API Sign: Change the S3 Provider into a signer

mod/provider/_provider.js

@@ -6,14 +6,11 @@ const file = require('./file')
 
 const cloudfront = require('./cloudfront')
 
-const s3 = require('./s3')
-
 module.exports = async (req, res) => {
 
   const provider = {
     cloudfront,
-    file,
-    s3
+    file
   }
 
   if (!Object.hasOwn(provider, req.params.provider)) {

mod/sign/_sign.js

@@ -9,9 +9,11 @@ The sign module provides access to different request signer methods.
 */
 
 const cloudinary = require('./cloudinary')
+const s3 = require('./s3')
 
 const signerModules = {
-  cloudinary
+  cloudinary,
+  s3
 }
 
 /**

mod/sign/s3.js

@@ -0,0 +1,97 @@
+/**
+@module /sign/s3
+
+Signs requests to S3. Provides functions for get, list, delete and put to S3. 
+*/
+
+const {
+    S3Client,
+    PutObjectCommand,
+    GetObjectCommand,
+    DeleteObjectCommand,
+    ListObjectsCommand
+} = require('@aws-sdk/client-s3')
+
+const { getSignedUrl } = require('@aws-sdk/s3-request-presigner');
+
+/**
+@function s3
+@async
+
+@description
+The s3 signer method signs requests for the s3 service.
+
+Provides methods for list, get, trash and put
+
+@param {Object} req HTTP request.
+@param {Object} res HTTP response.
+@param {Object} req.params Request parameter.
+@param {string} params.region
+@param {string} params.bucket
+@param {string} params.key
+@param {string} params.command
+
+@returns {Promise<String>} The signed url associated to the request params.
+**/
+module.exports = async function s3(req, res){
+
+  //Read credentials from an env key
+  const credentials = Object.fromEntries(new URLSearchParams(process.env.AWS_S3_CLIENT))
+
+  const s3Client = new S3Client({
+    credentials,
+    region: req.params.region
+  })
+
+  req.params.s3Client = s3Client
+
+  //Assign the corresponding function to the requested command
+  const commands = {
+    get: () => objectAction(req.params,GetObjectCommand),
+    trash: () => objectAction(req.params,DeleteObjectCommand),
+    put: () => objectAction(req.params,PutObjectCommand),
+    list: () => objectAction(req.params,ListObjectsCommand)
+  }
+
+  if (!Object.hasOwn(commands, req.params.command)) {
+    return res.status(400).send(`S3 command validation failed.`)
+  }
+
+  return commands[req.params.command]()
+}
+
+async function objectAction(reqParams, objectCommand) {
+
+    //The parameters required per action for S3
+    //S3 Parameters are capitalised
+    const actionParams = {
+        get: {'key':'Key','bucket': 'Bucket'},
+        list: {'bucket': 'Bucket'},
+        put: {'key': 'Key','bucket': 'Bucket','region': 'Region'},
+        trash: {'key': 'Key','bucket': 'Bucket'}
+    }
+
+    try {
+
+      //Transfrom our keys into aws key names
+      const commandParams = Object.keys(reqParams)
+            .filter(key => Object.keys(actionParams[reqParams.command]).includes(key))
+            .reduce((acc, key) => ({
+                ...acc,
+                ...{ [actionParams[reqParams.command][key]]: reqParams[key]}
+            }),
+            {}
+        )
+
+      const command = new objectCommand(commandParams)
+
+      const signedURL = await getSignedUrl(reqParams.s3Client, command, {
+        expiresIn: 3600,
+      });
+
+      return JSON.stringify(signedURL);
+
+    } catch (err) {
+      console.error(err)
+    }
+}