Arvados

h1. Keep-web flow

(Note: this page is an alternate explanation of the authoritative docs at https://godoc.org/git.curoverse.com/arvados.git/services/keep-web#hdr-Authorization_mechanisms)

Keep-web serves files from Keep collections as normal HTTP documents.

Considerations:

We are serving arbitrary files, which can include HTML files with Javascript.  We don't want serve these files as regular documents from Workbench, because this would expose a cross-site-scripting (XSS) attack where the HTML page is loaded and executed with the credentials of the viewing user.

This is mitigated two ways:

# By serving files with "content-disposition: attachment" which tells the browser to open up the download dialog straight away and don't try to show the files.

# Using separate a separate domain for downloading, so the browser won't send workbench cookies.

This raises the challenge: how to provide the API token to keep-web to enable download?

keepweb accepts an API token the following ways:

* With @Authorization: OAuth2@ header

* With @Authorization: Basic@ header

* With @?api_token=xxx@ query string

* With a cookie called @arvados_api_token@

* With @/t=xxx/@ at the start of the path

Constraints: 

# when doing a GET request, the API token must be either part of the request URI or a header (browser does not send the workbench cookie when keep-web is on a different domain)

# We want to hide the API token from the user unless it is a "sharing" link