Add first HAProxy configuration file

README.md

@@ -65,6 +65,25 @@ The project is currently deployed using an Apache Web Server instance which serv
 by itself and redirects requests other than `/index.html` to the Spring backend running on one of the
 workers picked by HAProxy which is running on the frontend server.
 
+## Introducing further workers
+
+Currently three worker servers are used with each one running one instance of our backend application,
+an Apache HTTP Server instance and a CockroachDB node.
+
+At the present time some configuration files need to be edited in order to introduce further workers.
+The workers are automatically assigned an IP address of the form `192.168.10.(10 + N)` where `N` is
+the index of the worker starting with 1.
+The IP address `192.168.10.10` is reserved for the frontend server running the load balancer.
+
+The following files currently need to be changed when one wants to add or remove a worker:
+
+- The `num_workers` variable in `Vagrantfile`
+- The `haproxy.cfg` file located at `/ansible/roles/frontend/files/haproxy/haproxy.cfg`
+- `/ansible/roles/worker/files/systemd/system/cockroach.service.d/override.conf`
+
+Both of the latter two files should be changed at some point to make use of Ansible's templating
+feature so that only `num_workers` has to be edited, at least this should be possible.
+
 ## API
 
 See [API.md](API.md) for more information on the structure of the API.

ansible/frontend.yml

@@ -6,6 +6,15 @@
       package:
         name: haproxy
         state: present
+    - name: Copy haproxy.cfg file to /etc/haproxy/
+      copy:
+        src: /vagrant/ansible/roles/frontend/files/haproxy/haproxy.cfg
+        dest: /etc/haproxy/haproxy.cfg
+    - name: Start and enable haproxy.service
+      systemd:
+        name: haproxy
+        state: started
+        enabled: yes
     
     - name: Install base-devel
       package:

ansible/roles/frontend/files/haproxy/haproxy.cfg

- 
+frontend main
+    bind *:80
+    use_backend workers
+
+backend workers
+    server worker-1 192.168.10.11:8080 check
+#   server worker-2 192.168.10.12:8080 check
+#   server worker-3 192.168.10.13:8080 check

ansible/worker.yml

@@ -14,10 +14,12 @@
 
     - name: Add aur_builder user
       block:
-        - user:
+        - name: Add aur_builder user
+          user:
             name: aur_builder
             group: wheel
-        - lineinfile:
+        - name: Remove password check for aur_builder user for binary /usr/bin/pacman
+          lineinfile:
             path: /etc/sudoers.d/00-aur_builder
             line: 'aur_builder ALL=(ALL) NOPASSWD: /usr/bin/pacman'
             create: yes