Image Server

Server

Posting New Images

An image needs to be uploaded to a namespace.

Namespaces allow to group image types. For example avatars will require different image sizes than product images.

Uploading an image requires a source, which is the URL of the original image.

curl -X POST http://localhost:7000/p?source=http://example.com/image.jpg

A binary file might be uploaded instead of providing an URL. The contents of the image need to be included in the body of the request.

> curl --data-binary "@./test/images/wine.jpg" -X POST http://localhost:7000/p
{
  "hash": "6e0072682e66287b662827da75b244a3",
  "height": 600,
  "width": 800,
  "content_type": "image/jpeg"
}

It is possible to process images when uploading an image by providing the desired image dimensions in the outputs parameter.

> curl --data-binary "@./test/images/wine.jpg" -X POST http://localhost:7000/p?outputs=x300.jpg,x300.webp
{
  "hash": "6e0072682e66287b662827da75b244a3",
  "height": 496,
  "width": 574,
  "content_type": "image/jpeg"
}

An upload request will block till all images have been created (various sizes) and uploaded (either manta or s3, configured in the app).

Image Information

The request returns the "Image Information" after an image is uploaded. The response includes properties of the image, and the image hash to be used to retrieve it in the future.

Image properties can be retrieved by visiting the info page. The response is the same as the one returned when creating the image. Please note url has partitioned the image hash /123/456/789/<REST_OF_HASH>/

> curl http://localhost:7000/p/6e0/072/682/e66287b662827da75b244a3/info.json
{
  "hash": "6e0072682e66287b662827da75b244a3",
  "height": 496,
  "width": 574,
  "content_type": "image/jpeg"
}

Image processing

Images can be processed on demand. This will re-size and also upload the image to the configured data store!

Dimensions

By Width
GET http://localhost:7000/p/6e0/072/682/e66287b662827da75b244a3/w200.jpg

Square
GET http://localhost:7000/p/6e0/072/682/e66287b662827da75b244a3/x200.jpg

Rectangle (width x height)
GET http://localhost:7000/p/6e0/072/682/e66287b662827da75b244a3/300x200.jpg

Quality

The default compression of the image can be modified by appending -q and the desired quality 1-100.

Square with quality 50
GET http://localhost:7000/p/6e0/072/682/e66287b662827da75b244a3/x200-q30.jpg

Cloud Storage

Images can be uploaded to either Amazon S3 or Joyent's Manta (we support only one upload config at a time)

To store images in S3 the following flags need to be set

--aws_access_key_id $AWS_ACCESS_KEY_ID --aws_secret_key $AWS_SECRET_KEY --aws_bucket $AWS_BUCKET --aws_region us-west-1

For Manta the following flags are required

--manta_url $MANTA_URL --manta_user $MANTA_USER --manta_key_id $MANTA_KEY_ID --sdc_identity $SDC_IDENTITY --remote_base_path $IMG_MANTA_BASE_PATH

Error Handling

Few errors will cause the server to return error pages

• Source image is not found: NotFound (404)

CLI

Images can be processed with the command line.

Command for manta task:

image --remote_base_path public/images --outputs x300.webp,x300.jpg process $MANTA_INPUT_FILE

Development

Set up the environment:

mkdir -p $GOPATH/src/github.com/image-server/
git clone https://github.com/image-server/image-server $GOPATH/src/github.com/image-server/image-server
ln -s $GOPATH/src/github.com/image-server/image-server ~/workspace/image-server
cd ~/workspace/image-server

Install dependencies:

Go needs to be installed with cross compilation. Imagemagick will require giflib and webp support.

On Mac

brew install --force go --with-cc-all
brew install --force giflib
brew install --force imagemagick --with-webp
make deps

Set up editor:

• Atom.io package go-plus

Compile the app:

To build the executables under ./bin

make build

Development Usage

There are few make helpers that start the development server. They all translate environment variables into flags.

S3

Required ENV variables: IMG_OUTPUTS, AWS_BUCKET, IMG_REMOTE_BASE_PATH, IMG_REMOTE_BASE_URL

make dev-server-s3

Manta

Required ENV variables: IMG_OUTPUTS, MANTA_URL, MANTA_USER, MANTA_KEY_ID, SDC_IDENTITY, IMG_MANTA_BASE_PATH

make dev-server-manta

No uploader, only store images locally

Required ENV variables: IMG_OUTPUTS

make dev-server

Tests

S3 tests make real HTTP calls when you have S3 ENV variables set.

make tests

Configuration

All configuration is passed by flags

go run main.go --help

Deploy

Make sure you increase the version number in core/version.go

make release

Statsd

To enable the statsd events, use the flag enable_statsd:

bin/images --enable_statsd

Statsd Events

A local cache was not found and the image was processed. This also tracks count of images sent to remote store.

stats.image_server.image_request

In addition, the format is tracked (jpg, gif, webp)

stats.image_server.image_request.jpg

Request failed to return an image

stats.image_server.image_request_fail

Every download from original source, and a 404 was returned

stats.image_server.original_downloaded

The original image is not available, and a 404 was returned

stats.image_server.original_unavailable

Prometheus metrics

Prometheus metrics are available on the admin port at /metrics

Profiling

The server allows to be profiled when started with the profile flag

bin/images --profile server

The profiling information is available on localhost:6060

It is important to run the profiler

You will need the profiled data from the server, and analize it with the same executable file used on the server.

You will need to download the profiled data from the server.

ssh example.com "curl http://localhost:6060/debug/pprof/heap" > images.pprof

Use go tool pprof to analize the profile. Remember to use the same executable file as the one on production.

go tool pprof --inuse_objects bin/solaris/images images.pprof

Benchmarks

Make sure your computer can handle enough simultaneous connections. MacOS X by default allows 128. Need a lot more!

$ sudo sysctl -w kern.ipc.somaxconn=2048

Also need to increase the limit of maximum open files

To find out the limits on your computer:

launchctl limit

Increase the limits!

launchctl limit maxfiles 400000 1000000

to increase them permanently