Add the redis server as a multihost sync example

Co-authored-by: Petr Šplíchal <psplicha@redhat.com>

docs/guide.rst

@@ -815,11 +815,17 @@ libraries, e.g. one of the following:
   * `a native beakerlib library`__ by Dalibor Pospisil, a
     distributed version of Ondrej Moris's library, supporting any
     number of hosts.
+  * `redis server`__ by Jan Scotka, a simple key-value exchange
+    solution between machines. The primary purpose is data
+    transfer. It is not a library prepared for synchronization,
+    but it's possible to use it as well. See the example to learn
+    how to set up a redis server and use it.
 
 __ https://github.com/beaker-project/rhts
 __ https://github.com/beakerlib/sync/tree/master/sync
 __ https://github.com/RedHat-SP-Security/keylime-tests/tree/main/Library/sync
 __ https://github.com/beakerlib/ControlFlow/tree/master/sync
+__ https://github.com/teemtee/tmt/tree/main/examples/redis
 
 
 Current Limits

examples/redis/.fmf/version

@@ -0,0 +1 @@
+1

examples/redis/ansible/setup_server.yml

@@ -0,0 +1,8 @@
+---
+- hosts: all
+  vars:
+    - version: "{{ ansible_distribution_version }}"
+  tasks:
+    - import_tasks: tasks/redis.yml
+    - import_tasks: tasks/redis_variables.yml
+...

examples/redis/ansible/tasks/redis.yml

@@ -0,0 +1,63 @@
+- name: setup syncing redis server
+  package: name={{ item }} state=present
+  with_items:
+  - redis
+  - firewalld
+  become: true
+
+- name: bind to all interfaces
+  ansible.builtin.lineinfile:
+    path: /etc/redis/redis.conf
+    regexp: '^bind '
+    line: "bind 0.0.0.0 -::0"
+  become: true
+
+- name: remove protected mode
+  ansible.builtin.lineinfile:
+    path: /etc/redis/redis.conf
+    regexp: '^protected-mode'
+    line: "protected-mode no"
+  become: true
+
+
+- name: Start redis service, if not started
+  ansible.builtin.service:
+    name: redis
+    state: restarted
+    enabled: yes
+  become: true
+
+
+- name: Start firewalld service, if not started
+  ansible.builtin.service:
+    name: firewalld
+    state: started
+    enabled: yes
+  become: true
+
+- name: add sshd to firewalld
+  ansible.posix.firewalld:
+    service: ssh
+    permanent: yes
+    state: enabled
+    immediate: true
+  become: true
+
+- name: add redis to firewalld
+  ansible.posix.firewalld:
+    service: redis
+    permanent: yes
+    state: enabled
+    immediate: true
+  become: true
+
+- name: add redis-sentinel to firewall
+  ansible.posix.firewalld:
+    service: redis-sentinel
+    permanent: yes
+    state: enabled
+    immediate: true
+  become: true
+
+# redis-cli -h $GUEST set variable value
+# redis-cli -h $GUEST get variable

examples/redis/ansible/tasks/redis_variables.yml

@@ -0,0 +1,5 @@
+- name: Set variables into redis database
+  ansible.builtin.shell: |
+    redis-cli set key value1
+  args:
+    executable: /bin/bash

examples/redis/plan.fmf

@@ -0,0 +1,43 @@
+description: |
+  This is an example how to use redis for data synchronization
+  between guests
+
+  how to send data to server:
+      redis-cli -h $GUEST set variable value
+
+  how to get data from server:
+      redis-cli -h $GUEST get variable
+
+  If you need more features like waiting for events or atomic
+  commands or deleting keys see doc for redis commands
+  https://redis.io/commands/
+
+discover:
+  - how: fmf
+    where:
+      - guest
+
+provision:
+  - how: virtual
+    role: server
+    image: fedora
+    connection: system
+  - how: virtual
+    role: guest
+    image: fedora
+    connection: system
+
+prepare:
+  - how: ansible
+    playbook:
+      - ansible/setup_server.yml
+    extra-args: '-vvv'
+    where:
+      - server
+  - how: install
+    package: redis
+    where:
+      - guest
+
+execute:
+  how: tmt

examples/redis/test.fmf

@@ -0,0 +1,3 @@
+summary: This is an example of the redis sync
+test: ./test.sh
+framework: shell

examples/redis/test.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -eux
+
+. "$TMT_TOPOLOGY_BASH"
+# verify that TOPLOGY to be defined to be able to run the tests.
+test -z "${TMT_ROLES[server]}" && exit 125
+
+SERVER=${TMT_GUESTS[${TMT_ROLES[server]}.hostname]}
+redis-cli -h $SERVER get key | grep value1