fluent/fluentd · error · Fluent::ConfigError

Cannot access directory for pid file: #{File.dirname(pid_pat

Error message

Cannot access directory for pid file: #{File.dirname(pid_path)}

What it means

When the pidfile does not exist yet, fluentd must create it, so it checks that the parent directory is writable (File.writable?(File.dirname(pid_path))) and aborts with this ConfigError when it is not. This covers a missing directory, a read-only mount, or a directory owned by another user. It fires before daemonize, i.e. at option-processing/startup time.

Source

Thrown at lib/fluent/daemonizer.rb:75

        end

        pid =
          begin
            Integer(File.read(pid_path), 10)
          rescue TypeError, ArgumentError
            return # ignore
          end

        begin
          Process.kill(0, pid)
          raise Fluent::ConfigError, "pid(#{pid}) is running"
        rescue Errno::EPERM
          raise Fluent::ConfigError, "pid(#{pid}) is running"
        rescue Errno::ESRCH
        end
      else
        unless File.writable?(File.dirname(pid_path))
          raise Fluent::ConfigError, "Cannot access directory for pid file: #{File.dirname(pid_path)}"
        end
      end
    end

    def install_at_exit_handlers(pidfile)
      at_exit do
        if File.exist?(pidfile)
          File.delete(pidfile)
        end
      end
    end
  end
end

View on GitHub (pinned to dd45c6e18d)

Solutions

1. Create the directory and hand it to the daemon user: mkdir -p /var/run/fluentd && chown fluent:fluent /var/run/fluentd
2. With systemd, use RuntimeDirectory=fluentd so the unit creates /run/fluentd with correct ownership each boot
3. Point --daemon at a path in a writable directory (e.g. /var/lib/fluentd or the user's runtime dir)
4. For quick tests, use a pidfile under /tmp or the current directory

Example fix

# before
$ fluentd --daemon /var/run/fluentd/fluentd.pid ...  # dir missing/root-owned

# after
$ sudo mkdir -p /var/run/fluentd && sudo chown fluent:fluent /var/run/fluentd
$ fluentd --daemon /var/run/fluentd/fluentd.pid ...

dir = File.dirname(pid_path)
FileUtils.mkdir_p(dir) unless Dir.exist?(dir)
abort "pid dir not writable: #{dir}" unless File.writable?(dir)

When it happens

Trigger: fluentd --daemon /var/run/fluentd/fluentd.pid when /var/run/fluentd does not exist or is root-owned 755 and fluentd runs as non-root; pidfile under /run (tmpfs wiped at boot); read-only filesystem mounts.

Common situations: Non-root daemon pointed at /var/run or /run paths; reboot clearing tmpfs directories not recreated by an init script; containers without the runtime dir baked in.

Related errors

• Cannot access pid file: #{pid_path}
• pid(#{pid}) is running
• out_secondary_file: `#{@directory}` should be writable
• Plugin storage path '#{@path}' is not readable/writable
• Directory is not writable for plugin storage file '#{@path}'

AI-assisted analysis of fluent/fluentd@dd45c6e18d (2026-08-21). Data as JSON: /api/errors/6779f68e5c9c23f4. Report an issue: GitHub.