diff --git a/.gitignore b/.gitignore
index 2228db3e..26c780bd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,4 @@ release.properties
 
 # Documentation build
 /docs/_site/
+.pr-train.yml
diff --git a/agent/pom.xml b/agent/pom.xml
index e953871c..cab6c58d 100644
--- a/agent/pom.xml
+++ b/agent/pom.xml
@@ -92,6 +92,11 @@
       <artifactId>mockito-core</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.github.stefanbirkner</groupId>
+      <artifactId>system-rules</artifactId>
+      <scope>test</scope>
+    </dependency>
 
     <!-- semantic metrics -->
     <dependency>
diff --git a/agent/src/main/java/com/spotify/ffwd/FastForwardAgent.java b/agent/src/main/java/com/spotify/ffwd/FastForwardAgent.java
index 7530124d..55090be7 100644
--- a/agent/src/main/java/com/spotify/ffwd/FastForwardAgent.java
+++ b/agent/src/main/java/com/spotify/ffwd/FastForwardAgent.java
@@ -52,13 +52,11 @@ public static void main(String[] argv) {
             path = Optional.of(Paths.get(argv[0]));
         }
 
-        final FastForwardAgent agent = setup(path, Optional.empty());
+        final FastForwardAgent agent = setup(path);
         run(agent);
     }
 
-    static FastForwardAgent setup(
-        final Optional<Path> configPath, final Optional<InputStream> configStream
-    ) {
+    static FastForwardAgent setup(final Optional<Path> configPath) {
         // needed for HTTP content decompression in:
         // com.spotify.ffwd.http.HttpModule
         System.setProperty("io.netty.noJdkZlibDecoder", "false");
@@ -102,12 +100,9 @@ static FastForwardAgent setup(
         final AgentCore.Builder builder = AgentCore.builder()
             .modules(modules)
             .statistics(statistics.statistics);
-
-        configStream.map(builder::configStream);
         configPath.map(builder::configPath);
 
         final AgentCore core = builder.build();
-
         return new FastForwardAgent(statistics, core);
     }
 
diff --git a/agent/src/test/java/com/spotify/ffwd/FfwdConfigurationTest.java b/agent/src/test/java/com/spotify/ffwd/FfwdConfigurationTest.java
index c6c9d680..5be5fdf4 100644
--- a/agent/src/test/java/com/spotify/ffwd/FfwdConfigurationTest.java
+++ b/agent/src/test/java/com/spotify/ffwd/FfwdConfigurationTest.java
@@ -23,28 +23,28 @@
 import static org.junit.Assert.assertEquals;
 
 import com.google.common.collect.ImmutableList;
-import com.google.inject.Injector;
 import com.spotify.ffwd.output.BatchingPluginSink;
 import com.spotify.ffwd.output.CoreOutputManager;
 import com.spotify.ffwd.output.FilteringPluginSink;
 import com.spotify.ffwd.output.OutputManager;
 import com.spotify.ffwd.output.PluginSink;
-import java.io.InputStream;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
-import java.util.function.Supplier;
-import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
 import org.junit.runner.RunWith;
 import org.mockito.runners.MockitoJUnitRunner;
 
 @RunWith(MockitoJUnitRunner.class)
 public class FfwdConfigurationTest {
 
-    @Before
-    public void setup() {
-    }
+    @Rule
+    public final EnvironmentVariables environmentVariables = new EnvironmentVariables();
 
     @Test
     public void testConfAllPluginsEnabled() {
@@ -90,17 +90,43 @@ public void testConfMixedPluginsEnabled() {
             "ffwd-mixed-plugins.yaml", expectedSinks);
     }
 
+    @Test
+    public void testConfigFromEnvVars() {
+        environmentVariables.set("FFWD_TTL", "100");
+        CoreOutputManager outputManager = getOutputManager(null);
+        assertEquals(100, outputManager.getTtl());
+    }
+
+    @Test
+    public void testIgnoreUnknownFields() {
+        Path configPath = resource("invalid.yaml");
+
+        String host = getOutputManager(configPath).getHost();
+        assertEquals("jimjam", host);
+    }
+
+    @Test
+    public void testMergeOrder() {
+        environmentVariables.set("FFWD_TTL", "100");
+        Path configPath = resource("basic-settings.yaml");
+        CoreOutputManager outputManager = getOutputManager(configPath);
+
+        assertEquals(100, outputManager.getTtl());
+        assertEquals("jimjam", outputManager.getHost());
+    }
+
+    private CoreOutputManager getOutputManager(final Path configPath) {
+        final FastForwardAgent agent = FastForwardAgent.setup(Optional.ofNullable(configPath));
+        return (CoreOutputManager) agent.getCore().getPrimaryInjector().getInstance(OutputManager.class);
+    }
+
     private void verifyLoadedSinksForConfig(
-        final String expectationString, final String configName,
+        final String expectationString,
+        final String configName,
         final List<List<String>> expectedSinks
     ) {
-        final InputStream configStream = stream(configName).get();
-
-        final FastForwardAgent agent =
-            FastForwardAgent.setup(Optional.empty(), Optional.of(configStream));
-        final Injector primaryInjector = agent.getCore().getPrimaryInjector();
-        final CoreOutputManager outputManager =
-            (CoreOutputManager) primaryInjector.getInstance(OutputManager.class);
+        final Path configPath = resource(configName);
+        final CoreOutputManager outputManager = getOutputManager(configPath);
         final List<PluginSink> sinks = outputManager.getSinks();
 
         final List<List<String>> sinkChains = new ArrayList<>();
@@ -130,7 +156,8 @@ private List<String> extractSinkChain(final PluginSink sink) {
         return sinkChain;
     }
 
-    private Supplier<InputStream> stream(String name) {
-        return () -> getClass().getClassLoader().getResourceAsStream(name);
+    private Path resource(String name) {
+        final String path = Objects.requireNonNull(getClass().getClassLoader().getResource(name)).getPath();
+        return Paths.get(path);
     }
 }
diff --git a/agent/src/test/resources/basic-settings.yaml b/agent/src/test/resources/basic-settings.yaml
new file mode 100644
index 00000000..583cfdaf
--- /dev/null
+++ b/agent/src/test/resources/basic-settings.yaml
@@ -0,0 +1,2 @@
+ttl: 50
+host: jimjam
\ No newline at end of file
diff --git a/agent/src/test/resources/invalid.yaml b/agent/src/test/resources/invalid.yaml
new file mode 100644
index 00000000..7b57fa6f
--- /dev/null
+++ b/agent/src/test/resources/invalid.yaml
@@ -0,0 +1,3 @@
+unknown_fake_property: true
+
+host: jimjam
\ No newline at end of file
diff --git a/core/pom.xml b/core/pom.xml
index f2e85f3e..eabd0594 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -30,6 +30,10 @@
       <groupId>org.jetbrains.kotlin</groupId>
       <artifactId>kotlin-stdlib-jdk8</artifactId>
     </dependency>
+    <dependency>
+      <groupId>com.uchuhimo</groupId>
+      <artifactId>konf</artifactId>
+    </dependency>
 
     <dependency>
       <groupId>com.fasterxml.jackson.module</groupId>
diff --git a/core/src/main/java/com/spotify/ffwd/AgentConfig.kt b/core/src/main/java/com/spotify/ffwd/AgentConfig.kt
index edb16876..5b2d6f96 100644
--- a/core/src/main/java/com/spotify/ffwd/AgentConfig.kt
+++ b/core/src/main/java/com/spotify/ffwd/AgentConfig.kt
@@ -16,40 +16,78 @@
 
 package com.spotify.ffwd
 
-import com.fasterxml.jackson.annotation.JsonCreator
-import com.fasterxml.jackson.annotation.JsonProperty
+import com.fasterxml.jackson.databind.module.SimpleModule
+import com.fasterxml.jackson.datatype.jdk8.Jdk8Module
 import com.spotify.ffwd.domain.SearchDomainDiscovery
 import com.spotify.ffwd.input.InputManagerModule
 import com.spotify.ffwd.output.OutputManagerModule
+import com.uchuhimo.konf.Config
+import com.uchuhimo.konf.ConfigSpec
 import java.net.InetAddress
 import java.net.InetSocketAddress
 import java.net.UnknownHostException
 import java.nio.file.Path
-import java.nio.file.Paths
 
-data class AgentConfig(
-    @JsonProperty("debug") var debug: Debug?,
-    @JsonProperty("host") var host: String = buildDefaultHost(),
-    @JsonProperty("tags") var tags: Map<String, String> = emptyMap(),
-    @JsonProperty("tagsToResource") var tagsToResource: Map<String, String> = emptyMap(),
-    @JsonProperty("riemannTags") var riemannTags: Set<String> = emptySet(),
-    @JsonProperty("skipTagsForKeys") var skipTagsForKeys: Set<String> = emptySet(),
-    @JsonProperty("automaticHostTag") var automaticHostTag: Boolean = true,
-    var input: InputManagerModule =
-        InputManagerModule.supplyDefault().get(),
-    @JsonProperty("output") var output: OutputManagerModule =
-        OutputManagerModule.supplyDefault().get(),
-    @JsonProperty("searchDomain") var searchDomain: SearchDomainDiscovery =
-        SearchDomainDiscovery.supplyDefault(),
-    @JsonProperty("asyncThreads") var asyncThreads: Int = 4,
-    @JsonProperty("schedulerThreads") var schedulerThreads: Int = 4,
-    @JsonProperty("bossThreads") var bossThreads: Int = 2,
-    @JsonProperty("workerThreads") var workerThreads: Int = 4,
-    @JsonProperty("ttl") var ttl: Long = 0,
-    // NB(hexedpackets): qlog is unused and can be removed once the config parser ignores unknown
-    // properties.
-    @JsonProperty("qlog") var qlog: String?
-)
+// Helper class to make interop with java easier. The configuration loading is done through the
+// static object.
+class AgentConfig(val config: Config) {
+    fun hasDebug(): Boolean = config.contains(Debug.host) or config.contains(Debug.port)
+
+    val debugLocalAddress =  config[Debug.localAddress]
+    val host = config[AgentConfig.host]
+    val tags = config[AgentConfig.tags]
+    val tagsToResource = config[AgentConfig.tagsToResource]
+    val riemannTags = config[AgentConfig.riemannTags]
+    val skipTagsForKeys = config[AgentConfig.skipTagsForKeys]
+    val automaticHostTag = config[AgentConfig.automaticHostTag]
+    val input: InputManagerModule = config[AgentConfig.input]
+    val output: OutputManagerModule = config[AgentConfig.output]
+    val searchDomain = config[AgentConfig.searchDomain]
+    val asyncThreads = config[AgentConfig.asyncThreads]
+    val schedulerThreads = config[AgentConfig.schedulerThreads]
+    val bossThreads = config[AgentConfig.bossThreads]
+    val workerThreads = config[AgentConfig.workerThreads]
+    val ttl = config[AgentConfig.ttl]
+
+    companion object : ConfigSpec("") {
+        object Debug : ConfigSpec() {
+            val host by optional("localhost")
+            val port by optional(19001)
+            val localAddress by lazy { InetSocketAddress(it[host], it[port]) }
+        }
+
+        val host by lazy { buildDefaultHost() }
+        val tags by optional(emptyMap<String, String>())
+        val tagsToResource by optional(emptyMap<String, String>())
+        val riemannTags by optional(emptySet<String>())
+        val skipTagsForKeys by optional(emptySet<String>())
+        val automaticHostTag by optional(true)
+        val input by lazy { InputManagerModule.supplyDefault().get() }
+        val output by lazy { OutputManagerModule.supplyDefault().get() }
+
+        val searchDomain by lazy { SearchDomainDiscovery.supplyDefault() }
+        val asyncThreads by optional(4)
+        val schedulerThreads by optional(4)
+        val bossThreads by optional(2)
+        val workerThreads by optional(4)
+        val ttl by optional(0)
+
+        @JvmStatic
+        fun load(path: Path, extraModule: SimpleModule): Config {
+            val config = Config { addSpec(AgentConfig) }
+            config.mapper
+                .registerModule(Jdk8Module())
+                .registerModule(extraModule)
+
+            // Load yaml config files with no prefix, then set it to "ffwd" for other sources.
+            return config
+                .from.yaml.file(path.toFile())
+                .withPrefix("ffwd")
+                .from.env()
+                .from.systemProperties()
+        }
+    }
+}
 
 private fun buildDefaultHost(): String {
     try {
@@ -57,12 +95,4 @@ private fun buildDefaultHost(): String {
     } catch (e: UnknownHostException) {
         throw RuntimeException("unable to get local host", e)
     }
-}
-
-data class Debug(
-    val localAddress: InetSocketAddress
-) {
-    @JsonCreator
-    constructor(@JsonProperty("host") host: String?, @JsonProperty port: Int?)
-        : this(InetSocketAddress(host ?: "localhost", port ?: 19001))
 }
\ No newline at end of file
diff --git a/core/src/main/java/com/spotify/ffwd/AgentCore.java b/core/src/main/java/com/spotify/ffwd/AgentCore.java
index 82de54b3..c0b19eb0 100644
--- a/core/src/main/java/com/spotify/ffwd/AgentCore.java
+++ b/core/src/main/java/com/spotify/ffwd/AgentCore.java
@@ -20,13 +20,8 @@
 
 package com.spotify.ffwd;
 
-import com.fasterxml.jackson.core.JsonParseException;
-import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.module.SimpleModule;
-import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
-import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
-import com.fasterxml.jackson.module.kotlin.KotlinModule;
 import com.google.common.collect.Lists;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.google.inject.AbstractModule;
@@ -65,6 +60,7 @@
 import com.spotify.ffwd.serializer.ToStringSerializer;
 import com.spotify.ffwd.statistics.CoreStatistics;
 import com.spotify.ffwd.statistics.NoopCoreStatistics;
+import com.uchuhimo.konf.Config;
 import eu.toolchain.async.AsyncCaller;
 import eu.toolchain.async.AsyncFramework;
 import eu.toolchain.async.AsyncFuture;
@@ -75,9 +71,7 @@
 import io.netty.util.HashedWheelTimer;
 import io.netty.util.Timer;
 import java.io.IOException;
-import java.io.InputStream;
 import java.lang.reflect.Constructor;
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
@@ -99,18 +93,16 @@ public class AgentCore {
     private static final Logger log = LoggerFactory.getLogger(AgentCore.class);
 
     private final List<Class<? extends FastForwardModule>> modules;
-    private final Optional<InputStream> configStream;
     private final Optional<Path> configPath;
     private final CoreStatistics statistics;
 
     private final Injector primaryInjector;
 
     private AgentCore(
-        final List<Class<? extends FastForwardModule>> modules, Optional<InputStream> configStream,
+        final List<Class<? extends FastForwardModule>> modules,
         Optional<Path> configPath, CoreStatistics statistics
     ) {
         this.modules = modules;
-        this.configStream = configStream;
         this.configPath = configPath;
         this.statistics = statistics;
 
@@ -150,18 +142,15 @@ private void waitUntilStopped(final Injector primary) throws InterruptedExceptio
     }
 
     private Thread setupShutdownHook(final Injector primary, final CountDownLatch shutdown) {
-        final Thread thread = new Thread() {
-            @Override
-            public void run() {
-                try {
-                    AgentCore.this.stop(primary);
-                } catch (Exception e) {
-                    log.error("AgentCore#stop(Injector) failed", e);
-                }
-
-                shutdown.countDown();
+        final Thread thread = new Thread(() -> {
+            try {
+                AgentCore.this.stop(primary);
+            } catch (Exception e) {
+                log.error("AgentCore#stop(Injector) failed", e);
             }
-        };
+
+            shutdown.countDown();
+        });
 
         thread.setName("ffwd-agent-core-shutdown-hook");
 
@@ -285,10 +274,9 @@ private Injector setupPrimaryInjector(
         modules.add(new AbstractModule() {
             @Override
             protected void configure() {
-                final Debug debug = config.getDebug();
-                if (debug != null) {
+                if (config.hasDebug()) {
                     bind(DebugServer.class).toInstance(
-                        new NettyDebugServer(debug.getLocalAddress()));
+                        new NettyDebugServer(config.getDebugLocalAddress()));
                 } else {
                     bind(DebugServer.class).toInstance(new NoopDebugServer());
                 }
@@ -386,32 +374,26 @@ protected void configure() {
         return early.createChildInjector(modules);
     }
 
-    private AgentConfig readConfig(Injector early) throws IOException {
-        final ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
+    /**
+     * Reads the configuration of the agent from multiple possible sources. In order of precedence,
+     * the following sources are loaded:
+     * - System properties
+     * - Environment variables
+     * - YAML file in specified location
+     * - YAML file bundled with JAR
+     *
+     * Values are merged, those higher on this list override those that are lower.
+     *
+     * @param early
+     * @return Data class of parsed config.
+     * @throws IOException when the passed config path is not valid YAML.
+     */
+    private AgentConfig readConfig(Injector early) {
         final SimpleModule module =
-            early.getInstance(Key.get(SimpleModule.class, Names.named("config")));
-
-        mapper.registerModule(new Jdk8Module());
-        mapper.registerModule(module);
-        mapper.registerModule(new KotlinModule());
+          early.getInstance(Key.get(SimpleModule.class, Names.named("config")));
 
-        final InputStream stream = configStream.orElseGet(() -> configPath
-            .map(this::getConfigStream)
-            .orElseGet(() -> getConfigStream(DEFAULT_CONFIG_PATH)));
-
-        try {
-            return mapper.readValue(stream, AgentConfig.class);
-        } catch (JsonParseException | JsonMappingException e) {
-            throw new IOException("Failed to parse configuration", e);
-        }
-    }
-
-    private InputStream getConfigStream(final Path path) {
-        try {
-            return Files.newInputStream(path);
-        } catch (IOException e) {
-            throw new RuntimeException("Failed to read configuration file '" + path + "'", e);
-        }
+        final Config config = AgentConfig.load(configPath.orElse(DEFAULT_CONFIG_PATH), module);
+        return new AgentConfig(config);
     }
 
     private List<FastForwardModule> loadModules(Injector injector) throws Exception {
@@ -451,19 +433,9 @@ public Injector getPrimaryInjector() {
 
     public static final class Builder {
         private List<Class<? extends FastForwardModule>> modules = Lists.newArrayList();
-        private Optional<InputStream> configStream = Optional.empty();
         private Optional<Path> configPath = Optional.empty();
         private CoreStatistics statistics = NoopCoreStatistics.get();
 
-        public Builder configStream(final InputStream configStream) {
-            if (configStream == null) {
-                throw new NullPointerException("'configStream' must not be null");
-            }
-
-            this.configStream = Optional.of(configStream);
-            return this;
-        }
-
         public Builder configPath(final Path configPath) {
             if (configPath == null) {
                 throw new NullPointerException("'configPath' must not be null");
@@ -492,7 +464,7 @@ public Builder statistics(CoreStatistics statistics) {
         }
 
         public AgentCore build() {
-            return new AgentCore(modules, configStream, configPath, statistics);
+            return new AgentCore(modules, configPath, statistics);
         }
     }
 }
diff --git a/core/src/main/java/com/spotify/ffwd/output/CoreOutputManager.java b/core/src/main/java/com/spotify/ffwd/output/CoreOutputManager.java
index af3351aa..3b500393 100644
--- a/core/src/main/java/com/spotify/ffwd/output/CoreOutputManager.java
+++ b/core/src/main/java/com/spotify/ffwd/output/CoreOutputManager.java
@@ -2,7 +2,7 @@
  * -\-\-
  * FastForward Core
  * --
- * Copyright (C) 2016 - 2018 Spotify AB
+ * Copyright (C) 2016 - 2019 Spotify AB
  * --
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,12 +42,13 @@
 import java.util.Set;
 import java.util.stream.Collectors;
 import lombok.Getter;
-import lombok.extern.slf4j.Slf4j;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-@Slf4j
 public class CoreOutputManager implements OutputManager {
     private static final String DEBUG_ID = "core.output";
     private static final String HOST = "host";
+    private static final Logger log = LoggerFactory.getLogger(CoreOutputManager.class);
 
     @Inject
     @Getter
@@ -84,10 +85,18 @@ public class CoreOutputManager implements OutputManager {
     @Named("host")
     private String host;
 
+    public String getHost() {
+        return host;
+    }
+
     @Inject
     @Named("ttl")
     private long ttl;
 
+    public long getTtl() {
+        return ttl;
+    }
+
     @Inject
     private DebugServer debug;
 
diff --git a/pom.xml b/pom.xml
index 114195e0..32de84aa 100644
--- a/pom.xml
+++ b/pom.xml
@@ -230,6 +230,11 @@
         <artifactId>kotlin-stdlib-jdk8</artifactId>
         <version>${kotlin.version}</version>
       </dependency>
+      <dependency>
+        <groupId>com.uchuhimo</groupId>
+        <artifactId>konf</artifactId>
+        <version>0.13.3</version>
+      </dependency>
 
       <dependency>
         <groupId>com.fasterxml.jackson.module</groupId>
@@ -355,9 +360,23 @@
         <version>1.9.5</version>
         <scope>test</scope>
       </dependency>
+      <dependency>
+        <groupId>com.github.stefanbirkner</groupId>
+        <artifactId>system-rules</artifactId>
+        <version>1.19.0</version>
+        <scope>test</scope>
+      </dependency>
+
     </dependencies>
   </dependencyManagement>
 
+  <dependencies>
+    <dependency>
+      <groupId>org.jetbrains.kotlin</groupId>
+      <artifactId>kotlin-stdlib-jdk8</artifactId>
+    </dependency>
+  </dependencies>
+
   <build>
     <extensions>
       <extension>