Updated July 30, 2023

Terraform module to deploy a pair of S3 buckets, one for configuration and one for logging, along with the necessary IAM role and instance profile to allow for EC2 instances to interact with the buckets. The instance profile will also include the AmazonSSMManagedInstanceCore policy to allow the use of SSM.

Resource Overview Diagram


Simple Example

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.0"

provider "aws" {
  region = "us-east-2"

module "ec2_conf_log" {
  source = "./.."
  namespace = "eg"
  name = "ecl"

data "aws_availability_zones" "available" {
  state = "available"

data "aws_vpc" "default" {
  default = true

data "aws_subnet" "default" {
  availability_zone = data.aws_availability_zones.available.names[0]
  default_for_az = true

data "aws_ami" "ubuntu" {
  most_recent = true

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]

  filter {
    name   = "virtualization-type"
    values = ["hvm"]

  owners = ["099720109477"] # Canonical

module "instance" {
  source                      = "cloudposse/ec2-instance/aws"
  version                     = "0.45.0"

  subnet                      = data.aws_subnet.default.id
  vpc_id                      = data.aws_vpc.default.id
  ami                         = data.aws_ami.ubuntu.id
  ami_owner                   = "099720109477"
  assign_eip_address          = true
  associate_public_ip_address = true
  disable_api_termination     = false
  instance_type               = "t3.medium"
  instance_profile            = module.ec2_conf_log.instance_profile_name

  namespace = "eg"
  name = "ecl"

Perform configuration

While this module does not prescribe a particular way of configuring the instances, one approach is to use a cron job to regularly update the instance from the S3 bucket. It is important here to consider race conditions where only part of an update has been pushed to the S3 bucket but not all objects are there yet. It may make sense to upload an archive to S3 and download that as a single object rather than uploading multiple objects.

Example crontab:

*/2 * * * * root /bin/bash /root/configure.sh &>/dev/null

Example configurations script:

#!/usr/bin/env bash

set -e

aws s3 cp s3://example-bucket-name/default /etc/nginx/sites-enabled/default

systemctl reload-or-restart nginx

The bucket name can be templated at instance creation time, with the crontab and script installed via cloud-init.


While this module does not prescribe a particular way of submitting logs from the instance to the logs bucket, one method is to use logrotate. The following example works on an Ubuntu instance to rotate all the logs in an EOTK project and upload only the nginx access logs to the logs bucket (excluding error logs and others):

/home/ubuntu/eotk/projects.d/sites.d/log.d/*.log {
  su ubuntu ubuntu
  create 644 ubuntu ubuntu
  # 1 week. 1 rotation per hour = 168 hours/rotations per week
  rotate 168
    # run once after all files are rotated
    ROTATED_DIR="$(dirname "$1")"

    TOKEN=`/usr/bin/curl --silent --request PUT "" --header "X-aws-ec2-metadata-token-ttl-seconds: 60"`
    REGION=`/usr/bin/curl --silent --header "X-aws-ec2-metadata-token: $TOKEN" | grep region | cut -d\" -f4`
    INSTANCE_ID=`/usr/bin/curl --silent --header "X-aws-ec2-metadata-token: $TOKEN" | grep instanceId | cut -d\" -f4`

    /usr/bin/aws s3 sync "$ROTATED_DIR/" "s3://$BUCKET_NAME/$INSTANCE_ID/" --region $REGION --exclude "*" --include "$INCLUDE_PATTERN" --quiet

    /home/ubuntu/eotk/eotk --local nxreload -a
    /home/ubuntu/eotk/eotk --local torreload -a

The bucket name can be templated at instance creation time, with the logrotate package and script installed via cloud-init.


terraform>= 1.0.11
aws>= 4.0






aws_iam_policy_document.assume_role_policydata source
aws_iam_policy_document.conf_bucketdata source
aws_iam_policy_document.log_bucketdata source


additional_tag_mapAdditional 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.
attributesID 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.
contextSingle 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.
“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”: [
“name”: null,
“namespace”: null,
“regex_replace_chars”: null,
“stage”: null,
“tags”: {},
“tenant”: null
delimiterDelimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.
descriptor_formatsDescribe 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).
disable_configuration_bucketDisable the creation of the configuration bucket.boolfalseno
disable_logs_bucketDisable the creation of the logs bucket.boolfalseno
disable_ssmDo not attach the AmazonSSMManagedInstanceCore policy to the instance profile.boolfalseno
enabledSet to false to prevent the module from creating any resourcesboolnullno
environmentID element. Usually used for region e.g. ‘uw2’, ‘us-west-2’, OR role ‘prod’, ‘staging’, ‘dev’, ‘UAT’stringnullno
id_length_limitLimit 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.
label_key_caseControls 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.
label_orderThe 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.
label_value_caseControls 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.
labels_as_tagsSet 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.
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.
nameID 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.
namespaceID element. Usually an abbreviation of your organization name, e.g. ’eg’ or ‘cp’, to help ensure generated IDs are globally uniquestringnullno
regex_replace_charsTerraform 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.
stageID element. Usually used to indicate role, e.g. ‘prod’, ‘staging’, ‘source’, ‘build’, ’test’, ‘deploy’, ‘release’stringnullno
tagsAdditional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.
tenantID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is forstringnullno


conf_bucket_arnThe ARN for the configuration (read-only) S3 bucket
conf_bucket_idThe ID for the configuration (read-only) S3 bucket
iam_role_arnThe ARN for the role attached to the instance profile
iam_role_nameThe name of the role attached to the instance profile
instance_profile_nameThe name for the IAM instance profile with the attached policies (bucket access and SSM)
log_bucket_arnThe ARN for the logs (read/write) S3 bucket
log_bucket_idThe ID for the logs (read/write) S3 bucket

Tags: aws terraform tor ec2 s3 cloud-init