Add new handler for obtaining metrics snapshot in "packets" format

6 files changed, 464 insertions, 102 deletions

diff --git a/container-core/src/main/java/com/yahoo/container/jdisc/state/MetricsPacketsHandler.java b/container-core/src/main/java/com/yahoo/container/jdisc/state/MetricsPacketsHandler.java
new file mode 100644
index 00000000000..50c64341581
--- /dev/null
+++ b/container-core/src/main/java/com/yahoo/container/jdisc/state/MetricsPacketsHandler.java
@@ -0,0 +1,188 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.container.jdisc.state;
+
+import com.google.inject.Inject;
+import com.yahoo.collections.Tuple2;
+import com.yahoo.component.provider.ComponentRegistry;
+import com.yahoo.container.jdisc.state.StateHandler.JSONObjectWithLegibleException;
+import com.yahoo.jdisc.Request;
+import com.yahoo.jdisc.Response;
+import com.yahoo.jdisc.Timer;
+import com.yahoo.jdisc.handler.AbstractRequestHandler;
+import com.yahoo.jdisc.handler.ContentChannel;
+import com.yahoo.jdisc.handler.ResponseDispatch;
+import com.yahoo.jdisc.handler.ResponseHandler;
+import com.yahoo.jdisc.http.HttpHeaders;
+import com.yahoo.metrics.MetricsPresentationConfig;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import static com.yahoo.container.jdisc.state.StateHandler.getSnapshotPreprocessor;
+
+/**
+ * This handler outputs metrics in a json-like format. Each individual metric is a json object (packet),
+ * but there is no outer array or object that wraps the metrics packets. This handler is not set up by
+ * default, but can be added to the applications's services configuration.
+ *
+ * Based on {@link StateHandler}.
+ *
+ * @author gjoranv
+ */
+public class MetricsPacketsHandler extends AbstractRequestHandler {
+    static final String APPLICATION_KEY = "application";
+    static final String TIMESTAMP_KEY   = "timestamp";
+    static final String STATUS_CODE_KEY = "status_code";
+    static final String STATUS_MSG_KEY  = "status_msg";
+    static final String METRICS_KEY     = "metrics";
+    static final String DIMENSIONS_KEY  = "dimensions";
+
+
+    private final StateMonitor monitor;
+    private final Timer timer;
+    private final SnapshotProvider snapshotPreprocessor;
+    private final String applicationName;
+
+    @Inject
+    public MetricsPacketsHandler(StateMonitor monitor,
+                                 Timer timer,
+                                 ComponentRegistry<SnapshotProvider> preprocessors,
+                                 MetricsPresentationConfig presentation,
+                                 MetricsPacketsHandlerConfig config) {
+        this.monitor = monitor;
+        this.timer = timer;
+        snapshotPreprocessor = getSnapshotPreprocessor(preprocessors, presentation);
+        applicationName = config.application();
+    }
+
+
+    @Override
+    public ContentChannel handleRequest(Request request, ResponseHandler handler) {
+        new ResponseDispatch() {
+            @Override
+            protected Response newResponse() {
+                Response response = new Response(Response.Status.OK);
+                response.headers().add(HttpHeaders.Names.CONTENT_TYPE, "application/json");
+                return response;
+            }
+
+            @Override
+            protected Iterable<ByteBuffer> responseContent() {
+                return Collections.singleton(ByteBuffer.wrap(buildMetricOutput()));
+            }
+        }.dispatch(handler);
+
+        return null;
+    }
+
+    private byte[] buildMetricOutput() {
+        try {
+            String output = getStatusPacket() + getAllMetricsPackets();
+            return output.getBytes(StandardCharsets.UTF_8);
+        } catch (JSONException e) {
+            throw new RuntimeException("Bad JSON construction.", e);
+        }
+    }
+
+    /**
+     * Exactly one status packet is added to the response.
+     */
+    private String getStatusPacket() throws JSONException {
+        JSONObject packet = new JSONObjectWithLegibleException();
+        packet.put(APPLICATION_KEY, applicationName);
+
+        StateMonitor.Status status = monitor.status();
+        packet.put(STATUS_CODE_KEY, status.ordinal());
+        packet.put(STATUS_MSG_KEY, status.name());
+        return jsonToString(packet);
+    }
+
+    private String jsonToString(JSONObject jsonObject) throws JSONException {
+        return jsonObject.toString(4);
+    }
+
+    private String getAllMetricsPackets() throws JSONException {
+        StringBuilder ret = new StringBuilder();
+        List<JSONObject> metricsPackets = getPacketsForSnapshot(getSnapshot(), applicationName, timer.currentTimeMillis());
+        for (JSONObject packet : metricsPackets) {
+            ret.append("\n\n"); // For legibility and parsing in unit tests
+            ret.append(jsonToString(packet));
+        }
+        return ret.toString();
+    }
+
+    private MetricSnapshot getSnapshot() {
+        if (snapshotPreprocessor == null) {
+            return monitor.snapshot();
+        } else {
+            return snapshotPreprocessor.latestSnapshot();
+        }
+    }
+
+    private List<JSONObject> getPacketsForSnapshot(MetricSnapshot metricSnapshot, String application, long timestamp) throws JSONException {
+        if (metricSnapshot == null) return Collections.emptyList();
+
+        List<JSONObject> packets = new ArrayList<>();
+
+        for (Map.Entry<MetricDimensions, MetricSet> snapshotEntry : metricSnapshot) {
+            MetricDimensions metricDimensions = snapshotEntry.getKey();
+            MetricSet metricSet = snapshotEntry.getValue();
+
+            JSONObjectWithLegibleException packet = new JSONObjectWithLegibleException();
+            addMetaData(timestamp, application, packet);
+            addDimensions(metricDimensions, packet);
+            addMetrics(metricSet, packet);
+            packets.add(packet);
+        }
+        return packets;
+    }
+
+    private void addMetaData(long timestamp, String application, JSONObjectWithLegibleException packet) {
+        packet.put(APPLICATION_KEY, application);
+        packet.put(TIMESTAMP_KEY, timestamp);
+
+    }
+
+    private void addDimensions(MetricDimensions metricDimensions, JSONObjectWithLegibleException packet) throws JSONException {
+        Iterator<Map.Entry<String, String>> dimensionsIterator = metricDimensions.iterator();
+        if (dimensionsIterator.hasNext()) {
+            JSONObject jsonDim = new JSONObjectWithLegibleException();
+            packet.put(DIMENSIONS_KEY, jsonDim);
+            for (Map.Entry<String, String> dimensionEntry : metricDimensions) {
+                jsonDim.put(dimensionEntry.getKey(), dimensionEntry.getValue());
+            }
+        }
+    }
+
+    private void addMetrics(MetricSet metricSet, JSONObjectWithLegibleException packet) throws JSONException {
+        JSONObjectWithLegibleException metrics = new JSONObjectWithLegibleException();
+        packet.put(METRICS_KEY, metrics);
+        for (Map.Entry<String, MetricValue> metric : metricSet) {
+            String name = metric.getKey();
+            MetricValue value = metric.getValue();
+            if (value instanceof CountMetric) {
+                metrics.put(name + ".count", ((CountMetric) value).getCount());
+            } else if (value instanceof GaugeMetric) {
+                GaugeMetric gauge = (GaugeMetric) value;
+                metrics.put(name + ".average", gauge.getAverage())
+                        .put(name + ".last", gauge.getLast())
+                        .put(name + ".max", gauge.getMax());
+                if (gauge.getPercentiles().isPresent()) {
+                    for (Tuple2<String, Double> prefixAndValue : gauge.getPercentiles().get()) {
+                        metrics.put(name + "." + prefixAndValue.first + "percentile", prefixAndValue.second.doubleValue());
+                    }
+                }
+            } else {
+                throw new UnsupportedOperationException("Unknown metric class: " + value.getClass().getName());
+            }
+        }
+    }
+
+}
diff --git a/container-core/src/main/java/com/yahoo/container/jdisc/state/StateHandler.java b/container-core/src/main/java/com/yahoo/container/jdisc/state/StateHandler.java
index 23c247fa438..da88a338049 100644
--- a/container-core/src/main/java/com/yahoo/container/jdisc/state/StateHandler.java
+++ b/container-core/src/main/java/com/yahoo/container/jdisc/state/StateHandler.java
@@ -54,11 +54,15 @@ public class StateHandler extends AbstractRequestHandler {
         this.monitor = monitor;
         this.timer = timer;
         this.config = buildConfigOutput(config);
+        snapshotPreprocessor = getSnapshotPreprocessor(preprocessors, presentation);
+    }
+
+    static SnapshotProvider getSnapshotPreprocessor(ComponentRegistry<SnapshotProvider> preprocessors, MetricsPresentationConfig presentation) {
         List<SnapshotProvider> allPreprocessors = preprocessors.allComponents();
         if (presentation.slidingwindow() && allPreprocessors.size() > 0) {
-            snapshotPreprocessor = allPreprocessors.get(0);
+            return allPreprocessors.get(0);
         } else {
-            snapshotPreprocessor = null;
+            return null;
         }
     }
 
@@ -298,7 +302,7 @@ public class StateHandler extends AbstractRequestHandler {
     }
 
     /** Produces a flat list of metric entries from a snapshot (which organizes metrics by dimensions) */
-    private static List<Tuple> flattenAllMetrics(MetricSnapshot snapshot) {
+    static List<Tuple> flattenAllMetrics(MetricSnapshot snapshot) {
         List<Tuple> metrics = new ArrayList<>();
         for (Map.Entry<MetricDimensions, MetricSet> snapshotEntry : snapshot) {
             for (Map.Entry<String, MetricValue> metricSetEntry : snapshotEntry.getValue()) {
@@ -308,7 +312,7 @@ public class StateHandler extends AbstractRequestHandler {
         return metrics;
     }
 
-    private static class Tuple {
+    static class Tuple {
 
         final MetricDimensions dim;
         final String key;
diff --git a/container-core/src/main/resources/configdefinitions/metrics-packets-handler.def b/container-core/src/main/resources/configdefinitions/metrics-packets-handler.def
new file mode 100644
index 00000000000..c295954fc5d
--- /dev/null
+++ b/container-core/src/main/resources/configdefinitions/metrics-packets-handler.def
@@ -0,0 +1,6 @@
+# Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+namespace=container.jdisc.state
+
+# The name of the application that is reporting metrics.
+application string
diff --git a/container-core/src/test/java/com/yahoo/container/jdisc/state/MetricsPacketsHandlerTest.java b/container-core/src/test/java/com/yahoo/container/jdisc/state/MetricsPacketsHandlerTest.java
new file mode 100644
index 00000000000..895cb885828
--- /dev/null
+++ b/container-core/src/test/java/com/yahoo/container/jdisc/state/MetricsPacketsHandlerTest.java
@@ -0,0 +1,145 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.container.jdisc.state;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.yahoo.jdisc.Metric;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import static com.yahoo.container.jdisc.state.MetricsPacketsHandler.APPLICATION_KEY;
+import static com.yahoo.container.jdisc.state.MetricsPacketsHandler.DIMENSIONS_KEY;
+import static com.yahoo.container.jdisc.state.MetricsPacketsHandler.METRICS_KEY;
+import static com.yahoo.container.jdisc.state.MetricsPacketsHandler.STATUS_CODE_KEY;
+import static com.yahoo.container.jdisc.state.MetricsPacketsHandler.STATUS_MSG_KEY;
+import static com.yahoo.container.jdisc.state.MetricsPacketsHandler.TIMESTAMP_KEY;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * @author gjoranv
+ */
+public class MetricsPacketsHandlerTest extends StateHandlerTestBase {
+
+    @Test
+    public void only_status_packet_is_returned_prior_to_first_snapshot() throws Exception {
+        metric.add("not_included", 1, null);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        assertEquals(1, packets.size());
+
+        JsonNode statusPacket = packets.get(0);
+        assertEquals(statusPacket.toString(), APPLICATION_NAME, statusPacket.get(APPLICATION_KEY).asText());
+        assertEquals(statusPacket.toString(), 0, statusPacket.get(STATUS_CODE_KEY).asInt());
+        assertEquals(statusPacket.toString(), "up", statusPacket.get(STATUS_MSG_KEY).asText());
+    }
+
+    @Test
+    public void metrics_are_included_after_snapshot() throws Exception {
+        metric.add("counter", 1, null);
+        incrementCurrentTimeAndAssertSnapshot(SNAPSHOT_INTERVAL);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        assertEquals(2, packets.size());
+
+        JsonNode counterPacket = packets.get(1);
+        assertCountMetric(counterPacket, "counter.count", 1);
+    }
+
+    @Test
+    public void metadata_is_included_in_each_metrics_packet() throws Exception {
+        metric.add("counter", 1, null);
+        incrementCurrentTimeAndAssertSnapshot(SNAPSHOT_INTERVAL);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        JsonNode counterPacket = packets.get(1);
+
+        assertTrue(counterPacket.has(TIMESTAMP_KEY));
+        assertTrue(counterPacket.has(APPLICATION_KEY));
+        assertEquals(APPLICATION_NAME, counterPacket.get(APPLICATION_KEY).asText());
+    }
+
+    @Test
+    public void expected_aggregators_are_output_for_gauge_metrics() throws Exception{
+        Metric.Context context = metric.createContext(Collections.singletonMap("dim1", "value1"));
+        metric.set("gauge", 0.2, null);
+        incrementCurrentTimeAndAssertSnapshot(SNAPSHOT_INTERVAL);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        JsonNode gaugeMetric = packets.get(1).get(METRICS_KEY);
+        assertEquals(0.2, gaugeMetric.get("gauge.last").asDouble(), 0.1);
+        assertEquals(0.2, gaugeMetric.get("gauge.average").asDouble(), 0.1);
+        assertEquals(0.2, gaugeMetric.get("gauge.max").asDouble(), 0.1);
+    }
+
+    @Test
+    public void dimensions_from_context_are_included() throws Exception {
+        Metric.Context context = metric.createContext(Collections.singletonMap("dim1", "value1"));
+        metric.add("counter", 1, context);
+        incrementCurrentTimeAndAssertSnapshot(SNAPSHOT_INTERVAL);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        JsonNode counterPacket = packets.get(1);
+
+        assertTrue(counterPacket.has(DIMENSIONS_KEY));
+        JsonNode dimensions = counterPacket.get(DIMENSIONS_KEY);
+        assertEquals("value1", dimensions.get("dim1").asText());
+    }
+
+    @Test
+    public void metrics_with_identical_dimensions_are_contained_in_the_same_packet() throws Exception {
+        Metric.Context context = metric.createContext(Collections.singletonMap("dim1", "value1"));
+        metric.add("counter1", 1, context);
+        metric.add("counter2", 2, context);
+        incrementCurrentTimeAndAssertSnapshot(SNAPSHOT_INTERVAL);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        assertEquals(2, packets.size());
+        JsonNode countersPacket = packets.get(1);
+
+        assertEquals("value1", countersPacket.get(DIMENSIONS_KEY).get("dim1").asText());
+
+        assertCountMetric(countersPacket, "counter1.count", 1);
+        assertCountMetric(countersPacket, "counter2.count", 2);
+    }
+
+    @Test
+    public void metrics_with_different_dimensions_get_separate_packets() throws Exception {
+        Metric.Context context1 = metric.createContext(Collections.singletonMap("dim1", "value1"));
+        Metric.Context context2 = metric.createContext(Collections.singletonMap("dim2", "value2"));
+        metric.add("counter1", 1, context1);
+        metric.add("counter2", 1, context2);
+        incrementCurrentTimeAndAssertSnapshot(SNAPSHOT_INTERVAL);
+        String response = requestAsString("http://localhost/metrics-packets");
+
+        List<JsonNode> packets = toJsonPackets(response);
+        assertEquals(3, packets.size());
+    }
+
+    private List<JsonNode> toJsonPackets(String response) throws Exception {
+        List<JsonNode> jsonPackets = new ArrayList<>();
+        String[] packets = response.split("\\n\\n");
+        ObjectMapper mapper = new ObjectMapper();
+        for (String packet : packets) {
+            jsonPackets.add(mapper.readTree(mapper.getFactory().createParser(packet)));
+        }
+        return jsonPackets;
+    }
+
+    private void assertCountMetric(JsonNode metricsPacket, String metricName, long expected) {
+        assertTrue(metricsPacket.has(METRICS_KEY));
+        JsonNode counterMetrics = metricsPacket.get(METRICS_KEY);
+        assertTrue(counterMetrics.has(metricName));
+        assertEquals(expected, counterMetrics.get(metricName).asLong());
+    }
+
+}
diff --git a/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTest.java b/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTest.java
index 41b195baeb3..b3a19e77391 100644
--- a/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTest.java
+++ b/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTest.java
@@ -2,92 +2,24 @@
 package com.yahoo.container.jdisc.state;
 
 import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.google.inject.AbstractModule;
 import com.yahoo.component.Vtag;
-import com.yahoo.container.core.ApplicationMetadataConfig;
-import com.yahoo.container.jdisc.config.HealthMonitorConfig;
 import com.yahoo.jdisc.Metric;
-import com.yahoo.jdisc.Response;
-import com.yahoo.jdisc.Timer;
-import com.yahoo.jdisc.application.ContainerBuilder;
-import com.yahoo.jdisc.application.MetricConsumer;
-import com.yahoo.jdisc.handler.BufferedContentChannel;
-import com.yahoo.jdisc.handler.ContentChannel;
-import com.yahoo.jdisc.handler.ResponseHandler;
-import com.yahoo.jdisc.test.TestDriver;
-import com.yahoo.metrics.MetricsPresentationConfig;
 import com.yahoo.vespa.defaults.Defaults;
-import org.junit.After;
-import org.junit.Before;
 import org.junit.Test;
 
-import java.io.InputStreamReader;
-import java.io.Reader;
-import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.TreeMap;
-import java.util.concurrent.ThreadFactory;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicLong;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Mockito.mock;
 
 /**
  * @author Simon Thoresen Hult
  */
-public class StateHandlerTest {
-
-    private final static long SNAPSHOT_INTERVAL = TimeUnit.SECONDS.toMillis(300);
-    private final static long META_GENERATION = 69;
-    private TestDriver driver;
-    private StateMonitor monitor;
-    private Metric metric;
-    private final AtomicLong currentTimeMillis = new AtomicLong(0);
-
-    @Before
-    public void startTestDriver() {
-        Timer timer = this.currentTimeMillis::get;
-        this.driver = TestDriver.newSimpleApplicationInstanceWithoutOsgi(new AbstractModule() {
-            @Override
-            protected void configure() {
-                bind(Timer.class).toInstance(timer);
-            }
-        });
-        ContainerBuilder builder = driver.newContainerBuilder();
-        HealthMonitorConfig healthMonitorConfig =
-                new HealthMonitorConfig(
-                        new HealthMonitorConfig.Builder()
-                                .snapshot_interval(TimeUnit.MILLISECONDS.toSeconds(SNAPSHOT_INTERVAL)));
-        ThreadFactory threadFactory = ignored -> mock(Thread.class);
-        this.monitor = new StateMonitor(healthMonitorConfig, timer, threadFactory);
-        builder.guiceModules().install(new AbstractModule() {
-
-            @Override
-            protected void configure() {
-                bind(StateMonitor.class).toInstance(monitor);
-                bind(MetricConsumer.class).toProvider(MetricConsumerProviders.wrap(monitor));
-                bind(ApplicationMetadataConfig.class).toInstance(new ApplicationMetadataConfig(
-                        new ApplicationMetadataConfig.Builder().generation(META_GENERATION)));
-                bind(MetricsPresentationConfig.class)
-                        .toInstance(new MetricsPresentationConfig(new MetricsPresentationConfig.Builder()));
-            }
-        });
-        builder.serverBindings().bind("http://*/*", builder.getInstance(StateHandler.class));
-        driver.activateContainer(builder);
-        metric = builder.getInstance(Metric.class);
-    }
-
-    @After
-    public void stopTestDriver() {
-        assertTrue(driver.close());
-    }
+public class StateHandlerTest extends StateHandlerTestBase {
 
     @Test
     public void testReportPriorToFirstSnapshot() throws Exception {
@@ -392,37 +324,8 @@ public class StateHandlerTest {
         assertEquals(Vtag.currentVersion.toString(), version.asText());
     }
 
-    private void incrementCurrentTimeAndAssertSnapshot(long val) {
-        currentTimeMillis.addAndGet(val);
-        assertTrue("Expected a new snapshot to be generated", monitor.checkTime());
-    }
-
     private void incrementCurrentTimeAndAssertNoSnapshot(long val) {
         currentTimeMillis.addAndGet(val);
         assertFalse("Expected no snapshot", monitor.checkTime());;
     }
-
-    private String requestAsString(String requestUri) throws Exception {
-        final BufferedContentChannel content = new BufferedContentChannel();
-        Response response = driver.dispatchRequest(requestUri, new ResponseHandler() {
-
-            @Override
-            public ContentChannel handleResponse(Response response) {
-                return content;
-            }
-        }).get(60, TimeUnit.SECONDS);
-        assertNotNull(response);
-        assertEquals(Response.Status.OK, response.getStatus());
-        StringBuilder str = new StringBuilder();
-        Reader in = new InputStreamReader(content.toStream(), StandardCharsets.UTF_8);
-        for (int c; (c = in.read()) != -1; ) {
-            str.append((char)c);
-        }
-        return str.toString();
-    }
-
-    private JsonNode requestAsJson(String requestUri) throws Exception {
-        ObjectMapper mapper = new ObjectMapper();
-        return mapper.readTree(mapper.getFactory().createParser(requestAsString(requestUri)));
-    }
 }
diff --git a/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTestBase.java b/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTestBase.java
new file mode 100644
index 00000000000..a806df1883f
--- /dev/null
+++ b/container-core/src/test/java/com/yahoo/container/jdisc/state/StateHandlerTestBase.java
@@ -0,0 +1,116 @@
+package com.yahoo.container.jdisc.state;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.inject.AbstractModule;
+import com.yahoo.container.core.ApplicationMetadataConfig;
+import com.yahoo.container.jdisc.config.HealthMonitorConfig;
+import com.yahoo.jdisc.Metric;
+import com.yahoo.jdisc.Response;
+import com.yahoo.jdisc.Timer;
+import com.yahoo.jdisc.application.ContainerBuilder;
+import com.yahoo.jdisc.application.MetricConsumer;
+import com.yahoo.jdisc.handler.BufferedContentChannel;
+import com.yahoo.jdisc.handler.ContentChannel;
+import com.yahoo.jdisc.handler.ResponseHandler;
+import com.yahoo.jdisc.test.TestDriver;
+import com.yahoo.metrics.MetricsPresentationConfig;
+import org.junit.After;
+import org.junit.Before;
+
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+
+/**
+ * @author Simon Thoresen Hult
+ * @author gjoranv
+ */
+public class StateHandlerTestBase {
+    final static long SNAPSHOT_INTERVAL = TimeUnit.SECONDS.toMillis(300);
+    final static long META_GENERATION = 69;
+    static final String APPLICATION_NAME = "state-handler-test-base";
+    TestDriver driver;
+    StateMonitor monitor;
+    Metric metric;
+    final AtomicLong currentTimeMillis = new AtomicLong(0);
+
+    @Before
+    public void startTestDriver() {
+        Timer timer = this.currentTimeMillis::get;
+        this.driver = TestDriver.newSimpleApplicationInstanceWithoutOsgi(new AbstractModule() {
+            @Override
+            protected void configure() {
+                bind(Timer.class).toInstance(timer);
+            }
+        });
+        ContainerBuilder builder = driver.newContainerBuilder();
+        HealthMonitorConfig healthMonitorConfig =
+                new HealthMonitorConfig(
+                        new HealthMonitorConfig.Builder()
+                                .snapshot_interval(TimeUnit.MILLISECONDS.toSeconds(SNAPSHOT_INTERVAL)));
+        ThreadFactory threadFactory = ignored -> mock(Thread.class);
+        this.monitor = new StateMonitor(healthMonitorConfig, timer, threadFactory);
+        builder.guiceModules().install(new AbstractModule() {
+
+            @Override
+            protected void configure() {
+                bind(StateMonitor.class).toInstance(monitor);
+                bind(MetricConsumer.class).toProvider(MetricConsumerProviders.wrap(monitor));
+                bind(ApplicationMetadataConfig.class).toInstance(new ApplicationMetadataConfig(
+                        new ApplicationMetadataConfig.Builder().generation(META_GENERATION)));
+                bind(MetricsPresentationConfig.class)
+                        .toInstance(new MetricsPresentationConfig(new MetricsPresentationConfig.Builder()));
+                bind(MetricsPacketsHandlerConfig.class).toInstance(new MetricsPacketsHandlerConfig(
+                        new MetricsPacketsHandlerConfig.Builder().application(APPLICATION_NAME)));
+            }
+        });
+        builder.serverBindings().bind("http://*/*", builder.getInstance(StateHandler.class));
+        builder.serverBindings().bind("http://*/metrics-packets", builder.getInstance(MetricsPacketsHandler.class));
+        driver.activateContainer(builder);
+        metric = builder.getInstance(Metric.class);
+    }
+
+    @After
+    public void stopTestDriver() {
+        assertTrue(driver.close());
+    }
+
+    String requestAsString(String requestUri) throws Exception {
+        final BufferedContentChannel content = new BufferedContentChannel();
+        Response response = driver.dispatchRequest(requestUri, new ResponseHandler() {
+
+            @Override
+            public ContentChannel handleResponse(Response response) {
+                return content;
+            }
+        }).get(60, TimeUnit.SECONDS);
+        assertNotNull(response);
+        assertEquals(Response.Status.OK, response.getStatus());
+        StringBuilder str = new StringBuilder();
+        Reader in = new InputStreamReader(content.toStream(), StandardCharsets.UTF_8);
+        for (int c; (c = in.read()) != -1; ) {
+            str.append((char)c);
+        }
+        return str.toString();
+    }
+
+    JsonNode requestAsJson(String requestUri) throws Exception {
+        ObjectMapper mapper = new ObjectMapper();
+        return mapper.readTree(mapper.getFactory().createParser(requestAsString(requestUri)));
+    }
+
+    void incrementCurrentTimeAndAssertSnapshot(long val) {
+        currentTimeMillis.addAndGet(val);
+        assertTrue("Expected a new snapshot to be generated", monitor.checkTime());
+    }
+
+}