Avoiding "(null)" in log output for unset VCL variable

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joeshaw

• February 01, 2016 21:16

In my log format string, I am using a VCL variable like resp.http.X-Foo. If that header is not set, (null) is output. To make parsing easier, I’d prefer if an empty string were output instead. Is that possible?

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  joeshaw

  • February 01, 2016 21:33

  I just came across the if() Fastly VCL extension. Could that be used here?

  https://docs.fastly.com/guides/vcl/miscellaneous-VCL-extensions#if

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  Caslyn Cole

  • February 01, 2016 21:41

  Hi Joe,

  Yep! This would be a great scenario to use the if() extension.

  You can add that directly into your logging format string, so it would look something like this: %h %l %u %t %r %>s if(resp.http.X-Foo, resp.http.X-Foo, "")

  Hopefully that helps!

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