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Terraform Module for provisioning multiple general purpose EC2 hosts for stateful applications.

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Cloud Posse

Terraform Module for providing N general purpose EC2 hosts.

If you only need to provision a single EC2 instance, consider using the terraform-aws-ec2-instance module instead.

IMPORTANT This module by-design does not provision an AutoScaling group. It was designed to provision a discrete number of instances suitable for running stateful services such as databases (e.g. Kafka, Redis, etc).

Included features:

  • Automatically create a Security Group
  • Option to switch EIP attachment
  • CloudWatch monitoring and automatic reboot if instance hangs
  • Assume Role capability

This project is part of our comprehensive "SweetOps" approach towards DevOps.

Terraform Open Source Modules

It's 100% Open Source and licensed under the APACHE2.

We literally have hundreds of terraform modules that are Open Source and well-maintained. Check them out!

Security & Compliance

Security scanning is graciously provided by Bridgecrew. Bridgecrew is the leading fully hosted, cloud-native solution providing continuous Terraform security and compliance.

Benchmark Description
Infrastructure Security Infrastructure Security Compliance
CIS KUBERNETES Center for Internet Security, KUBERNETES Compliance
CIS AWS Center for Internet Security, AWS Compliance
CIS AZURE Center for Internet Security, AZURE Compliance
PCI-DSS Payment Card Industry Data Security Standards Compliance
NIST-800-53 National Institute of Standards and Technology Compliance
ISO27001 Information Security Management System, ISO/IEC 27001 Compliance
SOC2 Service Organization Control 2 Compliance
CIS GCP Center for Internet Security, GCP Compliance
HIPAA Health Insurance Portability and Accountability Compliance

Usage

IMPORTANT: We do not pin modules to versions in our examples because of the difficulty of keeping the versions in the documentation in sync with the latest released versions. We highly recommend that in your code you pin the version to the exact version you are using so that your infrastructure remains stable, and update versions in a systematic way so that they do not catch you by surprise.

Note: add ${var.ssh_key_pair} private key to the ssh agent.

Include this repository as a module in your existing terraform code.

Simple example:

module "instance" {
  source = "cloudposse/ec2-instance-group/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"
  namespace                   = "eg"
  stage                       = "prod"
  name                        = "app"
  ami                         = "ami-a4dc46db"
  ami_owner                   = "099720109477"
  ssh_key_pair                = var.ssh_key_pair
  instance_type               = var.instance_type
  vpc_id                      = var.vpc_id
  security_groups             = var.security_groups
  subnet                      = var.subnet
  instance_count              = 3
}

Example with additional volumes and EIP

module "kafka_instance" {
  source = "cloudposse/ec2-instance-group/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"

  namespace                   = "eg"
  stage                       = "prod"
  name                        = "app"
  ami                         = "ami-a4dc46db"
  ami_owner                   = "099720109477"
  ssh_key_pair                = var.ssh_key_pair
  vpc_id                      = var.vpc_id
  security_groups             = var.security_groups
  subnet                      = var.subnet
  associate_public_ip_address = true
  additional_ips_count        = 1
  ebs_volume_count            = 2
  instance_count              = 3

  security_group_rules = [
    {
      type        = "egress"
      from_port   = 0
      to_port     = 65535
      protocol    = "-1"
      cidr_blocks = ["0.0.0.0/0"]
    },
    {
      type        = "ingress"
      from_port   = 22
      to_port     = 22
      protocol    = "tcp"
      cidr_blocks = ["0.0.0.0/0"]
    },
    {
      type        = "ingress"
      from_port   = 80
      to_port     = 80
      protocol    = "tcp"
      cidr_blocks = ["0.0.0.0/0"]
    },
    {
      type        = "ingress"
      from_port   = 443
      to_port     = 443
      protocol    = "tcp"
      cidr_blocks = ["0.0.0.0/0"]
    }
  ]
}

Additional complete working example with variations of how to use the module

In /examples directory

This module depends on these modules:

It is necessary to run terraform get or terraform init to download this module.

Now reference the label when creating an instance (for example):

resource "aws_ami_from_instance" "example" {
  count              = length(module.instance.*.id)
  name               = "app"
  source_instance_id = element(module.instance.*.id, count.index)
}

Makefile Targets

Available targets:

  help                                Help screen
  help/all                            Display help for all targets
  help/short                          This help short screen
  lint                                Lint terraform code

Requirements

Name Version
terraform >= 1.0
aws >= 2.0

Providers

Name Version
aws >= 2.0

Modules

Name Source Version
label cloudposse/label/null 0.25.0
security_group cloudposse/security-group/aws 0.3.1
ssh_key_pair cloudposse/key-pair/aws 0.19.0
this cloudposse/label/null 0.24.1

Resources

Name Type
aws_cloudwatch_metric_alarm.default resource
aws_ebs_volume.default resource
aws_eip.additional resource
aws_eip.default resource
aws_iam_instance_profile.default resource
aws_iam_role.default resource
aws_instance.default resource
aws_network_interface.additional resource
aws_network_interface_attachment.additional resource
aws_volume_attachment.default resource
aws_ami.info data source
aws_caller_identity.default data source
aws_iam_policy_document.default data source
aws_region.default data source

Inputs

Name Description Type Default Required
additional_ips_count Count of additional EIPs number 0 no
additional_tag_map Additional tags for appending to tags_as_list_of_maps. Not added to tags. map(string) {} no
ami The AMI to use for the instance string n/a yes
ami_owner Owner of the given AMI string n/a yes
applying_period The period in seconds over which the specified statistic is applied number 60 no
assign_eip_address Assign an Elastic IP address to the instance bool true no
associate_public_ip_address Associate a public IP address with the instance bool false no
attributes Additional attributes (e.g. 1) list(string) [] no
availability_zone Availability Zone the instance is launched in. If not set, will be launched in the first AZ of the region string "" no
comparison_operator The arithmetic operation to use when comparing the specified Statistic and Threshold. Possible values are: GreaterThanOrEqualToThreshold, GreaterThanThreshold, LessThanThreshold, LessThanOrEqualToThreshold string "GreaterThanOrEqualToThreshold" no
context 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.
any
{
"additional_tag_map": {},
"attributes": [],
"delimiter": null,
"enabled": true,
"environment": null,
"id_length_limit": null,
"label_key_case": null,
"label_order": [],
"label_value_case": null,
"name": null,
"namespace": null,
"regex_replace_chars": null,
"stage": null,
"tags": {}
}
no
default_alarm_action Default alarm action string "action/actions/AWS_EC2.InstanceId.Reboot/1.0" no
delete_on_termination Whether the volume should be destroyed on instance termination bool true no
delimiter Delimiter to be used between namespace, environment, stage, name and attributes.
Defaults to - (hyphen). Set to "" to use no delimiter at all.
string null no
disable_api_termination Enable EC2 Instance Termination Protection bool false no
ebs_device_names Name of the EBS device to mount list(string)
[
"/dev/xvdb",
"/dev/xvdc",
"/dev/xvdd",
"/dev/xvde",
"/dev/xvdf",
"/dev/xvdg",
"/dev/xvdh",
"/dev/xvdi",
"/dev/xvdj",
"/dev/xvdk",
"/dev/xvdl",
"/dev/xvdm",
"/dev/xvdn",
"/dev/xvdo",
"/dev/xvdp",
"/dev/xvdq",
"/dev/xvdr",
"/dev/xvds",
"/dev/xvdt",
"/dev/xvdu",
"/dev/xvdv",
"/dev/xvdw",
"/dev/xvdx",
"/dev/xvdy",
"/dev/xvdz"
]
no
ebs_iops Amount of provisioned IOPS. This must be set with a volume_type of io1 number 0 no
ebs_optimized Launched EC2 instance will be EBS-optimized bool false no
ebs_volume_count Count of EBS volumes that will be attached to the instance number 0 no
ebs_volume_encrypted Size of the EBS volume in gigabytes bool true no
ebs_volume_size Size of the EBS volume in gigabytes number 10 no
ebs_volume_type The type of EBS volume. Can be standard, gp2 or io1 string "gp2" no
enabled Set to false to prevent the module from creating any resources bool null no
environment Environment, e.g. 'uw2', 'us-west-2', OR 'prod', 'staging', 'dev', 'UAT' string null no
evaluation_periods The number of periods over which data is compared to the specified threshold number 5 no
generate_ssh_key_pair If true, create a new key pair and save the pem for it to the current working directory bool false no
id_length_limit Limit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for default, which is 0.
Does not affect id_full.
number null no
instance_count Count of ec2 instances to create number 1 no
instance_type The type of the instance string "t2.micro" no
ipv6_address_count Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet number 0 no
ipv6_addresses List of IPv6 addresses from the range of the subnet to associate with the primary network interface list(string) [] no
kms_key_id KMS key ID used to encrypt EBS volume. When specifying kms_key_id, ebs_volume_encrypted needs to be set to true string null no
label_key_case The letter case of label keys (tag names) (i.e. name, namespace, environment, stage, attributes) to use in tags.
Possible values: lower, title, upper.
Default value: title.
string null no
label_order The naming order of the id output and Name tag.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 5 elements, but at least one must be present.
list(string) null no
label_value_case The letter case of output label values (also used in tags and id).
Possible values: lower, title, upper and none (no transformation).
Default value: lower.
string null no
metadata_http_endpoint_enabled Whether the metadata service is available bool true no
metadata_http_tokens_required Whether or not the metadata service requires session tokens, also referred to as Instance Metadata Service Version 2. bool true no
metric_name The name for the alarm's associated metric. Allowed values can be found in https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/ec2-metricscollected.html string "StatusCheckFailed_Instance" no
metric_namespace The namespace for the alarm's associated metric. Allowed values can be found in https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/aws-namespaces.html string "AWS/EC2" no
metric_threshold The value against which the specified statistic is compared number 1 no
monitoring Launched EC2 instance will have detailed monitoring enabled bool true no
name Solution name, e.g. 'app' or 'jenkins' string null no
namespace Namespace, which could be your organization name or abbreviation, e.g. 'eg' or 'cp' string null no
permissions_boundary_arn Policy ARN to attach to instance role as a permissions boundary string "" no
private_ips Private IP address to associate with the instances in the VPC list(string) [] no
regex_replace_chars Regex to replace chars with empty string in namespace, environment, stage and name.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.
string null no
region AWS Region the instance is launched in string n/a yes
root_block_device_encrypted Whether to encrypt the root block device bool true no
root_iops Amount of provisioned IOPS. This must be set if root_volume_type is set to io1 number 0 no
root_volume_size Size of the root volume in gigabytes number 10 no
root_volume_type Type of root volume. Can be standard, gp2 or io1 string "gp2" no
security_group_description The Security Group description. string "EC2 instances Security Group" no
security_group_enabled Whether to create default Security Group for EC2 instances. bool true no
security_group_rules A list of maps of Security Group rules.
The values of map is fully complated with aws_security_group_rule resource.
To get more info see https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group_rule .
list(any)
[
{
"cidr_blocks": [
"0.0.0.0/0"
],
"description": "Allow all outbound traffic",
"from_port": 0,
"protocol": "-1",
"to_port": 65535,
"type": "egress"
}
]
no
security_group_use_name_prefix Whether to create a default Security Group with unique name beginning with the normalized prefix. bool false no
security_groups A list of Security Group IDs to associate with EC2 instances. list(string) [] no
source_dest_check Controls if traffic is routed to the instance when the destination address does not match the instance. Used for NAT or VPNs bool true no
ssh_key_pair SSH key pair to be provisioned on the instance string "" no
ssh_key_pair_path Path to where the generated key pairs will be created. Defaults to $${path.cwd} string "" no
stage Stage, e.g. 'prod', 'staging', 'dev', OR 'source', 'build', 'test', 'deploy', 'release' string null no
statistic_level The statistic to apply to the alarm's associated metric. Allowed values are: SampleCount, Average, Sum, Minimum, Maximum string "Maximum" no
subnet VPC Subnet ID the instance is launched in string n/a yes
tags Additional tags (e.g. map('BusinessUnit','XYZ') map(string) {} no
user_data Instance user data. Do not pass gzip-compressed data via this argument string "" no
vpc_id The ID of the VPC that the instance security group belongs to string n/a yes

Outputs

Name Description
alarm_ids CloudWatch Alarm IDs
aws_key_pair_name Name of AWS key pair
ebs_ids IDs of EBSs
eip_per_instance_count Number of EIPs per instance.
eni_to_eip_map Map of ENI with EIP
ids Disambiguated IDs list
instance_count Total number of instances created
name Instance(s) name
new_ssh_keypair_generated Was a new ssh_key_pair generated
primary_network_interface_ids IDs of the instance's primary network interface
private_dns Private DNS records of instances
private_ips Private IPs of instances
public_dns All public DNS records for the public interfaces and ENIs
public_ips List of Public IPs of instances (or EIP)
role_names Names of AWS IAM Roles associated with creating instance
security_group_arn EC2 instances Security Group ARN
security_group_id EC2 instances Security Group ID
security_group_ids ID on the new AWS Security Group associated with creating instance
security_group_name EC2 instances Security Group name
ssh_key_pem_path Path where SSH key pair was created (if applicable)

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Copyright

Copyright © 2017-2023 Cloud Posse, LLC

License

License

See LICENSE for full details.

Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
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  https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
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Contributors

Erik Osterman
Erik Osterman
Jamie Nelson
Jamie Nelson
Vladimir Syromyatnikov
Vladimir Syromyatnikov
Andriy Knysh
Andriy Knysh
Chris Weyl
Chris Weyl

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