diff --git a/roles/service-prometheus/tasks/alertmanager.yml b/roles/service-prometheus/tasks/alertmanager.yml
index 1264854..ce13073 100644
--- a/roles/service-prometheus/tasks/alertmanager.yml
+++ b/roles/service-prometheus/tasks/alertmanager.yml
@@ -3,6 +3,7 @@
 
 - name: set internal variables, part 1
   set_fact:
+    alertmanager_present: yes
     alertmanager_signature: "alertmanager-{{ alertmanager_version }}.linux-amd64"
 
 - name: set internal variables, part 2
diff --git a/roles/service-prometheus/tasks/node-exporter.yml b/roles/service-prometheus/tasks/node-exporter.yml
index b5c21a4..92d458d 100644
--- a/roles/service-prometheus/tasks/node-exporter.yml
+++ b/roles/service-prometheus/tasks/node-exporter.yml
@@ -4,6 +4,7 @@
 
 - name: set internal variables for convenience
   set_fact:
+    node_exporter_present: yes
     node_exporter_daemon_dir: "{{ prometheus_install_path }}/node_exporter-{{ node_exporter_version }}.linux-amd64"
     node_exporter_tarball_url: "https://github.com/prometheus/node_exporter/releases/download/v{{ node_exporter_version }}/node_exporter-{{ node_exporter_version }}.linux-amd64.tar.gz"
 
diff --git a/roles/service-prometheus/tasks/prometheus.yml b/roles/service-prometheus/tasks/prometheus.yml
index 1b773ff..fb8dd10 100644
--- a/roles/service-prometheus/tasks/prometheus.yml
+++ b/roles/service-prometheus/tasks/prometheus.yml
@@ -5,6 +5,7 @@
 
 - name: set internal variables for convenience
   set_fact:
+    prometheus_present: yes
     prometheus_daemon_dir: "{{ prometheus_install_path }}/prometheus-{{ prometheus_version }}.linux-amd64"
     prometheus_tarball_url: "https://github.com/prometheus/prometheus/releases/download/v{{ prometheus_version }}/prometheus-{{ prometheus_version }}.linux-amd64.tar.gz"