How to prevent variable substitution

[orbitalmedia]

Using this puppet code, my goal is to preserve the variable $upstream that is written to the config file. However it is always substituted for the actual value. The reason for the substitution is detailed here

$upstream = "http://acme.unix.local"
nginx::resource::vhost { 'acme.co':
listen_port => 8080,
server_name => [
'www.acme.co'
],
proxy => "$upstream",
}

This is intended ,
location / {
proxy_pass $upstream;
}

Unfortunately I am getting this result ,
location / {
proxy_pass http://acme.unix.local;
}

Any suggestions welome

[3flex]

This is Puppet interpolating the string. See https://docs.puppet.com/puppet/latest/reference/lang_variables.html#interpolation

If you don't want it to interpolate and pass $upstream as is then surround it with single quotes, i.e. proxy => '$upstream', or escape the dollar sign so the string isn't treated as a variable: proxy => "\$upstream"