Uploading files to Desk is a 3-step process

First, you need to create an authorization using /v2/files/ref.json It expects a full disclosure of what's intended to be uploaded

Request:

	{
	    "type": "attachment",
	    "filename": "the_file_name.jpeg",
	    "mimeType": "image/jpeg",
	    "disposition": "attachment"
	}

We will return an URL and a list of parameters that need to be sent along with the file

Response:

	{
	   "url": "http://url/",
	   "params": {
	       "Content-Type": "image/jpeg",
	       "bucket": "A_NAME",
	       "key": "A_VALUE_FOR_LATER",
	       "policy": "A_LONG_STRING",
	       "success_action_status": "201",
	       "x-amz-algorithm": "AWS4-HMAC-SHA256",
	       "x-amz-credential": "A_VALUE",
	       "x-amz-date": "ANOTHER_VALUE",
	       "x-amz-signature": "ANOTHER_LONG_STRING"
	   },
	   "file": {
	       "id": FILE_ID,
	       "mimeType": "image/jpeg",
	       "fileName": "the_file_name.jpeg",
	       "size": 0,
	       "disposition": "attachment",
	       "type": "attachment",
	       "createdAt": "2019-03-14T11:53:38.103518Z",
	       "updatedAt": "2019-03-14T11:53:38.103518Z",
	       "createdBy": {
	           "id": 1,
	           "type": "users"
	       },
	       "updatedBy": {
	           "id": 1,
	           "type": "users"
	       },
	       "state": "temp"
	   }
	}

Any tampering will cause the upload request to fail

Uploading the file with curl

	curl -X POST \
	  http://url/ \
	  -H ': ' \
	  -H 'cache-control: no-cache' \
	  -F Content-Type=image/jpeg \
	  -F key=A_VALUE_FOR_LATER \
	  -F policy=A_LONG_STRING \
	  -F success_action_status=201 \
	  -F x-amz-algorithm=AWS4-HMAC-SHA256 \
	  -F x-amz-credential=A_VALUE \
	  -F x-amz-date=ANOTHER_VALUE \
	  -F x-amz-signature=ANOTHER_LONG_STRING \
	  -F file=@YOUR_FILE_PATH \
	  -F bucket=A_NAME

Response:

<?xml version="1.0" encoding="UTF-8"?>
<PostResponse>

	<Bucket>A_NAME</Bucket>
	<Key>A_VALUE_FOR_LATER</Key>
	<ETag>SOME_STRING</ETag>
	<Location>/A_NAME/A_VALUE_FOR_LATER</Location>

</PostResponse>

Finally, you need to tell desk that the file has been uploaded

PATCH /v2/files/{FILE_ID}.json

Response:

	{
	    "file": {
	        "id": FILE_ID,
	        "mimeType": "image/jpeg",
	        "fileName": "the_file_name.jpeg",
	        "size": 14358,
	        "disposition": "attachment",
	        "type": "attachment",
	        "URL": "",
	        "createdAt": "2019-03-12T13:40:25.135843Z",
	        "updatedAt": "2019-03-12T13:40:25.135843Z",
	        "createdBy": {
	            "id": 1,
	            "type": "users"
	        },
	        "updatedBy": {
	            "id": 1,
	            "type": "users"
	        },
	        "state": "active"
	    }
	}