Fix OCSP-stapling-related errors due to missing resolver

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1057

roles/matrix-nginx-proxy/defaults/main.yml

@@ -289,7 +289,7 @@ matrix_nginx_proxy_floc_optout_enabled: true
 
 # HSTS Preloading Enable
 #
-# In its strongest and recommended form, the [HSTS policy](https://www.chromium.org/hsts) includes all subdomains, and 
+# In its strongest and recommended form, the [HSTS policy](https://www.chromium.org/hsts) includes all subdomains, and
 # indicates a willingness to be “preloaded” into browsers:
 # `Strict-Transport-Security: max-age=31536000; includeSubDomains; preload`
 # For more information visit:
@@ -357,6 +357,18 @@ matrix_nginx_proxy_self_check_validate_certificates: true
 # so we default to not following redirects as well.
 matrix_nginx_proxy_self_check_well_known_matrix_client_follow_redirects: none
 
+# For OCSP purposes, we need to define a resolver at the `server{}` level or `http{}` level (we do the latter).
+#
+# Otherwise, we get warnings like this:
+# > [warn] 22#22: no resolver defined to resolve r3.o.lencr.org while requesting certificate status, responder: r3.o.lencr.org, certificate: "/matrix/ssl/config/live/.../fullchain.pem"
+#
+# We point it to the internal Docker resolver, which likely delegates to nameservers defined in `/etc/resolv.conf`.
+#
+# When nginx proxy is disabled, our configuration is likely used by non-containerized nginx, so can't use the internal Docker resolver.
+# Pointing `resolver` to some public DNS server might be an option, but for now we impose DNS servers on people.
+# It might also be that no such warnings occur when not running in a container.
+matrix_nginx_proxy_http_level_resolver: "{{ '127.0.0.11' if matrix_nginx_proxy_enabled else '' }}"
+
 # By default, this playbook automatically retrieves and auto-renews
 # free SSL certificates from Let's Encrypt.
 #
@@ -416,7 +428,7 @@ matrix_ssl_pre_obtaining_required_service_start_wait_time_seconds: 60
 # Nginx Optimize SSL Session
 #
 # ssl_session_cache:
-# - Creating a cache of TLS connection parameters reduces the number of handshakes 
+# - Creating a cache of TLS connection parameters reduces the number of handshakes
 #   and thus can improve the performance of application.
 # - Default session cache is not optimal as it can be used by only one worker process
 #   and can cause memory fragmentation. It is much better to use shared cache.
@@ -425,7 +437,7 @@ matrix_ssl_pre_obtaining_required_service_start_wait_time_seconds: 60
 # ssl_session_timeout:
 # - Nginx by default it is set to 5 minutes which is very low.
 #   should be like 4h or 1d but will require you to increase the size of cache.
-# - Learn More: 
+# - Learn More:
 #     https://github.com/certbot/certbot/issues/6903
 #     https://github.com/mozilla/server-side-tls/issues/198
 #

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-base-domain.conf.j2

@@ -9,13 +9,13 @@
 	{% if matrix_nginx_proxy_floc_optout_enabled %}
 		add_header Permissions-Policy interest-cohort=() always;
 	{% endif %}
-	
+
 	{% if matrix_nginx_proxy_hsts_preload_enabled %}
 		add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
 	{% else %}
 		add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
 	{% endif %}
-	
+
 	add_header X-XSS-Protection "{{ matrix_nginx_proxy_xss_protection }}";
 
 	{% for configuration_block in matrix_nginx_proxy_proxy_domain_additional_server_configuration_blocks %}
@@ -77,13 +77,13 @@ server {
 	ssl_ciphers {{ matrix_nginx_proxy_ssl_ciphers }};
 	{% endif %}
 	ssl_prefer_server_ciphers {{ matrix_nginx_proxy_ssl_prefer_server_ciphers }};
-	
+
 	{% if matrix_nginx_proxy_ocsp_stapling_enabled %}
 		ssl_stapling on;
 		ssl_stapling_verify on;
 		ssl_trusted_certificate {{ matrix_ssl_config_dir_path }}/live/{{ matrix_nginx_proxy_base_domain_hostname }}/chain.pem;
 	{% endif %}
-	
+
 	{% if matrix_nginx_proxy_ssl_session_tickets_off %}
 		ssl_session_tickets off;
 	{% endif %}

roles/matrix-nginx-proxy/templates/nginx/conf.d/nginx-http.conf.j2

@@ -4,6 +4,11 @@
 #
 # Thus, we ensure a larger bucket size value is used.
 server_names_hash_bucket_size 64;
+
+{% if matrix_nginx_proxy_http_level_resolver %}
+	resolver {{ matrix_nginx_proxy_http_level_resolver }};
+{% endif %}
+
 {% for configuration_block in matrix_nginx_proxy_proxy_http_additional_server_configuration_blocks %}
 	{{- configuration_block }}
 {% endfor %}