Terraform 14 template_file and null_resource issue - amazon-web-services

Question

I'm trying to use null resource using local-exec-provisioner for enabling the s3 bucket logging on load balancer using the template file. Both of the terraform file and template file (lb-to-s3-log.tpl) are on same directory "/modules/lb-to-s3-log" however getting an error. Terraform file looks this way:
data "template_file" "lb-to-s3-log" {
template = file(".//modules/lb-to-s3-log/lb-to-s3-log.tpl")
vars = {
X_INFO1 = var.INFO1
X_INFO2 = var.INFO2
X_INFO3 = var.INFO3
}
}
resource "null_resource" "lb-to-s3-log" {
provisioner "local-exec" {
command = "aws elb modify-load-balancer-attributes --load-balancer-name ${var.LOAD_BALANCER_NAME[0]} --load-balancer-attributes ${data.template_file.lb-to-s3-log.rendered}"
}
}
WHERE:
var.INFO1 = test1
var.INFO2 = test2
var.INFO3 = test3
AND TEMPLATE (TPL) FILE CONTAINS:
{
"AccessLog": {
"Enabled": true,
"S3BucketName": "${X_INFO1}-${X_INFO2}-${X_INFO3}-logs",
"EmitInterval": 5,
"S3BucketPrefix": "${X_INFO1}-${X_INFO2}-${X_INFO3}-logs"
}
}
ERROR IM GETTING:
Error: Error running command 'aws elb modify-load-balancer-attributes --load-balancer-name awseb-e-5-AWSEBLoa-ABCDE0FGHI0V --load-balancer-attributes {
"AccessLog": {
"Enabled": true,
"S3BucketName": "test1-test2-test3-logs",
"EmitInterval": 5,
"S3BucketPrefix": "test1-test2-test3-logs"
}
}
': exit status 2. Output:
Error parsing parameter '--load-balancer-attributes': Invalid JSON: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
JSON received: {
/bin/sh: line 1: AccessLog:: command not found
/bin/sh: line 2: Enabled:: command not found
/bin/sh: line 3: S3BucketName:: command not found
/bin/sh: line 4: EmitInterval:: command not found
/bin/sh: line 5: S3BucketPrefix:: command not found
/bin/sh: -c: line 6: syntax error near unexpected token `}'
/bin/sh: -c: line 6: ` }'
ISSUE / PROBLEM:
The template file successfully updates the variable assignments (X_INFO1, X_INFO2, X_INFO23). Seems like the issue is on the ${data.template_file.lb-to-s3-log.rendered} of the aws cli command.
Same error when I tried to substitute the file from lb-s3log.tpl to lb-s3log.json.
I'm using Terraform v0.14, I followed the process of enabling s3 bucket for log storage of amazon classic load balancer from this documentation

Answer 1

The error is happening because you need to format the JSON to be escaped on the command line or to write the JSON as a file and then use file:// to refer to it.
Wrapping your JSON in single quotes should be enough to escape the shell issues:
data "template_file" "lb-to-s3-log" {
template = file(".//modules/lb-to-s3-log/lb-to-s3-log.tpl")
vars = {
X_INFO1 = var.INFO1
X_INFO2 = var.INFO2
X_INFO3 = var.INFO3
}
}
resource "null_resource" "lb-to-s3-log" {
provisioner "local-exec" {
command = "aws elb modify-load-balancer-attributes --load-balancer-name ${var.LOAD_BALANCER_NAME[0]} --load-balancer-attributes '${data.template_file.lb-to-s3-log.rendered}'"
}
}
You can use the local_file resource to render a file if you'd prefer that option:
data "template_file" "lb-to-s3-log" {
template = file(".//modules/lb-to-s3-log/lb-to-s3-log.tpl")
vars = {
X_INFO1 = var.INFO1
X_INFO2 = var.INFO2
X_INFO3 = var.INFO3
}
}
resource "local_file" "elb_attributes" {
content = data.template_file.lb-to-s3-log.rendered
filename = "${path.module}/elb-attributes.json"
}
resource "null_resource" "lb-to-s3-log" {
provisioner "local-exec" {
command = "aws elb modify-load-balancer-attributes --load-balancer-name ${var.LOAD_BALANCER_NAME[0]} --load-balancer-attributes file://${local_file.elb_attributes.filename}"
}
}
A better alternative here though, unless there's something fundamental preventing it, would be to have Terraform managing the ELB access logs by using the access_logs parameter to the resource:
resource "aws_elb" "bar" {
name = "foobar-terraform-elb"
availability_zones = ["us-west-2a", "us-west-2b", "us-west-2c"]
access_logs {
bucket = "foo"
bucket_prefix = "bar"
interval = 60
}
}
You might also want to consider moving to Application Load Balancers or possibly Network Load Balancers depending on your usage as ELBs are a deprecated service.
Finally, it's also worth noting that the template_file data source is deprecated since 0.12 and the templatefile function is preferred instead.