Docker best practices

- Install and remove OS and Go build deps in a single layer
- Use COPY instead of ADD
- WORKDIR now resolves ENV variables, use one
- Use VOLUMES for configuration and datastore
- Added launcher script start-inbucket.sh
- Made docker-run.sh more powerful

Dockerfile

@@ -4,19 +4,22 @@
 FROM golang:1.6-alpine
 MAINTAINER James Hillyerd, @jameshillyerd
 
-# Dependencies
-RUN apk update && apk add git
-
 # Configuration (WORKDIR doesn't support env vars)
 ENV INBUCKET_SRC $GOPATH/src/github.com/jhillyerd/inbucket
 ENV INBUCKET_HOME /opt/inbucket
-WORKDIR /opt/inbucket
-ENTRYPOINT ["bin/inbucket"]
-CMD ["/etc/opt/inbucket.conf"]
+WORKDIR $INBUCKET_HOME
+ENTRYPOINT ["/con/context/start-inbucket.sh"]
+CMD ["/con/configuration/inbucket.conf"]
 
 # Ports: SMTP, HTTP, POP3
 EXPOSE 10025 10080 10110
 
+# Persistent Volumes, following convention at:
+#   https://github.com/docker/docker/issues/9277
+# NOTE /con/context is also used, not exposed by default
+VOLUME /con/configuration
+VOLUME /con/data
+
 # Build Inbucket
-ADD . $INBUCKET_SRC/
+COPY . $INBUCKET_SRC/
 RUN "$INBUCKET_SRC/etc/docker/install.sh"

etc/docker/defaults/inbucket.conf

@@ -86,13 +86,13 @@ public.dir=%(install.dir)s/themes/%(theme)s/public
 
 # Path to the greeting HTML displayed on front page, can
 # be moved out of installation dir for customization
-greeting.file=/etc/opt/inbucket-greeting.html
+greeting.file=/con/configuration/greeting.html
 
 #############################################################################
 [datastore]
 
 # Path to the datastore, mail will be written into subdirectories
-path=/var/opt/inbucket
+path=/con/data
 
 # How many minutes after receipt should a message be stored until it's
 # automatically purged.  To retain messages until manually deleted, set this

etc/docker/defaults/start-inbucket.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+# start-inbucket.sh
+# description: start inbucket (runs within a docker container)
+
+CONF_SOURCE="$INBUCKET_HOME/defaults"
+CONF_TARGET="/con/configuration"
+
+set -eo pipefail
+
+install_default_config() {
+  local file="$1"
+  local source="$CONF_SOURCE/$file"
+  local target="$CONF_TARGET/$file"
+
+  if [ ! -e "$target" ]; then
+    echo "Installing default $file to $CONF_TARGET"
+    install "$source" "$target"
+  fi
+}
+
+install_default_config "inbucket.conf"
+install_default_config "greeting.html"
+
+exec "$INBUCKET_HOME/bin/inbucket" $* 

etc/docker/docker-run.sh

@@ -2,4 +2,61 @@
 # docker-run.sh
 # description: Launch Inbucket's docker image
 
-docker run -p 9000:10080 -p 2500:10025 -p 1100:10110 jhillyerd/inbucket
+# Docker Image Tag
+IMAGE="jhillyerd/inbucket"
+
+# Ports exposed on host:
+PORT_HTTP=9000
+PORT_SMTP=2500
+PORT_POP3=1100
+
+# Volumes exposed on host:
+VOL_CONFIG="/tmp/inbucket/config"
+VOL_DATA="/tmp/inbucket/data"
+
+set -eo pipefail
+
+main() {
+  local run_opts=""
+
+  for arg in $*; do
+    case "$arg" in
+      -h)
+        usage
+        exit
+        ;;
+      -r)
+        reset
+        ;;
+      -d)
+        run_opts="$run_opts -d"
+        ;;
+      *)
+        usage
+        exit 1
+        ;;
+    esac
+  done
+
+  docker run $run_opts \
+    -p $PORT_HTTP:10080 \
+    -p $PORT_SMTP:10025 \
+    -p $PORT_POP3:10110 \
+    -v "$VOL_CONFIG:/con/configuration" \
+    -v "$VOL_DATA:/con/data" \
+    "$IMAGE"
+}
+
+usage() {
+  echo "$0 [options]" 2>&1
+  echo "  -d    detach - detach and print container ID" 2>&1
+  echo "  -r    reset - purge config and data before startup" 2>&1
+  echo "  -h    help - print this message" 2>&1
+}
+
+reset() {
+  /bin/rm -rf "$VOL_CONFIG"
+  /bin/rm -rf "$VOL_DATA"
+}
+
+main $*

etc/docker/install.sh

@@ -4,9 +4,14 @@
 
 set -eo pipefail
 
-installdir="${INBUCKET_HOME}"
-srcdir="${INBUCKET_SRC}"
+installdir="$INBUCKET_HOME"
+srcdir="$INBUCKET_SRC"
 bindir="$installdir/bin"
+defaultsdir="$installdir/defaults"
+contextdir="/con/context"
+
+echo "### Installing OS Build Dependencies"
+apk add --no-cache --virtual .build-deps git
 
 # Setup
 export GOBIN="$bindir"
@@ -16,7 +21,7 @@ go clean
 
 # Build
 echo "### Fetching Dependencies"
-go get -d -t -v ./...
+go get -t -v ./...
 
 echo "### Testing Inbucket"
 go test ./...
@@ -25,9 +30,19 @@ echo "### Building Inbucket"
 go build -o inbucket -ldflags "-X 'main.BUILDDATE=$builddate'" -v .
 
 echo "### Installing Inbucket"
+set -x
 mkdir -p "$bindir"
-mkdir -p "/etc/opt"
-mv inbucket "$bindir"
-install etc/docker/inbucket.conf /etc/opt/inbucket.conf
-install etc/docker/greeting.html /etc/opt/inbucket-greeting.html
+install inbucket "$bindir"
+mkdir -p "$contextdir"
+install etc/docker/defaults/start-inbucket.sh "$contextdir"
 cp -r themes "$installdir/"
+mkdir -p "$defaultsdir"
+cp etc/docker/defaults/inbucket.conf "$defaultsdir"
+cp etc/docker/defaults/greeting.html "$defaultsdir"
+set +x
+
+echo "### Removing OS Build Dependencies"
+apk del .build-deps
+
+echo "### Removing $GOPATH"
+rm -rf "$GOPATH"