{#- prologue -#}
{%- set extra_proto = ['v3', 'v2'] -%}
{%- set confload = ( env.NGX_HTTP_CONFLOAD or '' ) | str_split_to_list -%}
{%- set proto = confload | list_intersect(extra_proto) -%}
{#- ALPN mapping -#}
{%- set proto = proto | re_sub('^v2$', 'h2=":443"; ma=3600') -%}
{%- set proto = proto | re_sub('^v3$', 'h3=":443"; ma=3600') -%}
{#- main part -#}
{%- if proto %}
{#- TODO: precise quotation #}
add_header  Alt-Svc  {{ (proto | join(', ')).__repr__() }};
{%- endif %}