yaml syntax error when defining variables using WHEN - yaml

Question

I defined these in defaults/main.yml:
- mode : production
- consul_server_address :192.168.1.5
when : mode == "production"
- consul_server_address :192.168.2.5
when : mode == "staging"
but I got:
The offending line appears to be:
- consul_server_address : 192.168.1.5
when : mode == "production"
^ here
When I add a space after colons on consul_server_address, the error changes to:
ERROR! The default/main.yml file for role 'dnsmasq' must contain a dictionary of
variables
I spent some time on yaml syntax but I think this idea is wrong and I should do using another ansible-playbook solution.

Answer 1

You start your YAML with:
- mode : production
- denotes a sequence item, so this line defines that the root element of your YAML document is a sequence. Another sequence item follows:
- consul_server_address : 192.168.1.5
But now, there is a line which is not a sequence item:
when : mode == "production"
This is invalid because we are at indentation level 0, which contains the root element, which is a sequence, which may only contain sequence items. But when : … is a mapping key and therefor illegal here.
What you probably want to do is this:
- mode : production
- consul_server_address : 192.168.1.5
when : mode == "production"
- consul_server_address : 192.168.2.5
when : mode == "staging"
By properly indenting the when lines, they are keys of the mapping contained in the sequence item.

Answer 2

Someone on Ansible's IRC channel suggested me to use groupvars/hostvars for this purpose.
I edited my hosts inventory file and did something like this:
[nginx-staging]
IP_ADDRESS OR FQDN
[nginx-staging:vars]
...
consul_server_address=192.168.2.5
[nginx-production]
IP_ADDRESS OR FQDN
[nginx-production:vars]
...
consul_server_address=192.168.1.5
and it worked for me with a simpler and more straight forward solution.