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Module: ses-lambda-forwarder

This is a terraform module that creates an email forwarder using a combination of AWS SES and Lambda running the aws-lambda-ses-forwarder NPM module.

Introduction​

This module provisions a NodeJS script as a AWS Lambda function that uses the inbound/outbound capabilities of AWS Simple Email Service (SES) to run a "serverless" email forwarding service.

Use this module instead of setting up an email server on a dedicated EC2 instance to handle email redirects. It uses AWS SES to receive email and then trigger a Lambda function to process it and forward it on to the chosen destination. This script will allow forwarding emails from any sender to verified destination emails (e.g. opt-in).

Limitations​

The SES service only allows sending email from verified addresses or domains. As such, it's mostly suitable for transactional emails (e.g. alerts or notifications). The incoming messages are modified to allow forwarding through SES and reflect the original sender. This script adds a Reply-To header with the original sender's email address, but the From header is changed to display the SES email address.

For example, an email sent by John Doe <[email protected]> to [email protected] will be transformed to:

From: John Doe at [email protected] <[email protected]>
Reply-To: [email protected]

To override this behavior, set a verified fromEmail address (e.g., [email protected]) in the config object and the header will look like this.

From: John Doe <[email protected]>
Reply-To: [email protected]

NOTE: SES only allows receiving email sent to addresses within verified domains. For more information, see: http://docs.aws.amazon.com/ses/latest/DeveloperGuide/verify-domains.html


Initially SES users are in a sandbox environment that has a number of limitations. See:
http://docs.aws.amazon.com/ses/latest/DeveloperGuide/limits.html



## Usage


For a complete example, see [examples/complete](https://github.com/cloudposse/terraform-aws-ses-lambda-forwarder/tree/main/examples/complete).

For automated tests of the complete example using [bats](https://github.com/bats-core/bats-core) and [Terratest](https://github.com/gruntwork-io/terratest) (which tests and deploys the example on AWS), see [test](https://github.com/cloudposse/terraform-aws-ses-lambda-forwarder/tree/main/test).

```hcl
variable "relay_email" \{
  default     = "[email protected]"
  description = "Email that used to relay from"
\}

variable "forward_emails" \{
  type = map(list(string))

  default = \{
    "[email protected]"  = ["[email protected]"]
    "[email protected]" = ["[email protected]"]
  \}

  description = "Emails forward map"
\}

module "ses_lambda_forwarder" \{
  source = "cloudposse/ses-lambda-forwarder/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"

  namespace  = var.namespace
  stage      = var.stage
  name       = var.name
  delimiter  = var.delimiter
  attributes = var.attributes
  tags       = var.tags

  region = var.region
  domain = var.domain

  relay_email    = var.relay_email
  forward_emails = var.forward_emails
\}

Variables​

Required Variables​

domain (string) required

Root domain name

region (string) required

AWS Region the SES should reside in

relay_email (string) required

Email that used to relay from

Optional Variables​

access_log_bucket_name (string) optional

Name of the S3 bucket where s3 access log will be sent to


Default value: ""

artifact_filename (string) optional

Artifact filename


Default value: "lambda.zip"

artifact_url (string) optional

URL template for the remote artifact


Default value: "https://artifacts.cloudposse.com/$${module_name}/$${git_ref}/$${filename}"

forward_emails (map(list(string))) optional

Map of forward emails


Default value:

\{
  "[email protected]": [
    "[email protected]"
  ]
\}
lambda_runtime (string) optional

Lambda runtime


Default value: "nodejs12.x"

s3_bucket_encryption_enabled (bool) optional

When set to 'true' the 'aws_s3_bucket' resource will have AES256 encryption enabled by default


Default value: true

spf (string) optional

DNS SPF record value


Default value: "v=spf1 include:amazonses.com -all"

tracing_config_mode (string) optional

Can be either PassThrough or Active. If PassThrough, Lambda will only trace the request from an upstream service if it contains a tracing header with 'sampled=1'. If Active, Lambda will respect any tracing header it receives from an upstream service.


Default value: "PassThrough"

versioning_enabled (bool) optional

A state of versioning. Versioning is a means of keeping multiple variants of an object in the same bucket


Default value: true

Context Variables​

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

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.


Required: No

Default value: { }

attributes (list(string)) optional

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.


Required: No

Default value: [ ]

context (any) optional

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.


Required: No

Default value:

\{
  "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
\}
delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.


Required: No

Default value: null

descriptor_formats (any) optional

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).


Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

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.


Required: No

Default value: null

label_key_case (string) optional

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.


Required: No

Default value: null

label_order (list(string)) optional

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.


Required: No

Default value: null

label_value_case (string) optional

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.


Required: No

Default value: null

labels_as_tags (set(string)) optional

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.


Required: No

Default value:

[
  "default"
]
name (string) optional

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.


Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

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.


Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.


Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs​

artifact_base64sha256

Base64 encoded SHA256 hash of the artifact file

artifact_file

Full path to the locally downloaded artifact

artifact_git_ref

Git commit hash corresponding to the artifact

artifact_url

URL corresponding to the artifact

lambda_function_arn

Lamnda Function ARN

lambda_function_source_code_size

The size in bytes of the Lambda Function .zip file

lambda_function_version

Latest published version of the Lambda Function

lambda_iam_policy_arn

Lamnda IAM Policy ARN

lambda_iam_policy_id

Lamnda IAM Policy ID

lambda_iam_policy_name

Lamnda IAM Policy name

s3_bucket_arn

Lamnda IAM Policy ARN

s3_bucket_domain_name

Lamnda IAM Policy ARN

s3_bucket_id

Lamnda IAM Policy name

ses_domain_identity_arn

The ARN of the domain identity

ses_domain_identity_verification_arn

The ARN of the domain identity

ses_receipt_rule_name

The name of the SES receipt rule

ses_receipt_rule_set_name

The name of the SES receipt rule set

Dependencies​

Requirements​

  • terraform, version: >= 0.13.0
  • aws, version: >= 2.0
  • external, version: >= 1.2
  • local, version: >= 1.3
  • template, version: >= 2.2

Providers​

  • aws, version: >= 2.0

Modules​

NameVersionSourceDescription
artifact0.8.0cloudposse/module-artifact/externaln/a
this0.25.0cloudposse/label/nulln/a

Resources​

The following resources are used by this module:

Data Sources​

The following data sources are used by this module: