terraform-aws-utils

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

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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.

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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
}

Important

In Cloud Posse's examples, we avoid pinning modules to specific versions to prevent discrepancies between the documentation and the latest released versions. However, for your own projects, we strongly advise pinning each module to the exact version you're using. This practice ensures the stability of your infrastructure. Additionally, we recommend implementing a systematic approach for updating versions to avoid unexpected changes.

Examples

Here is an example of using this module:

• examples/complete - complete example of using this module

Makefile Targets

Available targets:

  help                                Help screen
  help/all                            Display help for all targets
  help/short                          This help short screen
  lint                                Lint terraform code

Requirements

Name	Version
terraform	>= 0.14.0
aws	>= 2

Providers

Name	Version
aws	>= 2

Modules

Name	Source	Version
this	cloudposse/label/null	0.25.0

Resources

Name	Type
aws_iam_policy_document.by_account	data source
aws_iam_policy_document.by_region	data source
aws_regions.complete	data source
aws_regions.default	data source
aws_regions.not_opted_in	data source
aws_regions.opted_in	data source

Inputs

Name	Description	Type	Default	Required
additional_tag_map	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.	map(string)	{}	no
attributes	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.	list(string)	[]	no
context	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.	any	{ "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 }	no
delimiter	Delimiter to be used between ID elements. Defaults to - (hyphen). Set to "" to use no delimiter at all.	string	null	no
descriptor_formats	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).	any	{}	no
elb_logging_bucket_resource_arn	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.	string	""	no
elb_logging_region	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.	string	""	no
enabled	Set to false to prevent the module from creating any resources	bool	null	no
environment	ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'	string	null	no
id_length_limit	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.	number	null	no
label_key_case	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.	string	null	no
label_order	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.	list(string)	null	no
label_value_case	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.	string	null	no
labels_as_tags	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.	set(string)	[ "default" ]	no
name	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.	string	null	no
namespace	ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique	string	null	no
regex_replace_chars	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.	string	null	no
stage	ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'	string	null	no
tags	Additional tags (e.g. {'BusinessUnit': 'XYZ'}). Neither the tag keys nor the tag values will be modified by this module.	map(string)	{}	no
tenant	ID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is for	string	null	no

Outputs

Name	Description
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)").

Related Projects

Check out these related projects.

• terraform-provider-utils - The Cloud Posse Terraform Provider for various utilities (e.g. deep merging, stack configuration management).
• terraform-null-label - Terraform module designed to generate consistent names and tags for resources. Use terraform-null-label to implement a strict naming convention.

References

For additional context, refer to some of these links.

• Terraform Standard Module Structure - HashiCorp's standard module structure is a file and directory layout we recommend for reusable modules distributed in separate repositories.
• Terraform Module Requirements - HashiCorp's guidance on all the requirements for publishing a module. Meeting the requirements for publishing a module is extremely easy.
• Terraform Version Pinning - The required_version setting can be used to constrain which versions of the Terraform CLI can be used with your configuration
• AWS Regions and Zones - AWS documentation on regions and zones

✨ Contributing

This project is under active development, and we encourage contributions from our community.

Many thanks to our outstanding contributors:

For 🐛 bug reports & feature requests, please use the issue tracker.

In general, PRs are welcome. We follow the typical "fork-and-pull" Git workflow.

1. Review our Code of Conduct and Contributor Guidelines.
2. Fork the repo on GitHub
3. Clone the project to your own machine
4. Commit changes to your own branch
5. Push your work back up to your fork
6. Submit a Pull Request so that we can review your changes

NOTE: Be sure to merge the latest changes from "upstream" before making a pull request!

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License

Preamble to the Apache License, Version 2.0

Complete license is available in the LICENSE file.

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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  https://www.apache.org/licenses/LICENSE-2.0

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