README.md

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.

Terraform module to provision MongoDB using AWS-ECS

Terraform module that provisions Mongo container in ECS-EC2 container instance.

This module creates the following resources required for mongo container to be up and running in ECS cluster.

1. ECS cluster
2. ECS task definition and service for provided version of mongo
3. Roles required for EC2 to execute the task
4. EBS volume for persistent storage of mongo container

Approach:

This approach creates an ECS task for mongo and runs/manages that task on EC2 instance of provided instance type. This mongo task uses a docker plugin called rexray/ebs to provision and use EBS volume for persistent storage of mongo container.

Pros:

1. Simplified mongo infra management with just Terraform
2. Mongo task gets restarted automatically in case of failure
3. Easy version upgrades with minimal downtime
4. Auto provision of EBS volume
5. Built-in ECS monitoring provided in ECS dashboard
6. Data volume will not be lost unless deleted manually.

Cons:

1. Rolling deployments are not supported yet due to mongo single instance limitation.
2. EBS volume size should be chosen carefully because it is not possible to expand it later as it is managed by docker plugin

Terraform Versions

Terraform - 0.12.24

Terraform AWS provider version - 2.60

Prerequisites

1. Configure AWS credentials. Refer this for help.
2. Make sure that your AWS user has permissions required to create all resources in the diagram
3. Install Terraform (version mentioned above) from here

Usage

Note:
Change the inputs to match your requirement

module "mongo_ecs_ec2_cluster" {
    source = "path-to-the-module"

    security_group_id = "security-group-id"
    subnet_id = "subnet-id"
    ebs_volume_size = 5
    ebs_volume_type = "gp2"
    instance_type = "t3.medium"
    name = "mongo"
    region = "ap-southeast-1"
    stage = "Development"
    mongo_container_cpu = 512
    mongo_container_memory = 1024
    mongo_version = "4.0"
    
    tags = {
      Environment = "Development"
      TF-Managed = true
    }
}

Examples

Try out the module functionality with an example defined here. We are using Terragrunt for remote state management. Do install it in case you want remote backend for state.

1. Switch to examples directory cd examples
2. Initialize Terraform to download required plugins terraform init | terragrunt init
3. Run plan to find out all resources that are going to be created terraform plan | terragrunt plan
4. Run apply to create those resources terraform apply | terragrunt apply
5. Install mongo shell and run mongo <public_ip>:27017 to access mongodb
6. Make sure to destroy them once you are done exploring terraform destroy | terragrunt destroy

Note:

1. Make sure to delete the EBS volume manually as terraform destroy won't delete it.
2. If remote state is used then delete the state management resources (S3 bucket and Dynamo table) created by Terragrunt manually.

Inputs

Name	Description	Type	Default	Required
name	Name to be used on all the resources as identifier	string	n/a	yes
security_group_id	Id of the security group to attach to mongo instance	string	n/a	yes
subnet_id	Id of subnet to create mongo instance in (Private subnet recommended)	string	n/a	yes
ebs_volume_size	Size of EBS volume to be used by mongo container	number	n/a	yes
ebs_volume_type	Type of EBS volume to be used by mongo container	string	n/a	yes
instance_type	Type of EC2 instance to be used by ECS cluster for mongo task	string	n/a	yes
region	Region to be used for creating all the above resources	string	n/a	yes
stage	Stage of the deployment	string	n/a	yes
mongo_container_cpu	CPU capacity to be allocated for mongo container	number	n/a	yes
mongo_container_memory	Memory to be allocated for mongo container	number	n/a	yes
mongo_version	Version tag of mongo docker image	string	n/a	yes
tags	A map of default tags to add to all resources	map	{}	no

Outputs

Name	Description
ecs_cluster_arn	The arn of mongo ECS cluster
ecs_cluster_name	The name of mongo ECS cluster
ecs_cluster_region	The region where mongo ECS cluster is created
mongo_instance_private_ip	The private IPV4 address of mongo instance to connect to mongodb
mongo_instance_public_ip	The public IPV4 address of mongo instance to connect to mongodb (If created in public subnet)

Contributing

We appreciate your help!

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

License

Authors