Just in case youre curious, here is my complete Gitea stack using MariaDB as db and issue indexer, and Redis for cache, queue and sessions.

Disclaimer: I am neither a Gitea or MariaDB or Redis expert, i know nothing about anything…

version: "3.3"

networks:
  gitea:
    name: gitea
  traefikproxy:
    external: true

services:

  gitea:
    container_name: gitea
    image: gitea/gitea:1.20.5-rootless
    restart: unless-stopped
    labels:
      - traefik.enable=true
      - traefik.docker.network=traefikproxy
      - traefik.http.routers.gitea.rule=Host(`gitea.local.example.com`)
      - traefik.http.services.gitea.loadbalancer.server.port=3000
    networks:
      - gitea
      - traefikproxy
  # ports:
  #   - 7744:3000   # webui
  #   - 2200:22     # ssh    (needs more configuration)
    depends_on:
      gitea-mariadb:
        condition: service_healthy
      gitea-redis:
        condition: service_healthy
    environment:
      - TZ=Europe/Berlin
      - USER_UID=1000
      - USER_GID=1000
      - USER=username
      ### basic settings
      - "GITEA__default__APP_NAME=Gitea"
      - "GITEA__time__DEFAULT_UI_LOCATION=Europe/Berlin"
      - "GITEA__ui__DEFAULT_THEME=arc-green"
      - "GITEA__server__HTTP_PORT=3000"
      - "GITEA__server__OFFLINE_MODE=true"
      - "GITEA__server__ROOT_URL=https://gitea.local.example.com"
      #- "GITEA__server__LOCAL_ROOT_URL=http://localhost:3000/"
      #- "GITEA__server__DOMAIN="
      ### database settings
      - GITEA__database__DB_TYPE=mysql
      - GITEA__database__HOST=gitea-mariadb:3306
      - GITEA__database__NAME=gitea
      - GITEA__database__USER=gitea
      - GITEA__database__PASSWD=gitea
      ### use db as indexer
      - GITEA__indexer__ISSUE_INDEXER_TYPE=db
      ### redis for cache, session and queue
      - GITEA__cache__ENABLED=true
      - GITEA__cache__ADAPTER=redis
      - GITEA__cache__HOST=redis://gitea-redis:6379/0
      - GITEA__session__PROVIDER=redis
      - GITEA__session__PROVIDER_CONFIG=redis://gitea-redis:6379/1
      - GITEA__queue__TYPE=redis
      - GITEA__queue__CONN_STR=redis://gitea-redis:6379/2
      ### mail settings
      - "GITEA__mailer__ENABLED=true"
      - "GITEA__mailer__PROTOCOL=smtp+starttls"
      - "GITEA__mailer__SUBJECT_PREFIX=Gitea: "
      - "GITEA__mailer__FROM=example@gmail.com"
      - "GITEA__mailer__USER=example@gmail.com"
      - "GITEA__mailer__PASSWD=CHANGEME"
      - "GITEA__mailer__SMTP_ADDR=smtp.gmail.com"
      - "GITEA__mailer__SMTP_PORT=587"
      ### secret key and token
      ### generate once with:
      #      docker run -it --rm gitea/gitea:1.20.5-rootless gitea generate secret SECRET_KEY
      #      docker run -it --rm gitea/gitea:1.20.5-rootless gitea generate secret INTERNAL_TOKEN
      - "GITEA__security__SECRET_KEY=CHANGEME"
      - "GITEA__security__INTERNAL_TOKEN=CHANGEME"
    volumes:
      - ./data:/var/lib/gitea
      - ./config:/etc/gitea
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
    healthcheck:
      test: "wget --no-verbose --tries=1 --spider --no-check-certificate http://localhost:3000/api/healthz || exit 1"
      start_period: 60s
  # mem_limit: 250m
  # memswap_limit: 250m
  # mem_reservation: 125m
  # cpu_shares: 1024
  # cpus: 1.0


  gitea-mariadb:
    container_name: gitea-mariadb
    image: mariadb:11.1.2
    restart: unless-stopped
    networks:
      - gitea
  # ports:
  #   - 3306:3306
    environment:
      - TZ=Europe/Berlin
      - MYSQL_ROOT_PASSWORD=gitea
      - MYSQL_USER=gitea
      - MYSQL_PASSWORD=gitea
      - MYSQL_DATABASE=gitea
    volumes:
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
      - ./mariadb:/var/lib/mysql
    command: --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
    healthcheck:
      test: ["CMD-SHELL", "mariadb-admin --user=$${MYSQL_USER} --password=$${MYSQL_PASSWORD} --host=localhost ping"]
      start_period: 60s
  # mem_limit: 400m
  # memswap_limit: 400m
  # mem_reservation: 200m
  # cpus: 0.5


  gitea-redis:
    container_name: gitea-redis
    image: redis:7.2.2-alpine
    restart: unless-stopped
    networks:
      - gitea
  # ports:
  #   - 6379:6379
    volumes:
      - ./redis:/data
  ### run on Docker host and reboot:
  ###    echo "vm.overcommit_memory = 1" | sudo tee /etc/sysctl.d/nextcloud-aio-memory-overcommit.conf
    command: redis-server --save 30 1 --loglevel warning
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]
  # mem_limit: 150m
  # memswap_limit: 150m
  # mem_reservation: 25m
  # cpus: 0.5