pombredanne/kinto-attachment

Add attachments to Kinto records

Kinto Attachment

Attach files to Kinto records.

Install

pip install kinto-attachment

Setup

In the Kinto project settings

kinto.includes = kinto_attachment
kinto.attachment.base_url = http://cdn.service.org/files/
kinto.attachment.folder = {bucket_id}/{collection_id}
kinto.attachment.keep_old_files = true

If you want uploaded files to get gzipped when stored:

kinto.attachment.gzipped = true

Store files locally:

kinto.attachment.base_path = /tmp

Store on Amazon S3:

kinto.attachment.aws.access_key = <AWS access key>
kinto.attachment.aws.secret_key = <AWS secret key>
kinto.attachment.aws.bucket_name = <bucket name>
kinto.attachment.aws.acl = <AWS ACL permissions|public-read>

Note

access_key and secret_key may be omitted when using AWS Identity and Access Management (IAM).

See Pyramid Storage.

Default bucket

In order to upload files on the default bucket, the built-in default bucket plugin should be enabled before the kinto_attachment plugin.

In the configuration, this means adding it explicitly to includes:

kinto.includes = kinto.plugins.default_bucket
                 kinto_attachment

Production

• Make sure the base_url can be reached (and points to base_path if files are stored locally)
• Adjust the max size for uploaded files (e.g. client_max_body_size 10m; for NGinx)

For example, with NGinx

server {
    listen 80;

    location /v1 {
        ...
    }

    location /files {
        root /var/www/kinto;
    }
}

API

POST /{record-url}/attachment

It will create the underlying record if it does not exist.

Required

• attachment: a single multipart-encoded file

Optional

• data: attributes to set on record (serialized JSON)
• permissions: permissions to set on record (serialized JSON)

DELETE /{record-url}/attachment

Deletes the attachement from the record.

QueryString options

By default, the server will randomize the name of the attached files. If you don't want this behavior and prefer to keep the original file name, you can pass ?randomize=false in the QueryString.

By default, the server won't gzip files unless you specifically used the kinto.attachment.gzipped option if you want to force gzip to all collections.

You can overwite that option by passing a ?gzipped=true in the QueryString to specifically gzip some files.

Attributes

When a file is attached, the related record is given an attachment attribute with the following fields:

• filename: the original filename
• hash: a SHA-256 digest
• location: the URL of the attachment
• mimetype: the media type of the file
• size: size in bytes

{
    "data": {
        "attachment": {
            "filename": "IMG_20150219_174559.jpg",
            "hash": "hPME6i9avCf/LFaznYr+sHtwQEX7mXYHSu+vgtygpM8=",
            "location": "http://cdn.service.org/files/ffa9c7b9-7561-406b-b7f9-e00ac94644ff.jpg",
            "mimetype": "image/jpeg",
            "size": 1481798
        },
        "id": "c2ce1975-0e52-4b2f-a5db-80166aeca688",
        "last_modified": 1447834938251,
        "theme": "orange",
        "type": "wallpaper"
    },
    "permissions": {
        "write": ["basicauth:6de355038fd943a2dc91405063b91018bb5dd97a08d1beb95713d23c2909748f"]
    }
}

If the file is gzipped by the server, an original key is added in the attachment key, containing the file info before it's gzipped. The attachment keys are in that case referring to the gzipped file:

{
    "data": {
        "attachment": {
            "filename": "IMG_20150219_174559.jpg.gz",
            "hash": "hPME6i9avCf/LFaznYr+sHtwQEX7mXYHSu+vgtygpM8=",
            "location": "http://cdn.service.org/files/ffa9c7b9-7561-406b-b7f9-e00ac94644ff.jpg.gz",
            "mimetype": "application/x-gzip",
            "size": 14818,
            "original": {
                "filename": "IMG_20150219_174559.jpg",
                "hash": "hPME6i9avCf/LFaznYr+sHtwQEX7mXYHSu+vgtygpM8=",
                "mimetype": "image/jpeg",
                "size": 1481798
            }
        },
        "id": "c2ce1975-0e52-4b2f-a5db-80166aeca688",
        "last_modified": 1447834938251,
        "theme": "orange",
        "type": "wallpaper"
    },
    "permissions": {
        "write": ["basicauth:6de355038fd943a2dc91405063b91018bb5dd97a08d1beb95713d23c2909748f"]
    }
}

Usage

Using HTTPie

http --auth alice:passwd --form POST http://localhost:8888/v1/buckets/website/collections/assets/records/c2ce1975-0e52-4b2f-a5db-80166aeca689/attachment data='{"type": "wallpaper", "theme": "orange"}' "attachment@~/Pictures/background.jpg"

HTTP/1.1 201 Created
Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff
Content-Length: 209
Content-Type: application/json; charset=UTF-8
Date: Wed, 18 Nov 2015 08:22:18 GMT
Etag: "1447834938251"
Last-Modified: Wed, 18 Nov 2015 08:22:18 GMT
Location: http://localhost:8888/v1/buckets/website/collections/font/assets/c2ce1975-0e52-4b2f-a5db-80166aeca689
Server: waitress

{
    "filename": "IMG_20150219_174559.jpg",
    "hash": "hPME6i9avCf/LFaznYr+sHtwQEX7mXYHSu+vgtygpM8=",
    "location": "http://cdn.service.org/files/ffa9c7b9-7561-406b-b7f9-e00ac94644ff.jpg",
    "mimetype": "image/jpeg",
    "size": 1481798
}

Using Python requests

auth = ("alice", "passwd")
attributes = {"type": "wallpaper", "theme": "orange"}
perms = {"read": ["system.Everyone"]}

files = [("attachment", ("background.jpg", open("Pictures/background.jpg", "rb"), "image/jpeg"))]

payload = {"data": json.dumps(attributes), "permissions": json.dumps(perms)}
response = requests.post(SERVER_URL + endpoint, data=payload, files=files, auth=auth)

response.raise_for_status()

Using JavaScript

var headers = {Authorization: "Basic " + btoa("alice:passwd")};
var attributes = {"type": "wallpaper", "theme": "orange"};
var perms = {"read": ["system.Everyone"]};

// File object from input field
var file = form.elements.attachment.files[0];

// Build form data
var payload = new FormData();
// Multipart attachment
payload.append('attachment', file, "background.jpg");
// Record attributes and permissions JSON encoded
payload.append('data', JSON.stringify(attributes));
payload.append('permissions', JSON.stringify(perms));

// Post form using GlobalFetch API
var url = `${server}/buckets/${bucket}/collections/${collection}/records/${record}/attachment`;
fetch(url, {method: "POST", body: payload, headers: headers})
  .then(function (result) {
    console.log(result);
  });

Scripts

Two scripts are provided in this repository.

They rely on the kinto-client Python package, which can be installed in a virtualenv:

$ virtualenv env --python=python3
$ source env/bin/activate
$ pip install kinto-client

Or globally on your system (not recommended):

$ sudo pip install kinto-client

Upload files

upload.py takes a list of files and posts them on the specified server, bucket and collection:

$ python3 scripts/upload.py --server=$SERVER --bucket=$BUCKET --collection=$COLLECTION --auth "token:mysecret" README.rst pictures/*

If the --gzip option is passed, the files are gzipped before upload. Since the attachment attribute contains metadata of the compressed file the original file metadata are stored in a original attribute.

See python3 scripts/upload.py --help for more details about options.

Download files

download.py downloads the attachments from the specified server, bucket and collection and store them on disk:

$ python3 scripts/download.py --server=$SERVER --bucket=$BUCKET --collection=$COLLECTION --auth "token:mysecret"

If the record has an original attribute, the script decompresses the attachment after downloading it.

Files are stored in the current folder by default. See python3 scripts/download.py --help for more details about options.

Known limitations

• No support for chunk upload (#10)
• Files are not removed when server is purged with POST /v1/__flush__

Relative URL in records (workaround)

Currently the full URL is returned in records. This is very convenient for API consumers which can access the attached file just using the value in the location attribute.

However, the way it is implemented has a limitation: the full URL is stored in each record directly. This is annoying because changing the base_url setting won't actually change the location attributes on existing records.

As workaround, it is possible to set the kinto.attachment.base_url to an empty value. The location attribute in records will now contain a relative URL.

Using another setting kinto.attachment.extra.base_url, it is possible to advertise the base URL that can be preprended by clients to obtain the full attachment URL. If specified, it is going to be exposed in the capabilities of the root URL endpoint.

Run tests

Run a fake Amazon S3 server in a separate terminal:

make moto

Run the tests suite:

make tests

Notes

• API design discussion about mixing up attachment and record fields.