How to deploy and redeploy applications with Terraform? - amazon-web-services

Question

I'm looking into Terraform and how to use it to setup an AWS environment. So far I have the scripts for setting up a VPC with 3 public subnets, 3 private subnets, an Internet Gateway and 3 Nat Gateways. However I'm confused as to how one would go about deploy and redeploying applications in private subnets?
In my scenario we build micro-services using Spring Boot. The idea is to move to a state where we can have Elastic Load Balancers attached to the public subnets and host our applications in autoscale groups in the private subnets. However I can't find any good tutorials regarding Terraform that show you how to do this in a way that applications can be redeployed from Jenkins.
So far I've read about Opsworks and Code Deploy so would I need to use Terraform to setup these resources and then trigger the deployment scripts to send artefacts to S3 that are then redeployed?

Answer 1

For deploy/redeploy, you can use another solution by Hashicorp: Nomad. It uses the same language as Terraform to program tasks that you can run on a cluster. Tasks can be anything, for example: redeploy all my web app instances.

Answer 2

I'm using CodeDeploy with Terraform/Chef. The setup I'm using goes something like this:
1) Manually setup the CodeDeploy IAM Roles ahead of time.
2) Setup the CodeDeploy App/Group ahead of time.
3) Setup the Instance Profile using Terraform, like this:
resource "aws_iam_instance_profile" "code_deploy" {
name = "CodeDeploy"
roles = ["${var.codedeploy_instance_role}"]
}
4) Use the Instance Profile and the correct tags (that match your CodeDeploy app) when making an instance, like this:
iam_instance_profile = "${aws_iam_instance_profile.code_deploy.id}"
tags {
CD = "${var.tag_cd}"
}
5) Use Chef (or whatever your provisioner is) to setup CodeDeploy on the instance.
Then you're good to use CodeDeploy like normal.

Answer 3

Adding this so that in case someone is looking for more information, might find this useful.
Building on the Solution from Peter, I am setting up the CodeDeploy IAM Roles and CodeDeploy App/Group from Terraform as well. Here is what I have:
resource "aws_iam_role" "codedeploy_role_name" {
name = "codedeploy_role_name"
assume_role_policy = <<EOF
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service": [
"codedeploy.amazonaws.com",
"ec2.amazonaws.com"
]
},
"Action": "sts:AssumeRole"
}
]
}
EOF
}
resource "aws_codedeploy_app" "analytics_app" {
name = "analytics_app"
}
resource "aws_codedeploy_deployment_config" "analytics_deployment_config" {
deployment_config_name = "analytics_deployment_config"
minimum_healthy_hosts {
type = "HOST_COUNT"
value = 2
}
}
resource "aws_codedeploy_deployment_group" "analytics_group" {
app_name = "${aws_codedeploy_app.analytics_app.name}"
deployment_group_name = "analytics_group"
service_role_arn = "${aws_iam_role.codedeploy_role_name.arn}"
deployment_config_name = "analytics_deployment_config"
ec2_tag_filter {
key = "CodeDeploy"
type = "KEY_AND_VALUE"
value = "analytics"
}
auto_rollback_configuration {
enabled = true
events = ["DEPLOYMENT_FAILURE"]
}
}