multi-arch-builders/tofu: use poseidon/ct tf module for rendering butane/ignition

poseidon/ct has support for "snippets" which is an alternative for
the include files concept in butane, so we'll use that. Also plumb
through the splunk configuration to TF vars set via environment
variables.

Author: dustymabe

multi-arch-builders/coreos-aarch64-builder.bu

@@ -6,10 +6,6 @@
 #
 variant: fcos
 version: 1.4.0
-ignition:
-  config:
-    merge:
-      - local: builder-common.ign
 passwd:
   users:
     - name: builder

multi-arch-builders/coreos-aarch64-rhcos-builder.bu

@@ -44,6 +44,14 @@ can:
 export TF_VAR_distro=rhcos
 ```
 
+If you are deploying RHCOS you'll need to define variables for splunk configuration:
+
+```
+export TF_VAR_splunk_hostname=...
+export TF_VAR_splunk_sidecar_repo=...
+export TF_VAR_itpaas_splunk_repo=...
+```
+
 ## Running tofu
 ```bash
    # To begin using it, run 'init' within this directory.

multi-arch-builders/provisioning/aarch64/README.md

@@ -40,13 +40,57 @@ check "health_check_distro" {
   }
 }
 
-# Get ignition created for the multiarch builder
-resource "null_resource" "butane" {
-  provisioner "local-exec" {
-    command = "bash -x ./butane.sh" 
+
+# Variables used for splunk deployment, which is only
+# for RHCOS builders. Define them in the environment with:
+# export TF_VAR_splunk_hostname=...
+# export TF_VAR_splunk_sidecar_repo=...
+# export TF_VAR_itpaas_splunk_repo=...
+variable "splunk_hostname" {
+ type    = string
+ default = ""
+}
+variable "splunk_sidecar_repo" {
+ type    = string
+ default = ""
+}
+variable "itpaas_splunk_repo" {
+ type    = string
+ default = ""
+}
+# Check that if we are deploying a RHCOS builder the splunk
+# variables have been defined.
+check "health_check_rhcos_splunk_vars" {
+  assert {
+    condition = !(var.distro == "rhcos" && anytrue([
+                        var.splunk_hostname == "",
+                        var.splunk_sidecar_repo == "",
+                        var.itpaas_splunk_repo == ""
+                    ]))
+    error_message = "Must define splunk env vars for RCHOS builders"
   }
 }
 
+
+locals {
+    fcos_snippets = [
+      file("../../coreos-aarch64-builder.bu"),
+    ]
+    rhcos_snippets = [
+      file("../../coreos-aarch64-builder.bu"),
+      templatefile("../../builder-splunk.bu", {
+        SPLUNK_HOSTNAME = var.splunk_hostname
+        SPLUNK_SIDECAR_REPO = var.splunk_sidecar_repo
+        ITPAAS_SPLUNK_REPO = var.itpaas_splunk_repo
+      })
+    ]
+}
+data "ct_config" "butane" {
+  strict = true
+  content = file("../../builder-common.bu")
+  snippets = var.distro == "rhcos" ? local.rhcos_snippets : local.fcos_snippets
+}
+
 data "aws_region" "aws_region" {}
 
 # Gather information about the AWS image for the current region
@@ -83,7 +127,7 @@ resource "aws_instance" "coreos-aarch64-builder" {
     Name = "${var.project}-${formatdate("YYYYMMDD", timestamp())}"
   }
   ami           = local.ami 
-  user_data     = file("coreos-aarch64-builder.ign")
+  user_data     = data.ct_config.butane.rendered
   instance_type = "m6g.metal"
   vpc_security_group_ids = [aws_security_group.sg.id] 
   subnet_id              = local.aws_subnet_id