Policy syntax and inheritance for management policy types - AWS Organizations

Policy syntax and inheritance for management policy types

Important

The information in this section does not apply to SCPs. See the previous section Inheritance for service control policies.

Management policy types include:

Inheritance behaves differently for management policy types than it does for service control policies. The syntax for management policy types includes inheritance operators, which enable you to specify with fine granularity what elements from the parent policies are applied and what elements can be overridden or modified when inherited by child OUs and accounts.

The effective policy is the set of rules that are inherited from the organization root and OUs along with those directly attached to the account. The effective policy specifies the final set of rules that apply to the account. You can view the effective policy for an account that includes the effect of all of the inheritance operators in the policies applied. For more information, see Viewing effective tag policies.

This section explains how parent policies and child policies are processed into the effective policy for an account.

Terminology

This topic uses the following terms when discussing policy inheritance.

Policy inheritance

The interaction of policies at differing levels of an organization, moving from the top-level root of the organization, down through the organizational unit (OU) hierarchy to individual accounts.

You can attach policies to the organization root, OUs, individual accounts, and to any combination of these organization entities. Policy inheritance refers to policies that are attached to the organization root or to an OU. All accounts that are members of the organization root or OU where a policy is attached inheritthat policy.

For example, when policies are attached to the organization root, all accounts in the organization inherit that policy. That's because all accounts in an organization are always under the organization root. When you attach a policy to a specific OU, accounts that are directly under that OU or any child OU inherit that policy. Because you can attach policies to multiple levels in the organization, accounts might inherit multiple policy documents for a single policy type.

Parent policies

Policies that are attached higher in the organizational tree than policies that are attached to entities lower in the tree.

For example, if you attach policy A to the organization root, it's just a policy. If you also attach policy B to an OU under that root, policy A is the parent policy of Policy B. Policy B is the child policy of Policy A. Policy A and policy B merge to create the effective tag policy for accounts in the OU.

Child policies

Policies that are attached at a lower level in the organization tree than the parent policy.

Effective policies

The final, single policy document that specifies the rules that apply to an account. The effective policy is the aggregation of any policies the account inherits, plus any policy that is directly attached to the account. For example, tag policies enable you to view the effective tag policy that applies to any of your accounts. For more information, see Viewing effective tag policies.

Inheritance operators

Operators that control how inherited policies merge into a single effective policy. These operators are considered an advanced feature. Experienced policy authors can use them to limit what changes a child policy can make and how settings in policies merge.

Inheritance operators

Inheritance operators control how inherited policies and account policies merge into the account's effective policy. These operators include value-setting operators and child control operators.

When you use the visual editor in the AWS Organizations console, you can use only the @@assign operator. Other operators are considered an advanced feature. To use the other operators, you must manually author the JSON policy. Experienced policy authors can use inheritance operators to control what values are applied to the effective policy and limit what changes child policies can make.

Value-setting operators

You can use the following value-setting operators to control how your policy interacts with its parent policies:

  • @@assignOverwrites any inherited policy settings with the specified settings. If the specified setting isn't inherited, this operator adds it to the effective policy. This operator can apply to any policy setting of any type.

    • For single-valued settings, this operator replaces the inherited value with the specified value.

    • For multi-valued settings (JSON arrays), this operator removes any inherited values and replaces them with the values specified by this policy.

  • @@appendAdds the specified settings (without removing any) to the inherited ones. If the specified setting isn't inherited, this operator adds it to the effective policy. You can use this operator with only multi-valued settings.

    • This operator adds the specified values to any values in the inherited array.

  • @@removeRemoves the specified inherited settings from the effective policy, if they exist. You can use this operator with only multi-valued settings.

    • This operator removes only the specified values from the array of values inherited from the parent policies. Other values can continue to exist in the array and can be inherited by child policies.

Child control operators

Using child control operators is optional. You can use the @@operators_allowed_for_child_policies operator to control which value-setting operators child policies can use. You can allow all operators, some specific operators, or no operators. By default, all operators (@@all) are allowed.

  • "@@operators_allowed_for_child_policies":["@@all"] – Child OUs and accounts can use any operator in policies. By default, all operators are allowed in child policies.

  • "@@operators_allowed_for_child_policies":["@@assign", "@@append", "@@remove"] – Child OUs and accounts can use only the specified operators in child policies. You can specify one or more value-setting operators in this child control operator.

  • "@@operators_allowed_for_child_policies":["@@none"] – Child OUs and accounts can't use operators in policies. You can use this operator to effectively lock in the values that are defined in a parent policy so that child policies can't add, append, or remove those values.

Note

If an inherited child control operator limits the use of an operator, you can't reverse that rule in a child policy. If you include child control operators in a parent policy, they limit the value-setting operators in all child policies.

Policy inheritance examples

These examples show how policy inheritance works by showing how parent and child tag policies are merged into an effective tag policy for an account.

The examples assume that you have the organization structure shown in the following diagram.


                An organization with one root, two OUs, and several accounts.

Example 1: Allow child policies to overwrite only tag values

The following tag policy defines the CostCenter tag key and two acceptable values, Development and Support. If you attach it to the organization root, the tag policy is in effect for all accounts in the organization.

Policy A – Organization root tag policy

{ "tags": { "costcenter": { "tag_key": { "@@assign": "CostCenter" }, "tag_value": { "@@assign": [ "Development", "Support" ] } } } }

Assume that you want users in OU1 to use a different tag value for a key, and you want to enforce the tag policy for specific resource types. Because policy A doesn't specify which child control operators are allowed, all operators are allowed. You can use the @@assign operator and create a tag policy like the following to attach to OU1.

Policy B – OU1 tag policy

{ "tags": { "costcenter": { "tag_key": { "@@assign": "CostCenter" }, "tag_value": { "@@assign": [ "Sandbox" ] }, "enforced_for": { "@@assign": [ "redshift:*", "dynamodb:table" ] } } } }

Specifying the @@assign operator for the tag does the following when policy A and policy B merge to form the effective tag policy for an account:

  • Policy B overwrites the two tag values that were specified in the parent policy, policy A. The result is that Sandbox is the only compliant value for the CostCenter tag key.

  • The addition of enforced_for specifies that the CostCenter tag must be the specified tag value on all Amazon Redshift resources and Amazon DynamoDB tables.

As shown in the diagram, OU1 includes two accounts: 111111111111 and 222222222222.

Resultant effective tag policy for accounts 111111111111 and 222222222222

Note

You can't directly use the contents of a displayed effective policy as the contents of a new policy. The syntax doesn't include the operators needed to control merging with other child and parent policies. The display of an effective policy is intended only for understanding the results of the merger.

{ "tags": { "costcenter": { "tag_key": "CostCenter", "tag_value": [ "Sandbox" ], "enforced_for": [ "redshift:*", "dynamodb:table" ] } } }

Example 2: Append new values to inherited tags

There may be cases where you want all accounts in your organization to specify a tag key with a short list of acceptable values. For accounts in one OU, you may want to allow an additional value that only those accounts can specify when creating resources. This example specifies how to do that by using the @@append operator. The @@append operator is an advanced feature.

Like example 1, this example starts with policy A for the organization root tag policy.

Policy A – Organization root tag policy

{ "tags": { "costcenter": { "tag_key": { "@@assign": "CostCenter" }, "tag_value": { "@@assign": [ "Development", "Support" ] } } } }

For this example, attach policy C to OU2. The difference in this example is that using the @@append operator in policy C adds to, rather than overwrites, the list of acceptable values and the enforced_for rule.

Policy C – OU2 tag policy for appending values

{ "tags": { "costcenter": { "tag_key": { "@@assign": "CostCenter" }, "tag_value": { "@@append": [ "Marketing" ] }, "enforced_for": { "@@append": [ "redshift:*", "dynamodb:table" ] } } } }

Attaching policy C to OU2 has the following effects when policy A and policy C merge to form the effective tag policy for an account:

  • Because policy C includes the @@append operator, it allows for adding to, not overwriting, the list of acceptable tag values that are specified in Policy A.

  • As in policy B, the addition of enforced_for specifies that the CostCenter tag must be used as the specified tag value on all Amazon Redshift resources and Amazon DynamoDB tables. Overwriting (@@assign) and adding (@@append) have the same effect if the parent policy doesn't include a child control operator that restricts what a child policy can specify.

As shown in the diagram, OU2 includes one account: 999999999999. Policy A and policy C merge to create the effective tag policy for account 999999999999.

Effective tag policy for account 999999999999

Note

You can't directly use the contents of a displayed effective policy as the contents of a new policy. The syntax doesn't include the operators needed to control merging with other child and parent policies. The display of an effective policy is intended only for understanding the results of the merger.

{ "tags": { "costcenter": { "tag_key": "CostCenter", "tag_value": [ "Development", "Support", "Marketing" ], "enforced_for": [ "redshift:*", "dynamodb:table" ] } } }

Example 3: Remove values from inherited tags

There may be cases where the tag policy that is attached to the organization defines more tag values than you want an account to use. This example explains how to revise a tag policy using the @@remove operator. The @@remove is an advanced feature.

Like the other examples, this example starts with policy A for the organization root tag policy.

Policy A – Organization root tag policy

{ "tags": { "costcenter": { "tag_key": { "@@assign": "CostCenter" }, "tag_value": { "@@assign": [ "Development", "Support" ] } } } }

For this example, attach policy D to account 999999999999.

Policy D – Account 999999999999 tag policy for removing values

{ "tags": { "costcenter": { "tag_key": { "@@assign": "CostCenter" }, "tag_value": { "@@remove": [ "Development", "Marketing" ], "enforced_for": { "@@remove": [ "redshift:*", "dynamodb:table" ] } } } } }

Attaching policy D to account 999999999999 has the following effects when policy A, policy C, and policy D merge to form the effective tag policy:

  • Assuming you performed all of the previous examples, policies B, C, and C are child policies of A. Policy B is only attached to OU1, so it has no effect on account 9999999999999.

  • For account 9999999999999, the only acceptable value for the CostCenter tag key is Support.

  • Compliance is not enforced for the CostCenter tag key.

New effective tag policy for account 999999999999

Note

You can't directly use the contents of a displayed effective policy as the contents of a new policy. The syntax doesn't include the operators needed to control merging with other child and parent policies. The display of an effective policy is intended only for understanding the results of the merger.

{ "tags": { "costcenter": { "tag_key": "CostCenter", "tag_value": [ "Support" ] } } }

If you later add more accounts to OU2, their effective tag policies would be different than for account 999999999999. That's because the more restrictive policy D is only attached at the account level, and not to the OU.

Example 4: Restrict changes to child policies

There may be cases where you want to restrict changes in child policies. This example explains how to do that using child control operators.

This example starts with a new organization root tag policy and assumes that tag policies aren't yet attached to organization entities.

Policy E – Organization root tag policy for restricting changes in child policies

{ "tags": { "project": { "tag_key": { "@@operators_allowed_for_child_policies": ["@@none"], "@@assign": "Project" }, "tag_value": { "@@operators_allowed_for_child_policies": ["@@append"], "@@assign": [ "Maintenance", "Escalations" ] } } } }

When you attach policy E to the organization root, the policy prevents child policies from changing the Project tag key. However, child policies can overwrite or append tag values.

Assume you then attach the following policy F to an OU.

Policy F – OU tag policy

{ "tags": { "project": { "tag_key": { "@@assign": "PROJECT" }, "tag_value": { "@@append": [ "Escalations - research" ] } } } }

Merging policy E and policy F have the following effects on the OU's accounts:

  • Policy F is a child policy to Policy E.

  • Policy F attempts to change the case treatment, but it can't. That's because policy E includes the "@@operators_allowed_for_child_policies": ["@@none"] operator for the tag key.

  • However, policy F can append tag values for the key. That's because policy E includes "@@operators_allowed_for_child_policies": ["@@append"] for the tag value.

Effective policy for accounts in the OU

Note

You can't directly use the contents of a displayed effective policy as the contents of a new policy. The syntax doesn't include the operators needed to control merging with other child and parent policies. The display of an effective policy is intended only for understanding the results of the merger.

{ "tags": { "project": { "tag_key": "project", "tag_value": [ "Maintenance", "Escalations", "Escalations - research" ] } } }

Example 5: Conflicts with child control operators

Child control operators can exist in tag policies that are attached at the same level in the organization hierarchy. When that happens, the intersection of the allowed operators is used when the policies merge to form the effective policy for accounts.

Assume policy G and policy H are attached to the organization root.

Policy G – Organization root tag policy 1

{ "tags": { "project": { "tag_value": { "@@operators_allowed_for_child_policies": ["@@append"], "@@assign": [ "Maintenance" ] } } } }

Policy H – Organization root tag policy 2

{ "tags": { "project": { "tag_value": { "@@operators_allowed_for_child_policies": ["@@append", "@@remove"] } } } }

In this example, one policy at the organization root defines that the values for the tag key can only be appended to. The other policy attached to the organization root allows child policies to both append and remove values. The intersection of these two permissions is used for child policies. The result is that child policies can append values, but not remove values. Therefore, the child policy can append a value to the list of tag values but can't remove the Maintenance value.

Example 6: Conflicts with appending values at same hierarchy level

You can attach multiple tag policies to each organization entity. When you do this, the tag policies that are attached to the same organization entity might include conflicting information. Policies are evaluated based on the order in which they were attached to the organization entity. To change which policy is evaluated first, you can detach a policy and then reattach it.

Assume policy J is attached to the organization root first, and then policy K is attached to the organization root.

Policy J – First tag policy attached to the organization root

{ "tags": { "project": { "tag_key": { "@@assign": "PROJECT" }, "tag_value": { "@@append": ["Maintenance"] } } } }

Policy K – Second tag policy attached to the organization root

{ "tags": { "project": { "tag_key": { "@@assign": "project" } } } }

In this example, the tag key PROJECT is used in the effective tag policy because the policy that defined it was attached to the organization root first.

Policy JK – Effective tag policy for account

The effective policy for the account is as follows.

Note

You can't directly use the contents of a displayed effective policy as the contents of a new policy. The syntax doesn't include the operators needed to control merging with other child and parent policies. The display of an effective policy is intended only for understanding the results of the merger.

{ "tags": { "project": { "tag_key": " PROJECT", "tag_value": [ "Maintenance", "Escalations" ] } } }