Change APM Server check from OkHttp to URLConnection (#284)

closes #272

Author: kanagat kananinja nugusbayev

apm-agent-core/pom.xml

@@ -54,16 +54,6 @@
     </build>
 
     <dependencies>
-        <dependency>
-            <groupId>com.squareup.okhttp3</groupId>
-            <artifactId>okhttp</artifactId>
-            <version>${version.okhttp}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.squareup.okhttp3</groupId>
-            <artifactId>logging-interceptor</artifactId>
-            <version>${version.okhttp}</version>
-        </dependency>
         <dependency>
             <groupId>com.lmax</groupId>
             <artifactId>disruptor</artifactId>
@@ -102,6 +92,18 @@
             <version>${version.byte-buddy}</version>
         </dependency>
 
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>okhttp</artifactId>
+            <version>${version.okhttp}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>logging-interceptor</artifactId>
+            <version>${version.okhttp}</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>io.undertow</groupId>
             <artifactId>undertow-core</artifactId>

apm-agent-core/src/main/java/co/elastic/apm/report/ApmServerHealthChecker.java

@@ -19,50 +19,70 @@
  */
 package co.elastic.apm.report;
 
-import okhttp3.OkHttpClient;
-import okhttp3.Request;
-import okhttp3.Response;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import javax.net.ssl.HttpsURLConnection;
+import javax.net.ssl.SSLSocketFactory;
 import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
 
-// TODO use UrlConnection and remove OkHttp dependency
 class ApmServerHealthChecker implements Runnable {
     private static final Logger logger = LoggerFactory.getLogger(ApmServerHealthChecker.class);
-    private final OkHttpClient httpClient;
+
     private final ReporterConfiguration reporterConfiguration;
 
-    ApmServerHealthChecker(OkHttpClient httpClient, ReporterConfiguration reporterConfiguration) {
-        this.httpClient = httpClient;
+    ApmServerHealthChecker(ReporterConfiguration reporterConfiguration) {
         this.reporterConfiguration = reporterConfiguration;
     }
 
     @Override
     public void run() {
         boolean success;
         String message = null;
+        HttpURLConnection connection = null;
         try {
-            final Response response = httpClient.newCall(new Request.Builder()
-                .url(reporterConfiguration.getServerUrls().get(0).toString())
-                .build())
-                .execute();
-            final int status = response.code();
+            URL url = new URL(reporterConfiguration.getServerUrls().get(0).toString() + "/healthcheck");
+            if (logger.isDebugEnabled()) {
+                logger.debug("Starting healthcheck to {}", url);
+            }
+            connection = (HttpURLConnection) url.openConnection();
+            if (!reporterConfiguration.isVerifyServerCert()) {
+                if (connection instanceof HttpsURLConnection) {
+                    trustAll((HttpsURLConnection) connection);
+                }
+            }
+            if (reporterConfiguration.getSecretToken() != null) {
+                connection.setRequestProperty("Authorization", "Bearer " + reporterConfiguration.getSecretToken());
+            }
+            connection.setConnectTimeout((int) reporterConfiguration.getServerTimeout().getMillis());
+            connection.setReadTimeout((int) reporterConfiguration.getServerTimeout().getMillis());
+            connection.connect();
+
+            final int status = connection.getResponseCode();
+
             success = status < 300;
+
             if (!success) {
                 if (status == 404) {
                     message = "It seems like you are using a version of the APM Server which is not compatible with this agent. " +
                         "Please use APM Server 6.5.0 or newer.";
                 } else {
                     message = Integer.toString(status);
                 }
-            } else if (response.body() != null) {
+            } else  {
                 // prints out the version info of the APM Server
-                message = response.body().string();
+                message = HttpUtils.getBody(connection);
             }
         } catch (IOException e) {
             message = e.getMessage();
             success = false;
+        } finally {
+            if (connection != null) {
+                connection.disconnect();
+                connection = null;
+            }
         }
 
         if (success) {
@@ -71,4 +91,13 @@ public void run() {
             logger.warn("Elastic APM server is not available ({})", message);
         }
     }
+
+    private void trustAll(HttpsURLConnection connection) {
+        final SSLSocketFactory sf = SslUtils.getTrustAllSocketFactory();
+        if (sf != null) {
+            // using the same instances is important for TCP connection reuse
+            connection.setHostnameVerifier(SslUtils.getTrustAllHostnameVerifyer());
+            connection.setSSLSocketFactory(sf);
+        }
+    }
 }

apm-agent-core/src/main/java/co/elastic/apm/report/HttpUtils.java

@@ -0,0 +1,69 @@
+/*-
+ * #%L
+ * Elastic APM Java agent
+ * %%
+ * Copyright (C) 2018 Elastic and contributors
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+package co.elastic.apm.report;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+
+public class HttpUtils {
+
+    private static final Logger logger = LoggerFactory.getLogger(HttpUtils.class);
+
+    private HttpUtils() {
+
+    }
+
+    public static String getBody(HttpURLConnection connection) {
+        String body;
+        try {
+            if (connection == null || connection.getInputStream() == null)
+                return null;
+            body = readInputStream(connection.getInputStream());
+            return body;
+        } catch (final IOException e) {
+            logger.error("Reading inputStream: {}", e.getMessage());
+            try {
+                body = readInputStream(connection.getErrorStream());
+                return body;
+            } catch (IOException e1) {
+                logger.error("Reading errorStream: {}", e1.getMessage());
+            }
+        }
+        return null;
+    }
+
+    private static String readInputStream(final InputStream inputStream) throws IOException {
+        final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
+        final StringBuilder bodyString = new StringBuilder();
+        String line;
+        while ((line = bufferedReader.readLine()) != null) {
+            bodyString.append(line);
+        }
+        bufferedReader.close();
+        return bodyString.toString();
+    }
+
+}

apm-agent-core/src/main/java/co/elastic/apm/report/ReporterFactory.java

@@ -28,23 +28,15 @@
 import co.elastic.apm.report.processor.ProcessorEventHandler;
 import co.elastic.apm.report.serialize.DslJsonSerializer;
 import co.elastic.apm.util.VersionUtils;
-import okhttp3.Interceptor;
-import okhttp3.OkHttpClient;
-import okhttp3.Request;
-import okhttp3.Response;
-import okhttp3.logging.HttpLoggingInterceptor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.stagemonitor.configuration.ConfigurationRegistry;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
-import javax.net.ssl.SSLSocketFactory;
-import java.io.IOException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
-import java.util.concurrent.TimeUnit;
 
 public class ReporterFactory {
 
@@ -54,7 +46,6 @@ public class ReporterFactory {
     public Reporter createReporter(ConfigurationRegistry configurationRegistry, @Nullable String frameworkName,
                                    @Nullable String frameworkVersion) {
         final ReporterConfiguration reporterConfiguration = configurationRegistry.getConfig(ReporterConfiguration.class);
-        final OkHttpClient httpClient = getOkHttpClient(reporterConfiguration);
         ExecutorService healthCheckExecutorService = Executors.newFixedThreadPool(1, new ThreadFactory() {
             @Override
             public Thread newThread(Runnable r) {
@@ -64,7 +55,7 @@ public Thread newThread(Runnable r) {
                 return thread;
             }
         });
-        healthCheckExecutorService.submit(new ApmServerHealthChecker(httpClient, reporterConfiguration));
+        healthCheckExecutorService.submit(new ApmServerHealthChecker(reporterConfiguration));
         healthCheckExecutorService.shutdown();
         final ReportingEventHandler reportingEventHandler = getReportingEventHandler(configurationRegistry, frameworkName,
             frameworkVersion, reporterConfiguration);
@@ -87,45 +78,11 @@ private ReportingEventHandler getReportingEventHandler(ConfigurationRegistry con
             processorEventHandler, payloadSerializer);
     }
 
-    @Nonnull
-    OkHttpClient getOkHttpClient(ReporterConfiguration reporterConfiguration) {
-        final OkHttpClient.Builder builder = new OkHttpClient.Builder()
-            .connectTimeout(reporterConfiguration.getServerTimeout().getMillis(), TimeUnit.MILLISECONDS);
-        if (!reporterConfiguration.isVerifyServerCert()) {
-            disableCertificateValidation(builder);
-        }
-        if (logger.isTraceEnabled()) {
-            final HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
-            loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.HEADERS);
-            builder.addInterceptor(loggingInterceptor);
-        }
-        builder.addInterceptor(new Interceptor() {
-            @Override
-            public Response intercept(Chain chain) throws IOException {
-                Request originalRequest = chain.request();
-                Request requestWithUserAgent = originalRequest.newBuilder()
-                    .header("User-Agent", userAgent)
-                    .build();
-                return chain.proceed(chain.request());
-            }
-        });
-        return builder.build();
-    }
-
     private String getUserAgent() {
         String agentVersion = VersionUtils.getAgentVersion();
         if (agentVersion != null) {
             return "apm-agent-java " + agentVersion;
         }
         return "apm-agent-java";
     }
-
-    private void disableCertificateValidation(OkHttpClient.Builder builder) {
-        final SSLSocketFactory sf = SslUtils.getTrustAllSocketFactory();
-        if (sf != null) {
-            builder
-                .sslSocketFactory(sf, SslUtils.getTrustAllTrustManager())
-                .hostnameVerifier(SslUtils.getTrustAllHostnameVerifyer());
-        }
-    }
 }

apm-agent-core/src/test/java/co/elastic/apm/AbstractServletTest.java

@@ -67,7 +67,6 @@ final void initServer() throws Exception {
             .build();
     }
 
-
     protected Response get(String path) throws IOException {
         return httpClient.newCall(new okhttp3.Request.Builder().url("http://localhost:" + getPort() + path).build()).execute();
     }

apm-agent-plugins/apm-servlet-plugin/pom.xml

@@ -34,6 +34,18 @@
             <version>${version.spring}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>okhttp</artifactId>
+            <version>${version.okhttp}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>logging-interceptor</artifactId>
+            <version>${version.okhttp}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 

apm-agent-plugins/apm-servlet-plugin/src/test/java/co/elastic/apm/servlet/ServletInstrumentationTest.java

@@ -97,6 +97,7 @@ private void testInstrumentation(ElasticApmInstrumentation instrumentation, int
         final Response response = get(path);
         assertThat(response.code()).isEqualTo(200);
         assertThat(response.body().string()).isEqualTo("Hello World!");
+
         if (expectedTransactions > 0) {
             reporter.getFirstTransaction(500);
         }

elastic-apm-agent/pom.xml

@@ -44,14 +44,6 @@
                                     <pattern>com.lmax</pattern>
                                     <shadedPattern>co.elastic.apm.shaded.lmax</shadedPattern>
                                 </relocation>
-                                <relocation>
-                                    <pattern>okhttp</pattern>
-                                    <shadedPattern>co.elastic.apm.shaded.okhttp</shadedPattern>
-                                </relocation>
-                                <relocation>
-                                    <pattern>okio</pattern>
-                                    <shadedPattern>co.elastic.apm.shaded.okio</shadedPattern>
-                                </relocation>
                                 <relocation>
                                     <pattern>org.slf4j</pattern>
                                     <shadedPattern>co.elastic.apm.shaded.slf4j</shadedPattern>