Refactor the function to use async

eleven41 · Nov 17, 2015 · d750cab · d750cab
1 parent bb6fa26
commit d750cab
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diff --git a/README.md b/README.md
@@ -48,10 +48,28 @@ Create an IAM role with the following policy:
 }
 ```
 
+### Building the Lambda Package
+
+1. Clone this repo
+
+```
+git clone git@github.com:eleven41/aws-lambda-encrypt-s3-objects.git
+cd aws-lambda-encrypt-s3-objects
+```
+
+2. Install requirements
+
+```
+npm install async
+npm install aws-sdk
+```
+
+3. Zip up the folder using your favourite zipping utility
+
 ### Lambda Function
 
 1. Create a new Lambda function.
-2. Upload the file index.js as the code for your Lambda function.
+2. Upload the ZIP package for the lambda function using `index.handler` as the handler.
 3. Add an event source to your Lambda function:
  * Event Source Type: S3
  * Bucket: your source bucket

diff --git a/index.js b/index.js
@@ -1,10 +1,11 @@
-// Load up all dependencies
-var AWS = require('aws-sdk');
+console.log("Version 0.3.0");
 
-console.log("Version 0.2.0");
+// Load up all dependencies
+var AWS = require('aws-sdk');
+var async = require('async');
 
 // get reference to S3 client 
-var s3 = new AWS.S3();
+var s3 = new AWS.S3({ apiVersion: '2006-03-01' });
 
 // This is the entry-point to the Lambda function.
 exports.handler = function (event, context) {
@@ -14,71 +15,86 @@ exports.handler = function (event, context) {
         return;
     }
 
-    // Process all records in the event.
-    for (var i = 0; i < event.Records.length; ++i) {
-
-        var record = event.Records[i];
-        if (record.s3 == null) {
-            context.fail('Error', "Event record is missing s3 structure.");
-            return;
+    // Process all records in the event asynchronously.
+    async.each(event.Records, processRecord, function (err) {
+        if (err) {
+            context.fail('Error', "One or more objects could not be encrypted.");    
+        } else {
+            context.succeed();
         }
-
-        // The bucket and key are part of the event data
-        var bucket = record.s3.bucket.name;
-        var key = decodeURIComponent(record.s3.object.key.replace(/\+/g, " "));
-
-        console.log('Processing ' + bucket + '/' + key);
-
-        // Get the head data to determine if the object is already encrypted.
-        console.log('Getting object head');
-        s3.headObject({
-            Bucket: bucket,
-            Key: key
-        }, function (err, data) {
-            if (err) {
-                console.log('Error getting object head:');
-                console.log(err, err.stack); // an error occurred
-                context.fail('Error', "Error getting object head: " + err);
-            } else if (data.ServerSideEncryption != 'AES256') {
-
-                readConfig(bucket, function (err, config) {
-                    if (err) {
-                        console.log('Error reading configuration from tags:');
-                        console.log(err, err.stack); // an error occurred
-                        context.fail('Error', "Error reading configuration from tags: " + err);
-                    } else {
+    });
+};
 
-                        var storageClass = 'STANDARD';
-                        if (config.setReducedRedundancy)
-                            storageClass = 'REDUCED_REDUNDANCY';
-
-                        // Copy the object adding the encryption
-                        console.log('Updating object');
-                        s3.copyObject({
-                            Bucket: bucket,
-                            Key: key,
-
-                            CopySource: encodeURIComponent(bucket + '/' + key),
-                            MetadataDirective: 'COPY',
-                            ServerSideEncryption: 'AES256',
-                            StorageClass: storageClass
-                        }, function (err, data) {
-                            if (err) {
-                                console.log('Error updating object:');
-                                console.log(err, err.stack); // an error occurred
-                                context.fail('Error', "Error updating object: " + err);
-                            } else {
-                                context.succeed(bucket + '/' + key + ' updated.');
-                            }
-                        });
-                    }
-                });
-            } else {
-                context.succeed(bucket + '/' + key + " is already encrypted using 'AES256'.");
-            }
-        });
+// processRecord
+//
+// Iterator function for async.each (called by the handler above).
+//
+// 1. Gets the head of the object to determine it's current encryption state.
+// 2. Gets the encryption configuration from the bucket's tags.
+// 3. Copies the object with the desired encryption.
+function processRecord(record, callback) {
+    if (record.s3 == null) {
+        callback("Event record is missing s3 structure.");
+        return;
     }
-};
+
+    // The bucket and key are part of the event data
+    var bucket = record.s3.bucket.name;
+    var key = decodeURIComponent(record.s3.object.key.replace(/\+/g, " "));
+
+    console.log('Processing ' + bucket + '/' + key);
+
+    // Get the head data to determine if the object is already encrypted.
+    console.log('Getting object head');
+    s3.headObject({
+        Bucket: bucket,
+        Key: key
+    }, function (err, data) {
+        if (err) {
+            console.log('Error getting object head:');
+            console.log(err, err.stack); // an error occurred
+            callback("Error getting object head: " + bucket + '/' + key);
+        } else if (data.ServerSideEncryption != 'AES256') {
+
+            readConfig(bucket, function (err, config) {
+                if (err) {
+                    console.log('Error reading configuration from tags:');
+                    console.log(err, err.stack); // an error occurred
+                    callback("Error reading configuration from tags: " + err);
+                } else {
+
+                    var storageClass = 'STANDARD';
+                    if (config.setReducedRedundancy)
+                        storageClass = 'REDUCED_REDUNDANCY';
+
+                    // Copy the object adding the encryption
+                    console.log('Updating object');
+                    s3.copyObject({
+                        Bucket: bucket,
+                        Key: key,
+
+                        CopySource: encodeURIComponent(bucket + '/' + key),
+                        MetadataDirective: 'COPY',
+                        ServerSideEncryption: 'AES256',
+                        StorageClass: storageClass
+                    }, function (err, data) {
+                        if (err) {
+                            console.log('Error updating object:');
+                            console.log(err, err.stack); // an error occurred
+                            callback("Error updating object: " + err);
+                        } else {
+                            console.log(bucket + '/' + key + ' updated.');
+                            callback();
+                        }
+                    });
+                }
+            });
+        } else {
+            console.log(bucket + '/' + key + " is already encrypted using 'AES256'.");
+            callback();
+        }
+    });
+}
 
 // readConfig
 //
@@ -87,18 +103,27 @@ exports.handler = function (event, context) {
 // Once found, it calls the callback function passing
 // the configuration.
 function readConfig(bucketName, callback) {
+
+    var defaultConfig = {
+        setReducedRedundancy: false
+    };
+
     console.log("Getting tags for bucket '" + bucketName + "'");
     s3.getBucketTagging({
         Bucket: bucketName
     }, function (err, data) {
         if (err) {
-            callback(err, null);
+            if (err.code == 'NoSuchTagSet') {
+                // No tags on the bucket, so just send the defaults
+                callback(null, defaultConfig);
+            } else {
+                // Some other error
+                callback(err, null);
+            }
         } else {
 
             // Set defaults
-            var config = {
-                setReducedRedundancy: false
-            };
+            var config = defaultConfig;
 
             var tags = data.TagSet;