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50mm (Go package name fiftymm) is a HTML image gallery software written in Go. It can serve very minimalistic HTML galleries of your photographs.

You can set up 50mm to serve one album per domain (an example can be seen at, or you can set up 50mm to serve multiple albums per domain. An example of the later can be seen at

Why another web image gallery software?

Fair question. There are a couple of great options out there for web image galleries. But we had a very specific list of requirements we wanted, which is why we created 50mm:

  • Point it to an S3 bucket and it should just work. While a lot of the options out there allow you to upload your photos to an S3 bucket of your choice, none of them work the other way around. That is, you can't configure them to read images from an S3 bucket. You have to upload them via their web interfaces.
  • Images should not need to be uploaded via a web interface. Web interfaces don't provide the best experience when uploading a large number of big sized files. Whereas uploading reliably to S3 is a solved problem.
  • Shouldn't need to pre-process the images. There's a bunch of different services that offer on-demand image manipulation. The one we wanted to use was Imgix, but the actual service didn't matter. Only that there shouldn't be a pre-processing step.
  • Ideally, no database backend required for the images. It should serve whatever it finds in the S3 bucket, without needing to first sync up the list of images with some database. This one is a purely "nice to have". If we had found something that checked our other requirements and used a DB, we would have used that.

How do I use it?

You'll need a working installation of Go to build 50mm. At this time, we don't provide prebuilt binaries. You'll also want to have a web server where you can run this.

Deploying the web application

You can get and build the 50mm software by running:

go get

This should produce a binary file named 50mm inside the bin folder in your Go workspace. This is the server component of the application. To keep things organised, let's copy the binary file to a new folder, which I refer to in the rest of this documentation as the deploy folder.

Next copy the templates and static folders from $GOPATH/src/ into the deploy folder. Your deploy folder should now have the following structure, although the exact files in the static and templates folders may differ for different versions of the software. What matters is the placement of those folders relative to the binary file 50mm:

├── 50mm
├── static
│   ├── album.css
│   ├── base.css
│   ├── echo.min.js
│   ├── index.css
│   └── placeholder.png
└── templates
    ├── album.html
    └── index.html

Next we need to create a config folder to hold the configuration files for our sites and albums. This folder can be anywhere on your system, but I just create it inside the deploy folder to keep things simple.

Configure a new site and album

Inside the config folder, create a new INI file. Call it whatever you want, but it's best to name it after the site domain, as it allows you to easily find it again. For this example, I'll call it 50mm.ini. Here's the sample config file I use for my site:

Domain =
CanonicalSecure = 1
BucketRegion = eu-west-1
BucketName =
ResizingService = imgix
BaseUrl =
SiteTitle = 50mm
MetaTitle = 50mm | Photos by Jibran
HasAlbumIndex = 1

Path = /baku/
BucketPrefix = baku/
MetaTitle = Baku, Azerbaijan | Photos by Jibran
AlbumTitle = Baku, Azerbaijan

Path = /salalah/
BucketPrefix = salalah/
MetaTitle = Salalah, Oman | Photos by Jibran
AlbumTitle = Salalah, Oman

This configuration is for a site that has an index page, uses Imgix for optimised images, and has two albums. If you want to serve multiple sites, create multiple configuration files. Read on to understand what each of these configuration options mean.

The [DEFAULT] section holds configurations for the entire site. Any other section in the config file is parsed as configuration for an album in the site.

DEFAULT configuration options

  • Domain: This is the domain you want to configure your site on. 50mm will serve this site only if the request domain matches this.
  • CanonicalSecure: The 50mm server doesn't handle SSL connections. To get around this, 50mm is usually deployed behind a proxy server, like nginx. Right now 50mm doesn't look at any headers to tell if the original request was on a secure URL or not. If the CanonicalSecure configuration option is set to 1, 50mm assumes all requests are coming from a secure URL, and creates https URLs in the HTML it generates.
  • S3Host: The endpoint for your S3-compatible object store. You can safely ignore this if you are using Amazon S3.
  • BucketRegion: The AWS S3 region that hosts your photos bucket. If your object store doesn't have explicit regions try using "generic"
  • BucketName: Name of your S3 bucket.
  • UseImgix: If set to 1, the image URLs generated for your albums will use the Imgix image transformation service. This results in smaller image sizes and a faster web site, but Imgix is a paid service. If you turn this off (by setting the option to 0), the image URLs on your site will be AWS S3 URLs of the files you upload. deprecated, use ResizingService = imgix instead.
  • ResizingService The resizing service to use (i.e, how to format your resized URLs), valid options: imgix, thumbor, thumbor+cloudfront, see detailed documentation below.
  • ResizingServiceSecret = A shared secret key only required for thumbor resizing service in order to sign URLs.
  • AWSCloudfrontKeyPath = The path to your private key (a .pem file), set up in conjunction with amazon's cloudfront service, a path should look like /path/to/your/pk-something.pem, required only for thumbor+cloudfront resizing service.
  • AWSCloudfrontKeyPairId = The Key Pair Id provided by amazon when you generate a private key, required only for thumbor+cloudfront resizing service.
  • BaseUrl: The base URL for your Imgix account. Look at the section Imgix set up below to understand what value to put here. You can skip this option if you don't use Imgix.
  • AWSKeyId: The AWS access key for an IAM user that has read access to your photos bucket.
  • AWSKey: The AWS secret key for your IAM user.
  • SiteTitle: Name of the site, displayed as the H1 heading on all pages of the site.
  • MetaTitle: Used as the HTML page title for the home page of your site.
  • HasAlbumIndex: If set to 1, 50mm will create an index page for the website which lists all public albums (more on public/private albums in the next section). You can set this to 0 if you don't want the index page, for example if you want to keep your list of albums private.
  • AuthUser: You can use HTTP basic auth to provide simple password protection for your site. This is the username for that. If you don't need auth, skip this option.
  • AuthPass: The password for HTTP basic auth. Skip this option if you don't want auth.

Album configuration options

Any section in the INI file other than the DEFAULT is considered an album. Here's a list of the configuration options for an album:

  • Path: The path on which to serve this album. In our example config, the album "Salalah" is served on the URL
  • BucketPrefix: The prefix (folder) on the S3 bucket that stores the photos for this album. Each album must have a prefix.
  • MetaTitle: The HTML title for the album page.
  • AlbumTitle: The title used in the H2 tag on the album page.
  • InIndex: You can configure individual albums to not show up in the site index. The site index is the home page which lists all your configured albums. True by default. Set to 0 to turn this off.
  • AuthUser: In addition to having HTTP basic auth site wide, you can configure each album to have it's own authentication username and password. Skip this option if not required.
  • AuthPass: Password for album specific auth. Skip this option if not required.

There are a few things to remember about using authentication:

  • If your album has AuthUser and AuthPass set, then InIndex can not be true. This is to make sure that any albums you want to keep private don't show their photos on the site index.
  • If your album has auth configured, then accessing the album page will use the username and password for that album, wether your site has it's auth configured or not.
  • But if your album does not have any auth settings, and the site does, the album will use the username and password you configured for your site. This is another design decision to ensure that if a site is marked as private (by requiring auth), all it's albums are private as well.

You can also have albums served on the site root. So instead of showing a list of albums on the root domain, you can instead just show the album page. To configure this, set the HasAlbumIndex in the site config to 0 and set the Path for the album you want at the root to /.

Configuring Image Resizing Subsystem

You can use a few image transformation services to serve optimised images. To do so, you need to do some configuration.

Imgix (imgix)

Setting up imgix requires you set a source to point to the same AWS S3 bucket you have configured for the site.

Once that's done, you can copy the "Imgix Domain" for that source, which looks something like and use it as the value for BaseUrl in your site config.

Required configuration variables: ResizingService set to imgix, BaseUrl.

Thumbor (thumbor)

Thumbor is a popular open source image manipulation web application. It can be deployed as a standalone service. Many websites use Thumbor internally for their image manipulation. 50mm thumbor support requires you use a shared secret for security purposes (see their security documentation for details). The BaseUrl for thumbor is wherever your thumbor server lies, e.g:

Required configuration variables: ResizingService set to thumbor, BaseUrl, ResizingServiceSecret.

Thumbor + AWS Lambda + AWS Cloudfront (thumbor+cloudfront)

AWS provides a serverless image manipulation configuration that is easy to deploy. It runs thumbor under the hood and does it's distributed via Cloudfront. The Thumbor+Cloudfront system uses Cloudfront signed urls rather than thumbor signed urls, so the implementation and configuration is slightly more complex (see configuration options).

You will need to sort yourself a Cloudfront keypair. 50mm only needs your private key file (in pem format) and your access key id. Please take the usual precautions when configuring your private keys.

Required configuration variables: ResizingService set to thumbor+cloudfront, BaseUrl, AWSCloudfrontKeyPath, AWSCloudfrontKeyPairId.

Configuring Nginx

If you use Nginx as your reverse proxy in-front of 50mm, you can use a configuration file similar to this:

server {
    listen 80;

    location / {
        proxy_set_header Host $http_host;

You can also have SSL configured on Nginx if needed. Just remember to turn on the CanonicalSecure setting in your site config.

Set up the 50mm server (binary)

You can use whichever solution you want to keep the 50mm server running in the background. I personally use supervisord, but you can use init, upstart, systemd, or any other solution you want; including running it inside a tmux session if you feel brave!

Just remember to set the FIFTYMM_CONFIG_DIR and FIFTYMM_PORT environment variables.

Here's the supervisord config I use:


Set up the 50mm server (docker)

You may also choose to run 50mm in a docker environment, for the moment you'll have to build your own image with docker build -t 50mm:latest ., you may then run it with docker run -p <reachable_port>:80 -v /path/to/config/directory:/deploy/config 50mm:latest. Make sure your configuration reflects the domain as it would be seen in your browser.

Upload photos and bask in the glory!

Once the web app is up and running, you can upload photos to your S3 bucket (inside the folders/prefixes) you have configured for each album.

The app caches image keys for 1 hour in memory. If you want to clear that cache, restart the server binary and that's it.

The frontend uses echo to lazy load images that are not in view. It also unloads images that scroll out of the view. This was done because we usually have albums with tons of images, and having them all loaded at once would hog memory.

Customize album ordering

Sometimes the ordering of your photos matters - you want to images in a certain order and you don't want to rename all your photos to get that ordering.

In order to customize your album ordering in 50mm you'll have to build and upload a yaml file in to the corresponding bucket with the name ordering.yaml. The file has three main sections (each of which is optional), some basic examples:

cover: PA036337.jpg
  - PA036278.jpg
  - PA036279.jpg
  - PA036280.jpg
  - PA036281.jpg
  - PA036282.jpg
  - PA036278.jpg
  - PA036282.jpg
  - PA015843.jpg
  - PA015848.jpg
  - PA015852.jpg
  - PA015853.jpg
  - PA015854.jpg
  - PA015856.jpg
  - PA036278.jpg
  - PA036282.jpg
  - PA015843.jpg
  - PA015848.jpg
  - PA015852.jpg
  - PA015853.jpg
  - PA015854.jpg
  - PA015856.jpg
  - PA036278.jpg
  - PA036279.jpg
  - PA036278.jpg
  - PA036282.jpg
  - PA015843.jpg
  - PA015848.jpg

The section names are pretty self-explanatory, each element in the list should correspond to an image key in the corresponding bucket. A few important behaviours:

  1. 50mm processes the filenames in order. Filenames that exist in the actual bucket but not in the thumbnails or ordering sections causes the omitted filenames to appear later in the album (i.e: the ordering is a sort of "put these images first"). As an example, if your album has 50 images and your ordering section has specified two filenames, those files are plucked out of their spots in the bucket ordering and placed at the start of the album.
  2. If a filename is specified in the yaml file but does not exist in the bucket, we ignore that entry.
  3. Malformed yaml files are warned about but ultimately ignored.

Migrating from flickr

flickr_to_50mm is a sister project that can generate the ordering.yaml files by reading the flickr API. There is also flickrtouchr to download your photos from flickr if you no longer have the originals.

Final thoughts

50mm was created because of a frustration we felt. As amateur photographers, we take lots of photographs, and didn't find an easy solution to share those photos with our friends and family. 50mm is our answer to that frustration.

After having used 50mm for more than a month, we feel that for us, this is the solution we wanted. But there are a lot of missing features. Here's an initial list of things we plan to add:

  • Ability to view the original photo. If you use Imgix, the photos displayed on the site is resized down to best fit in the web page. But sometimes people need the originals, to edit, crop, whatever. We have plans to add small overlay buttons on the photos to allow that.
  • Download the entire album. If you're sharing photos from a trip, some of the people in those photos might want to keep a local copy of the entire album. Right now there's no easy way to download the entire album.

We'd love to hear feedback from other developers and amateur photographers about 50mm. If you want to use this for your own site but are not a developer (or are not that familiar with setting up software on web servers), we'd love to help you there as well.

Hit us up on


Create minimal HTML5 image galleries from S3 buckets.




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