location blocks, and if conditions in server context

[Peter Booth]

I agree that avoiding if is a good thing. But avoiding duplication isn’t always good. 

Have you considered a model where your configuration file is generated with a templating engine? The input file that you modify to add/remove/change configurations could be free of duplication but the conf file that nginx reads could be concrete and verbose 

Sent from my iPhone

> On Mar 7, 2018, at 11:55, Lucas Rolff <lucas at lucasrolff.com> wrote:
> 
> Hi guys,
>  
> I have a few hundred nginx zones, where I try to remove as much duplicate code as possible, and inherit as much as possible to prevent nginx from consuming memory (and also to keep things clean).
> 
> However I came across something today, that I don’t know how to get my head around without duplicating code, even within a single server context.
>  
> I have a set of distributed nginx servers, all these requires SSL certificates, where I use Let’s Encrypt to do this.
> When doing the Let’s Encrypt validation, it uses a path such as /.well-known/acme-challenge/<hash>
>  
> For this, I made a location block such as:
>  
>     location ~* /.well-known {
>         proxy_pass http://letsencrypt.validation.backend.com$request_uri;
>     }
>  
> Basically, I proxy_pass to the backend where I actually run the acme client – works great.
>  
> However, I have an option to force a redirect from http to https, and I’ve implemented that by doing an if condition on the server block level (so not within a location):
>  
>     if ($sslproxy_protocol = "http") {
>         return 301 https://$host$request_uri;
>     }
>  
> This means I have something like:
>  
> 1: location ~* /.well-known
> 2: if condition doing redirect if protocol is http
> 3: location /
> 4: location /api
> 5: location /test
>  
> All my templates include 1 to 3, and *might* have additional locations.
> I’ve decided to not put e.g. location /api inside the location / - because there’s things I don’t want to inherit, thus keeping them at the same “level”, and not a location context inside a location context.
> Things I don’t want to inherit, is stuff such as headers, max_ranges directive etc.
>  
> My issue is – because of this if condition that does the redirect to https – it also applies to my location ~* /.well-known – thus causing a redirect, and I want to prevent this, since it breaks the Let’s Encrypt validation (they do not accept 301 redirects).
>  
> A solution would be to move the if condition into each location block that I want to have redirected, but then I start repeating myself 1, 2 or even 10 times – which I don’t wanna do.
>  
> Is there a smart way without adding too much complexity, which is still super-fast (I know if is evil) ?
>  
> A config example is seen below:
>  
> server {
>     listen              80;
>     listen              443 ssl http2;
>  
>     server_name         secure.domain.com;
>  
>     access_log /var/log/nginx/secure.domain.com main;
>  
>     location ~* /.well-known {
>         proxy_pass http://letsencrypt.validation.backend.com$request_uri;
>     }
>  
>     if ($sslproxy_protocol = "http") {
>         return 301 https://$host$request_uri;
>     }
>  
>     location / {
>  
>         expires 10m;
>         etag off;
>  
>         proxy_ignore_client_abort   on;
>         proxy_intercept_errors      on;
>         proxy_next_upstream         error timeout invalid_header;
>         proxy_ignore_headers        Set-Cookie Vary X-Accel-Expires Expires Cache-Control;
>         more_clear_headers          Set-Cookie Cookie Upgrade;
>  
>         proxy_cache                 one;
>         proxy_cache_min_uses        1;
>         proxy_cache_lock            off;
>         proxy_cache_use_stale       error timeout invalid_header updating http_500 http_502 http_503 http_504;
>  
>         proxy_cache_valid 200           10m;
>         proxy_cache_valid any           1m;
>  
>         proxy_cache_revalidate      on;
>         proxy_ssl_server_name       on;
>  
>         include /etc/nginx/server.conf;
>  
>         proxy_set_header Host backend-host.com;
>  
>         proxy_cache_key    "http://backend-host.com-1-$request_uri";
>         proxy_pass         http://backend-host.com$request_uri;
>  
>         proxy_redirect              off;
>     }
> }
>  
> Thank you in advance!
>  
> Best Regards,
> Lucas Rolff
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