title: Make nginx configurable with kubernetes secret?
body: <p>I have a working openresty with lua-resty-openidc as ingress controller.
  Now, the nginx.conf is hardcoded in my image, with something like this :</p>
  
  <pre><code>    server {
          server_name  _;
          listen       80;
  
          location /OAuth2Client {
              access_by_lua_block {
                  local opts = {
                      discovery = "/.well-known/openid-configuration",
                      redirect_uri = "/authorization-code/callback",
                      client_id = "clientID",
                      client_secret = "clientSecret",
                      scope = "openid profile somethingElse",
                  }
      ...
              }
              proxy_pass http://clusterIp/OAuth2Client;
          }
      }
  </code></pre>
  
  <p>As Nginx doesn't accept environment variables, is there a simple way to make my nginx.conf configurable, for ex</p>
  
  <pre><code>    server {
          server_name  ${myServerName};
          listen       ${myServerPort};
  
          location /${specificProjectRoot} {
              access_by_lua_block {
                  local opts = {
                      discovery = "${oidc-provider-dev-url}/.well-known/openid-configuration",
                      redirect_uri = "${specificProjectRoot}/authorization-code/callback",
                      client_id = "${myClientId}",
                      client_secret = "${myClientSecret}",
                      scope = "${myScopes}",
                  }
      ...
              }
              proxy_pass http://${myClusterIP}/${specificProjectRoot};
          }
      }
  </code></pre>
  
  <p>so that whatever team in whatever namespace could reuse my image and just provide a kubernetes secret containing their specific config for their project ?</p>