Configserver flags REST API

Adds a new ZooKeeper backed flag source. It is defined in a new module
configserver-flags to allow as many as possible config server modules to depend
on it by minimizing dependencies.

The content of the ZK backed flag source can be viewed and modified through
REST API on the config server/controller. The data stored per flag looks like

  {
    "rules": [
      {
        "conditions": [
          { "type": "whitelist", "dimension": "hostname", "values": ["host1"] }
        ],
        "value": true
      }
    ]
  }

typical for enabling a feature flag on host1.

2 types of conditions are so far supported: whitelist and blacklist. All the
conditions must match in order for the value to apply. If the value is null (or
absent), the default value will be used. At the time the flag's value is
retrieved, it is resolved against the conditions with the current zone,
hostname, and/or application.

The same data structure is used for FileFlagSource for files in
/etc/vespa/flags with the ".2" extension.

The FlagSource component injected in the config server is changed to:
 1. Return the flag value if specified in /etc/vespa/flags, or otherwise
 2. return flag value from ZooKeeper (same as REST API)

The current flags (module) is also changed:
 - All flags must be defined in com.yahoo.vespa.flags.Flags. This allows the ZK
   backed flag source additional sanity checking when modifying flags.
 - If it makes sense to have different flag value depending on e.g. the
   application, then at some point before the value is retrieved, one has to
   bind the flag to that application (using with() to set up the fetch vector).

Future changes would be to 0. make a merged FlagSource in host admin, 1. add
support for viewing and modifying feature flags in dashboard, 2. in hv tool.

11 files changed, 415 insertions, 12 deletions

diff --git a/configserver/CMakeLists.txt b/configserver/CMakeLists.txt
index 5d3f88ac777..fe905ced973 100644
--- a/configserver/CMakeLists.txt
+++ b/configserver/CMakeLists.txt
@@ -14,6 +14,7 @@ install(CODE "execute_process(COMMAND mkdir -p \$ENV{DESTDIR}/\${CMAKE_INSTALL_P
 install(CODE "execute_process(COMMAND mkdir -p \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/config-models)")
 install(CODE "execute_process(COMMAND ln -snf \${CMAKE_INSTALL_PREFIX}/lib/jars/config-model-fat.jar \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/components/config-model-fat.jar)")
 install(CODE "execute_process(COMMAND ln -snf \${CMAKE_INSTALL_PREFIX}/lib/jars/configserver-jar-with-dependencies.jar \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/components/configserver.jar)")
+install(CODE "execute_process(COMMAND ln -snf \${CMAKE_INSTALL_PREFIX}/lib/jars/configserver-flags-jar-with-dependencies.jar \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/components/configserver-flags.jar)")
 install(CODE "execute_process(COMMAND ln -snf \${CMAKE_INSTALL_PREFIX}/lib/jars/flags-jar-with-dependencies.jar \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/components/flags.jar)")
 install(CODE "execute_process(COMMAND ln -snf \${CMAKE_INSTALL_PREFIX}/lib/jars/orchestrator-jar-with-dependencies.jar \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/components/orchestrator.jar)")
 install(CODE "execute_process(COMMAND ln -snf \${CMAKE_INSTALL_PREFIX}/lib/jars/service-monitor-jar-with-dependencies.jar \$ENV{DESTDIR}/\${CMAKE_INSTALL_PREFIX}/conf/configserver-app/components/service-monitor.jar)")
diff --git a/configserver/pom.xml b/configserver/pom.xml
index f932a963d14..210e584fd85 100644
--- a/configserver/pom.xml
+++ b/configserver/pom.xml
@@ -90,6 +90,12 @@
     </dependency>
     <dependency>
       <groupId>com.yahoo.vespa</groupId>
+      <artifactId>configserver-flags</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>com.yahoo.vespa</groupId>
       <artifactId>config-application-package</artifactId>
       <version>${project.version}</version>
       <type>test-jar</type>
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/ConfigServerBootstrap.java b/configserver/src/main/java/com/yahoo/vespa/config/server/ConfigServerBootstrap.java
index 0b1684b6735..f240129eda1 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/ConfigServerBootstrap.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/ConfigServerBootstrap.java
@@ -12,8 +12,8 @@ import com.yahoo.container.jdisc.state.StateMonitor;
 import com.yahoo.log.LogLevel;
 import com.yahoo.vespa.config.server.rpc.RpcServer;
 import com.yahoo.vespa.config.server.version.VersionState;
-import com.yahoo.vespa.flags.FeatureFlag;
 import com.yahoo.vespa.flags.FlagSource;
+import com.yahoo.vespa.flags.Flags;
 
 import java.time.Duration;
 import java.time.Instant;
@@ -30,7 +30,8 @@ import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 
-import static com.yahoo.vespa.config.server.ConfigServerBootstrap.RedeployingApplicationsFails.*;
+import static com.yahoo.vespa.config.server.ConfigServerBootstrap.RedeployingApplicationsFails.CONTINUE;
+import static com.yahoo.vespa.config.server.ConfigServerBootstrap.RedeployingApplicationsFails.EXIT_JVM;
 
 /**
  * Main component that bootstraps and starts config server threads.
@@ -45,7 +46,6 @@ import static com.yahoo.vespa.config.server.ConfigServerBootstrap.RedeployingApp
 public class ConfigServerBootstrap extends AbstractComponent implements Runnable {
 
     private static final Logger log = Logger.getLogger(ConfigServerBootstrap.class.getName());
-    private static final String bootstrapFeatureFlag = "config-server-bootstrap-in-separate-thread";
 
     // INITIALIZE_ONLY is for testing only
     enum Mode {BOOTSTRAP_IN_CONSTRUCTOR, BOOTSTRAP_IN_SEPARATE_THREAD, INITIALIZE_ONLY}
@@ -69,7 +69,7 @@ public class ConfigServerBootstrap extends AbstractComponent implements Runnable
                                  VersionState versionState, StateMonitor stateMonitor, VipStatus vipStatus,
                                  FlagSource flagSource) {
         this(applicationRepository, server, versionState, stateMonitor, vipStatus,
-             new FeatureFlag(bootstrapFeatureFlag, true, flagSource).value()
+                Flags.CONFIG_SERVER_BOOTSTRAP_IN_SEPARATE_THREAD.bindTo(flagSource).value()
                      ? Mode.BOOTSTRAP_IN_SEPARATE_THREAD
                      : Mode.BOOTSTRAP_IN_CONSTRUCTOR,
              EXIT_JVM);
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java b/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java
index 032bb88eaaa..2d5d5296762 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java
@@ -1,11 +1,11 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.config.server.application;
 
+import com.yahoo.component.Version;
 import com.yahoo.config.ConfigurationRuntimeException;
 import com.yahoo.config.model.api.ApplicationInfo;
 import com.yahoo.config.model.api.Model;
 import com.yahoo.config.provision.ApplicationId;
-import com.yahoo.component.Version;
 import com.yahoo.log.LogLevel;
 import com.yahoo.vespa.config.ConfigCacheKey;
 import com.yahoo.vespa.config.ConfigDefinitionKey;
@@ -15,17 +15,19 @@ import com.yahoo.vespa.config.GetConfigRequest;
 import com.yahoo.vespa.config.buildergen.ConfigDefinition;
 import com.yahoo.vespa.config.protocol.ConfigResponse;
 import com.yahoo.vespa.config.protocol.DefContent;
-import com.yahoo.vespa.config.server.rpc.ConfigResponseFactory;
 import com.yahoo.vespa.config.server.ServerCache;
-import com.yahoo.vespa.config.server.tenant.TenantRepository;
-import com.yahoo.vespa.config.server.rpc.UncompressedConfigResponseFactory;
 import com.yahoo.vespa.config.server.UnknownConfigDefinitionException;
 import com.yahoo.vespa.config.server.modelfactory.ModelResult;
 import com.yahoo.vespa.config.server.monitoring.MetricUpdater;
+import com.yahoo.vespa.config.server.rpc.ConfigResponseFactory;
+import com.yahoo.vespa.config.server.rpc.UncompressedConfigResponseFactory;
+import com.yahoo.vespa.config.server.tenant.TenantRepository;
 import com.yahoo.vespa.config.util.ConfigUtils;
-import com.yahoo.vespa.flags.FeatureFlag;
+import com.yahoo.vespa.flags.FetchVector;
 import com.yahoo.vespa.flags.FileFlagSource;
+import com.yahoo.vespa.flags.Flag;
 import com.yahoo.vespa.flags.FlagSource;
+import com.yahoo.vespa.flags.Flags;
 
 import java.util.Objects;
 import java.util.Set;
@@ -47,7 +49,7 @@ public class Application implements ModelResult {
     private final ServerCache cache;
     private final MetricUpdater metricUpdater;
     private final ApplicationId app;
-    private final FeatureFlag useConfigServerCache;
+    private final Flag<Boolean> useConfigServerCache;
 
     public Application(Model model, ServerCache cache, long appGeneration, boolean internalRedeploy,
                        Version vespaVersion, MetricUpdater metricUpdater, ApplicationId app) {
@@ -64,7 +66,9 @@ public class Application implements ModelResult {
         this.vespaVersion = vespaVersion;
         this.metricUpdater = metricUpdater;
         this.app = app;
-        this.useConfigServerCache = new FeatureFlag("use-config-server-cache", true, flagSource);
+        this.useConfigServerCache = Flags.USE_CONFIG_SERVER_CACHE
+                .with(FetchVector.Dimension.APPLICATION_ID, app.serializedForm())
+                .bindTo(flagSource);
     }
 
     /**
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagDataListResponse.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagDataListResponse.java
new file mode 100644
index 00000000000..4d9ba96b791
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagDataListResponse.java
@@ -0,0 +1,52 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http.flags;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.jdisc.Response;
+import com.yahoo.vespa.flags.FlagId;
+import com.yahoo.vespa.flags.json.FlagData;
+
+import java.io.OutputStream;
+import java.util.Map;
+import java.util.TreeMap;
+
+import static com.yahoo.yolean.Exceptions.uncheck;
+
+/**
+ * @author hakonhall
+ */
+public class FlagDataListResponse extends HttpResponse {
+    private static ObjectMapper mapper = new ObjectMapper();
+
+    private final String flagsV1Uri;
+    private final Map<FlagId, FlagData> flags;
+    private final boolean showDataInsteadOfUrl;
+
+    public FlagDataListResponse(String flagsV1Uri, Map<FlagId, FlagData> flags, boolean showDataInsteadOfUrl) {
+        super(Response.Status.OK);
+        this.flagsV1Uri = flagsV1Uri;
+        this.flags = flags;
+        this.showDataInsteadOfUrl = showDataInsteadOfUrl;
+    }
+
+    @Override
+    public void render(OutputStream outputStream) {
+        ObjectNode rootNode = mapper.createObjectNode();
+        // Order flags by ID
+        new TreeMap<>(flags).forEach((flagId, flagData) -> {
+            if (showDataInsteadOfUrl) {
+                rootNode.set(flagId.toString(), flagData.toJsonNode());
+            } else {
+                rootNode.putObject(flagId.toString()).put("url", flagsV1Uri + "/data/" + flagId.toString());
+            }
+        });
+        uncheck(() -> mapper.writeValue(outputStream, rootNode));
+    }
+
+    @Override
+    public String getContentType() {
+        return "application/json";
+    }
+}
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagDataResponse.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagDataResponse.java
new file mode 100644
index 00000000000..054b218ff2d
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagDataResponse.java
@@ -0,0 +1,31 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http.flags;
+
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.jdisc.Response;
+import com.yahoo.vespa.config.server.http.HttpConfigResponse;
+import com.yahoo.vespa.flags.json.FlagData;
+
+import java.io.OutputStream;
+
+/**
+ * @author hakonhall
+ */
+public class FlagDataResponse extends HttpResponse {
+    private final FlagData data;
+
+    FlagDataResponse(FlagData data) {
+        super(Response.Status.OK);
+        this.data = data;
+    }
+
+    @Override
+    public void render(OutputStream outputStream) {
+        data.serializeToOutputStream(outputStream);
+    }
+
+    @Override
+    public String getContentType() {
+        return HttpConfigResponse.JSON_CONTENT_TYPE;
+    }
+}
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagsHandler.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagsHandler.java
new file mode 100644
index 00000000000..3b4194fc474
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/FlagsHandler.java
@@ -0,0 +1,94 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http.flags;
+
+import com.google.inject.Inject;
+import com.yahoo.container.jdisc.HttpRequest;
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.container.jdisc.LoggingRequestHandler;
+import com.yahoo.restapi.Path;
+import com.yahoo.vespa.config.server.http.HttpHandler;
+import com.yahoo.vespa.config.server.http.NotFoundException;
+import com.yahoo.vespa.configserver.flags.FlagsDb;
+import com.yahoo.vespa.flags.FlagId;
+import com.yahoo.vespa.flags.Flags;
+import com.yahoo.vespa.flags.json.FlagData;
+
+import java.net.URI;
+import java.util.Objects;
+
+/**
+ * Handles /flags/v1 requests
+ *
+ * @author hakonhall
+ */
+public class FlagsHandler extends HttpHandler {
+    private final FlagsDb flagsDb;
+
+    @Inject
+    public FlagsHandler(LoggingRequestHandler.Context context, FlagsDb flagsDb) {
+        super(context);
+        this.flagsDb = flagsDb;
+    }
+
+    @Override
+    protected HttpResponse handleGET(HttpRequest request) {
+        Path path = new Path(request.getUri().getPath());
+        if (path.matches("/flags/v1")) return new V1Response(flagsV1Uri(request));
+        if (path.matches("/flags/v1/data")) return getFlagDataList(request);
+        if (path.matches("/flags/v1/data/{flagId}")) return getFlagData(findFlagId(request, path));
+        throw new NotFoundException("Nothing at path '" + path + "'");
+    }
+
+    @Override
+    protected HttpResponse handlePUT(HttpRequest request) {
+        Path path = new Path(request.getUri().getPath());
+        if (path.matches("/flags/v1/data/{flagId}")) return putFlagData(request, findFlagId(request, path));
+        throw new NotFoundException("Nothing at path '" + path + "'");
+    }
+
+    @Override
+    protected HttpResponse handleDELETE(HttpRequest request) {
+        Path path = new Path(request.getUri().getPath());
+        if (path.matches("/flags/v1/data/{flagId}")) return deleteFlagData(findFlagId(request, path));
+        throw new NotFoundException("Nothing at path '" + path + "'");
+    }
+
+    private String flagsV1Uri(HttpRequest request) {
+        URI uri = request.getUri();
+        return uri.getScheme() + "://" + uri.getHost() + ":" + uri.getPort() + "/flags/v1";
+    }
+
+    private HttpResponse getFlagDataList(HttpRequest request) {
+        return new FlagDataListResponse(flagsV1Uri(request), flagsDb.getAllFlags(),
+                Objects.equals(request.getProperty("recursive"), "true"));
+    }
+
+    private HttpResponse getFlagData(FlagId flagId) {
+        FlagData data = flagsDb.getValue(flagId).orElseThrow(() -> new NotFoundException("Flag " + flagId + " not set"));
+        return new FlagDataResponse(data);
+    }
+
+    private HttpResponse putFlagData(HttpRequest request, FlagId flagId) {
+        flagsDb.setValue(flagId, FlagData.deserialize(request.getData()));
+
+        // The set & get is not atomic, but no harm is done in showing an outdated flag value in the response.
+        return getFlagData(flagId);
+    }
+
+    private HttpResponse deleteFlagData(FlagId flagId) {
+        flagsDb.removeValue(flagId);
+        return new OKResponse();
+    }
+
+    private FlagId findFlagId(HttpRequest request, Path path) {
+        FlagId flagId = new FlagId(path.get("flagId"));
+
+        if (!Objects.equals(request.getProperty("force"), "true")) {
+            if (Flags.getAllFlags().stream().noneMatch(definition -> flagId.equals(definition.getUnboundFlag().id()))) {
+                throw new NotFoundException("There is no flag '" + flagId + "' (use ?force=true to override)");
+            }
+        }
+
+        return flagId;
+    }
+}
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/OKResponse.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/OKResponse.java
new file mode 100644
index 00000000000..19363fbdadc
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/OKResponse.java
@@ -0,0 +1,19 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http.flags;
+
+import com.yahoo.container.jdisc.EmptyResponse;
+import com.yahoo.jdisc.Response;
+
+/**
+ * @author hakonhall
+ */
+public class OKResponse extends EmptyResponse {
+    public OKResponse() {
+        super(Response.Status.OK);
+    }
+
+    @Override
+    public String getContentType() {
+        return "application/json";
+    }
+}
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/V1Response.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/V1Response.java
new file mode 100644
index 00000000000..26eb96f1ef5
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/flags/V1Response.java
@@ -0,0 +1,29 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http.flags;
+
+import com.yahoo.jdisc.Response;
+import com.yahoo.slime.Cursor;
+import com.yahoo.slime.Slime;
+import com.yahoo.text.Utf8;
+import com.yahoo.vespa.config.SlimeUtils;
+import com.yahoo.vespa.config.server.http.HttpConfigResponse;
+import com.yahoo.vespa.config.server.http.StaticResponse;
+
+import static com.yahoo.yolean.Exceptions.uncheck;
+
+/**
+ * @author hakonhall
+ */
+public class V1Response extends StaticResponse {
+    public V1Response(String flagsV1Uri) {
+        super(Response.Status.OK, HttpConfigResponse.JSON_CONTENT_TYPE, generateBody(flagsV1Uri));
+    }
+
+    private static String generateBody(String flagsV1Uri) {
+        Slime slime = new Slime();
+        Cursor root = slime.setObject();
+        Cursor data = root.setObject("data");
+        data.setString("url", flagsV1Uri + "/data");
+        return Utf8.toString(uncheck(() -> SlimeUtils.toJsonBytes(slime)));
+    }
+}
diff --git a/configserver/src/main/resources/configserver-app/services.xml b/configserver/src/main/resources/configserver-app/services.xml
index 5ba05a629c6..3e0572a8c99 100644
--- a/configserver/src/main/resources/configserver-app/services.xml
+++ b/configserver/src/main/resources/configserver-app/services.xml
@@ -60,7 +60,7 @@
     <!-- TODO Vespa 7: Remove scoreboard.xml, replaced by metrics-packets.xml -->
     <preprocess:include file='hosted-vespa/scoreboard.xml' required='false' />
 
-    <component id="com.yahoo.vespa.flags.FileFlagSource" bundle="flags"/>
+    <component id="com.yahoo.vespa.configserver.flags.ConfigServerFlagSource" bundle="flags"/>
 
     <preprocess:include file='hosted-vespa/metrics-packets.xml' required='false' />
     <preprocess:include file='controller/container.xml' required='false' />
@@ -103,6 +103,12 @@
       <binding>http://*/status</binding>
       <binding>https://*/status</binding>
     </handler>
+    <handler id='com.yahoo.vespa.config.server.http.flags.FlagsHandler' bundle='configserver'>
+      <binding>http://*/flags/v1</binding>
+      <binding>https://*/flags/v1</binding>
+      <binding>http://*/flags/v1/*</binding>
+      <binding>https://*/flags/v1/*</binding>
+    </handler>
     <handler id='com.yahoo.vespa.config.server.http.v2.TenantHandler' bundle='configserver'>
       <binding>http://*/application/v2/tenant/</binding>
       <binding>https://*/application/v2/tenant/</binding>
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/http/flags/FlagsHandlerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/http/flags/FlagsHandlerTest.java
new file mode 100644
index 00000000000..d88bd6ab4a5
--- /dev/null
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/http/flags/FlagsHandlerTest.java
@@ -0,0 +1,161 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http.flags;
+
+import com.yahoo.container.jdisc.HttpRequest;
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.jdisc.http.HttpRequest.Method;
+import com.yahoo.text.Utf8;
+import com.yahoo.vespa.config.server.http.SessionHandlerTest;
+import com.yahoo.vespa.configserver.flags.db.FlagsDbImpl;
+import com.yahoo.vespa.curator.mock.MockCurator;
+import com.yahoo.vespa.flags.FetchVector;
+import com.yahoo.vespa.flags.FlagId;
+import com.yahoo.vespa.flags.Flags;
+import com.yahoo.vespa.flags.UnboundFlag;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+
+import static com.yahoo.yolean.Exceptions.uncheck;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author hakonhall
+ */
+public class FlagsHandlerTest {
+    private static final UnboundFlag<Boolean> FLAG1 =
+            Flags.defineBoolean("id1", false, "desc1", "mod1");
+    private static final UnboundFlag<Boolean> FLAG2 =
+            Flags.defineBoolean("id2", true, "desc2", "mod2",
+                    FetchVector.Dimension.HOSTNAME, FetchVector.Dimension.APPLICATION_ID);
+
+    private static final String FLAGS_V1_URL = "https://foo.com:4443/flags/v1";
+
+    private final FlagsDbImpl flagsDb = new FlagsDbImpl(new MockCurator());
+    private final FlagsHandler handler = new FlagsHandler(FlagsHandler.testOnlyContext(), flagsDb);
+
+    @Test
+    public void testV1() {
+        verifySuccessfulRequest(Method.GET, "", "",
+                "{\"data\":{\"url\":\"https://foo.com:4443/flags/v1/data\"}}");
+        verifySuccessfulRequest(Method.GET, "/", "",
+                "{\"data\":{\"url\":\"https://foo.com:4443/flags/v1/data\"}}");
+    }
+
+    @Test
+    public void testData() {
+        // PUT flag with ID id1
+        verifySuccessfulRequest(Method.PUT, "/data/" + FLAG1.id(),
+                "{\n" +
+                        "  \"rules\": [\n" +
+                        "    {\n" +
+                        "      \"value\": true\n" +
+                        "    }\n" +
+                        "  ]\n" +
+                        "}",
+                "{\"rules\":[{\"value\":true}]}");
+
+        // GET on ID id1 should return the same as the put (this will also issue a payload for the get,
+        // which we assume will be ignored).
+        verifySuccessfulRequest(Method.GET, "/data/" + FLAG1.id(),
+                "", "{\"rules\":[{\"value\":true}]}");
+
+        // List all flags should list only id1
+        verifySuccessfulRequest(Method.GET, "/data",
+                "", "{\"id1\":{\"url\":\"https://foo.com:4443/flags/v1/data/id1\"}}");
+
+        // Should be identical to above: suffix / on path should be ignored
+        verifySuccessfulRequest(Method.GET, "/data/",
+                "", "{\"id1\":{\"url\":\"https://foo.com:4443/flags/v1/data/id1\"}}");
+
+        // PUT id2
+        verifySuccessfulRequest(Method.PUT, "/data/" + FLAG2.id(),
+                "{\n" +
+                        "  \"rules\": [\n" +
+                        "    {\n" +
+                        "      \"conditions\": [\n" +
+                        "        {\n" +
+                        "          \"type\": \"whitelist\",\n" +
+                        "          \"dimension\": \"hostname\",\n" +
+                        "          \"values\": [ \"host1\", \"host2\" ]\n" +
+                        "        },\n" +
+                        "        {\n" +
+                        "          \"type\": \"blacklist\",\n" +
+                        "          \"dimension\": \"application\",\n" +
+                        "          \"values\": [ \"app1\", \"app2\" ]\n" +
+                        "        }\n" +
+                        "      ],\n" +
+                        "      \"value\": true\n" +
+                        "    }\n" +
+                        "  ],\n" +
+                        "  \"attributes\": {\n" +
+                        "    \"zone\": \"zone1\"\n" +
+                        "  }\n" +
+                        "}\n",
+                "{\"rules\":[{\"conditions\":[{\"type\":\"whitelist\",\"dimension\":\"hostname\",\"values\":[\"host1\",\"host2\"]},{\"type\":\"blacklist\",\"dimension\":\"application\",\"values\":[\"app2\",\"app1\"]}],\"value\":true}],\"attributes\":{\"zone\":\"zone1\"}}");
+
+        // The list of flag data should return id1 and id2
+        verifySuccessfulRequest(Method.GET, "/data",
+                "",
+                "{\"id1\":{\"url\":\"https://foo.com:4443/flags/v1/data/id1\"},\"id2\":{\"url\":\"https://foo.com:4443/flags/v1/data/id2\"}}");
+
+        // Putting (overriding) id1 should work silently
+        verifySuccessfulRequest(Method.PUT, "/data/" + FLAG1.id(),
+                "{\n" +
+                        "  \"rules\": [\n" +
+                        "    {\n" +
+                        "      \"value\": false\n" +
+                        "    }\n" +
+                        "  ]\n" +
+                        "}\n",
+                "{\"rules\":[{\"value\":false}]}");
+
+        // Get all recursivelly displays all flag data
+        verifySuccessfulRequest(Method.GET, "/data?recursive=true", "",
+                "{\"id1\":{\"rules\":[{\"value\":false}]},\"id2\":{\"rules\":[{\"conditions\":[{\"type\":\"whitelist\",\"dimension\":\"hostname\",\"values\":[\"host1\",\"host2\"]},{\"type\":\"blacklist\",\"dimension\":\"application\",\"values\":[\"app2\",\"app1\"]}],\"value\":true}],\"attributes\":{\"zone\":\"zone1\"}}}");
+
+        // Deleting both flags
+        verifySuccessfulRequest(Method.DELETE, "/data/" + FLAG1.id(), "", "");
+        verifySuccessfulRequest(Method.DELETE, "/data/" + FLAG2.id(), "", "");
+
+        // And the list of data flags should now be empty
+        verifySuccessfulRequest(Method.GET, "/data", "", "{}");
+    }
+
+    @Test
+    public void testForcing() {
+        FlagId undefinedFlagId = new FlagId("undef");
+        HttpResponse response = handle(Method.PUT, "/data/" + undefinedFlagId, "");
+
+        assertEquals(404, response.getStatus());
+        assertEquals("application/json", response.getContentType());
+
+    }
+
+    private void verifySuccessfulRequest(Method method, String pathSuffix, String requestBody, String expectedResponseBody) {
+        HttpResponse response = handle(method, pathSuffix, requestBody);
+
+        assertEquals(200, response.getStatus());
+        assertEquals("application/json", response.getContentType());
+        String actualResponse = uncheck(() -> SessionHandlerTest.getRenderedString(response));
+
+        assertThat(actualResponse, is(expectedResponseBody));
+    }
+
+    private HttpResponse handle(Method method, String pathSuffix, String requestBody) {
+        String uri = FLAGS_V1_URL + pathSuffix;
+        HttpRequest request = HttpRequest.createTestRequest(uri, method, makeInputStream(requestBody));
+        return handler.handle(request);
+    }
+
+    private String makeUrl(String component) {
+        return FLAGS_V1_URL + "/" + component;
+    }
+
+    private InputStream makeInputStream(String content) {
+        return new ByteArrayInputStream(Utf8.toBytes(content));
+    }
+}
\ No newline at end of file