Nginx map - use variable multiple times or use multiple variables

[stmx38]

Hello,

We use Nginx map module to sent traffic to different upstreams based on the
HTTP header:

map $http_flow $flow_upstream {
  default "http://flow-dev";
  prod    "http://flow-prod";
  test    "http://flow-test";
  dev     "http://flow-dev";
}

  location / {
    proxy_read_timeout 5s;
    proxy_pass $flow_upstream;
  }

Now, we want to define a different timeouts to different flows:

map $http_flow $read_timeout {
  default 15s;
  prod    5s;
  test    10s;
  dev     15s;
}

  location / {
    proxy_read_timeout $read_timeout;
    proxy_pass $flow_upstream;
  }

Bunt Nginx config test show the error here:
nginx -t
nginx: [emerg] "proxy_send_timeout" directive invalid value in
/etc/nginx/conf.d/flow.conf:19
nginx: configuration file /etc/nginx/nginx.conf test failed

Can we use map in such a way?

Or maybe something like this:
map $http_flow $flow_upstream $read_timeout {
  default "http://flow-dev"  "15s";
  prod    "http://flow-prod" "5s";
  test    "http://flow-test" "10s";
  dev     "http://flow-dev"  "15s";
}

Thank you!

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,286421,286421#msg-286421