Unfurls the given url , returning nil if url is nil or not supported, or a map containing some or all of the following keys (all of which are optional):

• :url (String) The url of the resource, according to the server.
• :title (String) The title of the given url.
• :description (String) A brief textual description of the given url.
• :preview-url (String) The url of a preview image for the given url.

Options are:

• :follow-redirects (boolean, default true): Whether to follow 30x redirects.
• :timeout-ms (long, default 1000) Timeout in ms (used for both the socket and connect timeouts).
• :user-agent (String, default "https://github.com/pmonks/unfurl") User agent string to send in the HTTP request. This should be either a browser identification string, an email address, or a URL, as some servers will reject requests with User Agent values that aren’t in one of these domains.
• :max-content-length (long, default 16384) Maximum length (in bytes) of content to retrieve, using HTTP range requests (the entire content does not normally need to be retrieved in order to get the metadata unfurl uses).
• :proxy-host (String, default nil) HTTP proxy hostname.
• :proxy-port (long, default nil) HTTP proxy port.
• :http-headers (a map with String keys and String values, default nil) A map of any other HTTP request headers you might want unfurl to include in the requests it makes.

Throws on I/O errors, usually an ExceptionInfo with the ex-data containing:

• :request (a map with String keys and String values) Contains the details of the HTTP request that was attempted.
• :response (a map with String keys and String values) Contains the details of the HTTP response that was received (directly from clj-http).