Implement basic Velocity proxy

- Split entrypoint into functions for Minecraft and Velocity
- Implement Velocity Dockerfile based on JRE image
- Add velocity default build to ./builds
- Change error to warning for missing plugins.json build file

Makefile

@@ -14,11 +14,12 @@ PRUNE_IMAGES = \
 	localhost/minecraft:latest-spigot \
 	localhost/minecraft:latest-craftbukkit \
 	localhost/minecraft-jre:latest \
-	localhost/minecraft-jdk:latest
+	localhost/minecraft-jdk:latest \
+	localhost/velocity:latest
 
 .PHONY: all clean configure craftbukkit default install jdk jre spigot vanilla
 default: vanilla
-all: vanilla paper spigot craftbukkit
+all: vanilla paper spigot craftbukkit velocity
 
 jre:
 	$(DOCKER_COMPOSE_BUILD) minecraft-jre
@@ -38,6 +39,9 @@ spigot: jre jdk
 craftbukkit: jre jdk
 	$(DOCKER_COMPOSE_BUILD) minecraft-craftbukkit
 
+velocity: jre
+	$(DOCKER_COMPOSE_BUILD) minecraft-velocity
+
 install:
 	$(DOCKER_COMPOSE_UP)
 
@@ -70,8 +74,7 @@ define copy_build_files
 			echo "INFO: \"$${SRC_FILE}\" copied to \"$${DEST_FILE}\""; \
 		fi; \
 	else \
-		echo "ERROR: Source file \"$${SRC_FILE}\" does not exist."; \
+		echo "WARN: Source file \"$${SRC_FILE}\" does not exist."; \
-		exit 1; \
 	fi
 endef
 

builds/velocity/.env

@@ -0,0 +1,18 @@
+# No EULA requirement to run Velocity
+VERSION=3.3.0-SNAPSHOT
+VELOCITY_TAG=${VERSION}
+
+# Run
+RUN_IMAGE=${VELOCITY_IMAGE:-localhost/velocity}
+RUN_TAG=${VERSION}
+
+########################
+# Extra image settings #
+########################
+#
+# JAVA_VERSION=latest
+# JRE_IMAGE=localhost/minecraft-jre
+# JRE_TAG=latest
+#
+# VELOCITY_IMAGE=localhost/velocity
+#

docker-compose.build.yml

@@ -68,3 +68,15 @@ services:
       - minecraft-jdk
     environment:
       EULA: "${EULA:-false}"
+
+  minecraft-velocity:
+    build:
+      context: .
+      dockerfile: ./dockerfiles/Dockerfile.velocity
+      args:
+        VERSION: ${VERSION:-latest}
+    image: ${VELOCITY_IMAGE:-localhost/velocity}:${VELOCITY_TAG:-latest}
+    depends_on:
+      - minecraft-jre
+    environment:
+      EULA: "${EULA:-false}"

dockerfiles/Dockerfile.velocity

@@ -0,0 +1,90 @@
+FROM "${JRE_IMAGE:-localhost/minecraft-jre}":"${JRE_TAG:-latest}"
+
+# Server version to download
+ARG VERSION=latest
+
+# PaperMC base URL
+ARG BASE_URL="https://api.papermc.io/v2/projects/velocity/versions"
+
+# Consider turning bStats (https://bStats.org) on but I'm turning it off by
+# default because it collects information
+ARG BSTATS_ENABLED=false
+
+# For the entrypoint.sh script
+ENV VELOCITY=true
+
+# Download files
+USER root
+WORKDIR /app
+
+# Install expect
+RUN apt-get update && \
+    apt-get install -y expect && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Download and verify sha256sum for Velocity
+RUN set -eux && \
+  # Grab latest version if not specified
+  if [ "$VERSION" = "latest" ]; then \
+    VERSION="$( \
+      curl -s https://api.papermc.io/v2/projects/velocity | \
+        jq -r '.versions[-1]' \
+    )"; \
+  fi && \
+  # Get latest build for the specified version
+  BUILD="$( \
+    curl -s "${BASE_URL}/${VERSION}" \
+      | jq -r '.builds[-1]' \
+  )" && \
+  URL="${BASE_URL}/${VERSION}/builds/${BUILD}/downloads/velocity-${VERSION}-${BUILD}.jar" && \
+  curl -s -o /tmp/server.jar "$URL" && \
+  # Get SHA256 hash of server.jar and compare
+  SHA256="$(sha256sum /tmp/server.jar | awk '{print $1}')" && \
+  EXPECTED="$( \
+    curl -s "$BASE_URL/$VERSION/builds/$BUILD" \
+      | jq -r '.downloads.application.sha256' \
+  )" && \
+  if [ ! "$SHA256" = "$EXPECTED" ]; then \
+    echo "[ERROR] SHA256=\"$SHA256\" expected \"$EXPECTED\""; \
+    exit 1; \
+  fi && \
+  mv /tmp/server.jar /app/velocity.jar
+
+# Generate files as minecraft user
+USER minecraft
+WORKDIR /app
+
+# Start server to generate initial files
+RUN set -ux; \
+  expect -c "\
+    set timeout -1; \
+    spawn /usr/bin/java -Xms1G -Xmx1G -XX:+UseG1GC -XX:G1HeapRegionSize=4M \
+      -XX:+UnlockExperimentalVMOptions -XX:+ParallelRefProcEnabled \
+      -XX:+AlwaysPreTouch -XX:MaxInlineLevel=15 -jar velocity.jar; \
+    expect -re {\[[0-9]{2}:[0-9]{2}:[0-9]{2} INFO\]: Done .*!} { \
+      send \"stop\r\"; \
+      expect eof \
+    } \
+  " && \
+  # Disable bStats by default and clear server-uuid
+  cd /app/plugins/bStats/ || exit 1; \
+  sed -i.bak "s/^enabled=.*\$/enabled=${BSTATS_ENABLED}/" config.txt && \
+  diff --unified=1 config.txt.bak config.txt || true && rm config.txt.bak && \
+  sed -i.bak "s/^server-uuid=.*\$/server-uuid=/" config.txt && \
+  diff --unified=1 config.txt.bak config.txt || true && rm config.txt.bak && \
+  # Truncate forwarding secret
+  truncate -s 0 /app/forwarding.secret
+
+# Back to root to copy the entrypoint in
+USER root
+COPY ../entrypoint.sh /usr/local/bin/entrypoint.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh
+
+# Run app as minecraft user
+USER minecraft
+WORKDIR /app
+
+# Expose port and run entrypoint script
+EXPOSE 25565
+ENTRYPOINT ["entrypoint.sh"]

entrypoint.sh

@@ -1,19 +1,102 @@
 #!/bin/bash
+set -e
+
+# Set eula value in eula.txt
+set_eula() {
+  local EULA
+  EULA="${1:-false}"
+  EULAFILE="${EULAFILE:-/app/eula.txt}"
+  sed -i.bak "s/^eula=.*\$/eula=${EULA:-false}/" "$EULAFILE"
+  diff --unified=1 "${EULAFILE}.bak" "$EULAFILE"
+  rm "${EULAFILE}.bak"
+}
+
+# Update server.properties using env
+set_properties() {
+  # Basic settings
+  DEBUG="${DEBUG:-false}"
+  PREFIX="${PREFIX:-SETTINGS_}"
+  FILE="${FILE:-/app/server.properties}"
+
+  # Update server.properties
+  while IFS='=' read -r ENVVAR VALUE ; do
+    if echo "$ENVVAR" | grep -q "^${PREFIX}.*$"; then
+      KEY="${ENVVAR#"$PREFIX"}"
+      if ! grep -q "^${KEY}=" "$FILE"; then
+        echo "[WARN]: \"$KEY\" does not exist in $FILE and was not updated"
+      else
+        [ "$DEBUG" = "true" ] && echo "[DEBUG] Updating \"$KEY\" to \"$VALUE\""
+        sed -i.bak "s/^${KEY}=.*/${KEY}=${VALUE}/" "$FILE"
+        diff --unified=1 "${FILE}.bak" "$FILE"
+        rm "${FILE}.bak"
+      fi
+    else
+      if [ "$DEBUG" = "true" ]; then
+        echo "[DEBUG] \"$ENVVAR\" doesn't have the prefix \"$PREFIX\""
+      fi
+    fi
+  done < <(env)
+
+  # Show server.properties in DEBUG mode
+  if [ "$DEBUG" = "true" ]; then
+    echo "[DEBUG] Showing ${FILE}:"
+    cat "$FILE"
+  fi
+}
 
 # Check if the minecraft screen is still running
+# shellcheck disable=SC2317
 check_screen() {
-  if [ "$(screen -ls | grep -cE '[0-9]+\.minecraft')" -eq 1 ]; then
+  local SCREEN_NAME
+  SCREEN_NAME="$1"
+  if [ "$(screen -ls | grep -cE "[0-9]+\.$SCREEN_NAME")" -eq 1 ]; then
     return 0
   else
     return 1
   fi
 }
 
+# Find screen PID, strace it, and wait for it to exit
+wait_on_screen() {
+  local SCREEN_PID
+  local SCREEN_NAME
+  local STRACE_PID
+  local TAIL_PID
+
+  SCREEN_NAME="$1"
+
+  # Get screen PID
+  [ "$DEBUG" = "true" ] && screen -ls
+  SCREEN_PID="$(
+    screen -ls | grep -oE "[0-9]+\.$SCREEN_NAME" | cut -d. -f1
+  )"
+
+  # Check screen PID
+  if ! kill -0 "$SCREEN_PID" 2>/dev/null; then
+    echo "[ERROR] Cannot find \"$SCREEN_NAME\" screen (PID: \"$SCREEN_PID\")"
+    exit 1
+  fi
+
+  # Output logs to stdout (touch in case slow to create)
+  touch screenlog.0
+  tail -f screenlog.0 &
+  TAIL_PID="$!"
+
+  # Wait for screen to exit
+  strace -e exit -e signal=none -p "$SCREEN_PID" 2>/dev/null &
+  STRACE_PID="$!"
+  [ "$DEBUG" = "true" ] && ps aux
+  wait "$STRACE_PID"
+}
+
 # Function to stop the server gracefully
+# shellcheck disable=SC2317
 stop_server() {
-  if check_screen; then
+  local SCREEN_NAME
+  SCREEN_NAME="$1"
+  if check_screen "$SCREEN_NAME"; then
     # Run 'stop' inside screen and wait for the screen to exit
-    /usr/bin/screen -p 0 -S minecraft -X eval 'stuff "stop"\015'
+    /usr/bin/screen -p 0 -S "$SCREEN_NAME" -X eval 'stuff "stop"\015'
     wait "$STRACE_PID"
 
     # Stop tail -f to stdout
@@ -39,6 +122,51 @@ stop_server() {
   fi
 }
 
+# Start the Minecraft server
+minecraft_server() {
+  # Settings
+  JVM_OPTS="${JVM_OPTS:--Xms1G -Xmx2G}"
+
+  # Set EULA
+  set_eula "${EULA:-false}"
+
+  # Update server.properties using env
+  set_properties
+
+  # Set up a SIGTERM signal trap to stop the server
+  trap 'stop_server minecraft' SIGTERM
+
+  # Run server in screen (without attaching)
+  echo "[INFO] Starting Minecraft server"
+  /usr/bin/screen -dmS minecraft -L \
+    bash -c "/usr/bin/java $JVM_OPTS -jar server.jar --nogui"
+
+  # Wait for 'minecraft' screen PID to exit
+  wait_on_screen minecraft
+  exit 0
+}
+
+# Start the Velocity proxy Minecraft server
+velocity_server() {
+  # Settings
+  JVM_OPTS="${JVM_OPTS:--Xms1G -Xmx2G}"
+
+  # Set up a SIGTERM signal trap to stop the server
+  trap 'stop_server velocity' SIGTERM
+
+  # Start server
+  echo "[INFO] Starting Velocity server"
+  /usr/bin/screen -dmS velocity -L \
+    bash -c "
+      /usr/bin/java $JVM_OPTS -XX:+UseG1GC -XX:G1HeapRegionSize=4M \
+        -XX:+UnlockExperimentalVMOptions -XX:+ParallelRefProcEnabled \
+        -XX:+AlwaysPreTouch -XX:MaxInlineLevel=15 -jar velocity.jar
+    "
+
+  # Wait for 'velocity' screen PID to exit
+  wait_on_screen velocity
+}
+
 # Enable debug mode
 DEBUG="${DEBUG:-false}"
 if [ "$DEBUG" = "true" ]; then
@@ -47,69 +175,15 @@ if [ "$DEBUG" = "true" ]; then
   set -ux
 fi
 
-# Settings
+# Start Velocity proxy if VELOCITY='true' otherwise start a Minecraft server
-FILE="${FILE:-/app/server.properties}"
+VELOCITY="${VELOCITY:-false}"
-EULAFILE="${EULAFILE:-/app/eula.txt}"
+if [ "$VELOCITY" = "true" ]; then
-PREFIX="${PREFIX:-SETTINGS_}"
+  # Start Velocity proxy
-JVM_OPTS="${JVM_OPTS:--Xms1G -Xmx2G}"
+  velocity_server
-
-# Set EULA
-sed -i.bak "s/^eula=.*\$/eula=${EULA:-false}/" "$EULAFILE"
-diff --unified=1 "${EULAFILE}.bak" "$EULAFILE"
-rm "${EULAFILE}.bak"
-
-# Update server.properties using env
-while IFS='=' read -r ENVVAR VALUE ; do
-  if echo "$ENVVAR" | grep -q "^${PREFIX}.*$"; then
-    KEY="${ENVVAR#"$PREFIX"}"
-    if ! grep -q "^${KEY}=" "$FILE"; then
-      echo "[WARN]: \"$KEY\" does not exist in $FILE and was not updated"
 else
-      [ "$DEBUG" = "true" ] && echo "[DEBUG] Updating \"$KEY\" to \"$VALUE\""
+  # Start Minecraft
-      sed -i.bak "s/^${KEY}=.*/${KEY}=${VALUE}/" "$FILE"
+  minecraft_server
-      diff --unified=1 "${FILE}.bak" "$FILE"
-      rm "${FILE}.bak"
-    fi
-  else
-    if [ "$DEBUG" = "true" ]; then
-      echo "[DEBUG] \"$ENVVAR\" doesn't have the prefix \"$PREFIX\""
-    fi
-  fi
-done < <(env)
-
-# Show server.properties in DEBUG mode
-if [ "$DEBUG" = "true" ]; then
-  echo "[DEBUG] Showing ${FILE}:"
-  cat "$FILE"
 fi
 
-# Set up a SIGTERM signal trap to stop the server
+# Exit gracefully
-trap 'stop_server' SIGTERM
+exit 0
-
-# Run server in screen (without attaching)
-echo "[INFO] Starting Minecraft server"
-/usr/bin/screen -dmS minecraft -L \
-  bash -c "/usr/bin/java $JVM_OPTS -jar server.jar --nogui"
-
-# Get screen PID
-[ "$DEBUG" = "true" ] && screen -ls
-SCREEN_PID="$(
-  screen -ls | grep -oE '[0-9]+\.minecraft' | cut -d. -f1
-)"
-
-# Check screen PID
-if ! kill -0 "$SCREEN_PID" 2>/dev/null; then
-  echo "[ERROR] Cannot find Minecraft screen (PID: \"$SCREEN_PID\")"
-  exit 1
-fi
-
-# Output logs to stdout (touch in case slow to create)
-touch screenlog.0
-tail -f screenlog.0 &
-TAIL_PID="$!"
-
-# Wait for screen to exit
-strace -e exit -e signal=none -p "$SCREEN_PID" 2>/dev/null &
-STRACE_PID="$!"
-[ "$DEBUG" = "true" ] && ps aux
-wait "$STRACE_PID"