A minimal wekan docker-compose file to start Wekan without a mail server. You will get a "Internal Server Error" if you create your first user but don't worry the user will still be added to the database and you can login without any issues.

minimal-compose-wekan.yaml

version: '2'
services:
  wekandb:
    #-------------------------------------------------------------------------------------
    # ==== MONGODB FROM DOCKER HUB ====
    image: mongo:6
    #-------------------------------------------------------------------------------------
    container_name: wekan-db
    restart: always
    # command: mongod --oplogSize 128
    # Syslog: mongod --syslog --oplogSize 128 --quiet
    # Disable MongoDB logs:
    command: mongod --logpath /dev/null --oplogSize 128 --quiet
    networks:
      - wekan-tier
    expose:
      - 27017
    volumes:
      - /etc/localtime:/etc/localtime:ro
      - wekan-db:/data/db
      - wekan-db-dump:/dump
      #- /etc/timezone:/etc/timezone:ro # Do not use https://github.com/wekan/wekan/issues/5123
  wekan:
    image: ghcr.io/wekan/wekan:latest
    #-------------------------------------------------------------------------------------
    container_name: wekan-app
    restart: always
    networks:
      - wekan-tier
    ports:
      # Docker outsideport:insideport. Do not add anything extra here.
      # For example, if you want to have wekan on port 3001,
      # use 3001:8080 . Do not add any extra address etc here, that way it does not work.
      # remove port mapping if you use nginx reverse proxy, port 8080 is already exposed to wekan-tier network
      - 12345:8080
    environment:
      #-----------------------------------------------------------------
      # ==== WRITEABLE PATH FOR FILE UPLOADS ====
      - WRITABLE_PATH=/data
      #-----------------------------------------------------------------
      # ==== MONGO_URL ====
      - MONGO_URL=mongodb://wekandb:27017/wekan
      #---------------------------------------------------------------
      # ==== ROOT_URL SETTING ====
      # Change ROOT_URL to your real Wekan URL, for example:
      # If you have Caddy/Nginx/Apache providing SSL
      #  - https://example.com
      #  - https://boards.example.com
      # This can be problematic with avatars https://github.com/wekan/wekan/issues/1776
      #  - https://example.com/wekan
      # If without https, can be only wekan node, no need for Caddy/Nginx/Apache if you don't need them
      #  - http://example.com
      #  - http://boards.example.com
      #  - http://192.168.1.100    <=== using at local LAN
      - ROOT_URL=http://localhost #   <=== using only at same laptop/desktop where Wekan is installed
      #---------------------------------------------------------------
      # ==== EMAIL SETTINGS ====
      # Email settings are only at MAIL_URL and MAIL_FROM.
      # Admin Panel has test button, but it's not used for settings.
      #   see https://github.com/wekan/wekan/wiki/Troubleshooting-Mail
      #   For SSL in email, change smtp:// to smtps://
      # NOTE: Special characters need to be url-encoded in MAIL_URL.
      #       You can encode those characters for example at: https://www.urlencoder.org
      #- MAIL_URL=smtp://user:pass@mailserver.example.com:25/
      - MAIL_URL=
      - MAIL_FROM=
      #---------------------------------------------------------------
      # ==== WEKAN API AND EXPORT BOARD ====
      # Wekan Export Board works when WITH_API=true.
      # https://github.com/wekan/wekan/wiki/REST-API
      # https://github.com/wekan/wekan-gogs
      # If you disable Wekan API with false, Export Board does not work.
      - WITH_API=true
      #---------------------------------------------------------------
      # ==== RICH TEXT EDITOR IN CARD COMMENTS ====
      # https://github.com/wekan/wekan/pull/2560
      - RICHER_CARD_COMMENT_EDITOR=false
      #---------------------------------------------------------------
      # ==== CARD OPENED, SEND WEBHOOK MESSAGE ====
      # https://github.com/wekan/wekan/issues/2518
      - CARD_OPENED_WEBHOOK_ENABLED=false
      #---------------------------------------------------------------
      # ==== BIGEVENTS DUE ETC NOTIFICATIONS =====
      # https://github.com/wekan/wekan/pull/2541
      # Introduced a system env var BIGEVENTS_PATTERN default as "NONE",
      # so any activityType matches the pattern, system will send out
      # notifications to all board members no matter they are watching
      # or tracking the board or not. Owner of the wekan server can
      # disable the feature by setting this variable to "NONE" or
      # change the pattern to any valid regex. i.e. '|' delimited
      # activityType names.
      # a) Example
      #- BIGEVENTS_PATTERN=due
      # b) All
      #- BIGEVENTS_PATTERN=received|start|due|end
      # c) Disabled
      - BIGEVENTS_PATTERN=NONE
      #-----------------------------------------------------------------
      # ==== BROWSER POLICY AND TRUSTED IFRAME URL ====
      # Enable browser policy and allow one trusted URL that can have iframe that has Wekan embedded inside.
      # Setting this to false is not recommended, it also disables all other browser policy protections
      # and allows all iframing etc. See wekan/server/policy.js
      - BROWSER_POLICY_ENABLED=true
    depends_on:
      - wekandb
    volumes:
      - /etc/localtime:/etc/localtime:ro
      - wekan-files:/data:rw
volumes:
  wekan-files:
    driver: local
  wekan-db:
    driver: local
  wekan-db-dump:
    driver: local
networks:
  wekan-tier:
    driver: bridge