Move to IAM instance roles, instead of copying local creds to EC2

aws/compute.tf

@@ -1,3 +1,4 @@
+
 data "aws_ami" "centos7" {
   # See http://cavaliercoder.com/blog/finding-the-latest-centos-ami.html
   # https://wiki.centos.org/Cloud/AWS
@@ -21,15 +22,15 @@ locals {
 }
 
 resource "aws_instance" "mgmt" {
-  ami           = data.aws_ami.centos7.id
-  instance_type = var.management_shape
-  vpc_security_group_ids = [aws_security_group.mgmt.id]
-  subnet_id = aws_subnet.vpc_subnetwork.id
+  ami                         = data.aws_ami.centos7.id
+  instance_type               = var.management_shape
+  vpc_security_group_ids      = [aws_security_group.mgmt.id]
+  subnet_id                   = aws_subnet.vpc_subnetwork.id
   associate_public_ip_address = true
-  iam_instance_profile = aws_iam_instance_profile.describe_tags.id
+  iam_instance_profile        = aws_iam_instance_profile.manage_ec2.id
 
   user_data = data.template_file.bootstrap-script.rendered
-  key_name = aws_key_pair.ec2-user.key_name
+  key_name  = aws_key_pair.ec2-user.key_name
 
   depends_on = [aws_efs_mount_target.shared, aws_key_pair.ec2-user, aws_route53_record.shared, aws_route.internet_route]
 
@@ -50,13 +51,8 @@ resource "aws_instance" "mgmt" {
     content     = data.template_file.startnode-yaml.rendered
   }
 
-  provisioner "file" {
-    destination = "/tmp/aws-credentials.csv"
-    source      = pathexpand(var.aws_shared_credentials)
-  }
-
   tags = {
-    Name = local.mgmt_hostname
+    Name    = local.mgmt_hostname
     cluster = local.cluster_id
   }
 }

aws/iam.tf

@@ -1,10 +1,10 @@
-resource "aws_iam_instance_profile" "describe_tags" {
-  name = "describe_tags-${local.cluster_id}"
-  role = aws_iam_role.describe_tags.name
+resource "aws_iam_instance_profile" "manage_ec2" {
+  name = "manage_ec2_${local.cluster_id}"
+  role = aws_iam_role.manage_ec2.name
 }
 
-resource "aws_iam_role" "describe_tags" {
-  name = "describe_tags-${local.cluster_id}"
+resource "aws_iam_role" "manage_ec2" {
+  name = "manage_ec2_${local.cluster_id}"
   path = "/"
 
   assume_role_policy = <<EOF
@@ -24,27 +24,52 @@ resource "aws_iam_role" "describe_tags" {
 EOF
 
   tags = {
-    Name = "citc-describe_tags-${local.cluster_id}"
+    Name    = "manage_ec2_${local.cluster_id}"
     cluster = local.cluster_id
   }
 }
 
-resource "aws_iam_role_policy" "describe_tags" {
-  name = "describe_tags-${local.cluster_id}"
-  role = aws_iam_role.describe_tags.id
+resource "aws_iam_role_policy" "manage_ec2" {
+  name   = "manage_ec2_${local.cluster_id}"
+  role   = aws_iam_role.manage_ec2.id
+  policy = "${data.aws_iam_policy_document.manage_ec2.json}"
+}
 
-  policy = <<EOF
-{
-  "Version": "2012-10-17",
-  "Statement": [
-    {
-      "Action": [
-        "ec2:DescribeTags"
-      ],
-      "Effect": "Allow",
-      "Resource": "*"
+data "aws_iam_policy_document" "manage_ec2" {
+  statement {
+    sid = "1"
+
+    actions = [
+      "ec2:DescribeTags",
+      "ec2:DescribeInstances",
+      "ec2:DescribeImages",
+      "ec2:RunInstances",
+    ]
+
+    resources = [
+      "*",
+    ]
+  }
+
+  statement {
+    sid = "2"
+
+    actions = [
+      "ec2:TerminateInstances",
+      "route53:ChangeResourceRecordSets",
+    ]
+
+    resources = [
+      "*",
+    ]
+
+    condition {
+      test     = "StringLike"
+      variable = "iam:ResourceTag/cluster"
+
+      values = [
+        local.cluster_id
+      ]
     }
-  ]
-}
-EOF
+  }
 }

aws/provider.tf

@@ -24,6 +24,5 @@ provider "null" {
 
 provider "aws" {
   version     = "2.16.0"
-  profile     = var.profile  # refer to ~/.aws/credentials
   region      = var.region
 }

aws/variables.tf

@@ -28,7 +28,3 @@ variable "private_key_path" {
 variable "ansible_branch" {
   default = "5"
 }
-
-variable "aws_shared_credentials" {
-  default = "~/.aws/credentials"
-}