wip: Allow the API s3 endpoint to be used with multiple storage provi…

…ders #262

build/express-gateway/plugins/storage.js

@@ -0,0 +1,58 @@
+const logger = require('express-gateway/lib/logger').createLoggerWithLabel('[EG:s3]');
+const aws = require('aws-sdk');
+
+let storageProxies = {}
+
+module.exports = {
+  version: '1.2.0',
+  init: function (pluginContext) {
+    pluginContext.registerAdminRoute((app) => {
+      for (const [provider, options] of Object.entries(pluginContext.settings.providers)) {
+        logger.debug('Creating storage proxy ' + provider)
+        storageProxies[provider] = new aws.S3(options)
+      }
+      app.get(pluginContext.settings.endpointName + '/:provider/:bucket/*', (req, res) => {
+        const provider = req.params.provider
+        const storageProxy = storageProxies[provider]
+        if (storageProxy) {
+          storageProxy.getObject({
+            Bucket: req.params.bucket,
+            Key: req.params[0],
+            Range: req.headers.range // Forward range requests
+          })
+          .on('httpHeaders', (statusCode, headers) => { 
+            // Avoid catching event raised by connection initialization
+            // https://stackoverflow.com/questions/35782434/streaming-file-from-s3-with-express-including-information-on-length-and-filetype
+            if (headers['content-length']) {
+              res.status(statusCode);
+              res.set(headers);
+            } else logger.debug('Invalid response with status ' + statusCode)
+          })
+          .createReadStream()
+          .on('error', (err) => {
+            logger.debug(err);
+            return res.status(404).send(err);
+          })
+          .pipe(res);
+        } else {
+          logger.debug('Unknown provider: ' + provider)
+        }
+      });
+    });
+  },
+  schema: {
+    $id: 'http://express-gateway.io/plugins/storage.json',
+    type: 'object',
+    properties: {
+      endpointName: {
+        type: 'string',
+        default: '/storage'
+      },
+      providers: {
+        type: 'object',
+        default: {}
+      }
+    }, 
+    required: ['endpointName']
+  }
+};