Configuration Hot-Reload and Application Reinitialize

aah provides seamless configuration hot-reload and application reinitialize via OS Signal on non-dev environment profiles. It enables aah application to adapt to on-demand, immediately required changes without server/application restart.

Hot-Reload and Reinitialize performs:

Reloads configuration from directory config/*.
Reinitializes the application variables, routes, views, i18n, security and loggers, etc.
Reinitializes the access log and dump log if enabled.
Since v0.12.0 Publishes OnConfigHotReload event, configuration.

Note:

Any error occurs in the reload and reinitialize process will not affect running application.
Server related configuration changes such as address, port, timeouts, SSL certs, redirect http to https, let’s encrypt requires server restart.

For example

# *nix OS
$ kill -HUP <process-id>

Configuration

Since v0.12.0 Hot-Reload configurable options and it goes under config section runtime { ... }.

config_hotreload {
  # Enable or disable Hot-Reload feature.
  #
  # Default value is `true`.
  enable = true

  # OS Signal to listen for application hot-reload on non-dev environment
  # profile. Supported signals are `SIGHUP`, `SIGUSR1` and `SIGUSR2`.
  #
  # Default value is `SIGHUP`.
  #
  # Note: OS Windows does not support `SIGUSR1`, `SIGUSR2` signals.
  signal = "SIGUSR1"
}

Event: OnConfigHotReload

Event OnConfigHotReload is published just after the successful reload and reinitialize of aah application. Any error or failure event is not published.

Supports Multiple: Yes

func performActionAfterHotReload(e *aah.Event)  {
  // logic here
}

func init()  {
  // By default, a given function is executed as added sequence
  // unless `priority` is specified.
  aah.App().OnConfigHotReload(performActionAfterHotReload)
}

Sample Application Log

Application logs information would appear similar to below-

2018-05-19 22:51:08.452 WARN  aahwebsite sfo-aahweb-01 Hangup signal (SIGHUP) received
2018-05-19 22:51:08.452 INFO  aahwebsite sfo-aahweb-01 Application hot-reload and reinitialization starts ...
2018-05-19 22:51:08.455 INFO  aahwebsite sfo-aahweb-01 Configuration files reload succeeded
2018-05-19 22:51:08.456 INFO  aahwebsite sfo-aahweb-01 Configuration values reinitialize succeeded
2018-05-19 22:51:08.456 INFO  aahwebsite sfo-aahweb-01 Logging reinitialize succeeded
2018-05-19 22:51:08.456 INFO  aahwebsite sfo-aahweb-01 I18n reinitialize succeeded
2018-05-19 22:51:08.457 INFO  aahwebsite sfo-aahweb-01 Router reinitialize succeeded
2018-05-19 22:51:08.564 INFO  aahwebsite sfo-aahweb-01 View engine reinitialize succeeded
2018-05-19 22:51:08.564 INFO  aahwebsite sfo-aahweb-01 Security reinitialize succeeded
2018-05-19 22:51:08.564 INFO  aahwebsite sfo-aahweb-01 Access logging reinitialize succeeded
2018-05-19 22:51:08.564 INFO  aahwebsite sfo-aahweb-01 Application hot-reload and reinitialization was successful

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