Environment variable availability during hooks.
Map the NAME environment variable to different names, based on the stage.
$ up env set NAME Tobi
$ up env set -s staging NAME Loki
$ up env set -s production NAME Jane
Deploy each stage:
$ up
$ up production
View each response:
$ curl -s `up url`
# contains: Hello Loki from staging
$ curl -s `up url production`
# contains: Hello Jane from production
This example illustrates how environment variables are available at build time, so you may utilize vars mapped to the stage you are deploying to alter configuration, client-side builds, and so on. Note that UP_STAGE and NODE_ENV by default will be the target stage name (staging, production).