Feat: Add Support for Origin Groups (Failover Origins) (#174)

* Add Support for Origin Groups (failover origins)
* Add tests for `var.s3_origins` and `var.custom_origins`
* Add functionality such that if `s3_origin_config.origin_access_identity` in `var.s3_origins` is null or an empty string, translate it to the `origin_access_identity` used by the origin created by the module.

README.md

@@ -136,6 +136,47 @@ module "cdn" {
 }
 ```
 
+The following will create an Origin Group with the origin created by this module as a primary origin and an additional
+S3 bucket as a failover origin.
+
+```hcl
+module "s3_bucket" {
+  source  = "cloudposse/s3-bucket/aws"
+  # Cloud Posse recommends pinning every module to a specific version
+  # version = "x.x.x"
+
+  attributes = ["failover-assets"]
+}
+
+module "cdn" {
+  source = "cloudposse/cloudfront-s3-cdn/aws"
+  # Cloud Posse recommends pinning every module to a specific version
+  # version = "x.x.x"
+
+  aliases           = ["assets.cloudposse.com"]
+  dns_alias_enabled = true
+  parent_zone_name  = "cloudposse.com"
+  s3_origins = {
+    domain_name = module.s3_bucket.bucket_regional_domain_name
+    origin_id   = module.s3_bucket.bucket_id
+    origin_path = null
+    s3_origin_config = {
+      origin_access_identity = null # will get translated to the origin_access_identity used by the origin created by this module.
+    }
+  }
+  origin_groups = {
+    primary_origin_id  = null # will get translated to the origin id of the origin created by this module.
+    failover_origin_id = module.s3_bucket.bucket_id
+    failover_criteria  = [
+      403,
+      404,
+      500,
+      502
+    ]
+  }
+}
+```
+
 ### Background on CDNs, "Origins", S3 Buckets, and Web Servers
 
 #### CDNs and Origin Servers
@@ -435,6 +476,7 @@ Available targets:
 | <a name="input_ordered_cache"></a> [ordered\_cache](#input\_ordered\_cache) | An ordered list of [cache behaviors](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudfront_distribution#cache-behavior-arguments) resource for this distribution.<br>List in order of precedence (first match wins). This is in addition to the default cache policy.<br>Set `target_origin_id` to `""` to specify the S3 bucket origin created by this module. | <pre>list(object({<br>    target_origin_id = string<br>    path_pattern     = string<br><br>    allowed_methods = list(string)<br>    cached_methods  = list(string)<br>    compress        = bool<br><br>    cache_policy_id          = string<br>    origin_request_policy_id = string<br><br>    viewer_protocol_policy = string<br>    min_ttl                = number<br>    default_ttl            = number<br>    max_ttl                = number<br><br>    forward_query_string  = bool<br>    forward_header_values = list(string)<br>    forward_cookies       = string<br><br>    lambda_function_association = list(object({<br>      event_type   = string<br>      include_body = bool<br>      lambda_arn   = string<br>    }))<br><br>    function_association = list(object({<br>      event_type   = string<br>      function_arn = string<br>    }))<br>  }))</pre> | `[]` | no |
 | <a name="input_origin_bucket"></a> [origin\_bucket](#input\_origin\_bucket) | Name of an existing S3 bucket to use as the origin. If this is not provided, it will create a new s3 bucket using `var.name` and other context related inputs | `string` | `null` | no |
 | <a name="input_origin_force_destroy"></a> [origin\_force\_destroy](#input\_origin\_force\_destroy) | Delete all objects from the bucket so that the bucket can be destroyed without error (e.g. `true` or `false`) | `bool` | `false` | no |
+| <a name="input_origin_groups"></a> [origin\_groups](#input\_origin\_groups) | List of [Origin Groups](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudfront_distribution#origin-group-arguments) to create in the distribution.<br>The values of `primary_origin_id` and `failover_origin_id` must correspond to origin IDs existing in `var.s3_origins` or `var.custom_origins`.<br><br>If `primary_origin_id` is set to `null` or `""`, then the origin id of the origin created by this module will be used in its place.<br>This is to allow for the use case of making the origin created by this module the primary origin in an origin group. | <pre>list(object({<br>    primary_origin_id  = string<br>    failover_origin_id = string<br>    failover_criteria  = list(string)<br>  }))</pre> | `[]` | no |
 | <a name="input_origin_path"></a> [origin\_path](#input\_origin\_path) | An optional element that causes CloudFront to request your content from a directory in your Amazon S3 bucket or your custom origin. It must begin with a /. Do not add a / at the end of the path. | `string` | `""` | no |
 | <a name="input_origin_ssl_protocols"></a> [origin\_ssl\_protocols](#input\_origin\_ssl\_protocols) | The SSL/TLS protocols that you want CloudFront to use when communicating with your origin over HTTPS. | `list(string)` | <pre>[<br>  "TLSv1",<br>  "TLSv1.1",<br>  "TLSv1.2"<br>]</pre> | no |
 | <a name="input_override_origin_bucket_policy"></a> [override\_origin\_bucket\_policy](#input\_override\_origin\_bucket\_policy) | When using an existing origin bucket (through var.origin\_bucket), setting this to 'false' will make it so the existing bucket policy will not be overriden | `bool` | `true` | no |
@@ -449,7 +491,7 @@ Available targets:
 | <a name="input_s3_access_log_bucket_name"></a> [s3\_access\_log\_bucket\_name](#input\_s3\_access\_log\_bucket\_name) | Name of the existing S3 bucket where S3 Access Logs will be delivered. Default is not to enable S3 Access Logging. | `string` | `""` | no |
 | <a name="input_s3_access_log_prefix"></a> [s3\_access\_log\_prefix](#input\_s3\_access\_log\_prefix) | Prefix to use for S3 Access Log object keys. Defaults to `logs/${module.this.id}` | `string` | `""` | no |
 | <a name="input_s3_access_logging_enabled"></a> [s3\_access\_logging\_enabled](#input\_s3\_access\_logging\_enabled) | Set `true` to deliver S3 Access Logs to the `s3_access_log_bucket_name` bucket.<br>Defaults to `false` if `s3_access_log_bucket_name` is empty (the default), `true` otherwise.<br>Must be set explicitly if the access log bucket is being created at the same time as this module is being invoked. | `bool` | `null` | no |
-| <a name="input_s3_origins"></a> [s3\_origins](#input\_s3\_origins) | A list of S3 [origins](https://www.terraform.io/docs/providers/aws/r/cloudfront_distribution.html#origin-arguments) (in addition to the one created by this module) for this distribution.<br>S3 buckets configured as websites are `custom_origins`, not `s3_origins`. | <pre>list(object({<br>    domain_name = string<br>    origin_id   = string<br>    origin_path = string<br>    s3_origin_config = object({<br>      origin_access_identity = string<br>    })<br>  }))</pre> | `[]` | no |
+| <a name="input_s3_origins"></a> [s3\_origins](#input\_s3\_origins) | A list of S3 [origins](https://www.terraform.io/docs/providers/aws/r/cloudfront_distribution.html#origin-arguments) (in addition to the one created by this module) for this distribution.<br>S3 buckets configured as websites are `custom_origins`, not `s3_origins`.<br>Specifying `s3_origin_config.origin_access_identity` as `null` or `""` will have it translated to the `origin_access_identity` used by the origin created by the module. | <pre>list(object({<br>    domain_name = string<br>    origin_id   = string<br>    origin_path = string<br>    s3_origin_config = object({<br>      origin_access_identity = string<br>    })<br>  }))</pre> | `[]` | no |
 | <a name="input_s3_website_password_enabled"></a> [s3\_website\_password\_enabled](#input\_s3\_website\_password\_enabled) | If set to true, and `website_enabled` is also true, a password will be required in the `Referrer` field of the<br>HTTP request in order to access the website, and Cloudfront will be configured to pass this password in its requests.<br>This will make it much harder for people to bypass Cloudfront and access the S3 website directly via its website endpoint. | `bool` | `false` | no |
 | <a name="input_stage"></a> [stage](#input\_stage) | Stage, e.g. 'prod', 'staging', 'dev', OR 'source', 'build', 'test', 'deploy', 'release' | `string` | `null` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | Additional tags (e.g. `map('BusinessUnit','XYZ')` | `map(string)` | `{}` | no |
@@ -465,13 +507,16 @@ Available targets:
 
 | Name | Description |
 |------|-------------|
-| <a name="output_aliases"></a> [aliases](#output\_aliases) | Aliases of the CloudFront distibution |
+| <a name="output_aliases"></a> [aliases](#output\_aliases) | Aliases of the CloudFront distribution. |
 | <a name="output_cf_arn"></a> [cf\_arn](#output\_cf\_arn) | ARN of AWS CloudFront distribution |
 | <a name="output_cf_domain_name"></a> [cf\_domain\_name](#output\_cf\_domain\_name) | Domain name corresponding to the distribution |
 | <a name="output_cf_etag"></a> [cf\_etag](#output\_cf\_etag) | Current version of the distribution's information |
 | <a name="output_cf_hosted_zone_id"></a> [cf\_hosted\_zone\_id](#output\_cf\_hosted\_zone\_id) | CloudFront Route 53 zone ID |
 | <a name="output_cf_id"></a> [cf\_id](#output\_cf\_id) | ID of AWS CloudFront distribution |
 | <a name="output_cf_identity_iam_arn"></a> [cf\_identity\_iam\_arn](#output\_cf\_identity\_iam\_arn) | CloudFront Origin Access Identity IAM ARN |
+| <a name="output_cf_origin_groups"></a> [cf\_origin\_groups](#output\_cf\_origin\_groups) | List of Origin Groups in the CloudFront distribution. |
+| <a name="output_cf_origin_ids"></a> [cf\_origin\_ids](#output\_cf\_origin\_ids) | List of Origin IDs in the CloudFront distribution. |
+| <a name="output_cf_primary_origin_id"></a> [cf\_primary\_origin\_id](#output\_cf\_primary\_origin\_id) | The ID of the origin created by this module. |
 | <a name="output_cf_s3_canonical_user_id"></a> [cf\_s3\_canonical\_user\_id](#output\_cf\_s3\_canonical\_user\_id) | Canonical user ID for CloudFront Origin Access Identity |
 | <a name="output_cf_status"></a> [cf\_status](#output\_cf\_status) | Current status of the distribution |
 | <a name="output_logs"></a> [logs](#output\_logs) | Log bucket resource |

README.yaml

@@ -101,6 +101,47 @@ usage: |-
   }
   ```
 
+  The following will create an Origin Group with the origin created by this module as a primary origin and an additional
+  S3 bucket as a failover origin.
+
+  ```hcl
+  module "s3_bucket" {
+    source  = "cloudposse/s3-bucket/aws"
+    # Cloud Posse recommends pinning every module to a specific version
+    # version = "x.x.x"
+
+    attributes = ["failover-assets"]
+  }
+
+  module "cdn" {
+    source = "cloudposse/cloudfront-s3-cdn/aws"
+    # Cloud Posse recommends pinning every module to a specific version
+    # version = "x.x.x"
+
+    aliases           = ["assets.cloudposse.com"]
+    dns_alias_enabled = true
+    parent_zone_name  = "cloudposse.com"
+    s3_origins = {
+      domain_name = module.s3_bucket.bucket_regional_domain_name
+      origin_id   = module.s3_bucket.bucket_id
+      origin_path = null
+      s3_origin_config = {
+        origin_access_identity = null # will get translated to the origin_access_identity used by the origin created by this module.
+      }
+    }
+    origin_groups = {
+      primary_origin_id  = null # will get translated to the origin id of the origin created by this module.
+      failover_origin_id = module.s3_bucket.bucket_id
+      failover_criteria  = [
+        403,
+        404,
+        500,
+        502
+      ]
+    }
+  }
+  ```
+
   ### Background on CDNs, "Origins", S3 Buckets, and Web Servers
   
   #### CDNs and Origin Servers

docs/terraform.md

@@ -115,6 +115,7 @@
 | <a name="input_ordered_cache"></a> [ordered\_cache](#input\_ordered\_cache) | An ordered list of [cache behaviors](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudfront_distribution#cache-behavior-arguments) resource for this distribution.<br>List in order of precedence (first match wins). This is in addition to the default cache policy.<br>Set `target_origin_id` to `""` to specify the S3 bucket origin created by this module. | <pre>list(object({<br>    target_origin_id = string<br>    path_pattern     = string<br><br>    allowed_methods = list(string)<br>    cached_methods  = list(string)<br>    compress        = bool<br><br>    cache_policy_id          = string<br>    origin_request_policy_id = string<br><br>    viewer_protocol_policy = string<br>    min_ttl                = number<br>    default_ttl            = number<br>    max_ttl                = number<br><br>    forward_query_string  = bool<br>    forward_header_values = list(string)<br>    forward_cookies       = string<br><br>    lambda_function_association = list(object({<br>      event_type   = string<br>      include_body = bool<br>      lambda_arn   = string<br>    }))<br><br>    function_association = list(object({<br>      event_type   = string<br>      function_arn = string<br>    }))<br>  }))</pre> | `[]` | no |
 | <a name="input_origin_bucket"></a> [origin\_bucket](#input\_origin\_bucket) | Name of an existing S3 bucket to use as the origin. If this is not provided, it will create a new s3 bucket using `var.name` and other context related inputs | `string` | `null` | no |
 | <a name="input_origin_force_destroy"></a> [origin\_force\_destroy](#input\_origin\_force\_destroy) | Delete all objects from the bucket so that the bucket can be destroyed without error (e.g. `true` or `false`) | `bool` | `false` | no |
+| <a name="input_origin_groups"></a> [origin\_groups](#input\_origin\_groups) | List of [Origin Groups](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudfront_distribution#origin-group-arguments) to create in the distribution.<br>The values of `primary_origin_id` and `failover_origin_id` must correspond to origin IDs existing in `var.s3_origins` or `var.custom_origins`.<br><br>If `primary_origin_id` is set to `null` or `""`, then the origin id of the origin created by this module will be used in its place.<br>This is to allow for the use case of making the origin created by this module the primary origin in an origin group. | <pre>list(object({<br>    primary_origin_id  = string<br>    failover_origin_id = string<br>    failover_criteria  = list(string)<br>  }))</pre> | `[]` | no |
 | <a name="input_origin_path"></a> [origin\_path](#input\_origin\_path) | An optional element that causes CloudFront to request your content from a directory in your Amazon S3 bucket or your custom origin. It must begin with a /. Do not add a / at the end of the path. | `string` | `""` | no |
 | <a name="input_origin_ssl_protocols"></a> [origin\_ssl\_protocols](#input\_origin\_ssl\_protocols) | The SSL/TLS protocols that you want CloudFront to use when communicating with your origin over HTTPS. | `list(string)` | <pre>[<br>  "TLSv1",<br>  "TLSv1.1",<br>  "TLSv1.2"<br>]</pre> | no |
 | <a name="input_override_origin_bucket_policy"></a> [override\_origin\_bucket\_policy](#input\_override\_origin\_bucket\_policy) | When using an existing origin bucket (through var.origin\_bucket), setting this to 'false' will make it so the existing bucket policy will not be overriden | `bool` | `true` | no |
@@ -129,7 +130,7 @@
 | <a name="input_s3_access_log_bucket_name"></a> [s3\_access\_log\_bucket\_name](#input\_s3\_access\_log\_bucket\_name) | Name of the existing S3 bucket where S3 Access Logs will be delivered. Default is not to enable S3 Access Logging. | `string` | `""` | no |
 | <a name="input_s3_access_log_prefix"></a> [s3\_access\_log\_prefix](#input\_s3\_access\_log\_prefix) | Prefix to use for S3 Access Log object keys. Defaults to `logs/${module.this.id}` | `string` | `""` | no |
 | <a name="input_s3_access_logging_enabled"></a> [s3\_access\_logging\_enabled](#input\_s3\_access\_logging\_enabled) | Set `true` to deliver S3 Access Logs to the `s3_access_log_bucket_name` bucket.<br>Defaults to `false` if `s3_access_log_bucket_name` is empty (the default), `true` otherwise.<br>Must be set explicitly if the access log bucket is being created at the same time as this module is being invoked. | `bool` | `null` | no |
-| <a name="input_s3_origins"></a> [s3\_origins](#input\_s3\_origins) | A list of S3 [origins](https://www.terraform.io/docs/providers/aws/r/cloudfront_distribution.html#origin-arguments) (in addition to the one created by this module) for this distribution.<br>S3 buckets configured as websites are `custom_origins`, not `s3_origins`. | <pre>list(object({<br>    domain_name = string<br>    origin_id   = string<br>    origin_path = string<br>    s3_origin_config = object({<br>      origin_access_identity = string<br>    })<br>  }))</pre> | `[]` | no |
+| <a name="input_s3_origins"></a> [s3\_origins](#input\_s3\_origins) | A list of S3 [origins](https://www.terraform.io/docs/providers/aws/r/cloudfront_distribution.html#origin-arguments) (in addition to the one created by this module) for this distribution.<br>S3 buckets configured as websites are `custom_origins`, not `s3_origins`.<br>Specifying `s3_origin_config.origin_access_identity` as `null` or `""` will have it translated to the `origin_access_identity` used by the origin created by the module. | <pre>list(object({<br>    domain_name = string<br>    origin_id   = string<br>    origin_path = string<br>    s3_origin_config = object({<br>      origin_access_identity = string<br>    })<br>  }))</pre> | `[]` | no |
 | <a name="input_s3_website_password_enabled"></a> [s3\_website\_password\_enabled](#input\_s3\_website\_password\_enabled) | If set to true, and `website_enabled` is also true, a password will be required in the `Referrer` field of the<br>HTTP request in order to access the website, and Cloudfront will be configured to pass this password in its requests.<br>This will make it much harder for people to bypass Cloudfront and access the S3 website directly via its website endpoint. | `bool` | `false` | no |
 | <a name="input_stage"></a> [stage](#input\_stage) | Stage, e.g. 'prod', 'staging', 'dev', OR 'source', 'build', 'test', 'deploy', 'release' | `string` | `null` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | Additional tags (e.g. `map('BusinessUnit','XYZ')` | `map(string)` | `{}` | no |
@@ -145,13 +146,16 @@
 
 | Name | Description |
 |------|-------------|
-| <a name="output_aliases"></a> [aliases](#output\_aliases) | Aliases of the CloudFront distibution |
+| <a name="output_aliases"></a> [aliases](#output\_aliases) | Aliases of the CloudFront distribution. |
 | <a name="output_cf_arn"></a> [cf\_arn](#output\_cf\_arn) | ARN of AWS CloudFront distribution |
 | <a name="output_cf_domain_name"></a> [cf\_domain\_name](#output\_cf\_domain\_name) | Domain name corresponding to the distribution |
 | <a name="output_cf_etag"></a> [cf\_etag](#output\_cf\_etag) | Current version of the distribution's information |
 | <a name="output_cf_hosted_zone_id"></a> [cf\_hosted\_zone\_id](#output\_cf\_hosted\_zone\_id) | CloudFront Route 53 zone ID |
 | <a name="output_cf_id"></a> [cf\_id](#output\_cf\_id) | ID of AWS CloudFront distribution |
 | <a name="output_cf_identity_iam_arn"></a> [cf\_identity\_iam\_arn](#output\_cf\_identity\_iam\_arn) | CloudFront Origin Access Identity IAM ARN |
+| <a name="output_cf_origin_groups"></a> [cf\_origin\_groups](#output\_cf\_origin\_groups) | List of Origin Groups in the CloudFront distribution. |
+| <a name="output_cf_origin_ids"></a> [cf\_origin\_ids](#output\_cf\_origin\_ids) | List of Origin IDs in the CloudFront distribution. |
+| <a name="output_cf_primary_origin_id"></a> [cf\_primary\_origin\_id](#output\_cf\_primary\_origin\_id) | The ID of the origin created by this module. |
 | <a name="output_cf_s3_canonical_user_id"></a> [cf\_s3\_canonical\_user\_id](#output\_cf\_s3\_canonical\_user\_id) | Canonical user ID for CloudFront Origin Access Identity |
 | <a name="output_cf_status"></a> [cf\_status](#output\_cf\_status) | Current status of the distribution |
 | <a name="output_logs"></a> [logs](#output\_logs) | Log bucket resource |