ruby-on-railsamazon-s3aws-lambdacloudshrine

How to upload files and handle processing and validations - a very general overview?

The problem at hand

  1. I have a rails app.
  2. Users will be uploading files. Anywhere between 1 file to 3000 files. Sometimes they are zip files, and sometimes they are not. I do not want hold up the server with these files uploads, so I am looking for a solution around this problem.
  3. The zipped files will have to be unzipped.
  4. I then want to check whether: the user has previously uploaded the same files? i.e. if the user has already uploaded the same file(2) one week ago, then this is a problem: (i) either we don’t allow that particular file to be uploaded, or we ask the user: are you sure you want to upload the same file again?
  5. Then I want to store the keys/links to the files within the appropriate models/records on the back end.

Was wondering what the best workflow for handling the above could be: i.e a very general overview: in other words, could AWS Lambda / Google cloud computing etc. etc be best employed to handle the above problem? How would we use the Shrine gem, to best handle this situation? Would it make sense to use AWS Lambda rather than using background jobs?

My preferences are to use the Shrine gem for uploading.

My Ideas:

  1. In the client side, the user drags and drops the files the user wants to upload.
  2. All the files are then uploaded (whether zipped or otherwise) to a temporary bucket location via the Shrine gem.
  3. IF the zip files are uploaded then perhaps an AWS lambda function must be triggered to unzip the files. If that’s the case,then at the end of the day, the keys for these files must somehow be returned to the client, to handle validation issues – but then how would the AWS lambda function be able to return this request to the original client side where the request was originated? Or rather,should the AWS lambda function be generated from the client side,passing in the IDs of the unzipped blobs?
  4. Then we need to run some validations: we want to handle the situation where there are duplicate files. We will need to check with our rails backed as to whether those files have already been uploaded.
  5. After those validation issues are handled, then user submits the form, and all the keys are stored within the appropriate records.

These ideas are by no means prescriptive

Am seeking some very general advise on what the best way is of doing this all. I am by no means constrained to AWS: I could use Google or Azure just as easily. Any guidance on the above would be much appreciated.

Specific questions:

  1. How would the AWS lambda function get triggered?
  2. How would be be able to return the keys of the uploaded files back to the client?

What do I mean by general overview?

Here are some examples of general overviews:

(1) Uploading & Unzipping files to S3 through Rails hosted on Heroku?

(2) https://www.quora.com/How-do-I-extract-large-zip-files-in-AWS-Lambda

Any pointers in the right direction would be much appreciated.

Cheers!

Solution

  • This isn't a really difficult problem to solve if you are willing to change the process flow a little bit.

    In the client side, the user drags and drops the files the user wants to upload.

    When the user requests the upload operation to begin you can make HTTP GET requests to an API Gateway endpoint, backed with a Lambda. The Lambda can query for previous files uploaded by the client and send back a result set showing what files already exist. You then filter those out and send only what is considered new from the client to the server. This will save the user time in waiting for the upload to happen and save you time on the S3/Lambda side of not having to store duplicates or process them. This isn't a substitute for server-side validation though, you'll still want to do that. For legit clients, this will save you and them a lot of bandwidth and storage.

    All the files are then uploaded (whether zipped or otherwise) to a temporary bucket location via the Shrine gem.

    This works. As they enter the temp bucket, use a Lambda with an S3 event to process the files, unzip files, push any metadata needed into DynamoDb and delete the files from the temp bucket. In the temp bucket, I would place the files into a folder that is unique per request and user. I would take the user/client Id and a UUID of some kind and make that your folder name. Such as Johnathon+3b5339b8-c8db-4d5c-b678-406fcf073f4f, or encode this value into a Base64 string and make that your folder name. Store this in DynamoDb with each file uploaded into your permanent bucket with the Hash Key being the userid/clientid, a Sort Key being the full folder path + file name and an extra attribute of IsProcessed. The IsProcessed attribute will be updated by your Lambda that is processing the files and moving them to their permanent S3 bucket. If there are errors, you can put the error in this field. If it is successful then you put it in this field.

    the keys for these files must somehow be returned to the client, to handle validation issues – but then how would the AWS lambda function be able to return this request to the original client side where the request was originated? Or rather,should the AWS lambda function be generated from the client side,passing in the IDs of the unzipped blobs?

    The original API request to push the files to the temp S3 bucket would be able to return back to the client the folder name johnathon+3b5339b8-c8db-4d5c-b678-406fcf073f4f to the client. So let's say you made a HTTP POST to /jobs. You would return back 201 Created with a HTTP Header of Location /jobs/johnathon+3b5339b8-c8db-4d5c-b678-406fcf073f4f. Your client can then start polling /jobs/johnathon+3b5339b8-c8db-4d5c-b678-406fcf073f4f for the status of the process.

    Your response back to /jobs/johnathon+3b5339b8-c8db-4d5c-b678-406fcf073f4f can return the DynamoDB records. This would include all DynamoDB records for the HashKey matching the folder name. Your client side can look at all of the objects in the result set and check the IsProcessed attribute to see if everything worked out ok, or if there were issues.

    Then we need to run some validations: we want to handle the situation where there are duplicate files. We will need to check with our rails backed as to whether those files have already been uploaded.

    Handle this with the Lambda that is executed by the temporary bucket. Grab the files from the temp bucket folder, handle your business logic and back-end queries then push them to their final permanent bucket.

    After those validation issues are handled, then user submits the form, and all the keys are stored within the appropriate records.

    All of this would happen asynchronously, starting when the user submits the form. The client side needs to be able to handle this by making HTTP GET requests to the endpoint mentioned above, checking for the status of the process. This gives you some more flexibility as you can also publish SNS messages on failures as well, such as sending an email to the clients if they upload 3,000 files and you need to spend 30 minutes processing them.