Signing google static maps URL with fastly

gmaps_static_signing_url_with_fastly.vcl

sub vcl_recv {
    # Creates google static maps API signature and adds it as one of the query params on the fly. Basically signs URL.

    # Key is here: https://consers.google.com/apis/api/static-maps-backend.googleapis.com/ole.developstaticmap/ your_project
    set req.http.signature = digest.hmac_sha1_base64(digest.base64_decode("YOUR_KEY"), req.url);

    # Create safe-for-web version of the key by replacing '+' -> '-', and '\' -> '_'.
    set req.http.signature_url_safe = regsuball(regsuball(req.http.signature, "\+", "-"), "\\", "_");

    # Add signature query param to the request url
    set req.http.signed_url = querystring.add(req.url, "signature", req.http.signature_url_safe);

    # Replace originar request URL with signed/decorated one
    set req.url = req.http.signed_url;

    # cleanup headers that were used as variables
    unset req.http.signature;
    unset req.http.signature_url_safe;
    unset req.http.signed_url;

    return(lookup);
}