Imago

My first attempt at building somethng in Go. Imago is a simple web front-end to imagemagick to allow mostly arbitrary image file conversions. Not pretty or very secure, Imago is realy just a vehicle for me to familiarize myself with the language. Work requests are POSTed via the API as json objects, and a token is returned to the caller which can be used to check the job status. The conversion is executed asychronously via a pool of goroutine workers.

Running it

Be sure you have a valid settings.yml file. You can then simply run imago

API

Imago implements a simple RESTful API

Requesting an image conversion

You may request one or more image conversions by passing in an array of actions in a POST request to /api/v1/work:

{
  "actions" : [
    {
      "infile": "s3://mybucket/imago/foo.png",
      "outfile": "s3://mybucket/imago/out/foo 200x200.jpg",
      "operations" : ["resize 200X200", "quality 100"],
      "mimetype":  "image/jpg"
    },
    {
      "infile": "s3://mybucket/imago/foo.png",
      "outfile": "s3://mybucket/imago/out/foo-4xx4k.tiff",
      "operations" : ["resize 4000X4000"],
      "mimetype":  "image/tiff"
    }
  ]
}

infile and outfile point to files in s3 to convert. The files will be downloaded and converted using the imagemagick operations specidied in operations and reuploaded with the specified mimetype. Note that we use etags to ensure that we don't needlessly redownload files in a single session.For now, only the s3 remote file type is supported; other remote filesystem support is coming.

Once a job is submitted, a response is returned with the work id and current queue size (the number of jobs awaiting processing on the queue):

{
   "id": "f2fcbe5fd9754e80b4d90b509ea42168",
   "queue_length": 3,
   "status": "ok"
}

Checking the conversion progress

You may then fetch the status of your job with a GET request to:

/api/v1/work/f2fcbe5fd9754e80b4d90b509ea42168

You can long-poll, by adding a timeout (in seconds) as a query parameter

/api/v1/work/f2fcbe5fd9754e80b4d90b509ea42168?timeout=300 

In each case, a JSON package is returned with the status of your work request:

{
    "id": "e2ffd1057f2d46a9a5d599d8379741e0",
    "status": "done",
    "actions": [
        {
            "status": "done",
            "infile": "s3://mybucket/imago/foo.png",
            "outfile": "s3://mybucket/imago/out/foo 200x200.jpg",
            "mimetype": "image/jpg",
            "operations": [
                "resize 200X200",
                "quality 100"
            ],
            "output": "",
            "error": ""
        },
        {
            "status": "done",
            "infile": "s3://mybucket/imago/foo.png",
            "outfile": "s3://mybucket/imago/out/foo-4xx4k.tiff",
            "mimetype": "image/tiff",
            "operations": [
                "resize 4000X4000"
            ],
            "output": "",
            "error": ""
        }
    ]
}

Getting the work queue size

Jobs that cannot be processed right away get queued up. You may chack the queue size at any time by calling:

GET /api/v1/queue_length

You can adjust the queue size and number of workers available by tweaking settings.yml