computer-playbook/roles/nginx-docker-reverse-proxy/templates/headers/content_security_policy.conf.j2

{# Create a namespace to hold the accumulated CSP parts #}
{% set ns = namespace(csp_parts=[]) %}

{# List of directives to build dynamically (except img-src) #}
{% set directives = [
     'default-src',
     'connect-src',
     'frame-ancestors',
     'frame-src',
     'script-src',
     'style-src',
     'font-src'
] %}

{# Build each directive line #}
{% for directive in directives %}
  {# Always start with 'self' #}
  {% set tokens = ["'self'"] %}

  {# Add any unsafe flags for this directive #}
  {% for flag in applications | get_csp_flags(application_id, directive) %}
    {% set tokens = tokens + [flag] %}
  {% endfor %}

  {# If Matomo is enabled, allow its script and connect endpoints #}
  {% if applications | is_feature_enabled('matomo', application_id)
       and directive in ['script-src', 'connect-src'] %}
    {% set tokens = tokens + [web_protocol ~ '://' ~ domains.matomo] %}
  {% endif %}

  {# Append any extra whitelist URLs for this directive #}
  {% for url in applications | get_csp_whitelist(application_id, directive) %}
    {% set tokens = tokens + [url] %}
  {% endfor %}

  {# Store the completed directive line in the namespace #}
  {% set ns.csp_parts = ns.csp_parts + [directive ~ ' ' ~ (tokens | join(' ')) ~ ';'] %}
{% endfor %}

{# Add the (static) img-src directive #}
{% set ns.csp_parts = ns.csp_parts + ['img-src * data: blob:;'] %}

{# Emit the final header and hide any upstream header #}
add_header Content-Security-Policy "{{ ns.csp_parts | join(' ') }}" always;
proxy_hide_header Content-Security-Policy;