Environment variables in VCL

[Hugues Alary]

Hi Vlad,

Thanks for the suggestion. I was using Helm and I'm actually running into
this issue because I'm migrating away from Helm to use Kustomize. Using
`envsubst` is what I set out to do in the end! I'm not a fan of having to
add an init container just for templating, but ����‍♂️.

Cheers,
-Hugues

On Tue, Sep 10, 2019 at 1:55 PM Vlad Rusu <vlad.rusu at lola.tech> wrote:

> @Hugues
>
> I am also a heavy user in kube/openshift environments and this issue is
> addressed by means of templating.
>
> Using tools like helm would easily solve this for you. Helm has the value
> and it uses it when rendering the backends file - in the form of a
> configmap perhaps.
>
> If you can’t/don’t want to use helm, you can still “render” configuration
> by consuming values from the ENV by using envsubst for example. This is how
> we dis it before helm. Burn the backends.vcl file AT RUNTIME by passing the
> backends.vcl file through envsubst.
>
> Either way, my recommendation is to solve this through templating and not
> by trying to access ENV directly from the the backends VCL. I’m saying this
> having a proper SDLC in mind.
>
> Of course, dynamic backends and all other options Guillaume and
> Paul-Henning have mentioned are solid.
>
> Vlad Rusu
>
> On Tue, 10 Sep 2019 at 22:14, Hugues Alary <hugues at betabrand.com> wrote:
>
>> Guillaume, Poul-Henning, thank you for your suggestions.
>>
>> Regarding,
>> > - create a static backend point to you k8s proxy, and just set
>> req.http.host to whatever value you want.
>>
>> I don't think this would work for me since I'm working with a backend
>> definition, trying to change the IP address (/hostname) to which the
>> backend points to and not simply trying to change the Host header of the
>> request.
>>
>> Cheers,
>> -Hugues
>>
>>
>>
>> On Mon, Sep 9, 2019 at 11:54 PM Guillaume Quintard <
>> guillaume at varnish-software.com> wrote:
>>
>>> True, but that amounts to template processing :-)
>>>
>>> --
>>> Guillaume Quintard
>>>
>>>
>>> On Tue, Sep 10, 2019 at 8:44 AM Poul-Henning Kamp <phk at phk.freebsd.dk>
>>> wrote:
>>>
>>>> --------
>>>> In message <
>>>> CAJ6ZYQy5RnBjfCs88re6-hMfsQvyuzbOkHoofQ_c+suQNRQjig at mail.gmail.com>
>>>> , Guillaume Quintard writes:
>>>>
>>>> >I see two ways:
>>>>
>>>> There is a third way:
>>>>
>>>> You can use:
>>>>
>>>>         include "somefile"
>>>>
>>>> anywhere and everywhere in a VCL program.
>>>>
>>>> Before you start your varnishd, do this in a shell script:
>>>>
>>>>         echo "\"$ENVIRONMENT_VARIABLE_HOSTNAME\"" >
>>>> /somewhere/hostname.vcl
>>>>
>>>> Then in VCL:
>>>>
>>>>         backend b0 {
>>>>                 .host = include "/somewhere/hostname.vcl" ;
>>>>                 .port 80
>>>>                 ...
>>>>
>>>>
>>>>
>>>> --
>>>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>>>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>>>> FreeBSD committer       | BSD since 4.3-tahoe
>>>> Never attribute to malice what can adequately be explained by
>>>> incompetence.
>>>>
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> --
> Sent from my iPhone
>
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