From: Tom Clegg <tom@curii.com>
Date: Thu, 5 May 2022 21:21:33 +0000 (-0400)
Subject: 18794: Auto-reload workbench1 config, too.
X-Git-Tag: 2.5.0~184^2~3
X-Git-Url: https://git.arvados.org/arvados.git/commitdiff_plain/eaaec81f7cd6c26b3496d800f8e1827ab7a6445c

18794: Auto-reload workbench1 config, too.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>
---

diff --git a/apps/workbench/config/initializers/reload_config.rb b/apps/workbench/config/initializers/reload_config.rb
new file mode 100644
index 0000000000..259f54732c
--- /dev/null
+++ b/apps/workbench/config/initializers/reload_config.rb
@@ -0,0 +1,67 @@
+# Copyright (C) The Arvados Authors. All rights reserved.
+#
+# SPDX-License-Identifier: AGPL-3.0
+
+# Please don't edit this version. Instead, edit
+# services/api/config/initializers/reload_config.rb and update this
+# copy. Or find a more reasonable way to share the code.
+
+if !File.owned?(Rails.root.join('tmp'))
+  Rails.logger.debug("reload_config: not owner of #{Rails.root}/tmp, skipping")
+elsif ENV["ARVADOS_CONFIG"] == "none"
+  Rails.logger.debug("reload_config: no config in use, skipping")
+else
+  Thread.new do
+    lockfile = Rails.root.join('tmp', 'reload_config.lock')
+    File.open(lockfile, File::WRONLY|File::CREAT, 0600) do |f|
+      # Note we don't use LOCK_NB here. If we did, each time passenger
+      # kills the lock-holder process, we would be left with nobody
+      # checking for updates until passenger starts a new worker,
+      # which could be a long time.
+      Rails.logger.debug("reload_config: waiting for lock on #{lockfile}")
+      f.flock(File::LOCK_EX)
+
+      t_lastload = Rails.configuration.SourceTimestamp
+      hash_lastload = Rails.configuration.SourceSHA256
+      conffile = ENV['ARVADOS_CONFIG'] || "/etc/arvados/config.yml"
+      Rails.logger.info("reload_config: polling for updated mtime on #{conffile} with threshold #{t_lastload}")
+      while true
+        sleep 1
+        t = File.mtime(conffile)
+        # If the file is newer than 5s, re-read it even if the
+        # timestamp matches the previously loaded file. This enables
+        # us to detect changes even if the filesystem's timestamp
+        # precision cannot represent multiple updates per second.
+        if t.to_f != t_lastload.to_f || Time.now.to_f - t.to_f < 5
+          Open3.popen2("arvados-server", "config-dump", "-skip-legacy") do |stdin, stdout, status_thread|
+            confs = YAML.load(stdout, deserialize_symbols: false)
+            hash = confs["SourceSHA256"]
+          rescue => e
+            Rails.logger.info("reload_config: config file updated but could not be loaded: #{e}")
+            t_lastload = t
+            continue
+          end
+          if hash == hash_lastload
+            # If we reloaded a new or updated file, but the content is
+            # identical, keep polling instead of restarting.
+            t_lastload = t
+            continue
+          end
+
+          restartfile = Rails.root.join('tmp', 'restart.txt')
+          touchtime = Time.now
+          Rails.logger.info("reload_config: mtime on #{conffile} changed to #{t}, touching #{restartfile} to #{touchtime}")
+          begin
+            File.utime(touchtime, touchtime, restartfile)
+          rescue
+            File.open(restartfile, 'w') {}
+          end
+          # Even if passenger doesn't notice that we hit restart.txt
+          # and kill our process, there's no point waiting around to
+          # hit it again.
+          break
+        end
+      end
+    end
+  end
+end