Terraform MongoDB provisioner using AWS EC2

This module is part of a project to simplify the provisioning of MongoDB on AWS cloud using Terraform. You may also wish to consider one of the other approaches.

This module provision MongoDB server on AWS EC2 instance using Ansible provisioner.

This module uses undergreen.mongodb Ansible role to provision mongodb. So, you can use any of the platforms supported by undergreen.mongodb role while selecting the AMI ID.

Pros

1. Simplified MongoDB provisioner supporting Replication.
2. EC2 instances can be provisioned with newer MongoDB versions and attach to existing EBS data volumes if versions are compatible.
3. MongoDB can be provisioned in either public subnet or in private subnet using Bastion host.

Cons

1. Dynamic increase/decrease of number of replica nodes is not yet supported.
2. No out-of-the-box monitoring support.

Dependencies

1. Ansible provisioner

This module depends on the Ansible provisioner. See the installation instructions.

Download a Prebuilt release available on GitHub, rename it to terraform-provisioner-ansible and place it in ~/.terraform.d/plugins directory.

2. Install Ansible role undergreen.mongodb

> ansible-galaxy install undergreen.mongodb

3. SSH Keys

User needs to provide SSH keys for this module to perform remote provisioning.

You can generate SSH keys using the following command:

$ ssh-keygen -t rsa -b 4096 -C "[email protected]"

For more info on generating SSH keys refer https://help.github.com/en/github/authenticating-to-github/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent

Prerequisite

The data should be persistent across the EC2 restarts/termination. So a better approach would be to store MongoDB data on externally created EBS volume and attach/mount to EC2 instance.

Note: To attach EBS volume to an EC2 instance they both need to be in same availability_zone.

How to use this module?

We can use this module to provision MongoDB server either in public subnet or in a private subnet.

1. Provision MongoDB in Public Subnet

If we want to provision MongoDB in a public subnet then MongoDB server can be provisioned using SSH directly without requiring bastion host as follows:

module "mongodb" {
  source            = "path/to/module"
  vpc_id            = var.vpc_id
  subnet_id         = var.subnet_id
  ssh_user          = "ubuntu"
  instance_type     = "t2.micro"
  ami_filter_name   = "ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-*"
  ami_owners        = ["099720109477"]
  data_volumes      = var.data_volumes
  mongodb_version   = "4.2"
  replicaset_name   = "mongo-rp0"
  replica_count     = 1
  private_key       = file("~/.ssh/id_rsa")
  public_key        = file("~/.ssh/id_rsa.pub")
  tags = {
      Name        = "MongoDB Server"
      Environment = "terraform-mongo-testing"
  }
}

variable "data_volumes" {
  type = list(object({
    ebs_volume_id = string
    availability_zone = string
  }))
  description = "List of EBS volumes"
  default = []
}

output "mongo_server_public_ip" {
  value = module.mongodb.mongo_server_public_ip
}
output "mongo_server_private_ip" {
  value = module.mongodb.mongo_server_private_ip
}

For more details see Example 1 - mongodb-in-public-subnet

2. Provision MongoDB in Private Subnet

If we want to provision MongoDB in a private subnet then a Bastion host(a.k.a Jump host) is required to provision MongoDB using SSH.

module "mongodb" {
  source            = "path/to/module"
  vpc_id            = data.aws_vpc.default.id
  subnet_id         = data.aws_subnet.subnet.id
  ssh_user          = "ubuntu"
  instance_type     = "t2.micro"
  ami_filter_name   = "ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-*"
  ami_owners        = ["099720109477"]
  data_volumes      = var.data_volumes
  mongodb_version   = "4.2"
  replicaset_name   = "mongo-rp0"
  replica_count     = 1
  private_key       = file("~/.ssh/id_rsa")
  public_key        = file("~/.ssh/id_rsa.pub")
  bastion_host      = "BASTION_HOST_IP_HERE"
  tags = {
        Name        = "MongoDB Server"
        Environment = "terraform-mongo-testing"
  }
}

For more details see Example 2 - mongodb-in-private-subnet

Inputs

Name	Description	Type	Default	Required
vpc_id	The VPC ID to launch in	string	n/a	yes
subnet_id	The VPC Subnet ID to launch in	string	n/a	yes
data_volumes	The EBS volume ids and their respective availability zones.	list(object({ ebs_volume_id, availability_zone}))	n/a	yes
private_key	Path to private key file	string	n/a	yes
public_key	Path to public key file	string	n/a	yes
ssh_user	SSH user name	string	n/a	yes
bastion_host	Bastion host Public IP	string	n/a	yes
instance_type	The type of instance to start	string	"t2.micro"	no
ami	ID of AMI to use for the instance	string	""	no
ami_filter_name	AMI selection filter by name. This will be ignored if ami value is specified	string	"ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-*"	no
ami_owners	AMI owners filter criteria	list(string)	["self", "amazon", "aws-marketplace"]	no
keypair_name	Keypair name	string	"mongo-publicKey"	no
mongodb_version	MongoDB version to install	string	"4.2"	no
replicaset_name	MongoDB replicaset name	string	""	no
replica_count	Number of Replica nodes	number	1	no
tags	Tag for EC2	map(string)	{}	no

Outputs

Name	Description
mongo_server_public_ip	Public IP of provisioned MongoDB server
mongo_server_private_ip	Private IP of provisioned MongoDB server

Testing

1. Install Go https://golang.org/doc/install
2. Configure AWS Credentials as environment variables as mentioned above.

> cd test
> go test -v

Contributing

We appreciate your help!

Open an issue or submit a pull request for an enhancement. Browse through the current open issues.

License

Authors