til/ruby/check-if-a-url-resolves-to-200.md

Check If A URL Resolves To 200

Ruby's built-in Net::HTTP library allows us to make different kinds of HTTP requests. We can use it to make a HEAD request which will request the status of a URL without actually fetching its contents.

We can work directly with Net::HTTP using strings, but I find it is easier and less error-prone to get help from the URI class.

To make a #head request, we first need to establish a connection to the host with the #start method. Then we can initiate our request from that connection object.

url = 'https://my.app.com/path/to/video.mp4'
uri = URI(url)
conn = Net::HTTP.start(uri.host, uri.port, use_ssl: true)
resp = conn.head(uri.path)

resp.code
#=> "200"

We initiate the connection with the host and port of our URL. Then request the HEAD response for the path of our URL. If we are working with an https URL, we need to indicate that with use_ssl: true in the #start method options.