* templating (variables in playbooks and template lookups) has improved with regard to keeping the original instead of turning everything into a string.
You can override the `null_representation` setting to an empty string in your config file by setting the `ANSIBLE_NULL_REPRESENTATION` environment variable.
* Extras callbacks must be whitelisted in ansible.cfg. Copying is no longer necessary but whitelisting in ansible.cfg must be completed.
* dnf module has been rewritten. Some minor changes in behavior may be observed.
* win_updates has been rewritten and works as expected now.
Deprecated
----------
While all items listed here will show a deprecation warning message, they still work as they did in 1.9.x. Please note that they will be removed in 2.2 (Ansible always waits two major releases to remove a deprecated feature).
* Undefined variables within a `with_` loop’s list currently do not interrupt the loop, but they do issue a warning; in the future, they will issue an error.
* Setting any_errors_fatal on a task is no longer supported. This should be set at the play level only.
* Bare variables in the `environment` dictionary (for plays/tasks/etc.) are no longer supported. Variables specified there should use the full variable syntax: ‘{{foo}}’.
* Tags (or any directive) should no longer be specified with other parameters in a task include. Instead, they should be specified as an option on the task.
Here are some corner cases encountered when updating, these are mostly caused by the more stringent parser validation and the capture of errors that were previouslly ignored.
* Bad variable composition::
with_items: myvar_{{rest_of_name}}
This worked 'by accident' as the errors were retemplated and ended up resolving the variable, it was never intended as valid syntax and now properly returns an error, use the following instead.::
The task always ran without using privilege escalation (for that you need `become`) but was also silently ignored so the play 'ran' even though it should not, now this is a parsing error.
* Duplicate directives::
- task: dostuf
when: True
when: False
The first `when` was ignored and only the 2nd one was used as the play ran w/o warning it was ignoring one of the directives, now this produces a parsing error.
* Conflating variables and directives::
- role: {name=rosy, port=435 }
# in tasks/main.yml
- wait_for: port={{port}}
The `port` variable is reserved as a play/task directive for overriding the connection port, in previous versions this got conflated with a variable named `port` and was usable
later in the play, this created issues if a host tried to reconnect or was using a non caching connection. Now it will be correctly identified as a directive and the `port` variable
will appear as undefined, this now forces the use of non conflicting names and removes ambiguity when adding settings and varaibles to a role invocation..
* Bare operations on `with_`::
with_items: var1 + var2
An issue with the 'bare variable' features, which was supposed only tempate a single variable without the need of braces ({{ )}}, would in some versions of Ansible template full expressions.
Now you need to use proper templating and braces for all expressions everywhere except condtionals (`when`)::
In ansible-1.9.x, you would generally copy an existing plugin to create a new one. Simply implementing the methods and attributes that the caller of the plugin expected made it a plugin of that type. In ansible-2.0, most plugins are implemented by subclassing a base class for each plugin type. This way the custom plugin does not need to contain methods which are not customized.