install-packages: invoke package manager only when necessary

roles/install-packages/defaults/main.yml

@@ -0,0 +1,25 @@
+---
+
+COMMON_PKGS:
+  - bash-completion
+  - htop
+  - vim
+  - strace
+  - dmidecode
+  - nethogs
+  - sysbench
+  - fio
+  - rsync
+  - lsof
+
+EPEL_PKGS:
+  - iperf3
+  - nmap
+  - lvm2
+  - bind-utils
+  - psmisc # may work on deb/ubuntu also? - provides killall
+  - wget
+
+DEB_PKGS:
+  - "{{ common_pkgs }}"
+  - dnsutils

roles/install-packages/tasks/deb.yml

@@ -2,8 +2,5 @@
 
 - name: install packages (Debian/Ubuntu)
   package:
-    name: "{{ item }}"
-    state: latest
-  with_items:
-  - "{{ common_pkgs }}"
-  - dnsutils
+    name: "{{ (COMMON_PKGS + DEB_PKGS) | difference(ansible_facts.packages) }}"
+    state: present

roles/install-packages/tasks/el.yml

@@ -1,14 +1,6 @@
 ---
 
-- name: install packages (RHEL/CentOS/Fedora)
+- name: install packages (EPEL/Fedora)
   package:
-    name: "{{ item }}"
-    state: latest
-  with_items:
-  - "{{ common_pkgs }}"
-  - iperf3
-  - nmap
-  - lvm2
-  - bind-utils
-  - psmisc # may work on deb/ubuntu also? - provides killall
-  - wget
+    name: "{{ (COMMON_PKGS + EPEL_PKGS) | difference(ansible_facts.packages) }}"
+    state: present