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dns-primary

This component is responsible for provisioning the primary DNS zones into an AWS account. By convention, we typically provision the primary DNS zones in the dns account. The primary account for branded zones (e.g. example.com), however, would be in the prod account, while staging zone (e.g. example.qa) might be in the staging account.

The zones from the primary DNS zone are then expected to be delegated to other accounts via the dns-delegated component. Additionally, external records can be created on the primary DNS zones via the record_config variable.

Architecture​

Summary​

The dns account gets a single dns-primary component deployed. Every other account that needs DNS entries gets a single dns-delegated component, chaining off the domains in the dns account. Optionally, accounts can have a single dns-primary component of their own, to have apex domains (which Cloud Posse calls "vanity domains"). Typically, these domains are configured with CNAME (or apex alias) records to point to service domain entries.

Details​

The purpose of the dns account is to host root domains shared by several accounts (with each account being delegated its own subdomain) and to be the owner of domain registrations purchased from Amazon.

The purpose of the dns-primary component is to provision AWS Route53 zones for the root domains. These zones, once provisioned, must be manually configured into the Domain Name Registrar's records as name servers. A single component can provision multiple domains and, optionally, associated ACM (SSL) certificates in a single account.

Cloud Posse's architecture expects root domains shared by several accounts to be provisioned in the dns account with dns-primary and delegated to other accounts using the dns-delegated component, with each account getting its own subdomain corresponding to a Route 53 zone in the delegated account. Cloud Posse's architecture requires at least one such domain, called "the service domain", be provisioned. The service domain is not customer facing, and is provisioned to allow fully automated construction of host names without any concerns about how they look. Although they are not secret, the public will never see them.

Root domains used by a single account are provisioned with the dns-primary component directly in that account. Cloud Posse calls these "vanity domains". These can be whatever the marketing or PR or other stakeholders want to be.

After a domain is provisioned in the dns account, the dns-delegated component can provision one or more subdomains for each account, and, optionally, associated ACM certificates. For the service domain, Cloud Posse recommends using the account name as the delegated subdomain (either directly, e.g. "plat-dev", or as multiple subdomains, e.g. "dev.plat") because that allows dns-delegated to automatically provision any required host name in that zone.

There is no automated support for dns-primary to provision root domains outside of the dns account that are to be shared by multiple accounts, and such usage is not recommended. If you must, dns-primary can provision a subdomain of a root domain that is provisioned in another account (not dns). In this case, the delegation of the subdomain must be done manually by entering the name servers into the parent domain's records (instead of in the Registrar's records).

The architecture does not support other configurations, or non-standard component names.

Usage​

Stack Level: Global

Here's an example snippet for how to use this component. This component should only be applied once as the DNS zones it creates are global. This is typically done via the DNS stack (e.g. gbl-dns.yaml).

components:
  terraform:
    dns-primary:
      vars:
        domain_names:
          - example.net
        record_config:
          - root_zone: example.net
            name: ""
            type: A
            ttl: 60
            records:
              - 53.229.170.215
          # using a period at the end of a name
          - root_zone: example.net
            name: www.
            type: CNAME
            ttl: 60
            records:
              - example.net
          # using numbers as name requires quotes
          - root_zone: example.net
            name: "123456."
            type: CNAME
            ttl: 60
            records:
              - example.net
          # strings that are very long, this could be a DKIM key
          - root_zone: example.net
            name: service._domainkey.
            type: CNAME
            ttl: 60
            records:
              - !!str |-
                YourVeryLongStringGoesHere
tip

Use the acm component for more advanced certificate requirements.

Variables​

Required Variables​

region (string) required

AWS Region

Optional Variables​

alias_record_config optional

DNS Alias Record config


Type:

list(object({
root_zone              = string
name                   = string
type                   = string
zone_id                = string
record                 = string
evaluate_target_health = bool
}))

Default value: [ ]

dns_soa_config (string) optional

Root domain name DNS SOA record:

  • awsdns-hostmaster.amazon.com. ; AWS default value for administrator email address
  • 1 ; serial number, not used by AWS
  • 7200 ; refresh time in seconds for secondary DNS servers to refresh SOA record
  • 900 ; retry time in seconds for secondary DNS servers to retry failed SOA record update
  • 1209600 ; expire time in seconds (1209600 is 2 weeks) for secondary DNS servers to remove SOA record if they cannot refresh it
  • 60 ; nxdomain TTL, or time in seconds for secondary DNS servers to cache negative responses
    See SOA Record Documentation for more information.


Default value: "awsdns-hostmaster.amazon.com. 1 7200 900 1209600 60"

domain_names (list(string)) optional

Root domain name list, e.g. ["example.net"]


Default value: null

record_config optional

DNS Record config


Type:

list(object({
root_zone = string
name      = string
type      = string
ttl       = string
records   = list(string)
}))

Default value: [ ]

request_acm_certificate (bool) optional

Whether or not to request an ACM certificate for each domain


Default value: false

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​

acms

ACM certificates for domains

zones

DNS zones

Dependencies​

Requirements​

  • terraform, version: >= 1.0.0
  • aws, version: >= 4.9.0

Providers​

  • aws, version: >= 4.9.0

Modules​

NameVersionSourceDescription
acm0.16.3cloudposse/acm-request-certificate/awsn/a
iam_roleslatest../account-map/modules/iam-rolesn/a
this0.25.0cloudposse/label/nulln/a

Resources​

The following resources are used by this module:

Data Sources​

The following data sources are used by this module:

References​