diff --git a/terraform/main.tf b/terraform/main.tf
index 70de4cca917a86eae345dce98abe1ba0d56b3373..0ca1045c71d0a0dd54609337bf54b1c4cb708fb4 100644
--- a/terraform/main.tf
+++ b/terraform/main.tf
@@ -13,48 +13,48 @@ module "ignition" {
 }
 
 module "bootstrap" {
-  source           = "./modules/hcloud_coreos"
-  instance_count   = var.bootstrap == true ? 1 : 0
-  location         = var.location
-  name             = "bootstrap"
-  dns_domain       = var.dns_domain
-  dns_zone_id      = var.dns_zone_id
-  dns_internal_ip  = false
-  image            = data.hcloud_image.image.id
-  image_name       = var.image
-  server_type      = "cx41"
-  subnet           = hcloud_network_subnet.subnet.id
-  ignition_url     = var.bootstrap == true ? "http://${cloudflare_record.dns_a_ignition[0].name}/bootstrap.ign" : ""
+  source          = "./modules/hcloud_coreos"
+  instance_count  = var.bootstrap == true ? 1 : 0
+  location        = var.location
+  name            = "bootstrap"
+  dns_domain      = var.dns_domain
+  dns_zone_id     = var.dns_zone_id
+  dns_internal_ip = false
+  image           = data.hcloud_image.image.id
+  image_name      = var.image
+  server_type     = "cx41"
+  subnet          = hcloud_network_subnet.subnet.id
+  ignition_url    = var.bootstrap == true ? "http://${cloudflare_record.dns_a_ignition[0].name}/bootstrap.ign" : ""
 }
 
 module "master" {
-  source           = "./modules/hcloud_coreos"
-  instance_count   = var.replicas_master
-  location         = var.location
-  name             = "master"
-  dns_domain       = var.dns_domain
-  dns_zone_id      = var.dns_zone_id
-  dns_internal_ip  = false
-  image            = data.hcloud_image.image.id
-  image_name       = var.image
-  server_type      = "cx41"
-  subnet           = hcloud_network_subnet.subnet.id
-  ignition_url     = "https://api-int.${var.dns_domain}:22623/config/master"
-  ignition_cacert  = local.ignition_master_cacert
+  source          = "./modules/hcloud_coreos"
+  instance_count  = var.replicas_master
+  location        = var.location
+  name            = "master"
+  dns_domain      = var.dns_domain
+  dns_zone_id     = var.dns_zone_id
+  dns_internal_ip = false
+  image           = data.hcloud_image.image.id
+  image_name      = var.image
+  server_type     = "cx41"
+  subnet          = hcloud_network_subnet.subnet.id
+  ignition_url    = "https://api-int.${var.dns_domain}:22623/config/master"
+  ignition_cacert = local.ignition_master_cacert
 }
 
 module "worker" {
-  source           = "./modules/hcloud_coreos"
-  instance_count   = var.replicas_worker
-  location         = var.location
-  name             = "worker"
-  dns_domain       = var.dns_domain
-  dns_zone_id      = var.dns_zone_id
-  dns_internal_ip  = false
-  image            = data.hcloud_image.image.id
-  image_name       = var.image
-  server_type      = "cx41"
-  subnet           = hcloud_network_subnet.subnet.id
-  ignition_url     = "https://api-int.${var.dns_domain}:22623/config/worker"
-  ignition_cacert  = local.ignition_worker_cacert
+  source          = "./modules/hcloud_coreos"
+  instance_count  = var.replicas_worker
+  location        = var.location
+  name            = "worker"
+  dns_domain      = var.dns_domain
+  dns_zone_id     = var.dns_zone_id
+  dns_internal_ip = false
+  image           = data.hcloud_image.image.id
+  image_name      = var.image
+  server_type     = "cx41"
+  subnet          = hcloud_network_subnet.subnet.id
+  ignition_url    = "https://api-int.${var.dns_domain}:22623/config/worker"
+  ignition_cacert = local.ignition_worker_cacert
 }
diff --git a/terraform/modules/hcloud_coreos/variables.tf b/terraform/modules/hcloud_coreos/variables.tf
index ff5497b70684ecac3e6b39428d4cff6c0aabd103..43e060b2f160465e95c865d5232c6b3d237458d8 100644
--- a/terraform/modules/hcloud_coreos/variables.tf
+++ b/terraform/modules/hcloud_coreos/variables.tf
@@ -42,7 +42,7 @@ variable "user_data" {
 }
 
 variable "ssh_keys" {
-  type        = list
+  type        = list(any)
   description = "SSH key IDs or names which should be injected into the server at creation time"
   default     = []
 }
diff --git a/terraform/modules/hcloud_instance/main.tf b/terraform/modules/hcloud_instance/main.tf
index b2e2ea236eee954017713b39d04653b2a046fa0a..f315787af07a3427a9d9a9fb21b5febc7fdebb4a 100644
--- a/terraform/modules/hcloud_instance/main.tf
+++ b/terraform/modules/hcloud_instance/main.tf
@@ -19,7 +19,7 @@ resource "cloudflare_record" "dns-a" {
   name    = element(hcloud_server.server.*.name, count.index)
   value   = element(hcloud_server.server.*.ipv4_address, count.index)
   type    = "A"
-  ttl     = 1
+  ttl     = 120
 }
 
 resource "cloudflare_record" "dns-aaaa" {
@@ -28,7 +28,7 @@ resource "cloudflare_record" "dns-aaaa" {
   name    = element(hcloud_server.server.*.name, count.index)
   value   = "${element(hcloud_server.server.*.ipv6_address, count.index)}1"
   type    = "AAAA"
-  ttl     = 1
+  ttl     = 120
 }
 
 resource "hcloud_rdns" "dns-ptr-ipv4" {
diff --git a/terraform/modules/hcloud_instance/variables.tf b/terraform/modules/hcloud_instance/variables.tf
index 51566330f95f73d151ad272d2a4d063dd08a7695..bab208984f17c66e8ded36fad0b6dd8100fc6f5d 100644
--- a/terraform/modules/hcloud_instance/variables.tf
+++ b/terraform/modules/hcloud_instance/variables.tf
@@ -42,7 +42,7 @@ variable "user_data" {
 }
 
 variable "ssh_keys" {
-  type        = list
+  type        = list(any)
   description = "SSH key IDs or names which should be injected into the server at creation time"
   default     = []
 }
diff --git a/terraform/versions.tf b/terraform/versions.tf
index 3fc08e4c15f751a87f1f23cd6ccd76c4d2c1c3a5..03d603756a084cf53e2e682b43c3e49485fc8464 100644
--- a/terraform/versions.tf
+++ b/terraform/versions.tf
@@ -1,23 +1,23 @@
 terraform {
   required_providers {
     cloudflare = {
-      source = "cloudflare/cloudflare"
+      source  = "cloudflare/cloudflare"
       version = "2.14.0"
     }
     hcloud = {
-      source = "hetznercloud/hcloud"
+      source  = "hetznercloud/hcloud"
       version = "1.23.0"
     }
     template = {
-      source = "hashicorp/template"
+      source  = "hashicorp/template"
       version = "2.2.0"
     }
     local = {
-      source = "hashicorp/local"
+      source  = "hashicorp/local"
       version = "1.4.0"
     }
     random = {
-      source = "hashicorp/random"
+      source  = "hashicorp/random"
       version = "2.3.1"
     }
   }