nginx-proxy.conf

# Required for govuk_publishing_components:
#   Rack::Lint::LintError at /
#   env missing required key SERVER_NAME
proxy_set_header Host $http_host;

# Required to pass the original request header to apps, useful for apps running
# behind router
map $http_x_forwarded_host $proxy_x_forwarded_host {
  default $http_x_forwarded_host;
  ''      $http_host;
}

proxy_set_header X-Forwarded-Host $proxy_x_forwarded_host;

map $http_govuk_request_id $govuk_request_id {
  default $http_govuk_request_id;
  ''      $request_id;
}

proxy_set_header GOVUK-Request-Id $govuk_request_id;

# Required for external assets of frontend apps
add_header 'Access-Control-Allow-Origin' '*';

# Required for uploading files on various apps
client_max_body_size 500m;

proxy_read_timeout 200s;

# Rails 6.1 introduced a preload_links_header which can produce particularly
# large HTTP headers when running applications in development mode. These
# large headers can exhaust nginx proxy buffers causing a 502 response, to
# counter this these buffers are increased from their default 8k size.
proxy_buffer_size 128k;
proxy_buffers 8 128k;
proxy_busy_buffers_size 128k;