Zola macro for detecting if website is running in Cloudflare Pages or not, and to substitute a cloudflare pages URL for a canonical one

util.html

{# This macro will provide the canonical URL if running in production, see 'private' below #}
{%- macro cf_url_to_canonical() -%}
{{ self::cf_url_to_canonical_private() | trim }}
{%- endmacro  -%}

{# Note: 'private' because this macro leaves space, so it's trimmed in the 'public' version #}
{% macro cf_url_to_canonical_private() %}
{# https://developers.cloudflare.com/pages/platform/build-configuration/#environment-variables #}
{% set CF_PAGES = get_env(name="CF_PAGES", default="0") %}

{# If in cloudflare environment #}
{% if CF_PAGES == "1" %}

{# If git branch is 'main' (see config.toml), return canonical url #}
{% if get_env(name="CF_PAGES_BRANCH") == config.extra.main_branch %}
{{ config.extra.canonical_url }}

{# Otherwise return cloudflare provided URL#}
{% else %}
{{ get_env(name="CF_PAGES_URL") }}
{% endif %}
{% endif %}

{# Macro returns `base_url` if not in cloudflare environment #}
{% if CF_PAGES != "1" %}
{{ config.base_url }}
{% endif %}

{% endmacro %}