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cherouvim
Asked: 2013-07-20 01:13:29 +0800 CST

detect return code (mode) in varnish hook

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In vcl_recv I decide whether to pass or lookup based on the existence of a cookie:

sub vcl_recv {
    if (req.http.Cookie ~ "(JSESSIONID=)" ) {
            /* do not cache logged in users */
            return (pass);
    }
    return (lookup);
}

In vcl_fetch I fine tune caching for some pages:

sub vcl_fetch {

    /* custom rules block */
    if (req.url ~ "^/foo") { set beresp.ttl=30s; }
    if (req.url ~ "^/bar") { set beresp.ttl=1m; }
    if (req.url ~ "^/123") { set beresp.ttl=10m; }

    return (deliver);
}

How can I know within vcl_fetch whether I am in pass or lookup mode? I'd like to be able to avoid running the "custom rules block" if I am in lookup mode because the logged in users will anyway run in pass mode so these rules do not apply to them.

configuration

1 Answers

  1. You can always set a custom header in vcl_recv:

    sub vcl_recv {
  if (req.http.Cookie ~ "(JSESSIONID=)" ) {
    /* do not cache logged in users */
    set req.http.x-my-mark = "passed";
    return (pass);
  }
  return (lookup);
}
#...
sub vcl_fetch {
  if (req.http.x-my-mark == "passed") {
    /* custom rules block */
    if (req.url ~ "^/foo") { set beresp.ttl=30s; }
    if (req.url ~ "^/bar") { set beresp.ttl=1m; }
    if (req.url ~ "^/123") { set beresp.ttl=10m; }
  }

  return (deliver);
}

    But I think it will be much cleaner to put your login on vcl_pass[1] or just perform your original check on vcl_fetch:

    sub vcl_fetch {
  if (req.http.Cookie ~ "(JSESSIONID=)") {
    /* custom rules block */
    if (req.url ~ "^/foo") { set beresp.ttl=30s; }
    if (req.url ~ "^/bar") { set beresp.ttl=1m; }
    if (req.url ~ "^/123") { set beresp.ttl=10m; }
  }

  return (deliver);
}

    [1] https://www.varnish-software.com/static/book/VCL_functions.html#vcl-vcl-pass

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