mu yml env variables
mu allows users to refer to local environment variables within mu.yml,
using the special syntax:
${env:XXXXXX}
Lines containing this pattern are replaced with the environment variables of the user's local environment at the time of parsing.
This syntax ${env:XXXX} was chosen to distinguish the intention
of local environment substitution from other uses of ${XXXX}
in CloudFormation, that lack the env: prefix.
Although this feature is originally envisioned as being used for
yaml values (after the : character), there may also be an
occasional use for yaml keys. As implemented, the environment
variable substitution occurs on a line-by-line basis during
the parsing of the mu.yml.
NOTE: This effectively makes the environment an input to mu
itself, so if you use this feature extensively, you probably
want to consider a way of controlling this environment via
the creation of a setenv.sh file. Otherwise you may have
difficulties in replicating results from one user or system
to another.
See the example mu.yml in the directory ./examples/mu-yml-env-variables.