Condition contains in nginx.tmpl

I am trying to create a custom conditional using the contains function, as shown in this code.

### begin ssl_certificate {{ if (contains "health.co.id" $cert) }} ssl_certificate /etc/nginx/certs/STAR_health_co_id.pem; {{ end }} {{ if (contains "assistance.net" $cert) }} ssl_certificate /etc/nginx/certs/star_assistance_net.crt; {{ end }} ### end ssl_certificate

However, the condition does not evaluate to true, even though the cert variable contains the expected string.

What am I doing incorrectly here?