fluentd exits on SIGUSR1 if its logrotate feature is enabled

[abicky]

Here is an example:

• fluentd version: 59d9675
• OS: macOS 10.13.4

% bundle exec ./bin/fluentd -c ./fluent.conf --log /tmp/fluent.log --log-rotate-age 1 --log-rotate-size 1024 &
[1] 4387
% kill -USR1 4387
Unexpected error wrong number of arguments (given 2, expected 0..1)
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/2.4.0/logger.rb:715:in `reopen'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:364:in `reopen!'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:163:in `supervisor_sigusr1_handler'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:137:in `block in install_supervisor_signal_handlers'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/process_manager.rb:252:in `select'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/process_manager.rb:252:in `tick'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/multi_spawn_server.rb:91:in `wait_tick'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/multi_worker_server.rb:60:in `run'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/multi_spawn_server.rb:57:in `run'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/server.rb:123:in `main'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/daemon.rb:119:in `main'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/serverengine-2.0.6/lib/serverengine/daemon.rb:68:in `run'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:606:in `supervise'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:476:in `run_supervisor'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/command/fluentd.rb:310:in `<top (required)>'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/bin/fluentd:8:in `require'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/bin/fluentd:8:in `<top (required)>'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/cli/exec.rb:75:in `load'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/cli/exec.rb:75:in `kernel_load'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/cli/exec.rb:28:in `run'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/cli.rb:424:in `exec'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/vendor/thor/lib/thor.rb:387:in `dispatch'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/cli.rb:27:in `dispatch'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/vendor/thor/lib/thor/base.rb:466:in `start'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/cli.rb:18:in `start'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/bin/bundle:30:in `block in <main>'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/site_ruby/2.4.0/bundler/friendly_errors.rb:122:in `with_friendly_errors'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/bin/bundle:22:in `<main>'
[arabiki@MBP-3:~/ghq/src/github.com/fluent/fluentd]
%
[1]  + exit 1     bundle exec ./bin/fluentd -c ./fluent.conf --log /tmp/fluent.log  1  1024

I've tried to fix the error by the following change:

diff --git a/lib/fluent/log.rb b/lib/fluent/log.rb
index 097216c3..30108510 100644
--- a/lib/fluent/log.rb
+++ b/lib/fluent/log.rb
@@ -625,5 +625,12 @@ module Fluent
         super
       end
     end
+
+    def reopen(path, mode)
+      if mode != 'a'
+        raise "Unsupported mode: #{mode}"
+      end
+      super(path)
+    end
   end
 end

However, I found another error...

% bundle exec ./bin/fluentd -c ./fluent.conf --log /tmp/fluent.log --log-rotate-age 1 --log-rotate-size 1024 &
[1] 5731
% kill -USR1 5731
Unexpected error can't be called from trap context
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/2.4.0/monitor.rb:187:in `lock'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/2.4.0/monitor.rb:187:in `mon_enter'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/2.4.0/monitor.rb:212:in `mon_synchronize'
  /Users/arabiki/.anyenv/envs/rbenv/versions/2.4.2/lib/ruby/2.4.0/logger.rb:719:in `reopen'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/log.rb:633:in `reopen'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:364:in `reopen!'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:163:in `supervisor_sigusr1_handler'
  /Users/arabiki/ghq/src/github.com/fluent/fluentd/lib/fluent/supervisor.rb:137:in `block in install_supervisor_signal_handlers'
(snip)

[repeatedly]

Thanks! Will check after japan container day.