diff --git a/changelogs/fragments/undo_hashmerge_depr.yml b/changelogs/fragments/undo_hashmerge_depr.yml new file mode 100644 index 00000000000..5990ee4edf7 --- /dev/null +++ b/changelogs/fragments/undo_hashmerge_depr.yml @@ -0,0 +1,2 @@ +bugfixes: + - undeprecate hash_merge setting and add more docs clarifying its use and why not to use it. diff --git a/lib/ansible/config/base.yml b/lib/ansible/config/base.yml index 616514b71f2..3f1559fd1f6 100644 --- a/lib/ansible/config/base.yml +++ b/lib/ansible/config/base.yml @@ -786,23 +786,29 @@ DEFAULT_HASH_BEHAVIOUR: name: Hash merge behaviour default: replace type: string - choices: ["replace", "merge"] - description: - - This setting controls how variables merge in Ansible. - By default Ansible will override variables in specific precedence orders, as described in Variables. - When a variable of higher precedence wins, it will replace the other value. - - "Some users prefer that variables that are hashes (aka 'dictionaries' in Python terms) are merged. - This setting is called 'merge'. This is not the default behavior and it does not affect variables whose values are scalars - (integers, strings) or arrays. We generally recommend not using this setting unless you think you have an absolute need for it, - and playbooks in the official examples repos do not use this setting" - - In version 2.0 a ``combine`` filter was added to allow doing this for a particular variable (described in Filters). + choices: + replace: Any variable that is defined more than once is overwritten using the order from variable precedence rules (highest wins). + merge: Any dictionary variable will be recursively merged with new definitions across the different variable definition sources. + description: + - This setting controls how duplicate definitions of dictionary variables (aka hash, map, associative array) are handled in Ansible. + - This does not affect variables whose values are scalars (integers, strings) or arrays. + - "**WARNING**, changing this setting is not recommended as this is fragile and makes your content (plays, roles, collections) non portable, + leading to continual confusion and misuse. Don't change this setting unless you think you have an absolute need for it." + - We recommend avoiding reusing variable names and relying on the ``combine`` filter and ``vars`` and ``varnames`` lookups + to create merged versions of the individual variables. In our experience this is rarely really needed and a sign that too much + complexity has been introduced into the data structures and plays. + - For some uses you can also look into custom vars_plugins to merge on input, even substituting the default ``host_group_vars`` + that is in charge of parsing the ``host_vars/`` and ``group_vars/`` directories. Most users of this setting are only interested in inventory scope, + but the setting itself affects all sources and makes debugging even harder. + - All playbooks and roles in the official examples repos assume the default for this setting. + - Changing the setting to ``merge`` applies across variable sources, but many sources will internally still overwrite the variables. + For example ``include_vars`` will dedupe variables internally before updating Ansible, with 'last defined' overwriting previous definitions in same file. + - The Ansible project recommends you **avoid ``merge`` for new projects.** + - It is the intention of the Ansible developers to eventually deprecate and remove this setting, but it is being kept as some users do heavily rely on it. + New projects should **avoid 'merge'**. env: [{name: ANSIBLE_HASH_BEHAVIOUR}] ini: - {key: hash_behaviour, section: defaults} - deprecated: - why: this feature is fragile and not portable, leading to continual confusion and misuse - version: "2.13" - alternatives: the ``combine`` filter explicitly DEFAULT_HOST_LIST: name: Inventory Source default: /etc/ansible/hosts