Multi-stage Dockerfile sample

Author: ibmmqmet

samples/README.md

@@ -64,6 +64,11 @@ For example
   go run amqsput.go DEV.QUEUE.1 QM1
 ```
 
+The amqsput.go program also allows the queue and queue manager names to 
+be provided by environment variables, to show another configuration
+mechanism. That approach will often be used in container deployments,
+and is demonstrated in the runSample set of files.
+
 ### Publish/Subscribe testing
 You will probably want to run `amqssub` JUST BEFORE running `amqspub` to ensure
 there is something waiting to receive the publications when they are made. The
@@ -74,6 +79,10 @@ There is an set of files in here that will show how to create a container that r
 the `amqsput` program. The `runSample.sh` script drives the process. It will try to
 connect to a queue manager running on the host machine.
 
+The process is split into two pieces - the first is used to compile the program, and
+the second creates a (hopefully) smaller container with just the components needed
+to run the  program.
+
 ## More information
 Comments in the programs explain what they are doing. For more detailed information about the
 MQ API, the functions, structures, and constants, see the

samples/amqsbo.go

@@ -40,7 +40,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
-        "time"
+	"time"
 
 	"github.com/ibm-messaging/mq-golang/v5/ibmmq"
 )
@@ -210,7 +210,7 @@ func mainWithRc() int {
 				qMgrObject.Cmit()
 			} else {
 				// In real life, there would be some processing of the message here before deciding to backout or
-				// commit the transaction. But here we will always to the backout.
+				// commit the transaction. But here we will always do the backout.
 				qMgrObject.Back()
 
 				// Adding an increasing delay in here may help with some error conditions so you don't just spin quickly.

samples/amqsput.go

@@ -4,6 +4,9 @@
  *
  * The queue and queue manager name can be given as parameters on the
  * command line. Defaults are coded in the program.
+ * This sample also permits use of environment variables for the
+ * parameters, which might be preferable in some container
+ * deployments.
  *
  * A single message is put, containing a "hello" and timestamp.
  * Each MQI call prints its success or failure. The MsgId of the
@@ -14,7 +17,7 @@
 package main
 
 /*
-  Copyright (c) IBM Corporation 2018
+  Copyright (c) IBM Corporation 2018,2021
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
@@ -54,8 +57,16 @@ func main() {
 func mainWithRc() int {
 
 	// The default queue manager and queue to be used. These can be overridden on command line.
-	qMgrName := "QM1"
-	qName := "DEV.QUEUE.1"
+	// Environment variables can also be used as that works well in a number of common
+	// container deployment models.
+	qMgrName := os.Getenv("QMGR")
+	if qMgrName == "" {
+		qMgrName = "QM1"
+	}
+	qName := os.Getenv("QUEUE")
+	if qName == "" {
+		qName = "DEV.QUEUE.1"
+	}
 
 	fmt.Println("Sample AMQSPUT.GO start")
 

samples/runSample.Dockerfile

@@ -1,4 +1,4 @@
-# © Copyright IBM Corporation 2019, 2020
+# © Copyright IBM Corporation 2019, 2021
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,12 +12,29 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-ARG BASE_IMAGE=ubuntu:18.04
-FROM $BASE_IMAGE
 
+# This Dockerfile has two separate stages.
+#
+# The first stage is used to compile the Go program, where we need tools like the Go and C compilers.
+# The second stage is a runtime-only container that holds just the things we need to
+# execute the compiled program.
+#
+# Files and directories are copied from the builder container to the runtime container as needed.
+# Just for fun, I've used two different base images, trying to get the runtime image as small
+# as possible while still using a "regular" libc-based container.
+
+# Start by setting some global variables that can still be overridden on the build command line.
+ARG BASE_IMAGE=ubuntu:18.04
 ARG GOPATH_ARG="/go"
 ARG GOVERSION=1.13.15
 
+###########################################################
+# This starts the BUILD phase
+###########################################################
+FROM $BASE_IMAGE AS builder
+
+ARG GOVERSION
+ARG GOPATH_ARG
 ENV GOVERSION=${GOVERSION}   \
     GOPATH=$GOPATH_ARG \
     GOTAR=go${GOVERSION}.linux-amd64.tar.gz \
@@ -43,7 +60,7 @@ RUN export DEBIAN_FRONTEND=noninteractive \
     build-essential \
   && rm -rf /var/lib/apt/lists/*
 
-# Create location for the go programs and the MQ installation
+# Create a location for the go programs and the MQ installation
 RUN mkdir -p $GOPATH/src $GOPATH/bin $GOPATH/pkg \
   && chmod -R 777 $GOPATH \
   && cd /tmp       \
@@ -57,7 +74,7 @@ RUN mkdir -p $GOPATH/src $GOPATH/bin $GOPATH/pkg \
 # Location of the downloadable MQ client package \
 ENV RDURL="https://public.dhe.ibm.com/ibmdl/export/pub/software/websphere/messaging/mqdev/redist" \
     RDTAR="IBM-MQC-Redist-LinuxX64.tar.gz" \
-    VRMF=9.2.2.0
+    VRMF=9.2.3.0
 
 # Install the MQ client from the Redistributable package. This also contains the
 # header files we need to compile against. Setup the subset of the package
@@ -67,23 +84,48 @@ ENV genmqpkg_incnls=1 \
     genmqpkg_inctls=1
 
 RUN cd /opt/mqm \
- && curl -LO "$RDURL/$VRMF-$RDTAR" \
- && tar -zxf ./*.tar.gz \
- && rm -f ./*.tar.gz \
- && bin/genmqpkg.sh -b /opt/mqm
+  && curl -LO "$RDURL/$VRMF-$RDTAR" \
+  && tar -zxf ./*.tar.gz \
+  && rm -f ./*.tar.gz \
+  && bin/genmqpkg.sh -b /opt/mqm
 
 # We need the Go compiler in our PATH
 ENV PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/go-$GOVERSION/bin
 
 # Copy the source file over. We also need a go.mod file
 # The source for that has a different name in the repo so it doesn't accidentally get
-# used and we rename it during this copy.
-COPY amqsput.go $GOPATH_ARG/src
+# used. We rename it during this copy.
+COPY amqsput.go      $GOPATH_ARG/src
 COPY runSample.gomod $GOPATH_ARG/src/go.mod
 
 # Do the actual compile. This will automatically download the ibmmq package
 RUN cd $GOPATH_ARG/src && go build -o $GOPATH_ARG/bin/amqsput amqsput.go
 
-# The startup script will set MQSERVER and optionally set
-# more environment variables that will be passed to amqsput through this entrypoint.
-ENTRYPOINT /go/bin/amqsput $QUEUE $QMGR
+###########################################################
+# This starts the RUNTIME phase
+###########################################################
+# Now that there is a container with the compiled program we can build a smaller
+# runtime image. Start from one of the smaller base container images.
+FROM debian:stretch-slim
+ARG GOPATH_ARG
+ARG GOVERSION
+
+# Copy over the MQ runtime client code. This does preserve the .h files used during compile
+# but those are tiny so there's no real space-saving from deleting them here.
+COPY --from=builder /opt/mqm /opt/mqm
+
+# Create some directories that may be needed at runtime, depending on the container's
+# security environment.
+RUN mkdir -p /IBM/MQ/data/errors \
+  && mkdir -p /.mqm \
+  && chmod -R 777 /IBM \
+  && chmod -R 777 /.mqm \
+  && mkdir -p /go/bin
+
+# The actual program has all of the Go runtime embedded; we only need the single
+# binary along with the MQ client libraries, for it to run.
+COPY --from=builder $GOPATH_ARG/bin/amqsput /go/bin/amqsput
+
+# The startup script will set MQSERVER and optionally set more
+# environment variables that will be passed to amqsput through this entrypoint.
+ENTRYPOINT [ "/go/bin/amqsput" ]

samples/runSample.sh

@@ -10,8 +10,8 @@ function latestSemVer {
 # Assume repo tags have been created in a sensible order. Find the mq-golang
 # version in the root go.mod file and the current Git tag for this repo.
 # Then pick the latest version to create the Docker tag
-VERDEP=`cat ../go.mod | awk '/mq-golang/ {print $2}' `
-VERREPO=`git tag -l | sort | tail -1 `
+VERDEP=`cat ../../go.mod | awk '/mq-golang/ {print $2}' `
+VERREPO=`git tag -l 2>/dev/null| sort | tail -1 `
 
 VER=`latestSemVer $VERDEP $VERREPO`
 if [ -z "$VER" ]
@@ -25,6 +25,7 @@ echo Building container with tag $TAG:$VER
 
 # Build the container which includes compilation of the program
 docker build -t $TAG:$VER -f runSample.Dockerfile .
+
 if [ $? -eq 0 ]
 then
   # This line grabs a currently active IPv4 address for this machine. It's probably
@@ -36,7 +37,7 @@ then
 
   if [ ! -z "addr" ]
   then
-    # Run the container. Can override default command line values in amqsput voa
+    # Run the container. Can override default command line values in amqsput via
     # env vars here.
     docker run -e MQSERVER="SYSTEM.DEF.SVRCONN/TCP/$addr($port)" \
        -e QUEUE=DEV.QUEUE.1 \