Problem: if you’re hosting your own Mastodon instance and subscribe to some feed with images, your instance footprint would grow like hell. You can purge ‘old media,’ but that’ll ruin your bookmarks. This snippet will get all your media from bookmarks.

Generate a list of S3 URLs for media attached to bookmarked statuses. Output: export/bookmarked_media_s3_urls.txt

# script/list_bookmarked_media_s3.rb
#
# Generate list of S3 URLs for media attached to bookmarked statuses.
# Output: export/bookmarked_media_s3_urls.txt

require "fileutils"
require "uri"

S3_HOST   = "https://s3.andreybondarenko.com"
S3_BUCKET = "mastodon" # path-style bucket

EXPORT_DIR  = Rails.root.join("export")
OUTPUT_PATH = EXPORT_DIR.join("bookmarked_media_s3_urls.txt")

FileUtils.mkdir_p(EXPORT_DIR)

puts "Writing S3 URL list to: #{OUTPUT_PATH}"

File.open(OUTPUT_PATH, "w") do |out|
  Bookmark.includes(status: :media_attachments).find_each do |bookmark|
    status = bookmark.status
    next unless status

    status.media_attachments.each do |media|
      begin
        uploader = media.file if media.respond_to?(:file)
        next unless uploader

        key = nil

        # 1) Try file.path (often S3 key or local path)
        if uploader.respond_to?(:path) && uploader.path.present?
          path = uploader.path.to_s

          # If this is a local path with /system/ in it, strip everything up to /system/
          if path.include?("/system/")
            key = path.split("/system/", 2).last
            key = "system/#{key}"
          else
            # Otherwise assume it's already a key
            key = path.sub(%r{^/}, "")
          end
        end

        # 2) Fallback: parse from file.url if path wasn't usable
        if key.nil? && uploader.respond_to?(:url) && uploader.url.present?
          url = uploader.url.to_s

          if url.start_with?("http")
            uri = URI(url)
            # If path starts with /mastodon/, strip that as bucket prefix
            # /mastodon/system/... -> system/...
            path = uri.path.sub(%r{^/}, "")
            if path.start_with?("#{S3_BUCKET}/")
              key = path.sub(%r{^#{Regexp.escape(S3_BUCKET)}/}, "")
            else
              # If it's already like system/..., accept as key
              key = path
            end
          else
            # relative url like /system/media_attachments/...
            key = url.sub(%r{^/}, "")
          end
        end

        unless key && !key.empty?
          warn "Could not determine key for media #{media.id}, bookmark #{bookmark.id}"
          next
        end

        full_url = "#{S3_HOST}/#{S3_BUCKET}/#{key}"
        out.puts(full_url)
      rescue => e
        warn "Error for bookmark #{bookmark.id}, media #{media.id}: #{e.class} #{e.message}"
      end
    end
  end
end

puts "Done."