CyberFlameGO · July 21, 2022 18:32 · Mar 22, 2022 · Nov 5, 2021 · Jun 5, 2021 · May 22, 2021
diff --git a/README.md b/README.md
@@ -91,4 +91,16 @@ Run `bash --version` to confirm - I believe required features were added in vers
 Solutions:
 1. Upgrade bash to more modern version
 2. Replace the mentioned substitution to remove the lowercasing (remove the two `,,`).
-  From now on you need to make sure that `restart_on_crash` setting is lowercase.
+  From now on you need to make sure that `restart_on_crash` setting is lowercase.
+
+## Restart doesn't work
+
+### Script copied from Windows
+
+If you copied the script from Windows machine, there's a chance that DOS line endings were added.
+These endings are called `CRLF` typed as `\r\n`.
+Many Linux editors will display `^M` in place of `CR`/`\r`. 
+
+Solutions:
+1. Save the file using Linux line ending `LF`/`\n`
+2. Run a tool like `dos2unix` on the file to convert it for you
diff --git a/README.md b/README.md
@@ -1,3 +1,6 @@
+:warning: **This guide is for self-managed servers**.
+If you rented a server and got a website through which you manage your server - you are on so called shared-hosting and this guide won't work for you.
+
 # What is spigot restart script
 
 Spigot added a feature allowing for server to automatically restart on crashes,

diff --git a/README.md b/README.md
@@ -56,4 +56,36 @@ If someone can rewrite these scripts to Windows equivalents, I'll gladly add the
 
 If you have questions, its best to ask them here so others can see.
 Alternatively, reach me over on Discord `Prof_Bloodstone#0123`
-or email `[email protected]`.
+or email `[email protected]`.
+
+# Known issues
+
+### Illegal option -o pipefail
+
+Error: `start.sh: 4: set: Illegal option -o pipefail`
+
+It means that the script was started with a shell not supporting `pipefail` option.
+This is most common, when you start the script as `sh start.sh` while `sh` is symlinked to `dash` or other minimal shell:
+
+```sh
+$ which sh
+/bin/sh
+$ ls -l /bin/sh
+lrwxrwxrwx 1 root root 4 Feb 23 18:52 /bin/sh -> dash
+```
+
+Solution: Start it using bash - either use `bash start.sh`,
+or first mark the file as executable with `chmod +x start.sh`
+and then execute the file directly using `./start.sh`.
+
+### bad substitution
+
+Error: `start.sh: line 55: ${restart_on_crash,,}: bad substitution`
+
+It means that you sucessfully started the script using bash, but it's probably too old.
+Run `bash --version` to confirm - I believe required features were added in version `4`.
+
+Solutions:
+1. Upgrade bash to more modern version
+2. Replace the mentioned substitution to remove the lowercasing (remove the two `,,`).
+  From now on you need to make sure that `restart_on_crash` setting is lowercase.
diff --git a/README.md b/README.md
@@ -56,4 +56,4 @@ If someone can rewrite these scripts to Windows equivalents, I'll gladly add the
 
 If you have questions, its best to ask them here so others can see.
 Alternatively, reach me over on Discord `Prof_Bloodstone#0123`
-or email `paper@bloodstone.dev`.
+or email `papermc@bloodstone.dev`.
diff --git a/start.sh b/start.sh
@@ -8,6 +8,12 @@ set -euo pipefail
 readonly restart_flag='.restart_flag'
 # How long (in seconds) to wait before restarting
 readonly restart_delay=10
+# Whether to restart on crash or not
+# The `settings.restart-on-crash` setting in spigot.yml doesn't always work
+# but also sometimes server might not return proper exit code,
+# so it's best to keep both options enabled
+# Accepted values: y/yes/true/n/no/false
+readonly restart_on_crash='yes'
 # The name of your server jar
 readonly server_jar='paperclip.jar'
 # What will be passed to `-Xms` and `-Xmx`
@@ -45,6 +51,16 @@ readonly mc_args=(
 )
 # END OF SETTINGS
 
+should_restart_on_crash() {
+  case "${restart_on_crash,,}" in
+    y|yes|true) return 0;;
+    n|no|false) return 1;;
+    *)
+      printf 'ERROR: Invalid value for "restart_on_crash" variable: %s\n' "${restart_on_crash}" >&2
+      exit 1
+      ;;
+  esac
+}
 
 # The arguments that will be passed to java:
 readonly java_args=(
@@ -60,24 +76,32 @@ readonly java_args=(
 # unless restart script was called
 rm "${restart_flag}" &>/dev/null || true
 
+# Check if `restart_on_crash` has valid value
+should_restart_on_crash || true
+
 while :; do # Loop infinitely
-  # Run server, ignoring failure.
-  # This is so that you can control whether you want to restart on failure
-  # using `settings.restart-on-crash` setting in spigot.yml
-  java "${java_args[@]}" || true
+  # Run server
+  java "${java_args[@]}" || {
+    # Oops, server didn't exit gracefully
+    printf 'Detected server crash (exit code: %s)\n' "${?}" >&2
+    # Check if we should restart on crash or not
+    if should_restart_on_crash; then
+      touch "${restart_flag}"
+    fi
+  }
   # Check if restart file exists or exit
   if [ -e "${restart_flag}" ]; then
     # The flag exists - try to remove it
     rm "${restart_flag}" || {
       # If we can't remove it (permissions?), then exit to avoid endless restart loop
-      printf 'Error removing restart flag (exit code: %s) - cowardly exiting\n' "${?}"
+      printf 'Error removing restart flag (exit code: %s) - cowardly exiting\n' "${?}" >&2
       exit 1
     }
   else
     break # Flag doesn't exist, so break out of the loop
   fi
-  printf 'Restarting server in 10 seconds...\n'
+  printf 'Restarting server in 10 seconds, press Ctrl+C to abort.\n' >&2
   sleep "${restart_delay}" || break # Exit if sleep is interrupted (for example Ctrl+C)
 done
 
-printf 'Server stopped\n'
+printf 'Server stopped\n' >&2
diff --git a/00-README.md → README.md b/00-README.md → README.md
diff --git a/00-README.md b/00-README.md
@@ -0,0 +1,59 @@
+# What is spigot restart script
+
+Spigot added a feature allowing for server to automatically restart on crashes,
+as well as when authorized user executes `/restart` command.
+
+# How it works
+
+When server starts to shut down, it spawns a new process which runs your restart script,
+as specified in `spigot.yml` under `settings.restart-script`, which defaults to `./start.sh`.
+The idea is that the original server will stop completely, and the new instance will take its place.
+
+# Why is it an issue
+
+Because the new server is created before old one fully stopped, this means:
+
+1. You need enough spare resources, to temporarily run 2 servers at the same time,
+  as the old instance haven't freed up CPU/RAM while the new one starts and prepares itself.
+2. You might hit `Unable to bind to port` errors, because old server is still occupying the port.
+3. You might hit `Is another instance running` error, mentioning that `world/session.lock` is in use
+
+Because the new server is being detached, that means that if you use `tmux` or `screen` to start your server,
+it no longer will give you access to server console after restart.
+
+# How can this be fixed
+
+The solution is simple - don't let the restart script start any server,
+but instead have it communicate with your start script that when old instance is shut down,
+it should start a new one instead.
+
+# How can I do it?
+
+The easiest way is to simply create 2 scripts - `start.sh` which will be the start script,
+and `restart.sh` which will be used by Spigot to notify that a restart is needed.
+
+First, configure `spigot.yml` to use your restart script instead:
+
+```yaml
+settings:
+  restart-script: ./restart.sh
+```
+
+Finally, copy the attached to this gist `start.sh` and `restart.sh` scripts
+and place them in your server folder from where you start it,
+which usually is the same directory where server jar, settings and worlds are in.
+Make sure to understand what they do and change memory setting and other flags to your liking.
+You'll also need to mark them as executable, by running `chmod +x *.sh`.
+
+Now you can start your `tmux`/`screen` session as usual and run `./start.sh`. That's it!
+
+# But what about Windows?
+
+I haven't used Windows in years, so I don't know batch or PS language well enough.
+If someone can rewrite these scripts to Windows equivalents, I'll gladly add them.
+
+# I have questions / issues
+
+If you have questions, its best to ask them here so others can see.
+Alternatively, reach me over on Discord `Prof_Bloodstone#0123`
+or email `[email protected]`.
diff --git a/restart.sh b/restart.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env sh
+# We need to use sh, since it's hardcoded in spigot
+# Doesn't matter much, since it doesn't do much anyway
+
+# This script only creates a file which tells `start.sh` that it should restart, instead of exiting.
+
+# Make sure to change this, if you modified `restart_flag` in `start.sh`!
+touch .restart_flag
diff --git a/start.sh b/start.sh
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+# NOTE: We use bash for better readability and error handling here
+# but it's not hard to make it work with regular shell
+set -euo pipefail
+
+# SETTINGS
+# Path to file used to communicate from restart script
+readonly restart_flag='.restart_flag'
+# How long (in seconds) to wait before restarting
+readonly restart_delay=10
+# The name of your server jar
+readonly server_jar='paperclip.jar'
+# What will be passed to `-Xms` and `-Xmx`
+readonly heap_size='1G'
+# JVM startup flags, one per line for better readability
+# NOTE: -Xms and -Xmx are set separately
+# These are mostly "Aikar flags"
+# taken from: https://mcflags.emc.gs/
+readonly jvm_flags=(
+  -XX:+UseG1GC
+  -XX:+ParallelRefProcEnabled
+  -XX:MaxGCPauseMillis=200
+  -XX:+UnlockExperimentalVMOptions
+  -XX:+DisableExplicitGC
+  -XX:+AlwaysPreTouch
+  -XX:G1NewSizePercent=30
+  -XX:G1MaxNewSizePercent=40
+  -XX:G1HeapRegionSize=8M
+  -XX:G1ReservePercent=20
+  -XX:G1HeapWastePercent=5
+  -XX:G1MixedGCCountTarget=4
+  -XX:InitiatingHeapOccupancyPercent=15
+  -XX:G1MixedGCLiveThresholdPercent=90
+  -XX:G1RSetUpdatingPauseTimePercent=5
+  -XX:SurvivorRatio=32
+  -XX:+PerfDisableSharedMem
+  -XX:MaxTenuringThreshold=1
+  -Dusing.aikars.flags=https://mcflags.emc.gs
+  -Daikars.new.flags=true
+)
+# Minecraft args you might want to start your server with
+# Usually there isn't much to configure here:
+readonly mc_args=(
+  --nogui # Start the server without GUI
+)
+# END OF SETTINGS
+
+
+# The arguments that will be passed to java:
+readonly java_args=(
+  -Xms"${heap_size}" # Set heap min size
+  -Xmx"${heap_size}" # Set heap max size
+  "${jvm_flags[@]}" # Use jvm flags specified above
+  -jar "${server_jar}" # Run the server
+  "${mc_args[@]}" # And pass it these settings
+)
+
+# Remove restart flag, if it exists,
+# so that we won't restart the server after first stop,
+# unless restart script was called
+rm "${restart_flag}" &>/dev/null || true
+
+while :; do # Loop infinitely
+  # Run server, ignoring failure.
+  # This is so that you can control whether you want to restart on failure
+  # using `settings.restart-on-crash` setting in spigot.yml
+  java "${java_args[@]}" || true
+  # Check if restart file exists or exit
+  if [ -e "${restart_flag}" ]; then
+    # The flag exists - try to remove it
+    rm "${restart_flag}" || {
+      # If we can't remove it (permissions?), then exit to avoid endless restart loop
+      printf 'Error removing restart flag (exit code: %s) - cowardly exiting\n' "${?}"
+      exit 1
+    }
+  else
+    break # Flag doesn't exist, so break out of the loop
+  fi
+  printf 'Restarting server in 10 seconds...\n'
+  sleep "${restart_delay}" || break # Exit if sleep is interrupted (for example Ctrl+C)
+done
+
+printf 'Server stopped\n'
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