fix: use the correct agent (not slave)

Dockerfile

@@ -21,10 +21,9 @@
 #  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 #  THE SOFTWARE.
 
-#FROM adoptopenjdk/openjdk11:alpine
+FROM alpine:3.13
-FROM alpine:latest
 
-RUN apk add --no-cache openjdk11-jre-headless
+RUN apk add --no-cache openjdk11-jre-headless tini
 
 ARG VERSION=4.6
 ARG user=jenkins
@@ -44,6 +43,11 @@ RUN apk add --update --no-cache curl bash git git-lfs openssh-client openssl pro
   && chmod 644 /usr/share/jenkins/agent.jar \
   && ln -sf /usr/share/jenkins/agent.jar /usr/share/jenkins/slave.jar \
   && apk del curl
+
+COPY jenkins-agent /usr/local/bin/jenkins-agent
+RUN chmod +x /usr/local/bin/jenkins-agent &&\
+    ln -s /usr/local/bin/jenkins-agent /usr/local/bin/jenkins-slave
+
 USER ${user}
 ENV AGENT_WORKDIR=${AGENT_WORKDIR}
 RUN mkdir /home/${user}/.jenkins && mkdir -p ${AGENT_WORKDIR}
@@ -51,3 +55,5 @@ RUN mkdir /home/${user}/.jenkins && mkdir -p ${AGENT_WORKDIR}
 VOLUME /home/${user}/.jenkins
 VOLUME ${AGENT_WORKDIR}
 WORKDIR /home/${user}
+
+ENTRYPOINT ["/sbin/tini", "--", "/usr/local/bin/jenkins-agent"]

jenkins-agent

@@ -0,0 +1,117 @@
+#!/usr/bin/env sh
+
+# The MIT License
+#
+#  Copyright (c) 2015-2020, CloudBees, Inc.
+#
+#  Permission is hereby granted, free of charge, to any person obtaining a copy
+#  of this software and associated documentation files (the "Software"), to deal
+#  in the Software without restriction, including without limitation the rights
+#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+#  copies of the Software, and to permit persons to whom the Software is
+#  furnished to do so, subject to the following conditions:
+#
+#  The above copyright notice and this permission notice shall be included in
+#  all copies or substantial portions of the Software.
+#
+#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+#  THE SOFTWARE.
+
+# Usage jenkins-agent.sh [options] -url http://jenkins [SECRET] [AGENT_NAME]
+# Optional environment variables :
+# * JENKINS_TUNNEL : HOST:PORT for a tunnel to route TCP traffic to jenkins host, when jenkins can't be directly accessed over network
+# * JENKINS_URL : alternate jenkins URL
+# * JENKINS_SECRET : agent secret, if not set as an argument
+# * JENKINS_AGENT_NAME : agent name, if not set as an argument
+# * JENKINS_AGENT_WORKDIR : agent work directory, if not set by optional parameter -workDir
+# * JENKINS_WEB_SOCKET: true if the connection should be made via WebSocket rather than TCP
+# * JENKINS_DIRECT_CONNECTION: Connect directly to this TCP agent port, skipping the HTTP(S) connection parameter download.
+#                              Value: "<HOST>:<PORT>"
+# * JENKINS_INSTANCE_IDENTITY: The base64 encoded InstanceIdentity byte array of the Jenkins master. When this is set,
+#                              the agent skips connecting to an HTTP(S) port for connection info.
+# * JENKINS_PROTOCOLS:         Specify the remoting protocols to attempt when instanceIdentity is provided.
+
+if [ $# -eq 1 ]; then
+
+	# if `docker run` only has one arguments, we assume user is running alternate command like `bash` to inspect the image
+	exec "$@"
+
+else
+
+	# if -tunnel is not provided, try env vars
+	case "$@" in
+		*"-tunnel "*) ;;
+		*)
+		if [ ! -z "$JENKINS_TUNNEL" ]; then
+			TUNNEL="-tunnel $JENKINS_TUNNEL"
+		fi ;;
+	esac
+
+	# if -workDir is not provided, try env vars
+	if [ ! -z "$JENKINS_AGENT_WORKDIR" ]; then
+		case "$@" in
+			*"-workDir"*) echo "Warning: Work directory is defined twice in command-line arguments and the environment variable" ;;
+			*)
+			WORKDIR="-workDir $JENKINS_AGENT_WORKDIR" ;;
+		esac
+	fi
+
+	if [ -n "$JENKINS_URL" ]; then
+		URL="-url $JENKINS_URL"
+	fi
+
+	if [ -n "$JENKINS_NAME" ]; then
+		JENKINS_AGENT_NAME="$JENKINS_NAME"
+	fi
+
+	if [ "$JENKINS_WEB_SOCKET" = true ]; then
+		WEB_SOCKET=-webSocket
+	fi
+
+	if [ -n "$JENKINS_PROTOCOLS" ]; then
+		PROTOCOLS="-protocols $JENKINS_PROTOCOLS"
+	fi
+
+	if [ -n "$JENKINS_DIRECT_CONNECTION" ]; then
+		DIRECT="-direct $JENKINS_DIRECT_CONNECTION"
+	fi
+
+	if [ -n "$JENKINS_INSTANCE_IDENTITY" ]; then
+		INSTANCE_IDENTITY="-instanceIdentity $JENKINS_INSTANCE_IDENTITY"
+	fi
+
+	# if java home is defined, use it
+	JAVA_BIN="java"
+	if [ "$JAVA_HOME" ]; then
+		JAVA_BIN="$JAVA_HOME/bin/java"
+	fi
+
+	# if both required options are defined, do not pass the parameters
+	OPT_JENKINS_SECRET=""
+	if [ -n "$JENKINS_SECRET" ]; then
+		case "$@" in
+			*"${JENKINS_SECRET}"*) echo "Warning: SECRET is defined twice in command-line arguments and the environment variable" ;;
+			*)
+			OPT_JENKINS_SECRET="${JENKINS_SECRET}" ;;
+		esac
+	fi
+	
+	OPT_JENKINS_AGENT_NAME=""
+	if [ -n "$JENKINS_AGENT_NAME" ]; then
+		case "$@" in
+			*"${JENKINS_AGENT_NAME}"*) echo "Warning: AGENT_NAME is defined twice in command-line arguments and the environment variable" ;;
+			*)
+			OPT_JENKINS_AGENT_NAME="${JENKINS_AGENT_NAME}" ;;
+		esac
+	fi
+
+	#TODO: Handle the case when the command-line and Environment variable contain different values.
+	#It is fine it blows up for now since it should lead to an error anyway.
+
+	exec $JAVA_BIN $JAVA_OPTS -cp /usr/share/jenkins/agent.jar hudson.remoting.jnlp.Main -headless $TUNNEL $URL $WORKDIR $WEB_SOCKET $DIRECT $PROTOCOLS $INSTANCE_IDENTITY $OPT_JENKINS_SECRET $OPT_JENKINS_AGENT_NAME "$@"
+fi