open-consul/website/content/docs/ecs/get-started/migrate-existing-tasks.mdx
2021-11-16 10:55:23 -06:00

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---
layout: docs
page_title: Migrate Existing Tasks - AWS ECS
description: >-
Migrate Existing Tasks
---
# Migrate Existing Tasks
This topic describes how to migrate your existing ECS Tasks to use our [`mesh-task` Terraform module](https://registry.terraform.io/modules/hashicorp/consul-ecs/aws/latest/submodules/mesh-task).
## Define Tasks in Terraform
Your tasks must first be specified in Terraform using the [`ecs_task_definition`](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/ecs_task_definition)
resource so that they can then be converted to use the [`mesh-task` module](https://registry.terraform.io/modules/hashicorp/consul-ecs/aws/latest/submodules/mesh-task).
For example, your tasks should be defined with Terraform similar to the following:
```hcl
resource "aws_ecs_task_definition" "my_task" {
family = "my_task"
requires_compatibilities = ["FARGATE"]
network_mode = "awsvpc"
cpu = 256
memory = 512
execution_role_arn = "arn:aws:iam::111111111111:role/execution-role"
task_role_arn = "arn:aws:iam::111111111111:role/task-role"
container_definitions = jsonencode(
[{
name = "example-client-app"
image = "docker.io/org/my_task:v0.0.1"
essential = true
portMappings = [
{
containerPort = 9090
hostPort = 9090
protocol = "tcp"
}
]
cpu = 0
mountPoints = []
volumesFrom = []
}]
)
}
resource "aws_ecs_service" "my_task" {
name = "my_task"
cluster = "arn:aws:ecs:us-east-1:111111111111:cluster/my-cluster"
task_definition = aws_ecs_task_definition.my_task.arn
desired_count = 1
network_configuration {
subnets = ["subnet-abc123"]
}
launch_type = "FARGATE"
}
```
## Convert to the `mesh-task` Module
In order to add the necessary sidecar containers for your task to join the mesh,
you must use the [`mesh-task` module](https://registry.terraform.io/modules/hashicorp/consul-ecs/aws/latest/submodules/mesh-task).
The `mesh-task` module uses inputs similar to your old ECS task definition but
creates a new version of the task definition with additional containers.
The `mesh-task` module is used as follows:
```hcl
module "my_task" {
source = "hashicorp/consul/aws-ecs//modules/mesh-task"
version = "<latest version>"
family = "my_task"
container_definitions = [
{
name = "example-client-app"
image = "docker.io/org/my_task:v0.0.1"
essential = true
portMappings = [
{
containerPort = 9090
hostPort = 9090
protocol = "tcp"
}
]
cpu = 0
mountPoints = []
volumesFrom = []
}
]
port = "9090"
retry_join = ["<address of the Consul server>"]
}
```
The main differences are:
- You must remove the `execution_role_arn` and `task_role_arn` fields. The `mesh-task` module will create the task and execution roles.
- You must set the `port` field to the port that your application listens on.
If your application has no listening port, set `outbound_only = true` and remove the `port` field.
- You must add the `retry_join` field. This specifies the location of your Consul servers so that your task can join the mesh.
- You must remove the `jsonencode()` function from the `container_definitions` field.
The `mesh-task` module will create a new version of your task definition with the
necessary sidecar containers added so you can delete your existing `aws_ecs_task_definition`
resource.
## Next Steps
Now that your task(s) are migrated to the `mesh-task` module,
- Start at the [ECS Service section](/docs/ecs/get-started/install#ecs-service) of the Installation Guide to continue installing Consul on ECS.
- Refer to the [`mesh-task` reference documentation](https://registry.terraform.io/modules/hashicorp/consul-ecs/aws/latest/submodules/mesh-task?tab=inputs) for all available inputs to your mesh tasks.