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Terraform module designed to generate consistent names and tags for resources. Useterraform-null-label to implement a strict naming convention.

There are 6 inputs considered "labels" or "ID elements" (because the labels are used to construct the ID):

1. namespace
2. tenant
3. environment
4. stage
5. name
6. attributes

This module generates IDs using the following convention by default:{namespace}-{environment}-{stage}-{name}-{attributes}.However, it is highly configurable. The delimiter (e.g.-) is configurable. Each label item is optional (although you must provide at least one).So if you prefer the termstage toenvironment and do not needtenant, you can exclude themand the labelid will look like{namespace}-{stage}-{name}-{attributes}.

• Thetenant label was introduced in v0.25.0. To preserve backward compatibility, it is not included by default.
• Theattributes input is actually a list of strings and{attributes} expands to the list elements joined by the delimiter.
• Ifattributes is excluded butnamespace,stage, andenvironment are included,id will look like{namespace}-{environment}-{stage}-{name}.Excludingattributes is discouraged, though, because attributes are the main way modules modify the ID to ensure uniqueness when provisioning the same resource types.
• If you want the label items in a different order, you can specify that, too, with thelabel_order list.
• You can set a maximum length for theid, and the module will create a (probably) unique name that fits within that length.(The module uses a portion of the MD5 hash of the fullid to represent the missing part, so there remains a slight chance of name collision.)
• You can control the letter case of the generated labels which make up theid usingvar.label_value_case.
• By default, all of the non-empty labels are also exported as tags, whether they appear in theid or not.You can control which labels are exported as tags by settinglabels_as_tags to the list of labels you want exported,or the empty list[] if you want no labels exported as tags at all. Tags passed in via thetags variable arealways exported, and regardless of settings, empty labels are never exported as tags.You can control the case of the tag names (keys) for the labels usingvar.label_key_case.Unlike the tags generated from the label inputs, tags passed in via thetags input are not modified.

There is an unfortunate collision over the use of the keyname. Cloud Posse usesname in this moduleto represent the component, such aseks orrds. AWS uses a tag with the keyName to store the full human-friendlyidentifier of the thing tagged, which this module outputs asid, notname. So when converting input labelsto tags, the value of theName key is set to the moduleid output, and there is no tag corresponding to themodulename output. An emptyname label will not prevent theName tag from being exported.

It's recommended to use oneterraform-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.

For most purposes, theid output is sufficient to create an ID or label for a resource, and if you want a differentID or a different format, you would instantiate another instance ofnull-label and configure it accordingly. However,to accomodate situations where you want all the same inputs to generate multiple descriptors, this module providesthedescriptors output, which is a map of strings generated according to the format specified by thedescriptor_formats input. This feature is intentionally simple and minimally configurable and will not beenhanced to add more features that are already innull-label. Seeexamples/complete/descriptors.tf for examples.

AllCloud Posse Terraform modules use this module to ensure resources can be instantiated multiple times within an account and without conflict.

The Cloud Posse convention is to use labels as follows:

• namespace: A short (3-4 letters) abbreviation of the company name, to ensure globally unique IDs for things like S3 buckets
• tenant:(Rarely needed) When a company creates a dedicated resource per customer,tenant can be used to identify the customer the resource is dedicated to
• environment: Ashort abbreviation for the AWS region hosting the resource, orgbl for resources like IAM roles that have no region
• stage: The name or role of the account the resource is for, such asprod ordev
• name: The name of the component that owns the resources, such aseks orrds

NOTE: Thenull originally referred to the primary Terraformprovider used in this module.With Terraform 0.12, this module no longer needs any provider, but the name was kept for continuity.

• Releases of this module from0.23.0 onward only work with Terraform 0.13 or newer.
• Releases of this module from0.12.0 through0.22.1 supportHCL2 and are compatible with Terraform 0.12 or newer.
• Releases of this module prior to0.12.0 are compatible with earlier versions of terraform like Terraform 0.11.

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Cloud Posse Terraform modules share a commoncontext object that is meant to be passed from module to module.The context object is a single object that contains all the input values forterraform-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 thannull, will override the valuein the context object. In order to allow chaining of these objects, where the context object input to onemodule is transformed and passed on to the next module, all the variables default tonull or empty collections.The actual default values used when nothing is explicitly set are described in the documentation below.

For example, the default value ofdelimiter is shown asnull, but if you leave it set tonull,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. Instead, the new settingbecomes 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 canbe overwritten.

Because the purpose oflabels_as_tags is primarily to prevent tags from being generatedthat wouldconflict with the AWS provider'sdefault_tags, it is an exception to therule that variables override the setting in the context object. The value in the contextobject cannot be changed, so that later modules cannot re-enable a problematic tag.

module"eg_prod_bastion_label" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version = "x.x.x"namespace="eg"stage="prod"name="bastion"attributes=["public"]delimiter="-"tags={"BusinessUnit"="XYZ","Snapshot"="true"  }}

This will create anid with the value ofeg-prod-bastion-public because when generatingid, the default order isnamespace,environment,stage,name,attributes(you can override it by using thelabel_order variable, seeAdvanced 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_idname=module.eg_prod_bastion_label.idtags=module.eg_prod_bastion_label.tagsegress {from_port=0to_port=0protocol="-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.

module"eg_prod_bastion_label" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version = "x.x.x"namespace="eg"stage="prod"name="bastion"delimiter="-"tags={"BusinessUnit"="XYZ","Snapshot"="true"  }}module"eg_prod_bastion_abc_label" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version = "x.x.x"attributes=["abc"]tags={"BusinessUnit"="ABC"# Override the Business Unit tag set in the base label  }# Copy all other fields from the base labelcontext=module.eg_prod_bastion_label.context}resource"aws_security_group""eg_prod_bastion_abc" {name=module.eg_prod_bastion_abc_label.idtags=module.eg_prod_bastion_abc_label.tagsingress {from_port=22to_port=22protocol="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.tagsvpc_security_group_ids=[aws_security_group.eg_prod_bastion_abc.id]}module"eg_prod_bastion_xyz_label" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version = "x.x.x"attributes=["xyz"]context=module.eg_prod_bastion_label.context}resource"aws_security_group""eg_prod_bastion_xyz" {name=module.eg_prod_bastion_xyz_label.idtags=module.eg_prod_bastion_xyz_label.tagsingress {from_port=22to_port=22protocol="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.tagsvpc_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 andrequires its tags to be in this format, which this module can generate viaadditional_tag_map andtags_as_list_of_maps:

tags=[    {        key="Name",        propagate_at_launch=true,        value="namespace-stage-name"    },    {        key="Namespace",        propagate_at_launch=true,        value="namespace"    },    {        key="Stage",        propagate_at_launch=true,        value="stage"    }]

################################# 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 prefixname_prefix="${module.label.id}-"image_id=data.aws_ami.amazon_linux.idinstance_type="t2.micro"instance_initiated_shutdown_behavior="terminate"vpc_security_group_ids=[data.aws_security_group.default.id]monitoring {enabled=false  }# terraform-null-label example used here: Set tags on volumestag_specifications {resource_type="volume"tags=module.label.tags  }}####################### Autoscaling group  #######################resource"aws_autoscaling_group""default" {# terraform-null-label example used here: Set ASG name prefixname_prefix="${module.label.id}-"vpc_zone_identifier=data.aws_subnet_ids.all.idsmax_size=1min_size=1desired_capacity=1launch_template={    id= aws_launch_template.default.id    version="$$Latest"  }# terraform-null-label example used here: Set tags on ASG and EC2 Serverstags=module.label.tags_as_list_of_maps}

Seecomplete example for even more examples.

This example shows how you can pass thecontext 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 labelas a derivative of that.

module"label1" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version     = "x.x.x"namespace="CloudPosse"tenant="H.R.H"environment="UAT"stage="build"name="Winston Churchroom"attributes=["fire","water","earth","air"]label_order=["name","tenant","environment","stage","attributes"]tags={"City"="Dublin""Environment"="Private"  }}module"label2" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version     = "x.x.x"name="Charlie"tenant=""# setting to `null` would have no effectstage="test"delimiter="+"regex_replace_chars="/[^a-zA-Z0-9-+]/"additional_tag_map={    propagate_at_launch=true    additional_tag="yes"  }tags={"City"="London""Environment"="Public"  }context=module.label1.context}module"label3" {source="cloudposse/label/null"# Cloud Posse recommends pinning every module to a specific version# version     = "x.x.x"name="Starfish"stage="release"delimiter="."regex_replace_chars="/[^-a-zA-Z0-9.]/"tags={"Eat"="Carrot""Animal"="Rabbit"  }context=module.label1.context}

label1={"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"="-""id"="winstonchurchroom-hrh-uat-build-fire-water-earth-air""name"="winstonchurchroom""namespace"="cloudposse""stage"="build""tenant"="hrh"}label1_context={"additional_tag_map"= {}"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"=tostring(null)"enabled"=true"environment"="UAT""id_length_limit"=tonumber(null)"label_key_case"=tostring(null)"label_order"=tolist(["name","tenant","environment","stage","attributes",  ])"label_value_case"=tostring(null)"name"="Winston Churchroom""namespace"="CloudPosse""regex_replace_chars"=tostring(null)"stage"="build""tags"= {"City"="Dublin""Environment"="Private"  }"tenant"="H.R.H"}label1_normalized_context={"additional_tag_map"= {}"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"="-""enabled"=true"environment"="uat""id_length_limit"=0"label_key_case"="title""label_order"=tolist(["name","tenant","environment","stage","attributes",  ])"label_value_case"="lower""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-hrh-uat-build-fire-water-earth-air""Namespace"="cloudposse""Stage"="build""Tenant"="hrh"  }"tenant"="hrh"}label1_tags=tomap({"Attributes"="fire-water-earth-air""City"="Dublin""Environment"="Private""Name"="winstonchurchroom-hrh-uat-build-fire-water-earth-air""Namespace"="cloudposse""Stage"="build""Tenant"="hrh"})label2={"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"="+""id"="charlie+uat+test+fire+water+earth+air""name"="charlie""namespace"="cloudposse""stage"="test""tenant"=""}label2_context={"additional_tag_map"= {"additional_tag"="yes""propagate_at_launch"="true"  }"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"="+""enabled"=true"environment"="UAT""id_length_limit"=tonumber(null)"label_key_case"=tostring(null)"label_order"=tolist(["name","tenant","environment","stage","attributes",  ])"label_value_case"=tostring(null)"name"="Charlie""namespace"="CloudPosse""regex_replace_chars"="/[^a-zA-Z0-9-+]/""stage"="test""tags"= {"City"="London""Environment"="Public"  }"tenant"=""}label2_tags=tomap({"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"=tolist(["fire","water","earth","air",  ])"delimiter"=".""id"="starfish.h.r.h.uat.release.fire.water.earth.air""name"="starfish""namespace"="cloudposse""stage"="release""tenant"="h.r.h"}label3_context={"additional_tag_map"= {}"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"=".""enabled"=true"environment"="UAT""id_length_limit"=tonumber(null)"label_key_case"=tostring(null)"label_order"=tolist(["name","tenant","environment","stage","attributes",  ])"label_value_case"=tostring(null)"name"="Starfish""namespace"="CloudPosse""regex_replace_chars"="/[^-a-zA-Z0-9.]/""stage"="release""tags"= {"Animal"="Rabbit""City"="Dublin""Eat"="Carrot""Environment"="Private"  }"tenant"="H.R.H"}label3_normalized_context={"additional_tag_map"= {}"attributes"=tolist(["fire","water","earth","air",  ])"delimiter"=".""enabled"=true"environment"="uat""id_length_limit"=0"label_key_case"="title""label_order"=tolist(["name","tenant","environment","stage","attributes",  ])"label_value_case"="lower""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.h.r.h.uat.release.fire.water.earth.air""Namespace"="cloudposse""Stage"="release""Tenant"="h.r.h"  }"tenant"="h.r.h"}label3_tags=tomap({"Animal"="Rabbit""Attributes"="fire.water.earth.air""City"="Dublin""Eat"="Carrot""Environment"="Private""Name"="starfish.h.r.h.uat.release.fire.water.earth.air""Namespace"="cloudposse""Stage"="release""Tenant"="h.r.h"})

No providers.

No modules.

No resources.

{
  "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
}

[
  "default"
]

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 theissue tracker.

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

1. Review ourCode of Conduct andContributor 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 aPull Request so that we can review your changes

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

We useAtmos to streamline how Terraform tests are run. It centralizes configuration and wraps common test workflows with easy-to-use commands.

All tests are located in thetest/ folder.

Under the hood, tests are powered by Terratest together with our internalTest Helpers library, providing robust infrastructure validation.

Setup dependencies:

• Install Atmos (installation guide)
• Install Go1.24+ or newer
• Install Terraform or OpenTofu

To run tests:

• Run all tests:

  atmostest run

• Clean up test artifacts:

  atmostest clean

• Explore additional test options:

  atmostest --help

The configuration for test commands is centrally managed. To review what's being imported, see theatmos.yaml file.

Learn more about ourautomated testing in our documentation or implementingcustom commands with atmos.

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Licensed to the Apache Software Foundation (ASF) under oneor more contributor license agreements.  See the NOTICE filedistributed with this work for additional informationregarding copyright ownership.  The ASF licenses this fileto you under the Apache License, Version 2.0 (the"License"); you may not use this file except in compliancewith the License.  You may obtain a copy of the License at  https://www.apache.org/licenses/LICENSE-2.0Unless required by applicable law or agreed to in writing,software distributed under the License is distributed on an"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANYKIND, either express or implied.  See the License for thespecific language governing permissions and limitationsunder the License.

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