feat(web-app-gitea): add optional Redis integration for caching, sessions, and queues

This update introduces conditional Redis support for Gitea, allowing connection
to either a local or centralized Redis instance depending on configuration.
Includes resource limits for the Redis service and corresponding environment
variables for cache, session, and queue backends.

Reference: ChatGPT conversation on centralized vs per-app Redis architecture (2025-10-15).
https://chatgpt.com/share/68ef5930-49c8-800f-b6b8-069e6fefda01

roles/web-app-gitea/config/main.yml

@@ -49,5 +49,15 @@ docker:
         no_stop_required: true
       port:               3000
       name:               "gitea"
+      cpus:               1.0
+      mem_reservation:    1g
+      mem_limit:          2g
+      pids_limit:         1024
+    redis:
+      enabled:            false
+      cpus:               0.25
+      mem_reservation:    0.2g
+      mem_limit:          0.3g
+      pids_limit:         512
   volumes:
     data:             "gitea_data"

roles/web-app-gitea/templates/env.j2

@@ -20,6 +20,28 @@ DB_NAME={{ database_name }}
 DB_USER={{ database_username }}
 DB_PASSWD={{ database_password }}
 
+
+{% if GITEA_REDIS_ENABLED | bool %}
+# ------------------------------------------------
+# Redis Configuration for Gitea
+# ------------------------------------------------
+# @see https://docs.gitea.com/administration/config-cheat-sheet#cache-cache
+
+GITEA__cache__ENABLED=true
+GITEA__cache__ADAPTER=redis
+# use a different Redis DB index than oauth2-proxy
+GITEA__cache__HOST=redis://{{ GITEA_REDIS_ADDRESS }}/1
+
+# Store sessions in Redis (instead of the internal DB)
+GITEA__session__PROVIDER=redis
+GITEA__session__PROVIDER_CONFIG=network=tcp,addr={{ GITEA_REDIS_ADDRESS }},db=2,pool_size=100,idle_timeout=180
+
+# Use Redis for background task queues
+GITEA__queue__TYPE=redis
+GITEA__queue__CONN_STR=redis://{{ GITEA_REDIS_ADDRESS }}/3
+{% endif %}
+
+
 # SSH
 SSH_PORT={{ports.public.ssh[application_id]}}
 SSH_LISTEN_PORT=22

roles/web-app-gitea/vars/main.yml

@@ -28,3 +28,7 @@ GITEA_CONTAINER:  "{{ applications | get_app_conf(application_id, 'docker.servic
 GITEA_VOLUME:         "{{ applications | get_app_conf(application_id, 'docker.volumes.data') }}"
 GITEA_USER:           "git"
 GITEA_CONFIG:         "/data/gitea/conf/app.ini"
+
+## Redis
+GITEA_REDIS_ENABLED:  "{{ applications | get_app_conf(application_id, 'docker.services.redis.enabled') }}"
+GITEA_REDIS_ADDRESS:  "redis:6379"