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Document compare_policies utility in AWS guidelines. (#37174)

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Ed Costello 2018-03-10 10:19:55 +13:00 committed by Ryan Brown
parent cb53b717a4
commit 1ceaf84108
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39
lib/ansible/modules/cloud/amazon/GUIDELINES.md
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@ -385,19 +385,29 @@ argument_spec.update(
```
Note that AWS is unlikely to return the policy in the same order that is was submitted. Therefore,
a helper function has been created to order policies before comparison.
use the `compare_policies` helper function which handles this variance.
`compare_policies` takes two dictionaries, recursively sorts and makes them hashable for comparison
and returns True if they are different.
```python
# Get the policy from AWS
current_policy = aws_object.get_policy()
from ansible.module_utils.ec2 import compare_policies
# Compare the user submitted policy to the current policy but sort them first
if sort_json_policy_dict(user_policy) == sort_json_policy_dict(current_policy):
# Nothing to do
pass
else:
import json
......
# Get the policy from AWS
current_policy = json.loads(aws_object.get_policy())
user_policy = json.loads(module.params.get('policy'))
# Compare the user submitted policy to the current policy ignoring order
if compare_policies(user_policy, current_policy):
# Update the policy
aws_object.set_policy(user_policy)
else:
# Nothing to do
pass
```
### Dealing with tags
@ -472,13 +482,24 @@ Pass this function a list of security group names or combination of security gro
and this function will return a list of IDs. You should also pass the VPC ID if known because
security group names are not necessarily unique across VPCs.
#### compare_policies
Pass two dicts of policies to check if there are any meaningful differences and returns true
if there are. This recursively sorts the dicts and makes them hashable before comparison.
This method should be used any time policies are being compared so that a change in order
doesn't result in unnecessary changes.
#### sort_json_policy_dict
Pass any JSON policy dict to this function in order to sort any list contained therein. This is
useful because AWS rarely return lists in the same order that they were submitted so without this
function, comparison of identical policies returns false.
### compare_aws_tags
Note if your goal is to check if two policies are the same you're better to use the `compare_policies`
helper which sorts recursively.
#### compare_aws_tags
Pass two dicts of tags and an optional purge parameter and this function will return a dict
containing key pairs you need to modify and a list of tag key names that you need to remove. Purge