fix(valkey): install systemd unit in proper dir; check local and git versions to avoid unnecessary recompiles

ansible_collections/nullified/infrastructure/roles/valkey/tasks/main.yml

@@ -17,6 +17,7 @@
       - libssl-dev
       - libsystemd-dev
       - make
+      - pkgconf
       - python3-cryptography
       - ssl-cert
 - name: gather facts
@@ -48,8 +49,16 @@
     cmds:
       - tar -zxf {asset_dirname}/{asset_filename}
       - 'mv $(find . -maxdepth 1 -name valkey-io-valkey\* -type d) {{ valkey_install_dir }}/src'
+- name: fetch source version
+  become: true
+  ansible.builtin.command:
+    cmd: sed -En 's/#define VALKEY_VERSION "([0-9._-]+)"/\1/p' ./src/version.h
+    chdir: '{{ valkey_install_dir }}/src'
+  register: source_version_cmd
+  changed_when: false
 - name: compile Valkey (some tweaks taken from Valkey's Dockerfile
   become: true
+  when: source_version_cmd.stdout_lines[0] != valkey_installed_version
   args:
     chdir: '{{ valkey_install_dir }}/src'
   ansible.builtin.shell: '{{ item }}'