatypeConverter.printBase64Binary(credentialsBytes);
+            return String.format("Basic %s", encoded);
+        } catch (UnsupportedEncodingException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+}

simpleclient_pushgateway/src/main/java/io/prometheus/client/exporter/DefaultHttpConnectionFactory.java

@@ -0,0 +1,12 @@
+package io.prometheus.client.exporter;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class DefaultHttpConnectionFactory implements HttpConnectionFactory {
+    @Override
+    public HttpURLConnection create(String url) throws IOException {
+        return (HttpURLConnection) new URL(url).openConnection();
+    }
+}

simpleclient_pushgateway/src/main/java/io/prometheus/client/exporter/HttpConnectionFactory.java

@@ -0,0 +1,8 @@
+package io.prometheus.client.exporter;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+
+public interface HttpConnectionFactory {
+    HttpURLConnection create(String url) throws IOException;
+}

simpleclient_pushgateway/src/main/java/io/prometheus/client/exporter/PushGateway.java

@@ -55,10 +55,13 @@
  */
 public class PushGateway {
 
+  private static final int MILLISECONDS_PER_SECOND = 1000;
+
   // Visible for testing.
   protected final String gatewayBaseURL;
 
-  private static final int MILLISECONDS_PER_SECOND = 1000;
+  private HttpConnectionFactory connectionFactory = new DefaultHttpConnectionFactory();
+
   /**
    * Construct a Pushgateway, with the given address.
    * <p>
@@ -79,6 +82,10 @@ public PushGateway(URL serverBaseURL) {
       .toString();
   }
 
+  public void setConnectionFactory(HttpConnectionFactory connectionFactory) {
+    this.connectionFactory = connectionFactory;
+  }
+
   /**
    * Creates a URL instance from a String representation of a URL without throwing a checked exception.
    * Required because you can't wrap a call to another constructor in a try statement.
@@ -273,7 +280,7 @@ void doRequest(CollectorRegistry registry, String job, Map<String, String> group
         url += "/" + entry.getKey() + "/" + URLEncoder.encode(entry.getValue(), "UTF-8");
       }
     }
-    HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
+    HttpURLConnection connection = connectionFactory.create(url);
     connection.setRequestProperty("Content-Type", TextFormat.CONTENT_TYPE_004);
     if (!method.equals("DELETE")) {
       connection.setDoOutput(true);

simpleclient_pushgateway/src/test/java/io/prometheus/client/exporter/BasicAuthPushGatewayTest.java

@@ -0,0 +1,45 @@
+package io.prometheus.client.exporter;
+
+
+import static org.mockserver.model.HttpRequest.request;
+import static org.mockserver.model.HttpResponse.response;
+
+import java.io.IOException;
+
+import io.prometheus.client.CollectorRegistry;
+import io.prometheus.client.Gauge;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.mockserver.client.server.MockServerClient;
+import org.mockserver.junit.MockServerRule;
+
+public class BasicAuthPushGatewayTest {
+
+  @Rule
+  public MockServerRule mockServerRule = new MockServerRule(this);
+  private MockServerClient mockServerClient;
+
+  CollectorRegistry registry;
+  Gauge gauge;
+  PushGateway pushGateway;
+
+  @Before
+  public void setUp() {
+    registry = new CollectorRegistry();
+    gauge = Gauge.build().name("g").help("help").create();
+    pushGateway = new PushGateway("localhost:" + mockServerRule.getHttpPort());
+    pushGateway.setConnectionFactory(new BasicAuthHttpConnectionFactory("testUser", "testPwd"));
+  }
+
+  @Test
+  public void testAuthorizedPush() throws IOException {
+    mockServerClient.when(
+        request()
+          .withMethod("PUT")
+          .withHeader("Authorization", "Basic dGVzdFVzZXI6dGVzdFB3ZA==")
+          .withPath("/metrics/job/j")
+      ).respond(response().withStatusCode(202));
+    pushGateway.push(registry, "j");
+  }
+}