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Component: vpc-peering

This component is responsible for creating a peering connection between two VPCs existing in different AWS accounts.


Stack Level: Regional

Here's an example snippet for how to use this component.

Default VPC peering settings for all accounts:

# stacks/catalog/vpc-peering/defaults.yaml
workspace_enabled: true
component: vpc-peering
type: abstract
enabled: true
requester_allow_remote_vpc_dns_resolution: true
accepter_allow_remote_vpc_dns_resolution: true

Use case: Peering v1 accounts to v2

# stacks/catalogs/vpc-peering/ue1-prod.yaml
- catalog/vpc-peering/defaults

component: vpc-peering
- vpc-peering/defaults
accepter_region: us-east-1
accepter_vpc_id: vpc-xyz
accepter_aws_assume_role_arn: arn:aws:iam::<LEGACY ACCOUNT ID>:role/acme-vpc-peering

Use case: Peering v2 accounts to v2

component: vpc-peering
- vpc-peering/defaults
requester_vpc_component_name: vpc
accepter_region: us-east-1
accepter_stage_name: <fill-in-with-accepter-stage-name>
# Fill in with your own information
Name: acme-<tenant>-<environment>-<stage>-<name>

Legacy Account Configuration

The vpc-peering component peers the dev, prod, sandbox and staging VPCs to a VPC in the legacy account.

The dev, prod, sandbox and staging VPCs are the requesters of the VPC peering connection, while the legacy VPC is the accepter of the peering connection.

To provision VPC peering and all related resources with Terraform, we need the following information from the legacy account:

  • Legacy account ID
  • Legacy VPC ID
  • Legacy AWS region
  • Legacy IAM role (the role must be created in the legacy account with permissions to create VPC peering and routes). The name of the role could be acme-vpc-peering and the ARN of the role should look like arn:aws:iam::<LEGACY ACCOUNT ID>:role/acme-vpc-peering

Legacy Account IAM Role

In the legacy account, create IAM role acme-vpc-peering with the following policy:

NOTE: Replace <LEGACY ACCOUNT ID> with the ID of the legacy account.

"Version": "2012-10-17",
"Statement": [
"Effect": "Allow",
"Action": ["ec2:CreateRoute", "ec2:DeleteRoute"],
"Resource": "arn:aws:ec2:*:<LEGACY ACCOUNT ID>:route-table/*"
"Effect": "Allow",
"Action": [
"Resource": "*"
"Effect": "Allow",
"Action": [
"Resource": [
"arn:aws:ec2:*:<LEGACY ACCOUNT ID>:vpc-peering-connection/*",
"arn:aws:ec2:*:<LEGACY ACCOUNT ID>:vpc/*"
"Effect": "Allow",
"Action": ["ec2:DeleteTags", "ec2:CreateTags"],
"Resource": "arn:aws:ec2:*:<LEGACY ACCOUNT ID>:vpc-peering-connection/*"

Add the following trust policy to the IAM role:

NOTE: Replace <IDENTITY ACCOUNT ID> with the ID of the identity account in the new infrastructure.

"Version": "2012-10-17",
"Statement": [
"Effect": "Allow",
"Principal": {
"AWS": ["arn:aws:iam::<IDENTITY ACCOUNT ID>:root"]
"Action": ["sts:AssumeRole", "sts:TagSession"],
"Condition": {}

The trust policy allows the identity account to assume the role (and provision all the resources in the legacy account).


Provision the VPC peering connections in the dev, prod, sandbox and staging accounts by executing the following commands:

atmos terraform plan vpc-peering -s ue1-sandbox
atmos terraform apply vpc-peering -s ue1-sandbox

atmos terraform plan vpc-peering -s ue1-dev
atmos terraform apply vpc-peering -s ue1-dev

atmos terraform plan vpc-peering -s ue1-staging
atmos terraform apply vpc-peering -s ue1-staging

atmos terraform plan vpc-peering -s ue1-prod
atmos terraform apply vpc-peering -s ue1-prod


terraform>= 1.0.0
aws>= 3.0


aws.accepter>= 3.0




aws_vpc.accepterdata source


accepter_allow_remote_vpc_dns_resolutionAllow accepter VPC to resolve public DNS hostnames to private IP addresses when queried from instances in the requester VPCbooltrueno
accepter_aws_assume_role_arnAccepter AWS assume role ARNstringnullno
accepter_regionAccepter AWS regionstringn/ayes
accepter_stage_nameAccepter stage name if in v1stringnullno
accepter_vpcAccepter VPC map of id, cidr_block, or default arguments for the data sourceanyn/ayes
additional_tag_mapAdditional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id.
This is for some rare cases where resources want additional configuration of tags
and therefore take a list of maps with tag key, value, and additional configuration.
attributesID element. Additional attributes (e.g. workers or cluster) to add to id,
in the order they appear in the list. New attributes are appended to the
end of the list. The elements of the list are joined by the delimiter
and treated as a single ID element.
auto_acceptAutomatically accept peering requestbooltrueno
contextSingle object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as null to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.
"additional_tag_map": {},
"attributes": [],
"delimiter": null,
"descriptor_formats": {},
"enabled": true,
"environment": null,
"id_length_limit": null,
"label_key_case": null,
"label_order": [],
"label_value_case": null,
"labels_as_tags": [
"name": null,
"namespace": null,
"regex_replace_chars": null,
"stage": null,
"tags": {},
"tenant": null
delimiterDelimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.
descriptor_formatsDescribe additional descriptors to be output in the descriptors output map.
Map of maps. Keys are names of descriptors. Values are maps of the form
{<br/> format = string<br/> labels = list(string)<br/>}
(Type is any so the map values can later be enhanced to provide additional options.)
format is a Terraform format string to be passed to the format() function.
labels is a list of labels, in order, to pass to format() function.
Label values will be normalized before being passed to format() so they will be
identical to how they appear in id.
Default is {} (descriptors output will be empty).
enabledSet to false to prevent the module from creating any resourcesboolnullno
environmentID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'stringnullno
id_length_limitLimit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for keep the existing setting, which defaults to 0.
Does not affect id_full.
label_key_caseControls the letter case of the tags keys (label names) for tags generated by this module.
Does not affect keys of tags passed in via the tags input.
Possible values: lower, title, upper.
Default value: title.
label_orderThe order in which the labels (ID elements) appear in the id.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.
label_value_caseControls the letter case of ID elements (labels) as included in id,
set as tag values, and output by this module individually.
Does not affect values of tags passed in via the tags input.
Possible values: lower, title, upper and none (no transformation).
Set this to title and set delimiter to "" to yield Pascal Case IDs.
Default value: lower.
labels_as_tagsSet of labels (ID elements) to include as tags in the tags output.
Default is to include all labels.
Tags with empty values will not be included in the tags output.
Set to [] to suppress all generated tags.
The value of the name tag, if included, will be the id, not the name.
Unlike other null-label inputs, the initial setting of labels_as_tags cannot be
changed in later chained modules. Attempts to change it will be silently ignored.
nameID element. Usually the component or solution name, e.g. 'app' or 'jenkins'.
This is the only ID element not also included as a tag.
The "name" tag is set to the full id string. There is no tag with the value of the name input.
namespaceID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally uniquestringnullno
regex_replace_charsTerraform regular expression (regex) string.
Characters matching the regex will be removed from the ID elements.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.
regionAWS Regionstringn/ayes
requester_allow_remote_vpc_dns_resolutionAllow requester VPC to resolve public DNS hostnames to private IP addresses when queried from instances in the accepter VPCbooltrueno
requester_vpc_component_nameRequestor vpc component namestring"vpc"no
stageID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'stringnullno
tagsAdditional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.
tenantID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is forstringnullno


vpc_peeringVPC peering outputs