prefix variable consistency across modules

CONTRIBUTING.md

@@ -531,6 +531,27 @@ locals {
 }
 ```
 
+#### The `prefix` variable
+
+If you would like to use a "prefix" variable for resource names, please keep its definition consistent across all code:
+```hcl
+# variables.tf
+variable "prefix" {
+  description = "Optional prefix used for resource names."
+  type        = string
+  default     = null
+  validation {
+    condition = var.prefix != ""
+    error_message = "Prefix can not be empty, please use null instead."
+  }
+}
+
+# main.tf
+locals {
+  prefix = var.prefix == null ? "" : "${var.prefix}-"
+}
+```
+
 ### Interacting with checks, tests and tools
 
 Our modules are designed for composition and live in a monorepo together with several end-to-end blueprints, so it was inevitable that over time we found ways of ensuring that a change does not break consumers.

modules/cloud-function/README.md

@@ -163,7 +163,7 @@ module "cf-http" {
 | [bucket_name](variables.tf#L26) | Name of the bucket that will be used for the function code. It will be created with prefix prepended if bucket_config is not null. | <code>string</code> | ✓ |  |
 | [bundle_config](variables.tf#L31) | Cloud function source folder and generated zip bundle paths. Output path defaults to '/tmp/bundle.zip' if null. | <code title="object&#40;&#123;&#10;  source_dir  &#61; string&#10;  output_path &#61; string&#10;  excludes    &#61; list&#40;string&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
 | [name](variables.tf#L88) | Name used for cloud function and associated resources. | <code>string</code> | ✓ |  |
-| [project_id](variables.tf#L99) | Project id used for all resources. | <code>string</code> | ✓ |  |
+| [project_id](variables.tf#L103) | Project id used for all resources. | <code>string</code> | ✓ |  |
 | [bucket_config](variables.tf#L17) | Enable and configure auto-created bucket. Set fields to null to use defaults. | <code title="object&#40;&#123;&#10;  location             &#61; string&#10;  lifecycle_delete_age &#61; number&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
 | [description](variables.tf#L40) | Optional description. | <code>string</code> |  | <code>&#34;Terraform managed.&#34;</code> |
 | [environment_variables](variables.tf#L46) | Cloud function environment variables. | <code>map&#40;string&#41;</code> |  | <code>&#123;&#125;</code> |
@@ -172,14 +172,14 @@ module "cf-http" {
 | [ingress_settings](variables.tf#L76) | Control traffic that reaches the cloud function. Allowed values are ALLOW_ALL, ALLOW_INTERNAL_AND_GCLB and ALLOW_INTERNAL_ONLY . | <code>string</code> |  | <code>null</code> |
 | [labels](variables.tf#L82) | Resource labels. | <code>map&#40;string&#41;</code> |  | <code>&#123;&#125;</code> |
 | [prefix](variables.tf#L93) | Optional prefix used for resource names. | <code>string</code> |  | <code>null</code> |
-| [region](variables.tf#L104) | Region used for all resources. | <code>string</code> |  | <code>&#34;europe-west1&#34;</code> |
-| [secrets](variables.tf#L110) | Secret Manager secrets. Key is the variable name or mountpoint, volume versions are in version:path format. | <code title="map&#40;object&#40;&#123;&#10;  is_volume  &#61; bool&#10;  project_id &#61; number&#10;  secret     &#61; string&#10;  versions   &#61; list&#40;string&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
-| [service_account](variables.tf#L122) | Service account email. Unused if service account is auto-created. | <code>string</code> |  | <code>null</code> |
-| [service_account_create](variables.tf#L128) | Auto-create service account. | <code>bool</code> |  | <code>false</code> |
-| [trigger_config](variables.tf#L134) | Function trigger configuration. Leave null for HTTP trigger. | <code title="object&#40;&#123;&#10;  event    &#61; string&#10;  resource &#61; string&#10;  retry    &#61; bool&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
-| [v2](variables.tf#L163) | Whether to use Cloud Function version 2nd Gen or 1st Gen. | <code>bool</code> |  | <code>false</code> |
-| [vpc_connector](variables.tf#L144) | VPC connector configuration. Set create to 'true' if a new connector needs to be created. | <code title="object&#40;&#123;&#10;  create          &#61; bool&#10;  name            &#61; string&#10;  egress_settings &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
-| [vpc_connector_config](variables.tf#L154) | VPC connector network configuration. Must be provided if new VPC connector is being created. | <code title="object&#40;&#123;&#10;  ip_cidr_range &#61; string&#10;  network       &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
+| [region](variables.tf#L108) | Region used for all resources. | <code>string</code> |  | <code>&#34;europe-west1&#34;</code> |
+| [secrets](variables.tf#L114) | Secret Manager secrets. Key is the variable name or mountpoint, volume versions are in version:path format. | <code title="map&#40;object&#40;&#123;&#10;  is_volume  &#61; bool&#10;  project_id &#61; number&#10;  secret     &#61; string&#10;  versions   &#61; list&#40;string&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
+| [service_account](variables.tf#L126) | Service account email. Unused if service account is auto-created. | <code>string</code> |  | <code>null</code> |
+| [service_account_create](variables.tf#L132) | Auto-create service account. | <code>bool</code> |  | <code>false</code> |
+| [trigger_config](variables.tf#L138) | Function trigger configuration. Leave null for HTTP trigger. | <code title="object&#40;&#123;&#10;  event    &#61; string&#10;  resource &#61; string&#10;  retry    &#61; bool&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
+| [v2](variables.tf#L167) | Whether to use Cloud Function version 2nd Gen or 1st Gen. | <code>bool</code> |  | <code>false</code> |
+| [vpc_connector](variables.tf#L148) | VPC connector configuration. Set create to 'true' if a new connector needs to be created. | <code title="object&#40;&#123;&#10;  create          &#61; bool&#10;  name            &#61; string&#10;  egress_settings &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
+| [vpc_connector_config](variables.tf#L158) | VPC connector network configuration. Must be provided if new VPC connector is being created. | <code title="object&#40;&#123;&#10;  ip_cidr_range &#61; string&#10;  network       &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
 
 ## Outputs
 

modules/cloud-function/variables.tf

@@ -94,6 +94,10 @@ variable "prefix" {
   description = "Optional prefix used for resource names."
   type        = string
   default     = null
+  validation {
+    condition     = var.prefix != ""
+    error_message = "Prefix can not be empty, please use null instead."
+  }
 }
 
 variable "project_id" {

modules/cloud-run/README.md

@@ -214,21 +214,21 @@ module "cloud_run" {
 |---|---|:---:|:---:|:---:|
 | [containers](variables.tf#L27) | Containers. | <code title="list&#40;object&#40;&#123;&#10;  image &#61; string&#10;  options &#61; object&#40;&#123;&#10;    command &#61; list&#40;string&#41;&#10;    args    &#61; list&#40;string&#41;&#10;    env     &#61; map&#40;string&#41;&#10;    env_from &#61; map&#40;object&#40;&#123;&#10;      key  &#61; string&#10;      name &#61; string&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#10;  resources &#61; object&#40;&#123;&#10;    limits &#61; object&#40;&#123;&#10;      cpu    &#61; string&#10;      memory &#61; string&#10;    &#125;&#41;&#10;    requests &#61; object&#40;&#123;&#10;      cpu    &#61; string&#10;      memory &#61; string&#10;    &#125;&#41;&#10;  &#125;&#41;&#10;  ports &#61; list&#40;object&#40;&#123;&#10;    name           &#61; string&#10;    protocol       &#61; string&#10;    container_port &#61; string&#10;  &#125;&#41;&#41;&#10;  volume_mounts &#61; map&#40;string&#41;&#10;&#125;&#41;&#41;">list&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> | ✓ |  |
 | [name](variables.tf#L77) | Name used for cloud run service. | <code>string</code> | ✓ |  |
-| [project_id](variables.tf#L88) | Project id used for all resources. | <code>string</code> | ✓ |  |
+| [project_id](variables.tf#L92) | Project id used for all resources. | <code>string</code> | ✓ |  |
 | [audit_log_triggers](variables.tf#L18) | Event arc triggers (Audit log). | <code title="list&#40;object&#40;&#123;&#10;  service_name &#61; string&#10;  method_name  &#61; string&#10;&#125;&#41;&#41;">list&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>null</code> |
 | [iam](variables.tf#L59) | IAM bindings for Cloud Run service in {ROLE => [MEMBERS]} format. | <code>map&#40;list&#40;string&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
 | [ingress_settings](variables.tf#L65) | Ingress settings. | <code>string</code> |  | <code>null</code> |
 | [labels](variables.tf#L71) | Resource labels. | <code>map&#40;string&#41;</code> |  | <code>&#123;&#125;</code> |
 | [prefix](variables.tf#L82) | Optional prefix used for resource names. | <code>string</code> |  | <code>null</code> |
-| [pubsub_triggers](variables.tf#L93) | Eventarc triggers (Pub/Sub). | <code>list&#40;string&#41;</code> |  | <code>null</code> |
-| [region](variables.tf#L99) | Region used for all resources. | <code>string</code> |  | <code>&#34;europe-west1&#34;</code> |
-| [revision_annotations](variables.tf#L105) | Configure revision template annotations. | <code title="object&#40;&#123;&#10;  autoscaling &#61; object&#40;&#123;&#10;    max_scale &#61; number&#10;    min_scale &#61; number&#10;  &#125;&#41;&#10;  cloudsql_instances  &#61; list&#40;string&#41;&#10;  vpcaccess_connector &#61; string&#10;  vpcaccess_egress    &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
-| [revision_name](variables.tf#L119) | Revision name. | <code>string</code> |  | <code>null</code> |
-| [service_account](variables.tf#L125) | Service account email. Unused if service account is auto-created. | <code>string</code> |  | <code>null</code> |
-| [service_account_create](variables.tf#L131) | Auto-create service account. | <code>bool</code> |  | <code>false</code> |
-| [traffic](variables.tf#L137) | Traffic. | <code>map&#40;number&#41;</code> |  | <code>null</code> |
-| [volumes](variables.tf#L143) | Volumes. | <code title="list&#40;object&#40;&#123;&#10;  name        &#61; string&#10;  secret_name &#61; string&#10;  items &#61; list&#40;object&#40;&#123;&#10;    key  &#61; string&#10;    path &#61; string&#10;  &#125;&#41;&#41;&#10;&#125;&#41;&#41;">list&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>null</code> |
-| [vpc_connector_create](variables.tf#L156) | Populate this to create a VPC connector. You can then refer to it in the template annotations. | <code title="object&#40;&#123;&#10;  ip_cidr_range &#61; string&#10;  name          &#61; string&#10;  vpc_self_link &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
+| [pubsub_triggers](variables.tf#L97) | Eventarc triggers (Pub/Sub). | <code>list&#40;string&#41;</code> |  | <code>null</code> |
+| [region](variables.tf#L103) | Region used for all resources. | <code>string</code> |  | <code>&#34;europe-west1&#34;</code> |
+| [revision_annotations](variables.tf#L109) | Configure revision template annotations. | <code title="object&#40;&#123;&#10;  autoscaling &#61; object&#40;&#123;&#10;    max_scale &#61; number&#10;    min_scale &#61; number&#10;  &#125;&#41;&#10;  cloudsql_instances  &#61; list&#40;string&#41;&#10;  vpcaccess_connector &#61; string&#10;  vpcaccess_egress    &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
+| [revision_name](variables.tf#L123) | Revision name. | <code>string</code> |  | <code>null</code> |
+| [service_account](variables.tf#L129) | Service account email. Unused if service account is auto-created. | <code>string</code> |  | <code>null</code> |
+| [service_account_create](variables.tf#L135) | Auto-create service account. | <code>bool</code> |  | <code>false</code> |
+| [traffic](variables.tf#L141) | Traffic. | <code>map&#40;number&#41;</code> |  | <code>null</code> |
+| [volumes](variables.tf#L147) | Volumes. | <code title="list&#40;object&#40;&#123;&#10;  name        &#61; string&#10;  secret_name &#61; string&#10;  items &#61; list&#40;object&#40;&#123;&#10;    key  &#61; string&#10;    path &#61; string&#10;  &#125;&#41;&#41;&#10;&#125;&#41;&#41;">list&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>null</code> |
+| [vpc_connector_create](variables.tf#L160) | Populate this to create a VPC connector. You can then refer to it in the template annotations. | <code title="object&#40;&#123;&#10;  ip_cidr_range &#61; string&#10;  name          &#61; string&#10;  vpc_self_link &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
 
 ## Outputs
 

modules/cloud-run/variables.tf

@@ -83,6 +83,10 @@ variable "prefix" {
   description = "Optional prefix used for resource names."
   type        = string
   default     = null
+  validation {
+    condition     = var.prefix != ""
+    error_message = "Prefix can not be empty, please use null instead."
+  }
 }
 
 variable "project_id" {

modules/cloudsql-instance/README.md

@@ -149,9 +149,9 @@ module "db" {
 | [database_version](variables.tf#L50) | Database type and version to create. | <code>string</code> | ✓ |  |
 | [name](variables.tf#L97) | Name of primary instance. | <code>string</code> | ✓ |  |
 | [network](variables.tf#L102) | VPC self link where the instances will be deployed. Private Service Networking must be enabled and configured in this VPC. | <code>string</code> | ✓ |  |
-| [project_id](variables.tf#L113) | The ID of the project where this instances will be created. | <code>string</code> | ✓ |  |
-| [region](variables.tf#L118) | Region of the primary instance. | <code>string</code> | ✓ |  |
-| [tier](variables.tf#L138) | The machine type to use for the instances. | <code>string</code> | ✓ |  |
+| [project_id](variables.tf#L117) | The ID of the project where this instances will be created. | <code>string</code> | ✓ |  |
+| [region](variables.tf#L122) | Region of the primary instance. | <code>string</code> | ✓ |  |
+| [tier](variables.tf#L142) | The machine type to use for the instances. | <code>string</code> | ✓ |  |
 | [authorized_networks](variables.tf#L17) | Map of NAME=>CIDR_RANGE to allow to connect to the database(s). | <code>map&#40;string&#41;</code> |  | <code>null</code> |
 | [availability_type](variables.tf#L23) | Availability type for the primary replica. Either `ZONAL` or `REGIONAL`. | <code>string</code> |  | <code>&#34;ZONAL&#34;</code> |
 | [backup_configuration](variables.tf#L29) | Backup settings for primary instance. Will be automatically enabled if using MySQL with one or more replicas. | <code title="object&#40;&#123;&#10;  enabled            &#61; bool&#10;  binary_log_enabled &#61; bool&#10;  start_time         &#61; string&#10;  location           &#61; string&#10;  log_retention_days &#61; number&#10;  retention_count    &#61; number&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code title="&#123;&#10;  enabled            &#61; false&#10;  binary_log_enabled &#61; false&#10;  start_time         &#61; &#34;23:00&#34;&#10;  location           &#61; null&#10;  log_retention_days &#61; 7&#10;  retention_count    &#61; 7&#10;&#125;">&#123;&#8230;&#125;</code> |
@@ -161,12 +161,12 @@ module "db" {
 | [disk_type](variables.tf#L73) | The type of data disk: `PD_SSD` or `PD_HDD`. | <code>string</code> |  | <code>&#34;PD_SSD&#34;</code> |
 | [encryption_key_name](variables.tf#L79) | The full path to the encryption key used for the CMEK disk encryption of the primary instance. | <code>string</code> |  | <code>null</code> |
 | [flags](variables.tf#L85) | Map FLAG_NAME=>VALUE for database-specific tuning. | <code>map&#40;string&#41;</code> |  | <code>null</code> |
-| [ipv4_enabled](variables.tf#L149) | Add a public IP address to database instance. | <code>bool</code> |  | <code>false</code> |
+| [ipv4_enabled](variables.tf#L153) | Add a public IP address to database instance. | <code>bool</code> |  | <code>false</code> |
 | [labels](variables.tf#L91) | Labels to be attached to all instances. | <code>map&#40;string&#41;</code> |  | <code>null</code> |
-| [prefix](variables.tf#L107) | Prefix used to generate instance names. | <code>string</code> |  | <code>null</code> |
-| [replicas](variables.tf#L123) | Map of NAME=> {REGION, KMS_KEY} for additional read replicas. Set to null to disable replica creation. | <code title="map&#40;object&#40;&#123;&#10;  region              &#61; string&#10;  encryption_key_name &#61; string&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
-| [root_password](variables.tf#L132) | Root password of the Cloud SQL instance. Required for MS SQL Server | <code>string</code> |  | <code>null</code> |
-| [users](variables.tf#L143) | Map of users to create in the primary instance (and replicated to other replicas) in the format USER=>PASSWORD. For MySQL, anything afterr the first `@` (if persent) will be used as the user's host. Set PASSWORD to null if you want to get an autogenerated password. | <code>map&#40;string&#41;</code> |  | <code>null</code> |
+| [prefix](variables.tf#L107) | Optional prefix used to generate instance names. | <code>string</code> |  | <code>null</code> |
+| [replicas](variables.tf#L127) | Map of NAME=> {REGION, KMS_KEY} for additional read replicas. Set to null to disable replica creation. | <code title="map&#40;object&#40;&#123;&#10;  region              &#61; string&#10;  encryption_key_name &#61; string&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
+| [root_password](variables.tf#L136) | Root password of the Cloud SQL instance. Required for MS SQL Server | <code>string</code> |  | <code>null</code> |
+| [users](variables.tf#L147) | Map of users to create in the primary instance (and replicated to other replicas) in the format USER=>PASSWORD. For MySQL, anything afterr the first `@` (if persent) will be used as the user's host. Set PASSWORD to null if you want to get an autogenerated password. | <code>map&#40;string&#41;</code> |  | <code>null</code> |
 
 ## Outputs
 

modules/cloudsql-instance/variables.tf

@@ -105,9 +105,13 @@ variable "network" {
 }
 
 variable "prefix" {
-  description = "Prefix used to generate instance names."
+  description = "Optional prefix used to generate instance names."
   type        = string
   default     = null
+  validation {
+    condition     = var.prefix != ""
+    error_message = "Prefix can not be empty, please use null instead."
+  }
 }
 
 variable "project_id" {