Decouple flags REST API from config server

14 files changed, 832 insertions, 1 deletions

diff --git a/flags/pom.xml b/flags/pom.xml
index c1e9eca20ab..7ef082cc1bc 100644
--- a/flags/pom.xml
+++ b/flags/pom.xml
@@ -59,7 +59,18 @@
             <classifier>no_aop</classifier>
             <scope>provided</scope>
         </dependency>
-
+        <dependency>
+            <groupId>com.yahoo.vespa</groupId>
+            <artifactId>container-dev</artifactId>
+            <version>${project.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.yahoo.vespa</groupId>
+            <artifactId>zkfacade</artifactId>
+            <version>${project.version}</version>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/DefinedFlag.java b/flags/src/main/java/com/yahoo/vespa/flags/http/DefinedFlag.java
new file mode 100644
index 00000000000..8234e9df725
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/DefinedFlag.java
@@ -0,0 +1,47 @@
+// Copyright 2019 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.jdisc.Response;
+import com.yahoo.vespa.flags.FlagDefinition;
+import com.yahoo.vespa.flags.json.DimensionHelper;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * @author hakonhall
+ */
+public class DefinedFlag extends HttpResponse {
+    private static ObjectMapper mapper = new ObjectMapper();
+
+    private final FlagDefinition flagDefinition;
+
+    public DefinedFlag(FlagDefinition flagDefinition) {
+        super(Response.Status.OK);
+        this.flagDefinition = flagDefinition;
+    }
+
+    @Override
+    public void render(OutputStream outputStream) throws IOException {
+        ObjectNode rootNode = mapper.createObjectNode();
+        renderFlagDefinition(flagDefinition, rootNode);
+        mapper.writeValue(outputStream, rootNode);
+    }
+
+    static void renderFlagDefinition(FlagDefinition flagDefinition, ObjectNode definitionNode) {
+        definitionNode.put("description", flagDefinition.getDescription());
+        definitionNode.put("modification-effect", flagDefinition.getModificationEffect());
+        ArrayNode dimensionsNode = definitionNode.putArray("dimensions");
+        flagDefinition.getDimensions().forEach(dimension -> dimensionsNode.add(DimensionHelper.toWire(dimension)));
+    }
+
+    @Override
+    public String getContentType() {
+        return "application/json";
+    }
+
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/DefinedFlags.java b/flags/src/main/java/com/yahoo/vespa/flags/http/DefinedFlags.java
new file mode 100644
index 00000000000..e1db7dda6e0
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/DefinedFlags.java
@@ -0,0 +1,43 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+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.FlagDefinition;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author hakonhall
+ */
+public class DefinedFlags extends HttpResponse {
+    private static ObjectMapper mapper = new ObjectMapper();
+    private static final Comparator<FlagDefinition> sortByFlagId = Comparator.comparing(flagDefinition -> flagDefinition.getUnboundFlag().id());
+
+    private final List<FlagDefinition> flags;
+
+    public DefinedFlags(List<FlagDefinition> flags) {
+        super(Response.Status.OK);
+        this.flags = flags;
+    }
+
+    @Override
+    public void render(OutputStream outputStream) throws IOException {
+        ObjectNode rootNode = mapper.createObjectNode();
+        flags.stream().sorted(sortByFlagId).forEach(flagDefinition -> {
+            ObjectNode definitionNode = rootNode.putObject(flagDefinition.getUnboundFlag().id().toString());
+            DefinedFlag.renderFlagDefinition(flagDefinition, definitionNode);
+        });
+        mapper.writeValue(outputStream, rootNode);
+    }
+
+    @Override
+    public String getContentType() {
+        return "application/json";
+    }
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/ErrorResponse.java b/flags/src/main/java/com/yahoo/vespa/flags/http/ErrorResponse.java
new file mode 100644
index 00000000000..969903093a4
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/ErrorResponse.java
@@ -0,0 +1,66 @@
+// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+import com.yahoo.slime.Cursor;
+import com.yahoo.slime.Slime;
+
+import static com.yahoo.jdisc.Response.Status.BAD_REQUEST;
+import static com.yahoo.jdisc.Response.Status.FORBIDDEN;
+import static com.yahoo.jdisc.Response.Status.INTERNAL_SERVER_ERROR;
+import static com.yahoo.jdisc.Response.Status.METHOD_NOT_ALLOWED;
+import static com.yahoo.jdisc.Response.Status.NOT_FOUND;
+import static com.yahoo.jdisc.Response.Status.UNAUTHORIZED;
+
+/**
+ * A HTTP JSON response containing an error code and a message
+ *
+ * @author bratseth
+ */
+public class ErrorResponse extends SlimeJsonResponse {
+
+    public enum errorCodes {
+        NOT_FOUND,
+        BAD_REQUEST,
+        FORBIDDEN,
+        METHOD_NOT_ALLOWED,
+        INTERNAL_SERVER_ERROR,
+        UNAUTHORIZED
+    }
+
+    public ErrorResponse(int statusCode, String errorType, String message) {
+        super(statusCode, asSlimeMessage(errorType, message));
+    }
+
+    private static Slime asSlimeMessage(String errorType, String message) {
+        Slime slime = new Slime();
+        Cursor root = slime.setObject();
+        root.setString("error-code", errorType);
+        root.setString("message", message);
+        return slime;
+    }
+
+    public static ErrorResponse notFoundError(String message) {
+        return new ErrorResponse(NOT_FOUND, errorCodes.NOT_FOUND.name(), message);
+    }
+
+    public static ErrorResponse internalServerError(String message) {
+        return new ErrorResponse(INTERNAL_SERVER_ERROR, errorCodes.INTERNAL_SERVER_ERROR.name(), message);
+    }
+
+    public static ErrorResponse badRequest(String message) {
+        return new ErrorResponse(BAD_REQUEST, errorCodes.BAD_REQUEST.name(), message);
+    }
+
+    public static ErrorResponse forbidden(String message) {
+        return new ErrorResponse(FORBIDDEN, errorCodes.FORBIDDEN.name(), message);
+    }
+
+    public static ErrorResponse unauthorized(String message) {
+        return new ErrorResponse(UNAUTHORIZED, errorCodes.UNAUTHORIZED.name(), message);
+    }
+
+    public static ErrorResponse methodNotAllowed(String message) {
+        return new ErrorResponse(METHOD_NOT_ALLOWED, errorCodes.METHOD_NOT_ALLOWED.name(), message);
+    }
+
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/FlagDataListResponse.java b/flags/src/main/java/com/yahoo/vespa/flags/http/FlagDataListResponse.java
new file mode 100644
index 00000000000..5af97007997
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/FlagDataListResponse.java
@@ -0,0 +1,58 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+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 com.yahoo.vespa.flags.json.wire.WireFlagDataList;
+
+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 TreeMap<FlagId, FlagData> flags;
+    private final boolean recursive;
+
+    public FlagDataListResponse(String flagsV1Uri, Map<FlagId, FlagData> flags, boolean recursive) {
+        super(Response.Status.OK);
+        this.flagsV1Uri = flagsV1Uri;
+        this.flags = new TreeMap<>(flags);
+        this.recursive = recursive;
+    }
+
+    @Override
+    public void render(OutputStream outputStream) {
+        if (recursive) {
+            WireFlagDataList list = new WireFlagDataList();
+            flags.values().forEach(flagData -> list.flags.add(flagData.toWire()));
+            list.serializeToOutputStream(outputStream);
+        } else {
+            ObjectNode rootNode = mapper.createObjectNode();
+            ArrayNode flagsArray = rootNode.putArray("flags");
+            flags.forEach((flagId, flagData) -> {
+                ObjectNode object = flagsArray.addObject();
+                object.put("id", flagId.toString());
+                object.put("url", flagsV1Uri + "/data/" + flagId.toString());
+            });
+            uncheck(() -> mapper.writeValue(outputStream, rootNode));
+        }
+    }
+
+    @Override
+    public String getContentType() {
+        return "application/json";
+    }
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/FlagDataResponse.java b/flags/src/main/java/com/yahoo/vespa/flags/http/FlagDataResponse.java
new file mode 100644
index 00000000000..f6e81e030c7
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/FlagDataResponse.java
@@ -0,0 +1,30 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.jdisc.Response;
+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 "application/json";
+    }
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/FlagsHandler.java b/flags/src/main/java/com/yahoo/vespa/flags/http/FlagsHandler.java
new file mode 100644
index 00000000000..76f74cbe931
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/FlagsHandler.java
@@ -0,0 +1,138 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+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.log.LogLevel;
+import com.yahoo.restapi.Path;
+import com.yahoo.vespa.flags.FlagDefinition;
+import com.yahoo.vespa.flags.FlagId;
+import com.yahoo.vespa.flags.Flags;
+import com.yahoo.vespa.flags.json.FlagData;
+import com.yahoo.vespa.flags.persistence.FlagsDb;
+import com.yahoo.yolean.Exceptions;
+
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.util.Objects;
+
+/**
+ * Handles /flags/v1 requests
+ *
+ * @author hakonhall
+ */
+public class FlagsHandler extends LoggingRequestHandler {
+
+    private final FlagsDb flagsDb;
+
+    @Inject
+    public FlagsHandler(LoggingRequestHandler.Context context, FlagsDb flagsDb) {
+        super(context);
+        this.flagsDb = flagsDb;
+    }
+
+    @Override
+    public HttpResponse handle(HttpRequest request) {
+        try {
+            switch (request.getMethod()) {
+                case GET: return handleGET(request);
+                case DELETE: return handleDELETE(request);
+                case PUT: return handlePUT(request);
+                default: return ErrorResponse.methodNotAllowed("Method '" + request.getMethod() + "' is not supported");
+            }
+        }
+        catch (IllegalArgumentException e) {
+            return ErrorResponse.badRequest(Exceptions.toMessageString(e));
+        }
+        catch (RuntimeException e) {
+            log.log(LogLevel.WARNING, "Unexpected error handling '" + request.getUri() + "'", e);
+            return ErrorResponse.internalServerError(Exceptions.toMessageString(e));
+        }
+    }
+
+    private HttpResponse handleGET(HttpRequest request) {
+        Path path = new Path(request.getUri());
+        if (path.matches("/flags/v1")) return new V1Response(flagsV1Uri(request), "data", "defined");
+        if (path.matches("/flags/v1/data")) return getFlagDataList(request);
+        if (path.matches("/flags/v1/data/{flagId}")) return getFlagData(findFlagId(request, path));
+        if (path.matches("/flags/v1/defined")) return new DefinedFlags(Flags.getAllFlags());
+        if (path.matches("/flags/v1/defined/{flagId}")) return getDefinedFlag(findFlagId(request, path));
+        return ErrorResponse.notFoundError("Nothing at path '" + path + "'");
+    }
+
+    private HttpResponse handlePUT(HttpRequest request) {
+        Path path = new Path(request.getUri());
+        if (path.matches("/flags/v1/data/{flagId}")) return putFlagData(request, findFlagId(request, path));
+        return ErrorResponse.notFoundError("Nothing at path '" + path + "'");
+    }
+
+    private HttpResponse handleDELETE(HttpRequest request) {
+        Path path = new Path(request.getUri());
+        if (path.matches("/flags/v1/data/{flagId}")) return deleteFlagData(findFlagId(request, path));
+        return ErrorResponse.notFoundError("Nothing at path '" + path + "'");
+    }
+
+    private String flagsV1Uri(HttpRequest request) {
+        URI uri = request.getUri();
+        String port = uri.getPort() < 0 ? "" : ":" + uri.getPort();
+        return uri.getScheme() + "://" + uri.getHost() + port + "/flags/v1";
+    }
+
+    private HttpResponse getDefinedFlag(FlagId flagId) {
+        var definedFlag = Flags.getFlag(flagId).map(DefinedFlag::new);
+        if (definedFlag.isPresent()) {
+            return definedFlag.get();
+        }
+        return ErrorResponse.notFoundError("Flag " + flagId + " not defined");
+    }
+
+    private HttpResponse getFlagDataList(HttpRequest request) {
+        return new FlagDataListResponse(flagsV1Uri(request), flagsDb.getAllFlags(),
+                Objects.equals(request.getProperty("recursive"), "true"));
+    }
+
+    private HttpResponse getFlagData(FlagId flagId) {
+        var data = flagsDb.getValue(flagId).map(FlagDataResponse::new);
+        if (data.isPresent()) {
+            return data.get();
+        }
+        return ErrorResponse.notFoundError("Flag " + flagId + " not set");
+    }
+
+    private HttpResponse putFlagData(HttpRequest request, FlagId flagId) {
+        FlagData data;
+        try {
+            data = FlagData.deserialize(request.getData());
+        } catch (UncheckedIOException e) {
+            return ErrorResponse.badRequest("Failed to deserialize request data: " + Exceptions.toMessageString(e));
+        }
+
+        if (!isForce(request)) {
+            FlagDefinition definition = Flags.getFlag(flagId).get(); // FlagId has been validated in findFlagId()
+            data.validate(definition.getUnboundFlag().serializer());
+        }
+
+        flagsDb.setValue(flagId, data);
+        return new OKResponse();
+    }
+
+    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 (!isForce(request) && Flags.getFlag(flagId).isEmpty()) {
+            throw new IllegalArgumentException("There is no flag '" + flagId + "' (use ?force=true to override)");
+        }
+        return flagId;
+    }
+
+    private boolean isForce(HttpRequest request) {
+        return Objects.equals(request.getProperty("force"), "true");
+    }
+
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/OKResponse.java b/flags/src/main/java/com/yahoo/vespa/flags/http/OKResponse.java
new file mode 100644
index 00000000000..d094e2d5734
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/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.flags.http;
+
+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/flags/src/main/java/com/yahoo/vespa/flags/http/SlimeJsonResponse.java b/flags/src/main/java/com/yahoo/vespa/flags/http/SlimeJsonResponse.java
new file mode 100644
index 00000000000..dd71795ae43
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/SlimeJsonResponse.java
@@ -0,0 +1,38 @@
+// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.slime.JsonFormat;
+import com.yahoo.slime.Slime;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * A generic Json response using Slime for JSON encoding
+ *
+ * @author bratseth
+ */
+public class SlimeJsonResponse extends HttpResponse {
+
+    private final Slime slime;
+
+    public SlimeJsonResponse(Slime slime) {
+        super(200);
+        this.slime = slime;
+    }
+
+    public SlimeJsonResponse(int statusCode, Slime slime) {
+        super(statusCode);
+        this.slime = slime;
+    }
+
+    @Override
+    public void render(OutputStream stream) throws IOException {
+        new JsonFormat(true).encode(stream, slime);
+    }
+
+    @Override
+    public String getContentType() { return "application/json"; }
+
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/http/V1Response.java b/flags/src/main/java/com/yahoo/vespa/flags/http/V1Response.java
new file mode 100644
index 00000000000..e8ff0bd99a4
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/http/V1Response.java
@@ -0,0 +1,46 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+import com.yahoo.container.jdisc.HttpResponse;
+import com.yahoo.jdisc.Response;
+import com.yahoo.slime.Cursor;
+import com.yahoo.slime.JsonFormat;
+import com.yahoo.slime.Slime;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.List;
+
+/**
+ * @author hakonhall
+ */
+public class V1Response extends HttpResponse {
+
+    private final Slime slime;
+
+    public V1Response(String flagsV1Uri, String... names) {
+        super(Response.Status.OK);
+        this.slime = generateBody(flagsV1Uri, List.of(names));
+    }
+
+    @Override
+    public void render(OutputStream stream) throws IOException {
+        new JsonFormat(true).encode(stream, slime);
+    }
+
+    @Override
+    public String getContentType() {
+        return "application/json";
+    }
+
+    private static Slime generateBody(String flagsV1Uri, List<String> names) {
+        Slime slime = new Slime();
+        Cursor root = slime.setObject();
+        names.forEach(name -> {
+            Cursor data = root.setObject(name);
+            data.setString("url", flagsV1Uri + "/" + name);
+        });
+        return slime;
+    }
+
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/persistence/FlagsDb.java b/flags/src/main/java/com/yahoo/vespa/flags/persistence/FlagsDb.java
new file mode 100644
index 00000000000..2ed762f2895
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/persistence/FlagsDb.java
@@ -0,0 +1,68 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.persistence;
+
+import com.google.inject.Inject;
+import com.yahoo.path.Path;
+import com.yahoo.vespa.curator.Curator;
+import com.yahoo.vespa.flags.FlagId;
+import com.yahoo.vespa.flags.json.FlagData;
+import org.apache.curator.framework.recipes.cache.ChildData;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * @author hakonhall
+ */
+public class FlagsDb {
+
+    private static final Path ROOT_PATH = Path.fromString("/flags/v1");
+
+    private final Curator curator;
+    private final Curator.DirectoryCache cache;
+
+    @Inject
+    public FlagsDb(Curator curator) {
+        this.curator = curator;
+        curator.create(ROOT_PATH);
+        ExecutorService executorService = Executors.newFixedThreadPool(1);
+        this.cache = curator.createDirectoryCache(ROOT_PATH.getAbsolute(), true, false, executorService);
+        cache.start();
+    }
+
+    /** Get the String value of the flag. */
+    public Optional<FlagData> getValue(FlagId flagId) {
+        return Optional.ofNullable(cache.getCurrentData(getZkPathFor(flagId)))
+                       .map(ChildData::getData)
+                       .map(FlagData::deserializeUtf8Json);
+    }
+
+    /** Set the String value of the flag. */
+    public void setValue(FlagId flagId, FlagData data) {
+        curator.set(getZkPathFor(flagId), data.serializeToUtf8Json());
+    }
+
+    /** Get all flags that have been set. */
+    public Map<FlagId, FlagData> getAllFlags() {
+        List<ChildData> dataList = cache.getCurrentData();
+        return dataList.stream()
+                       .map(ChildData::getData)
+                       .map(FlagData::deserializeUtf8Json)
+                       .collect(Collectors.toMap(FlagData::id, Function.identity()));
+    }
+
+    /** Remove the flag value if it exists. */
+    public void removeValue(FlagId flagId) {
+        curator.delete(getZkPathFor(flagId));
+    }
+
+    private static Path getZkPathFor(FlagId flagId) {
+        return ROOT_PATH.append(flagId.toString());
+    }
+
+}
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/persistence/package-info.java b/flags/src/main/java/com/yahoo/vespa/flags/persistence/package-info.java
new file mode 100644
index 00000000000..d4753ed1756
--- /dev/null
+++ b/flags/src/main/java/com/yahoo/vespa/flags/persistence/package-info.java
@@ -0,0 +1,8 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+/**
+ * @author mpolden
+ */
+@ExportPackage
+package com.yahoo.vespa.flags.persistence;
+
+import com.yahoo.osgi.annotation.ExportPackage;
diff --git a/flags/src/test/java/com/yahoo/vespa/flags/http/FlagsHandlerTest.java b/flags/src/test/java/com/yahoo/vespa/flags/http/FlagsHandlerTest.java
new file mode 100644
index 00000000000..8ae1008ba22
--- /dev/null
+++ b/flags/src/test/java/com/yahoo/vespa/flags/http/FlagsHandlerTest.java
@@ -0,0 +1,203 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.http;
+
+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.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.UnboundBooleanFlag;
+import com.yahoo.vespa.flags.persistence.FlagsDb;
+import com.yahoo.yolean.Exceptions;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author hakonhall
+ */
+public class FlagsHandlerTest {
+    private static final UnboundBooleanFlag FLAG1 = Flags.defineFeatureFlag(
+            "id1", false, "desc1", "mod1");
+    private static final UnboundBooleanFlag FLAG2 = Flags.defineFeatureFlag(
+            "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 FlagsDb flagsDb = new FlagsDb(new MockCurator());
+    private final FlagsHandler handler = new FlagsHandler(FlagsHandler.testOnlyContext(), flagsDb);
+
+    @Test
+    public void testV1() {
+        String expectedResponse = "{" +
+                Stream.of("data", "defined")
+                        .map(name -> "\"" + name + "\":{\"url\":\"https://foo.com:4443/flags/v1/" + name + "\"}")
+                        .collect(Collectors.joining(",")) +
+                "}";
+        verifySuccessfulRequest(Method.GET, "", "", expectedResponse);
+        verifySuccessfulRequest(Method.GET, "/", "", expectedResponse);
+    }
+
+    @Test
+    public void testDefined() {
+        try (Flags.Replacer replacer = Flags.clearFlagsForTesting()) {
+            fixUnusedWarning(replacer);
+            Flags.defineFeatureFlag("id", false, "desc", "mod", FetchVector.Dimension.HOSTNAME);
+            verifySuccessfulRequest(Method.GET, "/defined", "",
+                    "{\"id\":{\"description\":\"desc\",\"modification-effect\":\"mod\",\"dimensions\":[\"hostname\"]}}");
+
+            verifySuccessfulRequest(Method.GET, "/defined/id", "",
+                    "{\"description\":\"desc\",\"modification-effect\":\"mod\",\"dimensions\":[\"hostname\"]}");
+        }
+    }
+
+    private void fixUnusedWarning(Flags.Replacer replacer) { }
+
+    @Test
+    public void testData() {
+        // PUT flag with ID id1
+        verifySuccessfulRequest(Method.PUT, "/data/" + FLAG1.id(),
+                "{\n" +
+                        "  \"id\": \"id1\",\n" +
+                        "  \"rules\": [\n" +
+                        "    {\n" +
+                        "      \"value\": true\n" +
+                        "    }\n" +
+                        "  ]\n" +
+                        "}",
+                "");
+
+        // GET on ID id1 should return the same as the put.
+        verifySuccessfulRequest(Method.GET, "/data/" + FLAG1.id(),
+                "", "{\"id\":\"id1\",\"rules\":[{\"value\":true}]}");
+
+        // List all flags should list only id1
+        verifySuccessfulRequest(Method.GET, "/data",
+                "", "{\"flags\":[{\"id\":\"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/",
+                "", "{\"flags\":[{\"id\":\"id1\",\"url\":\"https://foo.com:4443/flags/v1/data/id1\"}]}");
+
+        // Verify absent port => absent in response
+        assertThat(handleWithPort(Method.GET, -1, "/data", "", 200),
+                is("{\"flags\":[{\"id\":\"id1\",\"url\":\"https://foo.com/flags/v1/data/id1\"}]}"));
+
+        // PUT id2
+        verifySuccessfulRequest(Method.PUT, "/data/" + FLAG2.id(),
+                "{\n" +
+                        "  \"id\": \"id2\",\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",
+                "");
+
+        // GET on id2 should now return what was put
+        verifySuccessfulRequest(Method.GET, "/data/" + FLAG2.id(), "",
+                "{\"id\":\"id2\",\"rules\":[{\"conditions\":[{\"type\":\"whitelist\",\"dimension\":\"hostname\",\"values\":[\"host1\",\"host2\"]},{\"type\":\"blacklist\",\"dimension\":\"application\",\"values\":[\"app1\",\"app2\"]}],\"value\":true}],\"attributes\":{\"zone\":\"zone1\"}}");
+
+        // The list of flag data should return id1 and id2
+        verifySuccessfulRequest(Method.GET, "/data",
+                "",
+                "{\"flags\":[{\"id\":\"id1\",\"url\":\"https://foo.com:4443/flags/v1/data/id1\"},{\"id\":\"id2\",\"url\":\"https://foo.com:4443/flags/v1/data/id2\"}]}");
+
+        // Putting (overriding) id1 should work silently
+        verifySuccessfulRequest(Method.PUT, "/data/" + FLAG1.id(),
+                "{\n" +
+                        "  \"id\": \"id1\",\n" +
+                        "  \"rules\": [\n" +
+                        "    {\n" +
+                        "      \"value\": false\n" +
+                        "    }\n" +
+                        "  ]\n" +
+                        "}\n",
+                "");
+
+        // Verify PUT
+        verifySuccessfulRequest(Method.GET, "/data/" + FLAG1.id(), "", "{\"id\":\"id1\",\"rules\":[{\"value\":false}]}");
+
+        // Get all recursivelly displays all flag data
+        verifySuccessfulRequest(Method.GET, "/data?recursive=true", "",
+                "{\"flags\":[{\"id\":\"id1\",\"rules\":[{\"value\":false}]},{\"id\":\"id2\",\"rules\":[{\"conditions\":[{\"type\":\"whitelist\",\"dimension\":\"hostname\",\"values\":[\"host1\",\"host2\"]},{\"type\":\"blacklist\",\"dimension\":\"application\",\"values\":[\"app1\",\"app2\"]}],\"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", "", "{\"flags\":[]}");
+    }
+
+    @Test
+    public void testForcing() {
+        assertThat(handle(Method.PUT, "/data/" + new FlagId("undef"), "", 400),
+                containsString("There is no flag 'undef'"));
+
+        assertThat(handle(Method.PUT, "/data/" + new FlagId("undef") + "?force=true", "", 400),
+                containsString("No content to map due to end-of-input"));
+
+        assertThat(handle(Method.PUT, "/data/" + FLAG1.id(), "{}", 400),
+                containsString("Flag ID missing"));
+
+        assertThat(handle(Method.PUT, "/data/" + FLAG1.id(), "{\"id\": \"id1\",\"rules\": [{\"value\":\"string\"}]}", 400),
+                containsString("Wrong type of JsonNode: STRING"));
+
+        assertThat(handle(Method.PUT, "/data/" + FLAG1.id() + "?force=true", "{\"id\": \"id1\",\"rules\": [{\"value\":\"string\"}]}", 200),
+                is(""));
+    }
+
+    private void verifySuccessfulRequest(Method method, String pathSuffix, String requestBody, String expectedResponseBody) {
+        assertThat(handle(method, pathSuffix, requestBody, 200), is(expectedResponseBody));
+    }
+
+    private String handle(Method method, String pathSuffix, String requestBody, int expectedStatus) {
+        return handleWithPort(method, 4443, pathSuffix, requestBody, expectedStatus);
+    }
+
+    private String handleWithPort(Method method, int port, String pathSuffix, String requestBody, int expectedStatus) {
+        String uri = "https://foo.com" + (port < 0 ? "" : ":" + port) + "/flags/v1" + pathSuffix;
+        HttpRequest request = HttpRequest.createTestRequest(uri, method, makeInputStream(requestBody));
+        HttpResponse response = handler.handle(request);
+        assertEquals(expectedStatus, response.getStatus());
+        assertEquals("application/json", response.getContentType());
+        var outputStream = new ByteArrayOutputStream();
+        Exceptions.uncheck(() -> response.render(outputStream));
+        return outputStream.toString(StandardCharsets.UTF_8);
+    }
+
+    private InputStream makeInputStream(String content) {
+        return new ByteArrayInputStream(Utf8.toBytes(content));
+    }
+}
diff --git a/flags/src/test/java/com/yahoo/vespa/flags/persistence/FlagsDbTest.java b/flags/src/test/java/com/yahoo/vespa/flags/persistence/FlagsDbTest.java
new file mode 100644
index 00000000000..5102305af90
--- /dev/null
+++ b/flags/src/test/java/com/yahoo/vespa/flags/persistence/FlagsDbTest.java
@@ -0,0 +1,56 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.persistence;
+
+import com.yahoo.vespa.curator.mock.MockCurator;
+import com.yahoo.vespa.flags.FetchVector;
+import com.yahoo.vespa.flags.FlagId;
+import com.yahoo.vespa.flags.JsonNodeRawFlag;
+import com.yahoo.vespa.flags.json.Condition;
+import com.yahoo.vespa.flags.json.FlagData;
+import com.yahoo.vespa.flags.json.Rule;
+import org.junit.Test;
+
+import java.util.Map;
+import java.util.Optional;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * @author hakonhall
+ */
+public class FlagsDbTest {
+    @Test
+    public void test() {
+        MockCurator curator = new MockCurator();
+        FlagsDb db = new FlagsDb(curator);
+
+        Condition condition1 = new Condition(Condition.Type.WHITELIST, FetchVector.Dimension.HOSTNAME, "host1");
+        Rule rule1 = new Rule(Optional.of(JsonNodeRawFlag.fromJson("13")), condition1);
+        FlagId flagId = new FlagId("id");
+        FlagData data = new FlagData(flagId, new FetchVector().with(FetchVector.Dimension.ZONE_ID, "zone-a"), rule1);
+        db.setValue(flagId, data);
+
+        Optional<FlagData> dataCopy = db.getValue(flagId);
+        assertTrue(dataCopy.isPresent());
+
+        assertEquals("{\"id\":\"id\",\"rules\":[{\"conditions\":[{\"type\":\"whitelist\",\"dimension\":\"hostname\"," +
+                     "\"values\":[\"host1\"]}],\"value\":13}],\"attributes\":{\"zone\":\"zone-a\"}}",
+                     dataCopy.get().serializeToJson());
+
+        FlagId flagId2 = new FlagId("id2");
+        FlagData data2 = new FlagData(flagId2, new FetchVector().with(FetchVector.Dimension.ZONE_ID, "zone-a"), rule1);
+        db.setValue(flagId2, data2);
+        Map<FlagId, FlagData> flags = db.getAllFlags();
+        assertThat(flags.size(), equalTo(2));
+        assertThat(flags.get(flagId), notNullValue());
+        assertThat(flags.get(flagId2), notNullValue());
+
+        db.removeValue(flagId2);
+        assertFalse(db.getValue(flagId2).isPresent());
+    }
+}