kexpress/louis-deps

Louis [BETA]

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Service for transforming and uploading images to any S3 compatible storage.

Inspired from ospry and cloudinary.

Powered by https://github.com/h2non/bimg.

Why Louis

• dockerized application, no need for configuring enviroment

• supports custom transformations

• supports uploading collection of images as ZIP archive

• stores images in S3 compatible storage

• solves problem with deleting dumb images via upload-claim model

• can be safely replicated

• uses only PostgreSQL as data store

• opensource - feel free to open new issue or PRs

How it works

The upload flow lets developers make cross-browser uploads directly to configured S3 cloud storage. When an image and it's transformations successfully uploaded, Louis sends back metadata about the image. The metadata can be used immediately, or sent up to your own server for claiming. Unclaimed images will be deleted after some time.

!louis

See API description for more details on how to integrate.

Transformations

There are some implemented transformations which can be applied during the image upload.

To use transforms, there should be ensure-transform.json (take a look at https://github.com/KazanExpress/louis/blob/master/cmd/louis/ensure-transforms.json) file passed to Louis. For now Louis, inserts all new transformations from file to postgres during application start. This way of configuring will be definitely changed in the future.

Each element in transformations of ensure-transforms.json describes transformation rule:

• type - type of transform. For now it's either fill or fit

• name field represents unique name of transformation, it will be used in uploaded image url for that transform

• transformation will be applied to all new images which have same tag

• width and height parameters for transformation (note that it's not necessarily final size of transformed image)

• quality - compression parameter for transformations.

• cropPoints - top left and bottom right points of area to extract. Can be used only with transformation of type crop.

For now list is very short, but it will be extended in future:

Fit

The image is resized so that it takes up as much space as possible within a bounding box defined by the given width and height parameters. The original aspect ratio is retained and all of the original image is visible.

Fill

Fills image to given width & height.

Crop

Extracts area from original image by given in request X/Y of top left and bottom right points.

Limit

Can limit one of the sides of the image and scaling the second according to aspect ratio.

Note: if both width and height are set, then image will be limited by width.

Running with docker

bash
docker run kexpress/louis

Command line arguments

bash
./louis --env=<default: .env | path to file with environment variables> \
        --transforms-path=<default: ensure-transforms.json | path to file containing json description of transforms>

Configuration

Louis is configured using environment variables or .env configs (see example.env)

List of available configuration options:

Development

If you have problems with installing dependencies or building project. It's highly probably that they caused by https://github.com/h2non/bimg. Please check prerequisites and installation guides for these libs.

bash
# libvips is needed in order to install bimg
go get -v ./...

go build ./cmd/louis
./louis

Testing

As you remember louis uses some databases for storing data. And they are needed during tests. You can easily run them from docker-compose:

bash
cd build
docker-compose up -d

Monitoring with Prometheus

Metrics are exposed in port 8001 and route /metrics.