Improve install speed by not installing if the same file was previously installed

This is done by storing the checksum used on the server after
installation. This checksum file is then compared to the local checksum
file for the requested CNI plugins. If they do not match (hash has
changed or version is different), then plugins will be installed or
updated.

Author: IamTheFij

tasks/cni.yml

@@ -27,6 +27,24 @@
   when: not nomad_cni_checksum.stat.exists
   delegate_to: 127.0.0.1
 
+- name: Re-check CNI package checksum file
+  ansible.builtin.stat:
+    path: "{{ role_path }}/files/{{ nomad_cni_checksum_file }}"
+  become: false
+  tags: installation
+  register: nomad_cni_checksum
+  delegate_to: 127.0.0.1
+
+- name: Read previously installed checksum
+  ansible.builtin.stat:
+    path: "{{ nomad_cni_dir }}/{{ nomad_cni_checksum_file }}"
+  tags: installation
+  register: nomad_cni_remote_checksum
+
+- name: Check if new CNI should be installed
+  ansible.builtin.set_fact:
+    nomad_should_install_cni: "{{ not nomad_cni_remote_checksum.stat.exists or nomad_cni_remote_checksum.stat.checksum != nomad_cni_checksum.stat.checksum }}"
+
 - name: Get Nomad CNI package checksum # noqa no-changed-when
   ansible.builtin.shell: |
     set -o pipefail
@@ -37,13 +55,15 @@
   register: nomad_cni_sha256
   tags: installation
   delegate_to: 127.0.0.1
+  when: nomad_should_install_cni
 
 - name: Check Nomad CNI package file
   ansible.builtin.stat:
     path: "{{ role_path }}/files/{{ nomad_cni_pkg }}"
   become: false
   register: nomad_cni_package
   delegate_to: 127.0.0.1
+  when: nomad_should_install_cni
 
 - name: Download Nomad CNI
   ansible.builtin.get_url:
@@ -55,7 +75,9 @@
   become: false
   tags: installation
   delegate_to: 127.0.0.1
-  when: not nomad_cni_package.stat.exists
+  when:
+    - nomad_should_install_cni
+    - not nomad_cni_package.stat.exists
 
 - name: Create Temporary Directory for Extraction
   ansible.builtin.tempfile:
@@ -65,6 +87,7 @@
   register: install_temp
   tags: installation
   delegate_to: 127.0.0.1
+  when: nomad_should_install_cni
 
 - name: Unarchive Nomad CNI
   ansible.builtin.unarchive:
@@ -74,6 +97,7 @@
   become: false
   tags: installation
   delegate_to: 127.0.0.1
+  when: nomad_should_install_cni
 
 - name: Install Nomad CNI
   ansible.builtin.copy:
@@ -86,6 +110,14 @@
     - "{{ install_temp.path }}/*"
   tags: installation
   notify: Restart nomad
+  when: nomad_should_install_cni
+
+- name: Save install checksum record
+  copy:
+    src: "{{ role_path }}/files/{{ nomad_cni_checksum_file }}"
+    dest: "{{ nomad_cni_dir }}"
+  tags: installation
+  when: nomad_should_install_cni
 
 - name: Cleanup
   ansible.builtin.file:
@@ -94,3 +126,4 @@
   become: false
   tags: installation
   delegate_to: 127.0.0.1
+  when: nomad_should_install_cni