Mastodon v4.3+ patch to set custom char limit using `MAX_POST_CHARS` env variable

docker-compose.swarm.yml

# Example how you can "patch" Matodon running in docker swarm by exploiting "config mounts" 
# to avoid mounting files from local system
services:
  web:
    # original configuration
    # ...
    configs:
      - source: mastodon-remove-char-limit
        target: /mastodon/config/initializers/4_char_limit.rb

  
  sidekiq:
    # original configuration
    # ...
    configs:
      - source: mastodon-remove-char-limit
        target: /mastodon/config/initializers/4_char_limit.rb

configs:
  mastodon-remove-char-limit:
    # Replace `./mastodon_4_3_char_limit.rb` with path to file on your system, where you are running "docker service" command
    file: ./mastodon_4_3_char_limit.rb

docker-compose.yml

# Example how you can "patch" Matodon running in docker container

services:
  web:
    # original configuration
    # ...
    volumes:
      # Mount patch inside container. Replace `/opt/mastodon/mastodon_4_3_char_limit.rb` with path to file on local system.
      - /opt/mastodon/mastodon_4_3_char_limit.rb:/mastodon/config/initializers/4_char_limit.rb
      - ./public/system:/mastodon/public/system

  
  sidekiq:
    # original configuration
    # ...
    volumes:
      # Mount patch inside container. Replace `/opt/mastodon/mastodon_4_3_char_limit.rb` with path to file on local system.
      - /opt/mastodon/mastodon_4_3_char_limit.rb:/mastodon/config/initializers/4_char_limit.rb
      - ./public/system:/mastodon/public/system
    # ...

mastodon_4_3_char_limit.rb

# License: 0BSD
#
# Patch for Mastodon v4.3+
# Redefine StatusLengthValidator::MAX_CHARS to allow setting char limit from
# MAX_POST_CHARS environment variable.
#
# 1. Add this file to `config/initializers/`
# 2. Set `MAX_POST_CHARS` environment to the desired value
# 3. Restart app.
#
# This "patch" will survive upgrades, as long as location of `MAX_CHARS` constant
# is the same.

Rails.application.config.after_initialize do
  if defined?(StatusLengthValidator)
    # Uncomment this line if you don't like `already initialized constant` warning
    # StatusLengthValidator.send(:remove_const, :MAX_CHARS) if StatusLengthValidator.const_defined?(:MAX_CHARS)
    StatusLengthValidator.const_set :MAX_CHARS, ENV.fetch("MAX_POST_CHARS", 500).to_i
  end
end

# © 2025 by yopp (@[email protected])
#
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# purpose with or without fee is hereby granted.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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# AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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