From c7965a2696f5bce272654c875a775aab8b2cfbfe Mon Sep 17 00:00:00 2001
From: Thomas Klausner <domm@plix.at>
Date: Fri, 18 Aug 2023 10:40:37 +0300
Subject: [PATCH] Bug 31729: enable plackup hot restart in ktd

This patch implements a more idiomatoic way for hot-reloading. Instead
of adding a new daemon/watcher+inotify or use a Middleware, we can use
`plackup -R /path/to/dir`, which is the standard Perl way to do hot
reloading for plack apps.

Instead of calling `/usr/bin/perl starman` directly, we use
`plackup -s Starman`. And can then use `-R /kohadevbox/koha/Koha` to
watch that directory for changes and hot-reload the plack app.

I've added a new option `koha-plack --hot-reload`. Only if this option
is set AND we're running inside koha-testing-docker (by checking
KOHA_INSTANCE = "kohadev") hot reloading is enabled.

Test plan:

Before applying the patch:

* Start koha-testing-docker and enter the container

* Stop plack: koha-plack --stop kohadev

* Check the log: tail -n 4 /var/log/koha/kohadev/plack-error.log
  You should see lines like
    Worker processes cleaned up
    Server closing!

* Start it again: koha-plack --start kohadev
  Output should be "Starting Plack daemon for kohadev:"
  And you end back at the interactive shell

* Check the log: tail -n 4 /var/log/koha/kohadev/plack-error.log
  it should look like:
    Starman::Server (type Net::Server::PreFork) starting!
    Binding to UNIX socket file "/var/run/koha/kohadev/plack.sock"
    Starman: Accepting connections at unix://localhost:/var/run/koha/kohadev/plack.sock/

* Stop it again: koha-plack --stop kohadev

Now apply the patch.

As in koha-testing-docker the koha-plack script (after applying the
patch) is NOT installed to /sbin you have to call the dev version.

* Start the server with hot-reloading:
  debian/scripts/koha-plack --start --hot-reload kohadev

* Output should be:
  Starting Plack daemon for kohadev:Watching /kohadevbox/koha/Koha /etc/koha/sites/kohadev/plack.psgi for file updates.

* You are now NOT back in the shell, as the plack app is NOT running
  daemonized

* So you need to open another ktd --shell

* Check the log:
  tail -n 4 /var/log/koha/kohadev/plack-error.log
    Starman::Server (type Net::Server::PreFork) starting! pid(27638)
    Binding to UNIX socket file "/var/run/koha/kohadev/plack.sock"
    Starman: Accepting connections at unix://localhost:/var/run/koha/kohadev/plack.sock/

* Update a code file
  touch Koha/Biblios.pm

* in the other shell (where plack is running) you should see:
  -- /kohadevbox/koha/Koha/Biblios.pm updated.
  Killing the existing server
  Successfully killed! Restarting the new server process.

* Yay!

* If you want to still stop/restart plack manually, you can hit CTRL-C
  in the shell were you started plack to stop the process.
---
 debian/scripts/koha-plack | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/debian/scripts/koha-plack b/debian/scripts/koha-plack
index 6fe1860268..86ce5c2f68 100755
--- a/debian/scripts/koha-plack
+++ b/debian/scripts/koha-plack
@@ -60,6 +60,7 @@ $scriptname -h|--help
     --debugger-location   Specify the host:port for your debugger tool (defaults
                           to localhost:9000)
     --debugger-path       Specify the path for the debugger library
+    --hot-reload          Enable hot-reload (only in koha-testing-docker)
     --quiet|-q            Make the script quiet about non existent instance names
                           (useful for calling from another scripts).
     --help|-h             Display this help message
@@ -95,6 +96,7 @@ start_plack()
     logging="--access-log /var/log/koha/${instancename}/plack.log \
              --error-log /var/log/koha/${instancename}/plack-error.log"
     max_requests_and_workers="--max-requests ${PLACK_MAX_REQUESTS} --workers ${PLACK_WORKERS}"
+    plack_hot_reload=""
 
     if [ "$DEV_INSTALL" = "1" ]; then
         # Maybe we should switch off debug_mode if DEV_INSTALL is not set?
@@ -106,12 +108,18 @@ start_plack()
         daemonize=""
         logging="" # remote debugger takes care
         max_requests_and_workers="--workers 1"
-        STARMAN="/usr/bin/perl -d ${STARMAN}"
+        PLACKUP="/usr/bin/perl -d ${PLACKUP}"
     fi
 
-    STARMANOPTS="-M FindBin ${max_requests_and_workers} \
+    if [ "$hot_reload" = "yes" ] && [ "$KOHA_INSTANCE" = "kohadev" ] && [ -d "/kohadevbox/koha/Koha" ]; then
+        plack_hot_reload="-R /kohadevbox/koha/Koha";
+        daemonize=""
+    fi
+
+    PLACKUPOPTS="-M FindBin ${max_requests_and_workers} \
+	         -s Starman
                  --user=${instance_user} --group ${instancename}-koha \
-                 --pid ${PIDFILE} ${daemonize} ${logging} \
+                 --pid ${PIDFILE} ${daemonize} ${logging} ${plack_hot_reload}\
                  -E ${environment} --socket ${PLACKSOCKET} ${PSGIFILE}"
 
     if ! is_plack_running ${instancename}; then
@@ -123,7 +131,7 @@ start_plack()
         current_dir=$(pwd)
         eval cd ~$instance_user
 
-        if ${STARMAN} ${STARMANOPTS}; then
+        if ${PLACKUP} ${PLACKUPOPTS}; then
             log_end_msg 0
         else
             log_end_msg 1
@@ -398,13 +406,14 @@ _do_instance() {
     esac
 }
 
-STARMAN=$(which starman)
+PLACKUP=$(which plackup)
 op=""
 quiet="no"
 debug_mode="no"
 debugger_key=""
 debugger_location="localhost:9000"
 debugger_path=""
+hot_reload=""
 
 # Read command line parameters
 while [ $# -gt 0 ]; do
@@ -445,6 +454,9 @@ while [ $# -gt 0 ]; do
         --debugger-path)
             debugger_path="$2"
             shift 2 ;;
+	--hot-reload)
+            hot_reload="yes"
+            shift ;;
         -*)
             die "Error: invalid option switch ($1)" ;;
         *)
-- 
2.30.2