Define: Terraform - AWS - aws_instance - user_data

terraform aws_instance user_data example
terraform ec2 instance example
terraform ec2 example github
terraform aws security group
terraform aws tutorial pdf
terraform create ec2 instance in existing vpc
terraform-aws github
terraform stop ec2 instance

I'm working with Terraform, launching an ECS cluster.

I'm using a script that was written by someone else. I understand most of the launch configuration script, other than this one point:

I'm trying to find the link between the autoscaling group and the ECS cluster.

I have an aws_autoscaling_group which uses an aws_launch_configuration (see below). The aws_launch_configuration has a user_data parameter. This is the only link between the autoscaling group and the cluster that I can find.

Looking at the links (bottom) to the documentation, it's not giving a very good explanation of 'what' user_data is. Can someone please help me understand "how" the user_data links the autoscaling group with the cluster, and if at all possible give some example or link to what it's normally used for and how it's normally used.

...
resource "aws_launch_configuration" "ecs_host" {
  ...

  user_data = <<EOF
#!/bin/bash
echo ECS_CLUSTER=${var.cluster_name} >> /etc/ecs/ecs.config
EOF
}
...

terraform apply outputs:

  ...
  + aws_launch_configuration.ecs_host
      ...
      user_data: "4e27e8feea0896af43ada0c647877da3766f5dcb"
  ...

https://www.terraform.io/docs/providers/aws/r/instance.html#user_data https://www.terraform.io/docs/providers/aws/r/launch_configuration.html#user_data


official explanation by terraform

user_data - (Optional) The user data to provide when launching the instance. Do not pass gzip-compressed data via this argument; see user_data_base64 instead.

Offical aws document to explain what's user_data

https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ec2-instance-metadata.html

So in general, after you define the launch configuration and autoscaling group, the autoscaling group will make sure how many ec2 instances need be started (desired capacity).

When start a new instance, it will reference the launch configuration, which define which AWS AMI for the instance and what init command will be run. the init commands are saved in user_data script.

In your case, the user data script registers itself to nominated ECS cluster. So ecs cluster can discover these ec2 instances easily

echo ECS_CLUSTER=${var.cluster_name} >> /etc/ecs/ecs.config

In background, there is a docker container called amazon/amazon-ecs-agent running to help these registions and manage other containers (ecs services)

If you want to know the details, you can go through this document: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs-agent-install.html

EC2 Instance - AWS: aws_instance, Here is a sample of using user_data embedded into tf file: provider "aws" { region = "us-east-1" } resource "aws_key_pair" "terraform-demo" { key_name  user_data - SHA-1 hash of User Data supplied to the Instance. user_data_base64 - Base64 encoded contents of User Data supplied to the Instance. Valid UTF-8 contents can be decoded with the base64decode function. This attribute is only exported if get_user_data is true. tags - A map of tags assigned to the Instance.


Simply put user data is a script that is run upon bootstrapping an ec2 instance. You can automate actions that need to take place to ensure your ec2 is configured correctly, and specify them as user_data, instructing aws to run the script on machine bootstrap.

Terraform Tutorial - user_data - 2020, official explanation by terraform user_data - (Optional) The user data to provide when launching the instance. Do not pass gzip-compressed  AWS : Creating an EC2 instance and attaching Amazon EBS volume to the instance using Python boto module with User data AWS : Creating an instance to a new region by copying an AMI AWS : S3 (Simple Storage Service) 1


user_data attribute allows you to specify script payload or cloud daemon instructions. Data can be inline template as your case with the script, or file template where you will need to deal with the Template Provider. So when you want to create a new launch configuration, used for autoscaling groups this is one of the option to execute here a script, and got the output as the cluster's hash for instance.

The limitations are you cannot pass gzip-compressed data via this argument; see user_data_base64 instead and you should not store sensitive data, such as passwords, as user data.

Define: Terraform - AWS - aws_instance - user_data, perfect. Perhaps that could be a great example for the aws_instance page :) What is the output of terraform apply? on Oct 19, 2014. terraform crash with ec2 instance when trying to use user_data with a map #460. Closed. »Data Source: aws_instances Use this data source to get IDs or IPs of Amazon EC2 instances to be referenced elsewhere, e.g. to allow easier migration from another management solution or to make it easier for an operator to connect through bastion host(s).


Unclear how to add user_data to an aws_instance · Issue #145 , resource definition nor template_file or any of the vars: $ terraform plan -target=​aws_instance.test [49/1697] Refreshing Terraform state prior to  If you use ebs_block_device on an aws_instance, Terraform will assume management over the full set of non-root EBS block devices for the instance, treating additional block devices as drift. For this reason, ebs_block_device cannot be mixed with external aws_ebs_volume and aws_volume_attachment resources for a given instance.


provider/aws/aws_instance: template_file as user_data causes , First of all I should say that I'm not familiar with Terraform and it's just my notes about this tool. If you've never heard All variables used in networks.tf must be defined in vars.tf variable Another usefull thing is a user_data attribute. You can autoscalling group declaration is similar to aws_instance. Using a template seems to work fine, so I have a workaround. Maybe it's just the description in the doc on file and old examples that put me on the wrong foot.


Terraform by examples. Part 1 - Artem Penner, In CloudFormation you inject the bootstrapping logic for your AWS instance/​autoscaling group by using the function !Sub. 1.- If the userdata  Batch Job Definition can be imported using the arn, e.g. $ terraform import aws_batch_job_definition.test arn:aws:batch:us-east-1:123456789012:job-definition/sample Intro