Terraform module designed to generate consistent names and tags for resources. Use terraform-null-label to implement a strict naming convention.
A label follows the following convention: {namespace}-{environment}-{stage}-{name}-{attributes}. The delimiter (e.g. -) is configurable.
The label items are all optional. So if you prefer the term stage to environment you can exclude environment and the label id will look like {namespace}-{stage}-{name}-{attributes}.
If attributes are excluded but stage and environment are included, id will look like {namespace}-{environment}-{stage}-{name}
It's recommended to use one terraform-null-label module for every unique resource of a given resource type.
For example, if you have 10 instances, there should be 10 different labels.
However, if you have multiple different kinds of resources (e.g. instances, security groups, file systems, and elastic ips), then they can all share the same label assuming they are logically related.
All Cloud Posse modules use this module to ensure resources can be instantiated multiple times within an account and without conflict.
NOTE: The null refers to the primary Terraform provider used in this module.
Releases of this module from 0.12.0 onward support HCL2 and only work with Terraform 0.12 or newer. Releases prior to this are compatible with earlier versions of terraform like Terraform 0.11.
This project is part of our comprehensive "SweetOps" approach towards DevOps.
It's 100% Open Source and licensed under the APACHE2.
We literally have hundreds of terraform modules that are Open Source and well-maintained. Check them out!
IMPORTANT: The master branch is used in source just as an example. In your code, do not pin to master because there may be breaking changes between releases.
Instead pin to the release tag (e.g. ?ref=tags/x.y.z) of one of our latest releases.
Cloud Posse Terraform modules share a common context object that is meant to be passed from module to module.
The context object is a single object that contains all the input values for terraform-null-label.
However, each input value can also be specified individually by name as a standard Terraform variable,
and the value of those variables, when set to something other than null, will override the value
in the context object. In order to allow chaining of these objects, where the context object input to one
module is transformed and passed to the next module, all the variables default to null or empty collections.
The actual default values used when nothing is explicitly set are describe in the documentation below.
For example, the default value of delimiter is shown as null, but if you leave it set to null,
terraform-null-label will actually use the default delimiter - (hyphen).
A non-obvious but intentional consequence of this design is that once a module sets a non-default value, future modules in the chain cannot reset the value back to the original default. Insted, the new setting becomes the new default for downstream modules. Also, collections are not overwritten, they are merged, so once a tag is added, it will remain in the tag set and cannot be removed, although its value can be overwritten.
module "eg_prod_bastion_label" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=master"
namespace = "eg"
stage = "prod"
name = "bastion"
attributes = ["public"]
delimiter = "-"
tags = {
"BusinessUnit" = "XYZ",
"Snapshot" = "true"
}
}This will create an id with the value of eg-prod-bastion-public because when generating id, the default order is namespace, environment, stage, name, attributes
(you can override it by using the label_order variable, see Advanced Example 3).
Now reference the label when creating an instance:
resource "aws_instance" "eg_prod_bastion_public" {
instance_type = "t1.micro"
tags = module.eg_prod_bastion_label.tags
}Or define a security group:
resource "aws_security_group" "eg_prod_bastion_public" {
vpc_id = var.vpc_id
name = module.eg_prod_bastion_label.id
tags = module.eg_prod_bastion_label.tags
egress {
from_port = 0
to_port = 0
protocol = "-1"
cidr_blocks = ["0.0.0.0/0"]
}
}Here is a more complex example with two instances using two different labels. Note how efficiently the tags are defined for both the instance and the security group.
Click to show
module "eg_prod_bastion_abc_label" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=master"
namespace = "eg"
stage = "prod"
name = "bastion"
attributes = ["abc"]
delimiter = "-"
tags = {
"BusinessUnit" = "XYZ",
"Snapshot" = "true"
}
}
resource "aws_security_group" "eg_prod_bastion_abc" {
name = module.eg_prod_bastion_abc_label.id
tags = module.eg_prod_bastion_abc_label.tags
ingress {
from_port = 22
to_port = 22
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
}
resource "aws_instance" "eg_prod_bastion_abc" {
instance_type = "t1.micro"
tags = module.eg_prod_bastion_abc_label.tags
vpc_security_group_ids = [aws_security_group.eg_prod_bastion_abc.id]
}
module "eg_prod_bastion_xyz_label" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=master"
namespace = "eg"
stage = "prod"
name = "bastion"
attributes = ["xyz"]
delimiter = "-"
tags = {
"BusinessUnit" = "XYZ",
"Snapshot" = "true"
}
}
resource "aws_security_group" "eg_prod_bastion_xyz" {
name = module.eg_prod_bastion_xyz_label.id
tags = module.eg_prod_bastion_xyz_label.tags
ingress {
from_port = 22
to_port = 22
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
}
resource "aws_instance" "eg_prod_bastion_xyz" {
instance_type = "t1.micro"
tags = module.eg_prod_bastion_xyz_label.tags
vpc_security_group_ids = [aws_security_group.eg_prod_bastion_xyz.id]
}Here is a more complex example with an autoscaling group that has a different tagging schema than other resources and requires its tags to be in this format, which this module can generate:
Click to show
tags = [
{
key = Name,
propagate_at_launch = 1,
value = namespace-stage-name
},
{
key = Namespace,
propagate_at_launch = 1,
value = namespace
},
{
key = Stage,
propagate_at_launch = 1,
value = stage
}
]Autoscaling group using propagating tagging below (full example: autoscalinggroup)
################################
# terraform-null-label example #
################################
module "label" {
source = "../../"
namespace = "cp"
stage = "prod"
name = "app"
tags = {
BusinessUnit = "Finance"
ManagedBy = "Terraform"
}
additional_tag_map = {
propagate_at_launch = "true"
}
}
#######################
# Launch template #
#######################
resource "aws_launch_template" "default" {
# terraform-null-label example used here: Set template name prefix
name_prefix = "${module.label.id}-"
image_id = data.aws_ami.amazon_linux.id
instance_type = "t2.micro"
instance_initiated_shutdown_behavior = "terminate"
vpc_security_group_ids = [data.aws_security_group.default.id]
monitoring {
enabled = false
}
# terraform-null-label example used here: Set tags on volumes
tag_specifications {
resource_type = "volume"
tags = module.label.tags
}
}
######################
# Autoscaling group #
######################
resource "aws_autoscaling_group" "default" {
# terraform-null-label example used here: Set ASG name prefix
name_prefix = "${module.label.id}-"
vpc_zone_identifier = data.aws_subnet_ids.all.ids
max_size = "1"
min_size = "1"
desired_capacity = "1"
launch_template = {
id = "aws_launch_template.default.id
version = "$$Latest"
}
# terraform-null-label example used here: Set tags on ASG and EC2 Servers
tags = module.label.tags_as_list_of_maps
}See complete example for even more examples.
This example shows how you can pass the context output of one label module to the next label_module,
allowing you to create one label that has the base set of values, and then creating every extra label
as a derivative of that.
Click to show
module "label1" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=master"
namespace = "CloudPosse"
environment = "UAT"
stage = "build"
name = "Winston Churchroom"
attributes = ["fire", "water", "earth", "air"]
delimiter = "-"
label_order = ["name", "environment", "stage", "attributes"]
tags = {
"City" = "Dublin"
"Environment" = "Private"
}
}
module "label2" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=master"
context = module.label1.context
name = "Charlie"
stage = "test"
delimiter = "+"
tags = {
"City" = "London"
"Environment" = "Public"
}
}
module "label3" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=master"
name = "Starfish"
stage = "release"
context = module.label1.context
delimiter = "."
tags = {
"Eat" = "Carrot"
"Animal" = "Rabbit"
}
}This creates label outputs like this:
label1 = {
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "-"
"id" = "winstonchurchroom-uat-build-fire-water-earth-air"
"name" = "winstonchurchroom"
"namespace" = "cloudposse"
"stage" = "build"
}
label1_context = {
"additional_tag_map" = {}
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "-"
"enabled" = true
"environment" = "UAT"
"label_order" = [
"name",
"environment",
"stage",
"attributes",
]
"name" = "Winston Churchroom"
"namespace" = "CloudPosse"
"stage" = "build"
"tags" = {
"City" = "Dublin"
"Environment" = "Private"
}
}
label1_normalized_context = {
"additional_tag_map" = {}
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "-"
"enabled" = true
"environment" = "uat"
"id_length_limit" = 0
"label_order" = [
"name",
"environment",
"stage",
"attributes",
]
"name" = "winstonchurchroom"
"namespace" = "cloudposse"
"regex_replace_chars" = "/[^-a-zA-Z0-9]/"
"stage" = "build"
"tags" = {
"Attributes" = "fire-water-earth-air"
"City" = "Dublin"
"Environment" = "Private"
"Name" = "winstonchurchroom-uat-build-fire-water-earth-air"
"Namespace" = "cloudposse"
"Stage" = "build"
}
}
label1_tags = {
"Attributes" = "fire-water-earth-air"
"City" = "Dublin"
"Environment" = "Private"
"Name" = "winstonchurchroom-uat-build-fire-water-earth-air"
"Namespace" = "cloudposse"
"Stage" = "build"
}
label2 = {
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "+"
"id" = "charlie+uat+test+fire+water+earth+air"
"name" = "charlie"
"namespace" = "cloudposse"
"stage" = "test"
}
label2_context = {
"additional_tag_map" = {
"additional_tag" = "yes"
"propagate_at_launch" = "true"
}
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "+"
"enabled" = true
"environment" = "UAT"
"label_order" = [
"name",
"environment",
"stage",
"attributes",
]
"name" = "Charlie"
"namespace" = "CloudPosse"
"regex_replace_chars" = "/[^a-zA-Z0-9-+]/"
"stage" = "test"
"tags" = {
"City" = "London"
"Environment" = "Public"
}
}
label2_tags = {
"Attributes" = "fire+water+earth+air"
"City" = "London"
"Environment" = "Public"
"Name" = "charlie+uat+test+fire+water+earth+air"
"Namespace" = "cloudposse"
"Stage" = "test"
}
label2_tags_as_list_of_maps = [
{
"additional_tag" = "yes"
"key" = "Attributes"
"propagate_at_launch" = "true"
"value" = "fire+water+earth+air"
},
{
"additional_tag" = "yes"
"key" = "City"
"propagate_at_launch" = "true"
"value" = "London"
},
{
"additional_tag" = "yes"
"key" = "Environment"
"propagate_at_launch" = "true"
"value" = "Public"
},
{
"additional_tag" = "yes"
"key" = "Name"
"propagate_at_launch" = "true"
"value" = "charlie+uat+test+fire+water+earth+air"
},
{
"additional_tag" = "yes"
"key" = "Namespace"
"propagate_at_launch" = "true"
"value" = "cloudposse"
},
{
"additional_tag" = "yes"
"key" = "Stage"
"propagate_at_launch" = "true"
"value" = "test"
},
]
label3 = {
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "."
"id" = "starfish.uat.release.fire.water.earth.air"
"name" = "starfish"
"namespace" = "cloudposse"
"stage" = "release"
}
label3_context = {
"additional_tag_map" = {}
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "."
"enabled" = true
"environment" = "UAT"
"label_order" = [
"name",
"environment",
"stage",
"attributes",
]
"name" = "Starfish"
"namespace" = "CloudPosse"
"regex_replace_chars" = "/[^-a-zA-Z0-9.]/"
"stage" = "release"
"tags" = {
"Animal" = "Rabbit"
"City" = "Dublin"
"Eat" = "Carrot"
"Environment" = "Private"
}
}
label3_normalized_context = {
"additional_tag_map" = {}
"attributes" = [
"fire",
"water",
"earth",
"air",
]
"delimiter" = "."
"enabled" = true
"environment" = "uat"
"id_length_limit" = 0
"label_order" = [
"name",
"environment",
"stage",
"attributes",
]
"name" = "starfish"
"namespace" = "cloudposse"
"regex_replace_chars" = "/[^-a-zA-Z0-9.]/"
"stage" = "release"
"tags" = {
"Animal" = "Rabbit"
"Attributes" = "fire.water.earth.air"
"City" = "Dublin"
"Eat" = "Carrot"
"Environment" = "Private"
"Name" = "starfish.uat.release.fire.water.earth.air"
"Namespace" = "cloudposse"
"Stage" = "release"
}
}
label3_tags = {
"Animal" = "Rabbit"
"Attributes" = "fire.water.earth.air"
"City" = "Dublin"
"Eat" = "Carrot"
"Environment" = "Private"
"Name" = "starfish.uat.release.fire.water.earth.air"
"Namespace" = "cloudposse"
"Stage" = "release"
}
Available targets:
help Help screen
help/all Display help for all targets
help/short This help short screen
lint Lint terraform code
| Name | Version |
|---|---|
| terraform | >= 0.12.26 |
No provider.
| Name | Description | Type | Default | Required |
|---|---|---|---|---|
| additional_tag_map | Additional tags for appending to tags_as_list_of_maps. Not added to tags. |
map(string) |
{} |
no |
| attributes | Additional attributes (e.g. 1) |
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. |
object({ |
{ |
no |
| delimiter | Delimiter to be used between namespace, environment, stage, name and attributes.Defaults to - (hyphen). Set to "" to use no delimiter at all. |
string |
null |
no |
| enabled | Set to false to prevent the module from creating any resources | bool |
null |
no |
| environment | Environment, e.g. 'uw2', 'us-west-2', OR 'prod', 'staging', 'dev', 'UAT' | string |
null |
no |
| id_length_limit | Limit id to this many characters.Set to 0 for unlimited length.Set to null for default, which is 0.Does not affect id_full. |
number |
null |
no |
| label_order | The naming order of the id output and Name tag. Defaults to ["namespace", "environment", "stage", "name", "attributes"]. You can omit any of the 5 elements, but at least one must be present. |
list(string) |
null |
no |
| name | Solution name, e.g. 'app' or 'jenkins' | string |
null |
no |
| namespace | Namespace, which could be your organization name or abbreviation, e.g. 'eg' or 'cp' | string |
null |
no |
| regex_replace_chars | Regex to replace chars with empty string in namespace, environment, stage and name.If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits. |
string |
null |
no |
| stage | Stage, e.g. 'prod', 'staging', 'dev', OR 'source', 'build', 'test', 'deploy', 'release' | string |
null |
no |
| tags | Additional tags (e.g. map('BusinessUnit','XYZ') |
map(string) |
{} |
no |
| Name | Description |
|---|---|
| additional_tag_map | The merged additional_tag_map |
| attributes | List of attributes |
| context | Merged but otherwise unmodified input to this module, to be used as context input to other modules. Note: this version will have null values as defaults, not the values actually used as defaults. |
| delimiter | Delimiter between namespace, environment, stage, name and attributes |
| enabled | True if module is enabled, false otherwise |
| environment | Normalized environment |
| id | Disambiguated ID restricted to id_length_limit characters in total |
| id_full | Disambiguated ID not restricted in length |
| id_length_limit | The id_length_limit actually used to create the ID, with 0 meaning unlimited |
| label_order | The naming order actually used to create the ID |
| name | Normalized name |
| namespace | Normalized namespace |
| normalized_context | Normalized context of this module |
| regex_replace_chars | The regex_replace_chars actually used to create the ID |
| stage | Normalized stage |
| tags | Normalized Tag map |
| tags_as_list_of_maps | Additional tags as a list of maps, which can be used in several AWS resources |
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Check out these related projects.
- terraform-terraform-label - Terraform Module to define a consistent naming convention by (namespace, environment, stage, name, [attributes])
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Copyright © 2017-2020 Cloud Posse, LLC
See LICENSE for full details.
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
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