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    <p>Hi Per Buer,</p>
    <p>Thanks for your response and for the tips. Would go through them
      and try to implement. <br>
    </p>
    <p>Regarding the blank pages, I have sent a separate mail. <br>
    </p>
    <p>I have installed Varnish from source.  Since this is the first
      time with Varnish, we plan to start with simple scenarios for
      caching and then move on to more sophisticated ones for logged in
      users etc (also, as we scale up further).<br>
    </p>
    <p>Would really appreciate if you could help me resolving the issue
      so that I could move ahead with configuring and deploying Varnish.
      Following is the content of the mail with the issue:</p>
    <p>Hi,</p>
    <p>I am trying to set Varnish to cache content when login cookie is
      not present. Hence, I have modified the following subroutines:</p>
    <ul>
      <li>vcl_recv: If the login cookie is not present, return hash.</li>
      <li>vcl_back_response: If the login cookie is not present, cache
        the content (beresp.uncacheable set to false</li>
    </ul>
    <p>Whenever the vcl_recv is returning hash, varnish is generating
      blank page with content-length set 0. If vcl_recv returns pass,
      the page is served fine. <br>
    </p>
    <p>Following is the VCL:</p>
    <p>sub vcl_recv {<br>
          # Happens before we check if we have this in cache already.<br>
          #<br>
          # Typically you clean up the request here, removing cookies
      you don't need,<br>
          # rewriting the request, etc.<br>
          set req.backend_hint = uwsgi;<br>
      <br>
         if (req.http.Cookie !~ "jivaana_user=") {<br>
              return(hash);<br>
          }<br>
      }<br>
      <br>
      sub vcl_backend_response {<br>
          # Happens after we have read the response headers from the
      backend.<br>
          #<br>
          # Here you clean the response headers, removing silly
      Set-Cookie headers<br>
          # and other mistakes your backend does.<br>
          if (beresp.http.Set-Cookie !~ "jivaana_user=") {<br>
              if (beresp.ttl <= 0s) {<br>
                      set beresp.ttl = 120s;<br>
              }<br>
              set beresp.uncacheable = false;<br>
              return (deliver);<br>
      }</p>
    <p>Varnish log:</p>
    <p><br>
    </p>
    *   << BeReq    >> 3         <br>
    -   Begin          bereq 2 fetch<br>
    -   Timestamp      Start: 1463994442.986360 0.000000 0.000000<br>
    -   BereqMethod    GET<br>
    -   BereqURL       /catalogue/<br>
    -   BereqProtocol  HTTP/1.0<br>
    -   BereqHeader    Host: django_test<br>
    -   BereqHeader    Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8<br>
    -   BereqHeader    Upgrade-Insecure-Requests: 1<br>
    -   BereqHeader    User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS
    X 10_9_5) AppleWebKit/537.36 (KHTML, like Gecko)
    Chrome/50.0.2661.102 Safari/537.36<br>
    -   BereqHeader    Accept-Language: en-US,en;q=0.8<br>
    -   BereqHeader    X-Forwarded-For: 127.0.0.1<br>
    -   BereqHeader    Accept-Encoding: gzip<br>
    -   BereqProtocol  HTTP/1.1<br>
    -   BereqHeader    X-Varnish: 3<br>
    -   VCL_call       BACKEND_FETCH<br>
    -   VCL_return     fetch<br>
    -   BackendOpen    21 boot.uwsgi 127.0.0.1 9001 127.0.0.1 38213<br>
    -   Timestamp      Bereq: 1463994442.986883 0.000524 0.000524<br>
    -   Timestamp      Beresp: 1463994443.734972 0.748612 0.748088<br>
    -   BerespProtocol HTTP/1.1<br>
    -   BerespStatus   200<br>
    -   BerespReason   OK<br>
    -   BerespHeader   Expires: Mon, 23 May 2016 09:07:23 GMT<br>
    -   BerespHeader   Vary: Cookie<br>
    -   BerespHeader   Last-Modified: Mon, 23 May 2016 09:07:23 GMT<br>
    -   BerespHeader   Cache-Control: max-age=0<br>
    -   BerespHeader   X-Frame-Options: SAMEORIGIN<br>
    -   BerespHeader   Content-Type: text/html; charset=utf-8<br>
    -   BerespHeader   Set-Cookie: 
    csrftoken=5BUZRL4gdO7uTDtWXnbqQko3CelDmOAg; expires=Mon, 22-May-2017
    09:07:23 GMT; Max-Age=31449600; Path=/<br>
    -   BerespHeader   Date: Mon, 23 May 2016 09:07:23 GMT<br>
    -   TTL            RFC 0 10 -1 1463994444 1463994444 1463994443
    1463994443 0<br>
    -   VCL_call       BACKEND_RESPONSE<br>
    -   TTL            VCL 120 10 0 1463994444<br>
    -   VCL_return     deliver<br>
    -   Storage        file s0<br>
    -   ObjProtocol    HTTP/1.1<br>
    -   ObjStatus      200<br>
    -   ObjReason      OK<br>
    -   ObjHeader      Expires: Mon, 23 May 2016 09:07:23 GMT<br>
    -   ObjHeader      Vary: Cookie<br>
    -   ObjHeader      Last-Modified: Mon, 23 May 2016 09:07:23 GMT<br>
    -   ObjHeader      Cache-Control: max-age=0<br>
    -   ObjHeader      X-Frame-Options: SAMEORIGIN<br>
    -   ObjHeader      Content-Type: text/html; charset=utf-8<br>
    -   ObjHeader      Set-Cookie: 
    csrftoken=5BUZRL4gdO7uTDtWXnbqQko3CelDmOAg; expires=Mon, 22-May-2017
    09:07:23 GMT; Max-Age=31449600; Path=/<br>
    -   ObjHeader      Date: Mon, 23 May 2016 09:07:23 GMT<br>
    -   Fetch_Body     0 none -<br>
    -   BackendReuse   21 boot.uwsgi<br>
    -   Timestamp      BerespBody: 1463994443.735229 0.748869 0.000257<br>
    -   Length         0<br>
    -   BereqAcct      393 0 393 336 0 336<br>
    -   End            <br>
    <br>
    *   << Request  >> 2         <br>
    -   Begin          req 1 rxreq<br>
    -   Timestamp      Start: 1463994442.986091 0.000000 0.000000<br>
    -   Timestamp      Req: 1463994442.986091 0.000000 0.000000<br>
    -   ReqStart       127.0.0.1 56147<br>
    -   ReqMethod      GET<br>
    -   ReqURL         /catalogue/<br>
    -   ReqProtocol    HTTP/1.0<br>
    -   ReqHeader      Host: django_test<br>
    -   ReqHeader      Connection: close<br>
    -   ReqHeader      Cache-Control: max-age=0<br>
    -   ReqHeader      Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8<br>
    -   ReqHeader      Upgrade-Insecure-Requests: 1<br>
    -   ReqHeader      User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS
    X 10_9_5) AppleWebKit/537.36 (KHTML, like Gecko)
    Chrome/50.0.2661.102 Safari/537.36<br>
    -   ReqHeader      Accept-Encoding: gzip, deflate, sdch<br>
    -   ReqHeader      Accept-Language: en-US,en;q=0.8<br>
    -   ReqHeader      Cookie: pagemap=0,0,0,0,0,1,0';
    pagemap=0,0,0,0,0,0,0; jivaana_country=IN; mp_mixpanel__c=1;
    mp_mixpanel__c3=2; mp_mixpanel__c4=2; mp_mixpanel__c5=0;
    _ga=GA1.1.1762020660.1447765749;
    mp_774636c1ed2371eaf99455f71871069c_mixpanel=%7B%22distinct_id%22%3A%20<br>
    -   ReqHeader      If-Modified-Since: Mon, 23 May 2016 09:03:11 GMT<br>
    -   ReqHeader      X-Forwarded-For: 127.0.0.1<br>
    -   VCL_call       RECV<br>
    -   ReqUnset       Cookie: pagemap=0,0,0,0,0,1,0';
    pagemap=0,0,0,0,0,0,0; jivaana_country=IN; mp_mixpanel__c=1;
    mp_mixpanel__c3=2; mp_mixpanel__c4=2; mp_mixpanel__c5=0;
    _ga=GA1.1.1762020660.1447765749;
    mp_774636c1ed2371eaf99455f71871069c_mixpanel=%7B%22distinct_id%22%3A%20<br>
    -   VCL_return     hash<br>
    -   ReqUnset       Accept-Encoding: gzip, deflate, sdch<br>
    -   ReqHeader      Accept-Encoding: gzip<br>
    -   VCL_call       HASH<br>
    -   VCL_return     lookup<br>
    -   VCL_call       MISS<br>
    -   VCL_return     fetch<br>
    -   Link           bereq 3 fetch<br>
    -   Timestamp      Fetch: 1463994443.735287 0.749196 0.749196<br>
    -   RespProtocol   HTTP/1.1<br>
    -   RespStatus     200<br>
    -   RespReason     OK<br>
    -   RespHeader     Expires: Mon, 23 May 2016 09:07:23 GMT<br>
    -   RespHeader     Vary: Cookie<br>
    -   RespHeader     Last-Modified: Mon, 23 May 2016 09:07:23 GMT<br>
    -   RespHeader     Cache-Control: max-age=0<br>
    -   RespHeader     X-Frame-Options: SAMEORIGIN<br>
    -   RespHeader     Content-Type: text/html; charset=utf-8<br>
    -   RespHeader     Set-Cookie: 
    csrftoken=5BUZRL4gdO7uTDtWXnbqQko3CelDmOAg; expires=Mon, 22-May-2017
    09:07:23 GMT; Max-Age=31449600; Path=/<br>
    -   RespHeader     Date: Mon, 23 May 2016 09:07:23 GMT<br>
    -   RespHeader     X-Varnish: 2<br>
    -   RespHeader     Age: 0<br>
    -   RespHeader     Via: 1.1 varnish-v4<br>
    -   VCL_call       DELIVER<br>
    -   VCL_return     deliver<br>
    -   Timestamp      Process: 1463994443.735341 0.749249 0.000054<br>
    -   RespHeader     Accept-Ranges: bytes<br>
    -   RespHeader     Content-Length: 0<br>
    -   Debug          "RES_MODE 2"<br>
    -   RespHeader     Connection: close<br>
    -   Timestamp      Resp: 1463994443.735410 0.749319 0.000070<br>
    -   ReqAcct        929 0 929 476 0 476<br>
    -   End            <br>
    <br>
    *   << Session  >> 1         <br>
    -   Begin          sess 0 HTTP/1<br>
    -   SessOpen       127.0.0.1 56147 0.0.0.0:9003 127.0.0.1 9003
    1463994442.985890 18<br>
    -   Link           req 2 rxreq<br>
    -   SessClose      RESP_CLOSE 0.750<br>
    -   End            <br>
    <br>
    Thanks,<br>
    Pinakee<br>
    <div class="moz-cite-prefix">On 23/05/16 11:21 pm, Per Buer wrote:<br>
    </div>
    <blockquote
cite="mid:CAOXZevD+gBcsPCna7DUsmDF1dd=s9pELNbNxOHJG0k0S9JHANw@mail.gmail.com"
      type="cite">
      <div dir="ltr"><br>
        <div class="gmail_extra"><br>
          <div class="gmail_quote">On Fri, May 20, 2016 at 4:38 PM,
            Pinakee BIswas <span dir="ltr"><<a
                moz-do-not-send="true" href="mailto:pinakee@waltzz.com"
                target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:pinakee@waltzz.com">pinakee@waltzz.com</a></a>></span> wrote:<br>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Hi,<br>
              <br>
              I am a beginner with Varnish and planning to deploy it for
              our ecommerce live platform. I am trying to learn Varnish
              and VCL and having trouble for our specific scenario:<br>
              <br>
              I would like to cache pages when a user is not logged in -
              and this is determined by a cookie (which is standard).
              The ecommerce platform is based on python Django - and
              there are bunch of other cookies which are not relevant
              for caching but they can't be unset/removed as they are
              needed by the origin/backend server.<br>
              <br>
              Hence, the solution would be to check if the login cookie
              is present or not. If login cookie not present, cache the
              page and fetch from cache else pass it to the backend.<br>
            </blockquote>
            <div><br>
            </div>
            <div>Two tips. One is the cookie VMOD, which helps when
              dealing with cookies. If you don't wanna use it you can
              also look at the example here: <a moz-do-not-send="true"
href="https://www.varnish-cache.org/docs/4.1/users-guide/increasing-your-hitrate.html#cookies">https://www.varnish-cache.org/docs/4.1/users-guide/increasing-your-hitrate.html#cookies</a>
              - it will at least point you in the right direction.</div>
            <div><br>
            </div>
            <div> </div>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">I
              tried implementing the above logic in vcl_recv and
              vcl_backend_response with my limited knowledge, but
              varnish started serving blank pages.<br>
            </blockquote>
            <div><br>
            </div>
            <div>That sounds like a backend bug.</div>
            <div><br>
            </div>
          </div>
          -- <br>
          <div class="gmail_signature">
            <div dir="ltr">
              <div>
                <div dir="ltr">
                  <table
style="border-bottom-width:1px;padding-top:5px;border-top-style:solid;width:550px;padding-bottom:5px;border-bottom-color:rgb(238,238,238);border-top-width:1px;border-bottom-style:solid;line-height:1.5em;border-top-color:rgb(238,238,238);color:rgb(102,102,102);font-size:12px;font-family:'Helvetica
                    Neue',Arial,sans-serif;margin-top:20px" border="0"
                    cellpadding="0" cellspacing="0">
                    <tbody>
                      <tr>
                        <td width="100"><img moz-do-not-send="true"
                            src="http://www.varnish-software.com/static/media/logo-email.png"></td>
                        <td><font color="#222222"><span
                              style="font-size:14px"><b>Per Buer</b></span></font><br>
                          CTO | Varnish Software AS<br>
                          Cell: <a moz-do-not-send="true"
                            value="+4790181750"
                            style="color:rgb(17,85,204)">+47 95839117</a><br>
                          <span style="font-weight:bold">We Make
                            Websites Fly!<br>
                            <a moz-do-not-send="true"
                              href="https://www.varnish-software.com/"
                              style="color:rgb(17,85,204)"
                              target="_blank">www.varnish-software.com</a></span></td>
                      </tr>
                    </tbody>
                  </table>
                  <br>
                  <div style="color:rgb(136,136,136)"><a
                      moz-do-not-send="true"
                      href="http://info.varnish-software.com/signature"
                      target="_blank"><img moz-do-not-send="true"
                        src="http://files.varnish-software.com/signature.png"></a><br>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </blockquote>
    <br>
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