How do I build an image uploading site?

I’m thinking of building a site similar to imgur or TinyPic for personal usage and learning. I don’t have any questions on how to do this with Elixir but I was curious about the infrastructure: how do these sites work? Obviously I can’t upload the actual file to a database, so I’m assuming I hash them and store that in the database… but where do the images go?

I’m also curious about cost and stuff. Like I said, this is for personal usage and I’ll probably upload less than 10mb a month, so hopefully it’ll be cheap.

For those not familiar, I want a site where I upload an image and get a link. Pretty simple.


I am currently working on a small side project which also involves uploading files. I put a path to my configuration file (config/config.exs) where I store all the data. The database entry for each uploaded document then has a “filename” field where the local filename is referenced. If you just want an image upload, you can leave all this aside - you don’t even need a database and can just serve the files directly out of the directory.

To avoid duplicate names, I use a very simple function that uses the upload filename (i.e. “image.png”), puts a random number in front of it and base64 encode it (you could just leave out the base64 encoding obviously). I know that I won’t store many files so this is enough for me.

I found this guide on uploading files very helpful:

As for the pricing, you can get really cheap VPS from OVH, use the free AWS tier or spin up a $5 DigitalOcean droplet. At least that’s what I am using right now.

Why not use something like Arc to handle uploads?

A few more you might be interested in:

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I’m using Arc, and it’s awesome. You should try it too! :smiley:
Here is good tutorial for starting point :

@AstonJ @alzearafat I will use Arc! I mostly meant where do I store the images? This post is fairly language-agnostic and more about the architecture of the app.

Thanks @Rukenshia! I will look into this and your answer :slight_smile:

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I mostly meant where do I store the images?

Personally I’d used AWS S3; I use it for a site with a lot of large
images and my monthly bill is around $0.98 US :slight_smile:


Ya especially since Arc already works with S3, you won’t need to build anything custom to work with another storage service.

I implemented uploading files with (GitHub), and I simply made a /files folder where I store the images. I actually get a sha-256 hash of the image data to both avoid duplicating content, as well as providing unique filenames. In your database, you can simply store this hash.

My (non-ARC) upload code starts here, with the saving-specific code here. It also creates a thumbnail in there if you’re interested, but if you use ARC (which was a little complicated/overkill for me) then the implementation details would be different for you.

In the off chance that you use Docker when deploying it, you can set it up as a persistent volume as in my docker-compose.yml. This makes it so that when you re-up the web server docker image, the volume persists. (Be sure to read up on the volume documentation for this :smile:)

As for cheap, there is an AWS free tier if you aren’t aware. It ends up being free for a year anyway, during which time you could maybe find somewhere else to host it. :eyes:

Lot of answers! Thank you very much to everyone—love the Elixir community.

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If you are doing this for learning, don’t use Arc. Store your files in a /data folder at the root of your application. Generate a UUID using . Store the file as data/uuid/filename.ext and just return a url similar to . Create a simple ImageController which serves images from that path using send_file.

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I would store them as files in a /shared/uploads directory on the server (then configure your deployment tool so that it doesn’t overwrite the shared folder).

I wouldn’t store them in the DB - this will make db backups huge and slower than if simple files.

Arc should be able to configure the storage directory and naming conventions :slight_smile:

Why this recommendation?

Generate a UUID using .

Why not just use :os.system_time ?

iex(1)> :os.system_time

Isn’t that better than taking on a dependency just for UUID’s?

how fast are you uploading new files that :os.system_time is not unique enough?

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In this particular instance (the fact that this is a personal project), system time would work.
However for more serious sites, I’d definitely reach for a uuid because it is standardized and can be stored nicely in a database and wouldn’t ever create a collision. I could definitely see a case of two users uploading at the same instance.

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and imagine the day you have two different machines …

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