Add config_file option

CHANGELOG.md

@@ -4,6 +4,7 @@
  * Add support for Spring's JMS flavor - instrumenting `org.springframework.jms.listener.SessionAwareMessageListener`
  * Add support to legacy ApacheHttpClient APIs (which adds support to Axis2 configured to use ApacheHttpClient)
  * Added support for setting `server_urls` dynamically via properties file [#723](https://github.com/elastic/apm-agent-java/issues/723)
+ * Add [`config_file`](https://www.elastic.co/guide/en/apm/agent/java/current/config-core.html#config-config-file) option 
 
 ## Bug Fixes
  * Some JMS Consumers and Producers are filtered due to class name filtering in instrumentation matching

apm-agent-core/src/main/java/co/elastic/apm/agent/configuration/CoreConfiguration.java

@@ -24,6 +24,7 @@
  */
 package co.elastic.apm.agent.configuration;
 
+import co.elastic.apm.agent.bci.ElasticApmAgent;
 import co.elastic.apm.agent.bci.methodmatching.MethodMatcher;
 import co.elastic.apm.agent.bci.methodmatching.configuration.MethodMatcherValueConverter;
 import co.elastic.apm.agent.configuration.converter.TimeDuration;
@@ -36,6 +37,7 @@
 import org.stagemonitor.configuration.converter.ListValueConverter;
 import org.stagemonitor.configuration.converter.MapValueConverter;
 import org.stagemonitor.configuration.converter.StringValueConverter;
+import org.stagemonitor.configuration.source.ConfigurationSource;
 
 import javax.annotation.Nullable;
 import java.util.Arrays;
@@ -45,6 +47,7 @@
 import java.util.Map;
 
 import static co.elastic.apm.agent.configuration.validation.RangeValidator.isInRange;
+import static co.elastic.apm.agent.logging.LoggingConfiguration.AGENT_HOME_PLACEHOLDER;
 
 public class CoreConfiguration extends ConfigurationOptionProvider {
 
@@ -53,6 +56,8 @@ public class CoreConfiguration extends ConfigurationOptionProvider {
     public static final String SERVICE_NAME = "service_name";
     public static final String SAMPLE_RATE = "transaction_sample_rate";
     private static final String CORE_CATEGORY = "Core";
+    public static final String DEFAULT_CONFIG_FILE = AGENT_HOME_PLACEHOLDER + "/elasticapm.properties";
+    public static final String CONFIG_FILE = "config_file";
     private final ConfigurationOption<Boolean> active = ConfigurationOption.booleanOption()
         .key(ACTIVE)
         .configurationCategory(CORE_CATEGORY)
@@ -360,6 +365,14 @@ public class CoreConfiguration extends ConfigurationOptionProvider {
         .description("Disables the collection of breakdown metrics (`span.self_time`)")
         .buildWithDefault(true);
 
+    private final ConfigurationOption<String> configFileLocation = ConfigurationOption.stringOption()
+        .key(CONFIG_FILE)
+        .configurationCategory(CORE_CATEGORY)
+        .description("Sets the path of the agent config file.\n" +
+            "The special value `_AGENT_HOME_` is a placeholder for the folder the elastic-apm-agent.jar is in.\n" +
+            "The location can either be in the classpath of the application or on the file system.")
+        .buildWithDefault(DEFAULT_CONFIG_FILE);
+
     public boolean isActive() {
         return active.get();
     }
@@ -450,4 +463,29 @@ public Map<String, String> getGlobalLabels() {
     public boolean isBreakdownMetricsEnabled() {
         return breakdownMetrics.get();
     }
+
+    /*
+     * Makes sure to not initialize ConfigurationOption, which would initialize the logger
+     */
+    @Nullable
+    public static String getConfigFileLocation(List<ConfigurationSource> configurationSources) {
+        String configFileLocation = DEFAULT_CONFIG_FILE;
+        for (ConfigurationSource configurationSource : configurationSources) {
+            String valueFromSource = configurationSource.getValue(CONFIG_FILE);
+            if (valueFromSource != null) {
+                configFileLocation = valueFromSource;
+                break;
+            }
+        }
+        if (configFileLocation.contains(AGENT_HOME_PLACEHOLDER)) {
+            String agentHome = ElasticApmAgent.getAgentHome();
+            if (agentHome != null) {
+                return configFileLocation.replace(AGENT_HOME_PLACEHOLDER, agentHome);
+            } else {
+                return null;
+            }
+        } else {
+            return configFileLocation;
+        }
+    }
 }

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/ElasticApmTracerBuilder.java

@@ -24,7 +24,6 @@
  */
 package co.elastic.apm.agent.impl;
 
-import co.elastic.apm.agent.bci.ElasticApmAgent;
 import co.elastic.apm.agent.configuration.AgentArgumentsConfigurationSource;
 import co.elastic.apm.agent.configuration.ApmServerConfigurationSource;
 import co.elastic.apm.agent.configuration.CoreConfiguration;
@@ -35,7 +34,6 @@
 import co.elastic.apm.agent.impl.stacktrace.StacktraceConfiguration;
 import co.elastic.apm.agent.logging.LoggingConfiguration;
 import co.elastic.apm.agent.report.ApmServerClient;
-import co.elastic.apm.agent.report.ApmServerHealthChecker;
 import co.elastic.apm.agent.report.Reporter;
 import co.elastic.apm.agent.report.ReporterConfiguration;
 import co.elastic.apm.agent.report.ReporterFactory;
@@ -149,6 +147,9 @@ private ConfigurationRegistry getDefaultConfigurationRegistry(List<Configuration
         }
     }
 
+    /*
+     * Must not initialize any loggers with this as the logger is configured based on configuration.
+     */
     private List<ConfigurationSource> getConfigSources(@Nullable String agentArguments) {
         List<ConfigurationSource> result = new ArrayList<>();
         if (agentArguments != null && !agentArguments.isEmpty()) {
@@ -167,9 +168,9 @@ public String getName() {
                 return "Inline configuration";
             }
         });
-        String agentHome = ElasticApmAgent.getAgentHome();
-        if (agentHome != null && PropertyFileConfigurationSource.isPresent(agentHome + "/elasticapm.properties")) {
-            result.add(new PropertyFileConfigurationSource(agentHome + "/elasticapm.properties"));
+        String configFileLocation = CoreConfiguration.getConfigFileLocation(result);
+        if (configFileLocation != null && PropertyFileConfigurationSource.isPresent(configFileLocation)) {
+            result.add(new PropertyFileConfigurationSource(configFileLocation));
         }
         // looks if we can find a elasticapm.properties on the classpath
         // mainly useful for unit tests

apm-agent-core/src/main/java/co/elastic/apm/agent/logging/LoggingConfiguration.java

@@ -59,7 +59,7 @@ public class LoggingConfiguration extends ConfigurationOptionProvider {
     private static final String DEFAULT_LOG_FILE = SYSTEM_OUT;
 
     private static final String LOGGING_CATEGORY = "Logging";
-    private static final String AGENT_HOME_PLACEHOLDER = "_AGENT_HOME_";
+    public static final String AGENT_HOME_PLACEHOLDER = "_AGENT_HOME_";
     private static final String DEPRECATED_LOG_LEVEL_KEY = "logging.log_level";
     private static final String DEPRECATED_LOG_FILE_KEY = "logging.log_file";
 

apm-agent-core/src/test/java/co/elastic/apm/agent/impl/ElasticApmTracerBuilderTest.java

@@ -0,0 +1,62 @@
+/*-
+ * #%L
+ * Elastic APM Java agent
+ * %%
+ * Copyright (C) 2018 - 2019 Elastic and contributors
+ * %%
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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.agent.impl;
+
+import co.elastic.apm.agent.configuration.CoreConfiguration;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.stagemonitor.configuration.ConfigurationRegistry;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ElasticApmTracerBuilderTest {
+
+
+    @AfterEach
+    void tearDown() {
+        System.clearProperty("elastic.apm." + CoreConfiguration.CONFIG_FILE);
+    }
+
+    @Test
+    void testConfigFileLocation(@TempDir Path tempDir) throws IOException {
+        Path file = Files.createFile(tempDir.resolve("elastic-apm-test.properties"));
+        Files.write(file, List.of("instrument=false"));
+        System.setProperty("elastic.apm." + CoreConfiguration.CONFIG_FILE, file.toString());
+
+        ConfigurationRegistry configurationRegistry = new ElasticApmTracerBuilder().build().getConfigurationRegistry();
+        CoreConfiguration config = configurationRegistry.getConfig(CoreConfiguration.class);
+
+        // tests that changing non-dynamic properties also works
+        assertThat(config.isInstrument()).isFalse();
+        configurationRegistry.getString(CoreConfiguration.CONFIG_FILE);
+        assertThat(configurationRegistry.getString(CoreConfiguration.CONFIG_FILE)).isEqualTo(file.toString());
+    }
+}

docs/configuration.asciidoc

@@ -74,6 +74,7 @@ Click on a key to get more information.
 ** <<config-trace-methods-duration-threshold>>
 ** <<config-boot-delegation-packages>>
 ** <<config-breakdown-metrics>>
+** <<config-config-file-location>>
 * <<config-http>>
 ** <<config-capture-body>>
 ** <<config-capture-body-content-types>>
@@ -535,6 +536,28 @@ Disables the collection of breakdown metrics (`span.self_time`)
 | `elastic.apm.breakdown_metrics` | `breakdown_metrics` | `ELASTIC_APM_BREAKDOWN_METRICS`
 |============
 
+[float]
+[[config-config-file-location]]
+==== `config_file_location`
+
+Sets the path of the agent config file.
+The special value `_AGENT_HOME_` is a placeholder for the folder the elastic-apm-agent.jar is in.
+The location can either be in the classpath of the application or on the file system.
+
+
+[options="header"]
+|============
+| Default                          | Type                | Dynamic
+| `_AGENT_HOME_/elasticapm.properties` | String | false
+|============
+
+
+[options="header"]
+|============
+| Java System Properties      | Property file   | Environment
+| `elastic.apm.config_file_location` | `config_file_location` | `ELASTIC_APM_CONFIG_FILE_LOCATION`
+|============
+
 [[config-http]]
 === HTTP configuration options
 [float]
@@ -1446,6 +1469,16 @@ The default unit for this option is `ms`
 #
 # breakdown_metrics=true
 
+# Sets the path of the agent config file.
+# The special value `_AGENT_HOME_` is a placeholder for the folder the elastic-apm-agent.jar is in.
+# The location can either be in the classpath of the application or on the file system.
+#
+# This setting can not be changed at runtime. Changes require a restart of the application.
+# Type: String
+# Default value: _AGENT_HOME_/elasticapm.properties
+#
+# config_file_location=_AGENT_HOME_/elasticapm.properties
+
 ############################################
 # HTTP                                     #
 ############################################

pom.xml

@@ -58,7 +58,7 @@
         <version.error_prone>2.2.0</version.error_prone>
         <version.h2>1.4.196</version.h2>
         <version.jackson>2.9.9</version.jackson>
-        <version.junit-jupiter>5.3.2</version.junit-jupiter>
+        <version.junit-jupiter>5.5.1</version.junit-jupiter>
         <version.junit.vintage>4.12</version.junit.vintage>
         <version.logback>1.2.3</version.logback>
         <version.okhttp>3.9.1</version.okhttp>