Extract URL from Text Field into a New Field Called URL

I'm inputting a field called text. this field may at times contain a URL.What I would like to do is extract the URL's from text, and put them in a new field called URL.

I tried grok, but it seems like grok patterns need a specific log format in order for it to work. For an example, the following will work:

5546 hello www.google.com
{id} {text} {URL}

But the following wouldn't

4324 hello my name is Ryan www.yahoo.com
{id} {text} {URL}

instead, it would take hello as text, and not take www.yahoo.com as the URL. Is there a way around this? Please note that sometimes, the text might look like the following:

www.gmail.com hello everyone 

What filter can I use in order to extract the URL from the text coming into Logstash?

Thank you.

The grok filter is the right tool for the job. Since the position of the URL isn't the same all the time you can't use a grok expression that extracts word N from the input text. Instead you need to construct a pattern that recognizes the URL itself, i.e. by looking for a word that starts with "www.", or perhaps any space-delimited sequence of characters that begins with something that looks like a domain name. For example,


captures into the field url anything that begins like a hostname with at least two labels ("www.google.com", "google.com" but not "com") followed by any number of non-space characters.

(Strictly speaking I believe a URL needs to begin with a scheme, like http://.)