mandible

A ready-to-deploy uploader that you can run on AWS EC2 or Heroku. It accepts an image via a REST interface and returns information about a file. Also, supports processing steps such as compression and thumbnail generation.

Features:

Supported file types

• JPG
• PNG
• GIF

Pluggable storage layers

• S3
• Local

Pluggable authentication scheme

• Time-grant HMAC

Processing Steps:

• Compression
• Thumbnail generation

Installation

Docker

Pull down the mandible config file and edit it:

wget https://raw.githubusercontent.com/Imgur/mandible/master/config/default.conf.json -O ~/mandible/conf.json

vim ~/mandible/conf.json

To start mandible (port settings could change based on your conf.json):

docker run --name mandible -v ~/mandible:/etc/mandible -d -p 80:8080 imgur/mandible

To stop mandible:

docker stop mandible

To run it again:

docker run mandible

(Optional) Authentication

• Set the following environment variable
  • AUTHENTICATION_HMAC_KEY

S3 Storage Layer

Add the following to the Stores array in your conf.json file:

    {
        "Type" : "s3",
        "BucketName" : "",
        "AWSKey": "",
        "AWSSecret": "",
        "StoreRoot" : "",
        "Region" : "us-east-1",
        "NamePathRegex" : "",
        "NamePathMap" : "${ImageSize}/${ImageName}"
    }

REST API:

Interfacing with mandible is extremely simple:

Upload an image file:

POST /file

with the following multi-part/form-data

• image - file

Upload an image from a URL:

POST /url

with the following multi-part/form-data

• image - string

Upload an image from base64 data:

POST /base64

with the following multi-part/form-data

• image - image encoded as base64 data

Thumbnail generation during upload:

To generate thumbnails with an upload request, pass the following JSON as form-data, keyed under thumbs

{
    "name1": {
        "width": x,
        "height": y,
        "shape": ("square" | "thumb" | "circle")
    },
    "name2": {
        "width": x2,
        "height": y2,
        "shape": ("square" | "thumb" | "circle")
    },

    ...
}

Note: Square thumbnails don't preserve aspect ratio, whereas the 'thumb' type does

On the fly thumbnail generation:

this will return content-type: image/... and serve up a thumbnail.

GET /thumbnail

with the following get parameters:

• uid - Unique ID of the image
• thumbs - JSON of the following format:

{
    "name for the thumbnail": {
        "shape": ("square" | "thumb" | "circle" | "custom") // required
        "width": int,
        "height": int,
        "max_width": int,
        "max_height": int,
        "crop_gravity": string, // e.g. "nw" for north west of the image
        "crop_height": int,
        "crop_width": int,
        "quaity": int,
        "crop_ratio": string, // e.g. "2:1"
        "format": string, // one of: jpg, png, gif, webm,
        "nostore": bool, // if true, the resulting thumbnail won't be added to the backing storage
    }
}

OCR endpoint

Runs OCR on the given image and returns text

GET /ocr

with the following get parameters:

• uid - Unique ID of the image

returns:

{
    "hash": string, //uid of the image
    "ocrtext": string // text returned from OCR
}

Example usage (assuming localhost)

URL Upload with thumbnails:

curl -i http://127.0.0.1:8080/url \
-d 'image=http://i.imgur.com/s9zxmYe.jpg' \
-d 'thumbs={"small": {"width": 20, "height": 20, "shape": "square"}, "profile": {"width": 50, "height": 50, "shape": "circle"}}'

Response:

{
    "data": {
        "width": 380,
        "height": 430,
        "link": "https://s3.amazonaws.com/gophergala/original/CUqU4If",
        "mime": "image/jpeg",
        "name": "",
        "size": 82199,
        "thumbs": {
            "profile":"https://s3.amazonaws.com/gophergala/t/CUqU4If/profile",
            "small": "https://s3.amazonaws.com/gophergala/t/CUqU4If/small"
        }
    },
    "status": 200,
    "success": true
}

File Upload with thumbnails:

curl -i http://127.0.0.1:8080/file \
-F 'image=@/tmp/cat.gif' \
-F 'thumbs={"small": {"width": 20, "height": 20, "shape": "square"}}'

Response:

{
    "data": {
        "width": 354,
        "height": 200,
        "link": "https://s3.amazonaws.com/gophergala/original/L4ASjMX",
        "mime": "image/gif",
        "name": "cat.gif",
        "size": 3511100,
        "thumbs": {
            "small":"https://s3.amazonaws.com/gophergala/t/L4ASjMX/small"
        }
    },
    "status": 200,
    "success": true
}

Authenticated upload

Uses HTTP headers Authentication and X-Authentication-HMAC. Generate HMACs by base64-encoding a JSON blob like below. Example MAC generator. Supplying the client with the Authentication blob and MAC is out of scope for this project. In the future we will support symmetric and asymmetric encryption of the authentication blobs.

Request to my own account with proper authorization:

curl -i http://127.0.0.1:8080/user/1/url \
-d 'image=http://i.imgur.com/s9zxmYe.jpg' \
-H 'Authorization: {"user_id":1,"grant_time":"2010-06-01T00:00:00Z","grant_duration_sec":31536000}' \
-H 'X-Authorization-HMAC: tCtGb04n4nvd/94+Xd6vAx9+pJw51ZmX1vH7E+BlTtc='

Response:

{"data":{"link":"/tmp/original/J/a/Jafq9IH","mime":"image/jpeg","name":"s9zxmYe.jpg","hash":"Jafq9IH","size":81881,"width":380,"height":430,"ocrtext":"change\np.roject .\n\n  \n  \n\n  forg@ot to git p.ull before\n- .-+#~+):,-r,ad)q..,i,ng so/ /","thumbs":{},"user_id":"\u0001"},"status":200,"success":true}

Request to other user's account:

curl -i http://127.0.0.1:8080/user/2/url \
-d 'image=http://i.imgur.com/s9zxmYe.jpg' \
-H 'Authorization: {"user_id":1,"grant_time":"2010-06-01T00:00:00Z","grant_duration_sec":31536000}' \
-H 'X-Authorization-HMAC: tCtGb04n4nvd/94+Xd6vAx9+pJw51ZmX1vH7E+BlTtc='

Response:

HTTP/1.1 401 Unauthorized
Date: Mon, 08 Jun 2015 21:04:41 GMT
Content-Length: 0
Content-Type: text/plain; charset=utf-8

HMAC prevents account forgery

curl -i http://127.0.0.1:8080/user/1/url \
-d 'image=http://i.imgur.com/s9zxmYe.jpg' \
-H 'Authorization: {"user_id":1,"grant_time":"2010-06-01T00:00:00Z","grant_duration_sec":31536000}' \
-H 'X-Authorization-HMAC: foobar'

Response:

HTTP/1.1 401 Unauthorized
Date: Mon, 08 Jun 2015 21:04:41 GMT
Content-Length: 0
Content-Type: text/plain; charset=utf-8

Contributing

The easiest way to develop on this project is to use the built-in docker image. We are using the Go 1.5 vendor experiment, which means if you import a package you must vendor the source code into this repository using Godep.