Trouble running multi-line user_data scripts with AWS Lightsail and Terraform

It appears you're encountering an issue with multi-line user data scripts in AWS Lightsail when using Terraform. This is a common challenge when working with user data in cloud environments.

For your Lightsail instance, there are a few approaches you can try:

1. Base64 encoding: When using a file for user data, you may need to base64 encode it. Try modifying your Terraform configuration to:

user_data = base64encode(file("${path.module}/scripts/setup.sh"))

2. Semicolon separation: Instead of using newlines, try converting your multi-line script into a single line with semicolons:

user_data = "#!/bin/bash; apt-get update -y; apt-get install -y curl git docker.io; systemctl start docker; systemctl enable docker; curl -L https://packages.gitlab.com/install/repositories/runner/gitlab-runner/script.deb.sh | bash; apt-get install -y gitlab-runner"

3. Use local variables: Define your script as a local variable with proper heredoc syntax:

locals {
user_data_script = <<EOF
#!/bin/bash
apt-get update -y
apt-get install -y curl git docker.io
systemctl start docker
systemctl enable docker
curl -L https://packages.gitlab.com/install/repositories/runner/gitlab-runner/script.deb.sh | bash
apt-get install -y gitlab-runner
EOF
}

resource "aws_lightsail_instance" "example" {
# other configuration...
user_data = base64encode(local.user_data_script)
}

If these approaches don't work, you might consider an alternative strategy:

• Create a minimal user data script that just downloads and executes a more comprehensive script from a secure location (like an S3 bucket)
• Use terraform_data with a local-exec provisioner for complex setup tasks after the instance is created
• Consider using EC2 if you need more advanced user data capabilities, as it has more robust support for complex initialization scripts

For long-term maintenance, if you find Lightsail's user data limitations too restrictive for your use case, EC2 might be a better fit as it offers more flexibility with user data scripts and integrates well with Terraform.
Sources
User data terraform | AWS re:Post
Run commands when you launch an EC2 instance with user data input - Amazon Elastic Compute Cloud
Best practices - AWS Prescriptive Guidance