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Module: utils

This terraform-aws-utils module provides some simple utilities to use when working in AWS.

Introduction​

This terraform-aws-utils module provides some simple utilities to use when working in AWS. More complex utilities are available through Cloud Posse's utils Terraform provider terraform-provider-utils.

Compact Alternative Codes (Abbreviations)​

This module's primary function is to provide compact alternative codes for Regions, Availability Zones, and Local Zones, codes which are guaranteed to use only digits and lower case letters: no hyphens. Conversions to and from official codes and alternative codes are handled via lookup maps.

  • The short abbreviations for regions are variable length (generally 4-6 characters, but length limits not guaranteed) and strictly algorithmically derived so that people can more easily interpret them. The short region code abbreviations typically match the prefix of the Availability Zone IDs in that region, but this is not guaranteed. The short abbreviations for local regions are generally of the form AWS uses, with the region prefix and dashes removed.
  • The fixed abbreviations are always exactly 3 characters for regions and 4 characters for availability zones and local zones, but have some exceptional cases (China, Africa, Asia-Pacific South, US GovCloud) that have non-obvious abbreviations. If a future new region causes a conflict with an established local zone abbreviation, we may change the local zone abbreviation to keep the region mappings consistent. For example, the local zone us-east-1-mci-1a would have been abbreviated mc1a had we released it earlier, and that would have conflicted with the new (in 2022) me-central-1a which would also be abbreviated mc1a in keeping with the general pattern of using the first letter of each of the first 2 parts. We might have chosen to change the abbreviation for us-east-1-mci-1 so we could use mc1a for me-central-1a. (As it happens, we added them both at the same time and avoided this collision.) If we were to make such a change, this would be a breaking change for people using the affected local zone, so we recommend using the short abbreviations if you are using local zones, which are far less likely to have conflicts in the future.
  • The identity "abbreviations" are not abbreviations but are instead the official codes (output equals input, which is why it is called "identity"). This map is provided to simplify algorithmic choice of region code abbreviation when you want to include a "no abbreviation" option.

We currently support Local Zones but not Wavelength Zones. If we support Wavelength Zones in the future, it is likely that the fixed-length abbreviations for them will be non-intuitive, or we may only provide short and not fixed abbreviations for them.

The intention is that existing region mappings will never change, and if new regions or zones are created that conflict with existing ones, they will be given non-standard mappings so as not to conflict. However, as stated above, we may choose to change a local region abbreviation if it conflicts with the obvious abbreviation for a newly created region. We have picked abbreviations for local zones with avoiding such future collisions in mind, but we cannot predict the future. (Both bos and den fit the pattern for region abbreviations, but we do not envision a future bo-south-1 or de-north-1 region.)

ELB Logging​

This module provides Elastic Load Balancing Account IDs per region to be used in configuring S3 Bucket Permissions to allow access logs to be stored in S3.

However, the account IDs have no other purpose, and as AWS expands, it has become more complicated to create the correct bucket policy. The policy for region me-central-1 is different than the policy for us-east-1. So now this module has a new feature: you provide the full AWS region code for the region where logging is to take place (elb_logging_region), and the S3 bucket ARN for where logs are to be stored (elb_logging_bucket_resource_arn), and this module will output the appropriate S3 bucket policy (in JSON) to attach to your S3 bucket.

NOTE: The region must be known at Terraform "plan" time. Use a configuration input, such as what you used to configure the Terraform AWS Provider, not an output from some resource or module.

Region Display Names​

There is no AWS API that reliably returns the human-friendly display name (e.g. "Europe (Stockholm)") given the API-friendly region name. So this module provides region_display_name_map to implement this functionality.

Enabled and Disabled Regions​

For convenience, this module provides lists of enabled and disabled regions in the current account. Note that since these lists are dynamic, they cannot be used in Terraform count or for_each resource expressions.

Usage​

Here's how to invoke this example module in your projects

locals {
  shorten_regions   = true
  naming_convention = local.shorten_regions ? "to_short" : "identity"
  az_map            = module.example.region_az_alt_code_maps[local.naming_convention]
}

module "utils_example_complete" {
  source  = "cloudposse/utils/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version     = "x.x.x"
}

module "label" {
  source = "cloudposse/label/null"
  # Cloud Posse recommends pinning every module to a specific version
  # version     = "x.x.x"

  attributes = [local.az_map["us-east-2"]]

  context = module.this.context
}

Examples​

Here is an example of using this module:

Variables​

Required Variables​

Optional Variables​

elb_logging_bucket_resource_arn (string) optional

The AWS Resource ARN to use in the policy granting access to Load Balancer Logging.
Typically of the form arn:aws:s3:::_bucket-name_/_prefix_/AWSLogs/_your-aws-account-id_/*.
Required to generate elb_logging_s3_bucket_policy_json.
See AWS Documentation.



Default value: ""

elb_logging_region (string) optional

Full region (e.g. us-east-1) where ELB logging is taking place. Required to generate elb_s3_bucket_policy_json.
Must be known at "plan" time.



Default value: ""

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​

all_regions

A list of all regions regardless of availability to the account

disabled_regions

A list of regions that are disabled in the account

elb_logging_account

Map of full region to ELB logging account

elb_logging_s3_bucket_policy_json

The S3 bucket policy (in JSON) to attach to the S3 bucket to allow Load Balancer logs to be added.
Requires elb_logging_bucket_resource_arn and elb_logging_region inputs.


enabled_regions

A list of regions that are enabled in the account

region_az_alt_code_maps

Collection of maps converting between official AWS Region, Availability Zone, and Local Zone codes and shorter unofficial codes using only lower case letters and digits. Inspired for use in naming and tagging so that region or AZ code will be 1 semantic unit.


  • to_fixed = Map of regions to 3-character codes and Availability Zones to 4-character codes
  • to_short = Map of regions and Availability Zones to compact (usually 4-6 characters) codes
  • from_fixed = Map of fixed codes back to full region or Availability Zone codes
  • from_short = Map of short codes back to full region or Availability Zone codes
  • identity = Identity map of full region and Availability Zone codes back to themselves

region_display_name_map

Map of full region names to user-friendly display names (e.g. "eu-west-3" = "Europe (Paris)").


Dependencies​

Requirements​

  • terraform, version: >= 0.14.0
  • aws, version: >= 2

Providers​

  • aws, version: >= 2

Modules​

NameVersionSourceDescription
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: