Feature/agent config (#3)

* add ConfigurationResolver

* refactor test

* remove tests

* update README

* add system-lambda for testing

* refactoring

* refactor ConnectionManager

README.md

@@ -29,7 +29,8 @@ contain extension jars) for the `otel.javaagent.extensions` value.
 ## Network communication
 
 The extension contains a client, who is able to communicate with other servers via HTTPS.
-To configure TLS 
+You can set the server url via system or environmental properties.
+You have the option to use a keystore for TLS:
 
 1. Provide a local keystore, which contains the certificate of your server
 2. Modify the startup command to add the path to the keystore as well as the password. For example:
@@ -38,6 +39,7 @@ To configure TLS
      java -javaagent:path/to/opentelemetry-javaagent.jar \
           -Dotel.javaagent.extensions=build/libs/opentelemetry-javaagent.jar \
           -Dotel.service.name="my-service" \
+          -Dinspectit.config.http.url="https://{server-host:port}/api/v1/connections" \
           -Djavax.net.ssl.trustStore="path\to\keystore\agent-keystore.jks" \
           -Djavax.net.ssl.trustStorePassword="password"
           -jar myapp.jar
@@ -50,7 +52,7 @@ The repository was build upon this example project: https://github.com/open-tele
 ### Why Gepard?
 Gepard is the German name for the animal cheetah as well as an acronym for: 
 
-"**G**anzheitliche, **e**ffizienz-orientierte, **P**erformance **A**nwendungsüberwachung mit **R**eporting und **D**iagnose"
+"**G**anzheitliche, **e**ffizienz-orientierte, **P**erformance **A**nwendungsüberwachung mit **R**eporting und **D**iagnose",
 
-meaning: holistic, efficiency-orientated, performance application monitoring with reporting and diagnostics.
+which means: holistic, efficiency-orientated, performance application monitoring with reporting and diagnostics.
 

build.gradle

@@ -107,6 +107,8 @@ dependencies {
 
     testImplementation("org.junit.jupiter:junit-jupiter-api:${versions.junit}")
     testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:${versions.junit}")
+    // configure environmental variables
+    testImplementation("com.github.stefanbirkner:system-lambda:1.2.1")
 
     // Otel Java instrumentation that we use and extend during integration tests
     otel("io.opentelemetry.javaagent:opentelemetry-javaagent:${versions.opentelemetryJavaagent}")
@@ -145,6 +147,11 @@ tasks {
         inputs.files(layout.files(tasks.shadowJar))
         inputs.files(layout.files(tasks.extendedAgent))
 
+        // Necessary to use system-lambda in tests
+        // See: https://github.com/stefanbirkner/system-lambda/issues/10
+        jvmArgs '--add-opens', 'java.base/java.util=ALL-UNNAMED'
+        jvmArgs '--add-opens', 'java.base/java.lang=ALL-UNNAMED'
+
         systemProperty 'io.opentelemetry.smoketest.agentPath', configurations.otel.singleFile.absolutePath
         systemProperty 'io.opentelemetry.smoketest.extendedAgentPath', tasks.extendedAgent.archiveFile.get().asFile.absolutePath
         systemProperty 'io.opentelemetry.smoketest.extensionPath', tasks.shadowJar.archiveFile.get().asFile.absolutePath
@@ -156,9 +163,7 @@ tasks {
 
     assemble.dependsOn(shadowJar)
 
-    dockerPrepare {
-        dependsOn extendedAgent
-    }
+    dockerPrepare.dependsOn(extendedAgent)
 
     docker {
         Provider<Directory> agentJar = layout.buildDirectory.dir("/libs/opentelemetry-javaagent.jar")

src/main/java/rocks/inspectit/gepard/agent/InspectitAgentExtension.java

@@ -6,16 +6,14 @@
 import net.bytebuddy.agent.builder.AgentBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import rocks.inspectit.gepard.agent.config.ConfigurationResolver;
 import rocks.inspectit.gepard.agent.notify.NotificationManager;
 
 @SuppressWarnings("unused")
 @AutoService(AgentExtension.class)
 public class InspectitAgentExtension implements AgentExtension {
   private static final Logger log = LoggerFactory.getLogger(InspectitAgentExtension.class);
 
-  /** Hard coded server url, which should configurable be in the future */
-  private static final String SERVER_URL = "https://localhost:8080/api/v1/connections";
-
   /**
    * Entrypoint for the inspectIT gepard extension
    *
@@ -28,9 +26,15 @@ public class InspectitAgentExtension implements AgentExtension {
   public AgentBuilder extend(AgentBuilder agentBuilder, ConfigProperties config) {
     log.info("Starting inspectIT Gepard agent extension ...");
 
-    boolean successful = NotificationManager.sendStartNotification(SERVER_URL);
-    if (successful) log.info("Successfully notified configuration server about start");
-    else log.info("Could not notify configuration server about start");
+    String url = ConfigurationResolver.getServerUrl();
+    if (url.isEmpty()) log.info("No configuration server url was provided");
+    else {
+      log.info("Sending start notification to configuration server with url: {}", url);
+      boolean successful = NotificationManager.sendStartNotification(url);
+
+      if (successful) log.info("Successfully notified configuration server about start");
+      else log.warn("Could not notify configuration server about start");
+    }
 
     return agentBuilder;
   }

src/main/java/rocks/inspectit/gepard/agent/config/ConfigurationResolver.java

@@ -0,0 +1,31 @@
+package rocks.inspectit.gepard.agent.config;
+
+import java.util.Objects;
+
+/**
+ * This resolver provides the configured configuration server url. Currently, it is possible to
+ * configure the url via system properties or environmental properties. System properties are higher
+ * prioritized than environmental properties.
+ */
+public class ConfigurationResolver {
+
+  private static final String SERVER_URL_SYSTEM_PROPERTY = "inspectit.config.http.url";
+
+  private static final String SERVER_URL_ENV_PROPERTY = "INSPECTIT_CONFIG_HTTP_URL";
+
+  private ConfigurationResolver() {}
+
+  /**
+   * Get the configured configuration server url. If no url was configured, an empty string will be
+   * returned.
+   *
+   * @return the configured configuration server url
+   */
+  public static String getServerUrl() {
+    String serverUrlSystemProperty = System.getProperty(SERVER_URL_SYSTEM_PROPERTY);
+    if (Objects.nonNull(serverUrlSystemProperty)) return serverUrlSystemProperty;
+
+    String serverUrlEnvProperty = System.getenv(SERVER_URL_ENV_PROPERTY);
+    return Objects.nonNull(serverUrlEnvProperty) ? serverUrlEnvProperty : "";
+  }
+}

src/main/java/rocks/inspectit/gepard/agent/notify/http/HttpClientHolder.java

@@ -1,8 +1,10 @@
 package rocks.inspectit.gepard.agent.notify.http;
 
+import java.io.File;
 import java.io.IOException;
 import java.security.GeneralSecurityException;
-import java.security.cert.X509Certificate;
+import java.security.KeyStore;
+import java.util.Objects;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 import org.apache.hc.client5.http.config.RequestConfig;
@@ -13,7 +15,6 @@
 import org.apache.hc.client5.http.ssl.*;
 import org.apache.hc.core5.http.nio.ssl.TlsStrategy;
 import org.apache.hc.core5.ssl.SSLContexts;
-import org.apache.hc.core5.ssl.TrustStrategy;
 import org.apache.hc.core5.util.Timeout;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -75,15 +76,20 @@ private static RequestConfig getRequestConfig() {
    */
   private static AsyncClientConnectionManager getConnectionManager()
       throws GeneralSecurityException, IOException {
-    TrustStrategy trustStrategy =
-        (chain, authType) -> {
-          final X509Certificate certificate = chain[0];
-          // Later the CN should be configurable
-          return "CN=localhost".equalsIgnoreCase(certificate.getSubjectX500Principal().getName());
-        };
-    SSLContext sslContext = SSLContexts.custom().loadTrustMaterial(trustStrategy).build();
-    HostnameVerifier hostnameVerifier = HttpsSupport.getDefaultHostnameVerifier();
+    String keystorePath = System.getProperty("javax.net.ssl.trustStore");
+    String keystorePassword = System.getProperty("javax.net.ssl.trustStorePassword");
+    SSLContext sslContext;
+
+    if (Objects.nonNull(keystorePath) || Objects.nonNull(keystorePassword)) {
+      KeyStore keyStore =
+          KeyStore.getInstance(new File(keystorePath), keystorePassword.toCharArray());
+      sslContext = SSLContexts.custom().loadTrustMaterial(keyStore, null).build();
+    } else {
+      log.info("No keystore found. Using default SSL context");
+      sslContext = SSLContexts.custom().loadTrustMaterial(TrustAllStrategy.INSTANCE).build();
+    }
 
+    HostnameVerifier hostnameVerifier = HttpsSupport.getDefaultHostnameVerifier();
     TlsStrategy tlsStrategy =
         ClientTlsStrategyBuilder.create()
             .setSslContext(sslContext)

src/main/java/rocks/inspectit/gepard/agent/notify/http/exception/ClientConfigurationException.java

@@ -1,11 +1,9 @@
 package rocks.inspectit.gepard.agent.notify.http.exception;
 
-/**
- * Exception, for errors in the configuration of the HTTP client
- */
+/** Exception, for errors in the configuration of the HTTP client */
 public class ClientConfigurationException extends RuntimeException {
 
-    public ClientConfigurationException(String message, Throwable cause) {
-        super(message, cause);
-    }
+  public ClientConfigurationException(String message, Throwable cause) {
+    super(message, cause);
+  }
 }

src/test/java/rocks/inspectit/gepard/agent/config/ConfigurationResolverTest.java

@@ -0,0 +1,60 @@
+package rocks.inspectit.gepard.agent.config;
+
+import static com.github.stefanbirkner.systemlambda.SystemLambda.restoreSystemProperties;
+import static com.github.stefanbirkner.systemlambda.SystemLambda.withEnvironmentVariable;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class ConfigurationResolverTest {
+
+  private static final String SERVER_URL_SYSTEM_PROPERTY = "inspectit.config.http.url";
+
+  private static final String SERVER_URL_ENV_PROPERTY = "INSPECTIT_CONFIG_HTTP_URL";
+
+  private static final String TEST_URL = "https://inspectit.rocks/";
+
+  @Test
+  void resolverReturnsUrlIfSystemPropertyExists() throws Exception {
+    restoreSystemProperties(
+        () -> {
+          System.setProperty(SERVER_URL_SYSTEM_PROPERTY, TEST_URL);
+
+          String url = ConfigurationResolver.getServerUrl();
+
+          assertEquals(TEST_URL, url);
+        });
+  }
+
+  @Test
+  void resolverReturnsUrlIfEnvironmentPropertyExists() throws Exception {
+    String url =
+        withEnvironmentVariable(SERVER_URL_ENV_PROPERTY, TEST_URL)
+            .execute(ConfigurationResolver::getServerUrl);
+
+    assertEquals(TEST_URL, url);
+  }
+
+  @Test
+  void resolverReturnsSystemPropertyIfSystemAndEnvPropertyExist() throws Exception {
+    String envTestUrl = TEST_URL + "1";
+    restoreSystemProperties(
+        () -> {
+          System.setProperty(SERVER_URL_SYSTEM_PROPERTY, TEST_URL);
+
+          String url =
+              withEnvironmentVariable(SERVER_URL_ENV_PROPERTY, envTestUrl)
+                  .execute(ConfigurationResolver::getServerUrl);
+
+          assertEquals(TEST_URL, url);
+        });
+  }
+
+  @Test
+  void resolverReturnsEmptyStringIfNoPropertyExists() {
+    String url = ConfigurationResolver.getServerUrl();
+
+    assertTrue(url.isEmpty());
+  }
+}