A simple image resizer using Golang and AWS Lambda.

• OUTPUT_BUCKET - output bucket
• SIZES - a JSON that containers resized image size,width and save directory.

Examples:

OUTPUT_BUCKET: my-bucket

SIZES:[{"OutputDirectory":"/thumbnail/","SizeWidth":600,"SizeHeight":300},{"OutputDirectory":"/medium/","SizeWidth":1920,"SizeHeight":1020}]

Simplity execute the build.sh script

1. Create a S3

2. Create a SQS

3. Create the following policies:

   • SQS Policy

     {
         "Version": "2012-10-17",
         "Statement": [
             {
                 "Sid": "SQSRole",
                 "Effect": "Allow",
                 "Action": [
                     "sqs:DeleteMessage",
                     "sqs:ChangeMessageVisibility",
                     "sqs:ReceiveMessage",
                     "sqs:GetQueueAttributes"
                 ],
                 "Resource": "<%your-sqs-arn%>"
             }
         ]
     }
     

   • S3 Policy

             {
         "Version": "S3-role",
         "Statement": [
             {
                 "Sid": "VisualEditor0",
                 "Effect": "Allow",
                 "Action": [
                     "s3:PutObject",
                     "s3:GetObjectAcl",
                     "s3:GetObject",
                     "s3:PutObjectTagging",
                     "s3:PutObjectAcl"
                 ],
                 "Resource": "<%your-s3-bucket-arn%>/*"
             }
         ]
     }
     

4. Create a role with following policies: SQS Role, S3 Role and AWSLambdaBasicExecutionRole.

5. Create a S3 event notification to post to SQS whenever a file is uploaded

6. Apply following policy to your SQS(Access policy tab)

   {
       "Version": "2012-10-17",
       "Id": "golang-resizer",
       "Statement": [
           {
           "Sid": "golang-resizer",
           "Effect": "Allow",
           "Principal": {
               "Service": "s3.amazonaws.com"
           },
           "Action": "SQS:SendMessage",
           "Resource": "<%your-sqs-arn%>",
           "Condition": {
               "ArnLike": {
               "aws:SourceArn": "<%your-s3-bucket-arn%>"
               }
           }
           }
       ]
   }
   

7. Create a Lambda function with role from step 4, handler main and trigger with SQS queue created from step 2.