Aws IAM group: Setup readonly access on log group on Terraform - amazon-ec2

Question

Does someone know how to setup read-only access to specific log groups?
resource "aws_iam_policy" "logs" {
name = "AWSLogs${title(var.product)}"
description = "Logging policy for ${title(var.product)}"
policy = <<EOF
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"logs:Get*",
"logs:List*",
"logs:Filter*"
],
"Resource": [
"arn:aws:logs:::log-group:${aws_cloudwatch_log_group.one.arn}:log-stream:*",
"arn:aws:logs:::log-group:${aws_cloudwatch_log_group.two.arn}:log-stream:*",
"arn:aws:logs:::log-group:${aws_cloudwatch_log_group.three.arn}:log-stream:*"
]
},
{
"Effect": "Allow",
"Action": [
"logs:DescribeLogGroups"
],
"Resource": "*"
}
]
}
EOF
}
resource "aws_iam_group_policy_attachment" "logs" {
group = "${aws_iam_group.logs.name}"
policy_arn = "${aws_iam_policy.logs.arn}"
}
resource "aws_iam_group" "logs" {
name = "${title(var.product)}Logs"
}
I'm currently struggeling to setup to only have access on specified log groups, but I can only get access to them when I set my resource to "*". This is not possible when I setup this dedicated to predefined log groups. Does someone have a good practice or solution? When I try this solution above I only get
Not authorized to perform: logs:FilterLogEvents
, when I try to access it via an user which is part of the IAM group "logs".

Answer 1

aws_cloudwatch_log_group.one.arn already is the full ARN of the one log group, i.e.,
arn:aws:logs:us-east-1:123456789012:log-group:one
So refer only to that in the Resources list:
resource "aws_iam_policy" "logs" {
name = "AWSLogs${title(var.product)}"
description = "Logging policy for ${title(var.product)}"
policy = <<EOF
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"logs:Get*",
"logs:List*",
"logs:Filter*"
],
"Resource": [
"${aws_cloudwatch_log_group.one.arn}:log-stream:*",
"${aws_cloudwatch_log_group.two.arn}:log-stream:*",
"${aws_cloudwatch_log_group.three.arn}:log-stream:*"
]
},
{
"Effect": "Allow",
"Action": [
"logs:DescribeLogGroups"
],
"Resource": "*"
}
]
}
EOF
}

Answer 2

I was able to kind of solve this by adding a Condition filtering by tags to the Statement and making sure that the log groups and streams are tagged correspondingly:
"Condition": {
"StringEquals": {
"aws:ResourceTag/sometagname": "sometagvalue"
}
}