vpc-peering

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

Usage

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
components:
  terraform:
    vpc-peering/defaults:
      settings:
        spacelift:
          workspace_enabled: true
      metadata:
        component: vpc-peering
        type: abstract
      vars:
        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
import:
  - catalog/vpc-peering/defaults

components:
  terraform:
    vpc-peering-use1:
      metadata:
        component: vpc-peering
        inherits:
          - vpc-peering/defaults
      vars:
        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

vpc-peering/<stage>-vpc0:
  metadata:
    component: vpc-peering
    inherits:
      - vpc-peering/defaults
  vars:
    requester_vpc_component_name: vpc
    accepter_region: us-east-1
    accepter_stage_name: <fill-in-with-accepter-stage-name>
    accepter_vpc:
      tags:
        # 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": [
        "ec2:DescribeVpcPeeringConnections",
        "ec2:DescribeVpcs",
        "ec2:ModifyVpcPeeringConnectionOptions",
        "ec2:DescribeSubnets",
        "ec2:DescribeVpcAttribute",
        "ec2:DescribeRouteTables"
      ],
      "Resource": "*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "ec2:AcceptVpcPeeringConnection",
        "ec2:DeleteVpcPeeringConnection",
        "ec2:CreateVpcPeeringConnection",
        "ec2:RejectVpcPeeringConnection"
      ],
      "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).

Provisioning

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

Variables

Required Variables

accepter_region (string) required

Accepter AWS region

accepter_vpc (any) required

Accepter VPC map of id, cidr_block, or default arguments for the data source

region (string) required

AWS Region

Optional Variables

accepter_allow_remote_vpc_dns_resolution (bool) optional

Allow accepter VPC to resolve public DNS hostnames to private IP addresses when queried from instances in the requester VPC

Default value: true

accepter_aws_assume_role_arn (string) optional

Accepter AWS assume role ARN

Default value: null

accepter_stage_name (string) optional

Accepter stage name if in v1

Default value: null

add_attribute_tag (bool) optional

If true will add additional attribute tag to the requester and accceptor resources

Default value: true

auto_accept (bool) optional

Automatically accept peering request

Default value: true

requester_allow_remote_vpc_dns_resolution (bool) optional

Allow requester VPC to resolve public DNS hostnames to private IP addresses when queried from instances in the accepter VPC

Default value: true

requester_role_arn (string) optional

Requester AWS assume role ARN, if not provided it will be assumed to be the current terraform role.

Default value: null

requester_vpc_component_name (string) optional

Requester vpc component name

Default value: "vpc"

requester_vpc_id (string) optional

Requester VPC ID, if not provided, it will be looked up by component using variable requester_vpc_component_name

Default value: null

Context Variables

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

Additional 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.

Required: No

Default value: { }

attributes (list(string)) optional

ID 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.

Required: No

Default value: [ ]

context (any) optional

Single 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.

Required: No

Default value:

{
  "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": [
    "unset"
  ],
  "name": null,
  "namespace": null,
  "regex_replace_chars": null,
  "stage": null,
  "tags": {},
  "tenant": null
}

delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.

Required: No

Default value: null

descriptor_formats (any) optional

Describe 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).

Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

Limit 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.

Required: No

Default value: null

label_key_case (string) optional

Controls 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.

Required: No

Default value: null

label_order (list(string)) optional

The 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.

Required: No

Default value: null

label_value_case (string) optional

Controls 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.

Required: No

Default value: null

labels_as_tags (set(string)) optional

Set 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.
Notes:
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.

Required: No

Default value:

[
  "default"
]

name (string) optional

ID 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.

Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

Terraform 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.

Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.

Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs

vpc_peering

VPC peering outputs

Dependencies

Requirements

• terraform, version: >= 1.0.0
• aws, version: >= 3.0

Providers

• aws, version: >= 3.0

Modules

Name	Version	Source	Description
iam_roles	latest	../account-map/modules/iam-roles	n/a
requester_vpc	1.8.0	cloudposse/stack-config/yaml//modules/remote-state	n/a
this	0.25.0	cloudposse/label/null	n/a
vpc_peering	1.0.0	cloudposse/vpc-peering-multi-account/aws	n/a

Resources

The following resources are used by this module:

Data Sources

The following data sources are used by this module:

• aws_vpc.accepter (data source)

• cloudposse/terraform-aws-components - Cloud Posse's upstream component