How do I pass boolean Environmental Variables to a `when` step in CircleCI? - bash

Question

I want to do something along the lines of
commands:
send-slack:
parameters:
condition:
type: env_var_name
steps:
- when:
# only send if it's true
condition: << parameters.condition >>
steps:
- run: # do some stuff if it's true
jobs:
deploy:
steps:
- run:
name: Prepare Message
command: |
# Do Some stuff dynamically to figure out what message to send
# and save it to success_message or failure_message
echo "export success_message=true" >> $BASH_ENV
echo "export failure_message=false" >> $BASH_ENV
- send-slack:
text: "yay"
condition: success_message
- send-slack:
text: "nay"
condition: failure_message
```

Answer 1

Based on this documentation, you cannot use environment variables as conditions in CircleCI. This is because the when logic is done when the configuration is processed (ie, before the job actually runs and the environment variables are set). As an alternative, I would add the logic to a separate run step (or the same initial one).
jobs:
deploy:
steps:
- run:
name: Prepare Message
command: |
# Do Some stuff dynamically to figure out what message to send
# and save it to success_message or failure_message
echo "export success_message=true" >> $BASH_ENV
echo "export failure_message=false" >> $BASH_ENV
- run:
name: Send Message
command: |
if $success_message; then
# Send success message
fi
if $failure_message; then
# Send failure message
fi
Here is a relevant ticket on the CircleCI discussion board.