WIP: Metadata Proxy Server

lib/storage/metadata/proxy/BucketdRoutes.js

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+'use strict'; // eslint-disable-line strict
+
+const errors = require('../../../errors');
+const { getURIComponents, getRequestBody, sendResponse } = require('./utils');
+
+
+class BucketdRoutes {
+    /**
+     * Create a new Bucketd routes instance
+     * This class implements the bucketd Metadata protocol and is used in
+     * the Metadata Proxy Server to implement this protocol on top of
+     * various metadata backends.
+     *
+     * Implementation note: the adaptations performed in the methods of
+     * the class MetadataWrapper are not required in this context.
+     * For this reason, the methods of the `client' instance are directly
+     * called from this class, somewhat defeating the encapsulation of the
+     * wrapper.
+     *
+     * @param {Arsenal.storage.metadata.MetadataWrapper} metadataWrapper - to
+     *              be used as a translation target for the bucketd protocol.
+     * @param {werelogs.Logger} logger -
+     */
+    constructor(metadataWrapper, logger) {
+        this._metadataWrapper = metadataWrapper;
+        this._logger = logger;
+    }
+
+    // Metadata Wrapper's wrapper
+
+    // `attributes' context methods
+
+    _getBucketAttributes(req, res, bucketName, logger) {
+        return this._metadataWrapper.client.getBucketAttributes(
+            bucketName, logger, (err, data) =>
+                sendResponse(req, res, logger, err, data));
+    }
+
+    _putBucketAttributes(req, res, bucketName, data, logger) {
+        return this._metadataWrapper.client.putBucketAttributes(
+            bucketName, data, logger, err =>
+                sendResponse(req, res, logger, err));
+    }
+
+    // `bucket' context methods
+
+    _createBucket(req, res, bucketName, data, logger) {
+        return this._metadataWrapper.client.createBucket(
+            bucketName, data, logger, err =>
+                sendResponse(req, res, logger, err));
+    }
+
+    _deleteBucket(req, res, bucketName, logger) {
+        return this._metadataWrapper.client.deleteBucket(
+            bucketName, logger, err =>
+                sendResponse(req, res, logger, err));
+    }
+
+    _putObject(req, res, bucketName, objectName, objectValue, params, logger) {
+        return this._metadataWrapper.client.putObject(
+            bucketName, objectName, objectValue,
+            params, logger, (err, data) =>
+                sendResponse(req, res, logger, err, data));
+    }
+
+    _getObject(req, res, bucketName, objectName, params, logger) {
+        return this._metadataWrapper.client.getObject(
+            bucketName, objectName, params, logger, (err, data) =>
+                sendResponse(req, res, logger, err, data));
+    }
+
+    _deleteObject(req, res, bucketName, objectName, params, logger) {
+        return this._metadataWrapper.client.deleteObject(
+            bucketName, objectName, params, logger, (err, data) =>
+                sendResponse(req, res, logger, err, data));
+    }
+
+    _listObject(req, res, bucketName, params, logger) {
+        const listingParameters = params || {};
+        if (listingParameters.listingType === undefined) {
+            listingParameters.listingType = 'Delimiter';
+        }
+        if (listingParameters.maxKeys) {
+            listingParameters.maxKeys = Number.parseInt(params.maxKeys, 10);
+        }
+        return this._metadataWrapper.client.listObject(
+            bucketName, listingParameters, logger, (err, data) =>
+                sendResponse(req, res, logger, err,
+                             this._destringifyValues(data)));
+    }
+
+    // Misc
+    /* //XXX sub-optimal
+     * listing retrieved from the metadataWrapper is not well formatted for
+     * the purpose of this server. The `value' fields are stringified twice and
+     * have to be deserialized here before being sent to the client.
+     */
+    _destringifyValues(data) {
+        const newContents = data.Contents.map(entry => {
+            const value = JSON.parse(entry.value);
+            return { key: entry.key, value };
+        });
+        const alteredData = data;
+        alteredData.Contents = newContents;
+        return alteredData;
+    }
+
+    _createRequestLogger(req) {
+        const uids = req.headers['x-scal-request-uids'];
+        const logger = uids === undefined ?
+              this._logger.newRequestLogger() :
+              this._logger.newRequestLoggerFromSerializedUids(uids);
+        logger.trace('new request', { method: req.method, url: req.url });
+        return logger;
+    }
+
+    // Internal routes
+
+    /**
+     * Handle routes related to operations on buckets attributes
+     *
+     * @param {http.IncomingMessage} req - request being processed
+     * @param {http.OutgoingMessage} res - response associated to the request
+     * @param {object} uriComponents -
+     * @param {werelogs.Logger} logger -
+     * @return {undefined}
+     */
+    _attributesRoutes(req, res, uriComponents, logger) {
+        if (uriComponents.bucketName === undefined) {
+            logger.error('Missing bucket name for attributes route',
+                         { uriComponents });
+            return sendResponse(req, res, logger, errors.BadRequest);
+        }
+        switch (req.method) {
+        case 'GET':
+            return this._getBucketAttributes(
+                req, res,
+                uriComponents.bucketName, logger, (err, attrs) =>
+                    sendResponse(req, res, logger, err, attrs));
+        case 'POST':
+            return getRequestBody(req, (err, body) => {
+                if (err) {
+                    return sendResponse(req, res, logger, err);
+                }
+                return this._putBucketAttributes(
+                    req, res,
+                    uriComponents.bucketName, body, logger, err =>
+                        sendResponse(req, res, logger, err));
+            });
+        default:
+            return sendResponse(req, res, logger, errors.RouteNotFound);
+        }
+    }
+
+    /**
+     * Handle routes related to operations on buckets
+     *
+     * @param {http.IncomingMessage} req - request being processed
+     * @param {http.OutgoingMessage} res - response associated to the request
+     * @param {object} uriComponents -
+     * @param {werelogs.Logger} logger -
+     * @return {undefined}
+     */
+    _bucketRoutes(req, res, uriComponents, logger) {
+        if (uriComponents.bucketName === undefined) {
+            logger.error('Missing bucket name for bucket route',
+                         { uriComponents });
+            return sendResponse(req, res, logger, errors.BadRequest);
+        }
+        switch (req.method) {
+        case 'GET':
+            return this._listObject(req, res,
+                                    uriComponents.bucketName,
+                                    uriComponents.options,
+                                    logger);
+        case 'DELETE':
+            return this._deleteBucket(req, res,
+                                      uriComponents.bucketName, logger);
+        case 'POST':
+            return getRequestBody(req, (err, body) => {
+                if (err) {
+                    return sendResponse(req, res, logger, err);
+                }
+                return this._createBucket(req, res,
+                                          uriComponents.bucketName,
+                                          body, logger);
+            });
+        default:
+            return sendResponse(req, res, logger, errors.RouteNotFound);
+        }
+    }
+
+    /**
+     * Handle routes related to operations on objects
+     *
+     * @param {http.IncomingMessage} req - request being processed
+     * @param {http.OutgoingMessage} res - response associated to the request
+     * @param {object} uriComponents -
+     * @param {werelogs.Logger} logger -
+     * @return {undefined}
+     */
+    _objectRoutes(req, res, uriComponents, logger) {
+        if (uriComponents.bucketName === undefined) {
+            logger.error('Missing bucket name for bucket route',
+                         { uriComponents });
+            return sendResponse(req, res, logger, errors.BadRequest);
+        }
+        switch (req.method) {
+        case 'GET':
+            return this._getObject(req, res,
+                                   uriComponents.bucketName,
+                                   uriComponents.objectName,
+                                   uriComponents.options,
+                                   logger);
+        case 'DELETE':
+            return this._deleteObject(req, res,
+                                      uriComponents.bucketName,
+                                      uriComponents.objectName,
+                                      uriComponents.options,
+                                      logger);
+        case 'POST':
+            return getRequestBody(req, (err, body) =>
+                                  this._putObject(req, res,
+                                                  uriComponents.bucketName,
+                                                  uriComponents.objectName,
+                                                  body,
+                                                  uriComponents.options,
+                                                  logger));
+        default:
+            return sendResponse(req, res, logger, errors.RouteNotFound);
+        }
+    }
+
+    /**
+     * Handle default routes. e.g. URI starting with /default/
+     * (or anything excepted an underscore)
+     *
+     * @param {http.IncomingMessage} req - request being processed
+     * @param {http.OutgoingMessage} res - response associated to the request
+     * @param {object} uriComponents -
+     * @param {werelogs.Logger} logger -
+     * @return {undefined}
+     */
+    _defaultRoutes(req, res, uriComponents, logger) {
+        switch (uriComponents.context) {
+        case 'leader':
+        case 'informations':
+        case 'parallel':
+            logger.trace(`${uriComponents.context} operation`);
+            return sendResponse(req, res, logger, errors.NotImplemented);
+        case 'metadataInformation':
+            return sendResponse(req, res, logger, undefined,
+                                '{"metadataVersion":2}');
+        case 'bucket':
+            logger.trace(`${uriComponents.context} operation`);
+            if (uriComponents.objectName) {
+                return this._objectRoutes(req, res, uriComponents, logger);
+            }
+            return this._bucketRoutes(req, res, uriComponents, logger);
+        case 'attributes':
+            logger.trace(`${uriComponents.context} operation`);
+            return this._attributesRoutes(req, res, uriComponents, logger);
+        default:
+            logger.error('invalid URI', { uriComponents });
+            return sendResponse(req, res, logger, errors.RouteNotFound);
+        }
+    }
+
+    /**
+     * Handle admin routes. e.g. URI starting with /_/
+     *
+     * @param {http.IncomingMessage} req - request being processed
+     * @param {http.OutgoingMessage} res - response associated to the request
+     * @param {object} uriComponents -
+     * @param {werelogs.Logger} logger -
+     * @return {undefined}
+     */
+    _adminRoutes(req, res, uriComponents, logger) {
+        return sendResponse(req, res, logger, errors.NotImplemented);
+    }
+
+    // The route dispatching method
+
+    /**
+     * dispatch the HTTP request to the appropriate handling function.
+     *
+     * @param {http.IncomingMessage} req - request being processed
+     * @param {http.OutgoingMessage} res - response associated to the request
+     * @return {undefined}
+     */
+    dispatch(req, res) {
+        const adminNamespace = '_';
+        const logger = this._createRequestLogger(req);
+        const uriComponents = getURIComponents(req.url, logger);
+        if (!uriComponents) {
+            return sendResponse(req, res, logger, errors.BadRequest);
+        }
+        switch (uriComponents.namespace) {
+        case adminNamespace:
+            return this._adminRoutes(req, res, uriComponents, logger);
+        default: // coincidently matches the `default' literal namespace as well
+            return this._defaultRoutes(req, res, uriComponents, logger);
+        }
+    }
+}
+
+module.exports = BucketdRoutes;

lib/storage/metadata/proxy/README.md

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+# Metatada Proxy Server
+
+## Design goals
+
+## Design choices
+
+## Implementation details
+
+## How to run the proxy server
+
+```js
+const werelogs = require('werelogs');
+const MetadataWrapper = require('arsenal')
+                            .storage.metadata.MetadataWrapper;
+const Server = require('arsenal')
+                            .storage.metadata.proxy.Server;
+
+const logger = new werelogs.Logger('MetadataProxyServer',
+                                   'debug', 'debug');
+const metadataWrapper = new MetadataWrapper('mem', {},
+                                            null, logger);
+const server = new Server(metadataWrapper,
+                          {
+                              port: 9001,
+                              workers: 1,
+                          },
+                          logger);
+server.start(() => {
+    logger.info('Metadata Proxy Server successfully started. ' +
+                `Using the ${metadataWrapper.implName} backend`);
+});
+
+```