Use jlink to shrink JDKs

Dockerfile

@@ -12,8 +12,8 @@ COPY . .
 # build the analyzer binary and automatically set the AnalyzerVersion
 # variable to the most recent version from the CHANGELOG.md file
 RUN CHANGELOG_VERSION=$(grep -m 1 '^## v.*$' "CHANGELOG.md" | sed 's/## v//') && \
-        PATH_TO_MODULE=`go list -m` && \
-        go build -ldflags="-X '$PATH_TO_MODULE/metadata.AnalyzerVersion=$CHANGELOG_VERSION'" -o analyzer
+    PATH_TO_MODULE=`go list -m` && \
+    go build -ldflags="-X '$PATH_TO_MODULE/metadata.AnalyzerVersion=$CHANGELOG_VERSION'" -o analyzer
 
 FROM alpine:3.14
 
@@ -57,7 +57,9 @@ COPY --chown=gitlab config /home/gitlab
 
 WORKDIR /home/gitlab
 
+RUN apk add --no-cache binutils
 RUN bash /home/gitlab/install.sh
+RUN apk del binutils
 
 ENV HOME=/home/gitlab
 ENV MAVEN_REPO_PATH=/home/gitlab

config/install.sh

@@ -33,30 +33,40 @@ asdf current
 # shellcheck source=/dev/null
 . "$ASDF_DATA_DIR"/plugins/ant/set-ant-home.bash
 
+asdf list java | while read -r jdk_version; do
+  (
+    cd "$ASDF_DATA_DIR/installs/java"
+    jlink_bin="./$jdk_version/bin/jlink"
+    "$jlink_bin" --verbose --add-modules ALL-MODULE-PATH --strip-debug --no-man-pages --no-header-files --compress=2 --output ./shrunk
+    rm -rf "$jdk_version"
+    mv shrunk "$jdk_version"
+  )
+done
+
 # Ensure that Java is working correctly by printing the version.
-asdf list java | while read -r jdk_version ; do
+asdf list java | while read -r jdk_version; do
   java_bin="$(asdf which java "$jdk_version")"
-  $java_bin -version 2&> /dev/null
+  $java_bin -version 2 &>/dev/null
   exit_code=$?
   if [ $exit_code -ne 0 ]; then
-      echo "Java installation check failed. Attempted to run '$java_bin -version' and got exit code $exit_code" && exit 1
+    echo "Java installation check failed. Attempted to run '$java_bin -version' and got exit code $exit_code" && exit 1
   fi
-done;
+done
 
 # Install SpotBugs CLI
-cd /spotbugs; \
-  mkdir -p dist; \
-  curl -LO "https://repo.maven.apache.org/maven2/com/github/spotbugs/spotbugs/${SCANNER_VERSION}/spotbugs-${SCANNER_VERSION}.tgz"; \
-  tar xzf "spotbugs-${SCANNER_VERSION}.tgz" -C dist --strip-components 1; \
-  rm -f "spotbugs-${SCANNER_VERSION}.tgz"
+cd /spotbugs
+mkdir -p dist
+curl -LO "https://repo.maven.apache.org/maven2/com/github/spotbugs/spotbugs/${SCANNER_VERSION}/spotbugs-${SCANNER_VERSION}.tgz"
+tar xzf "spotbugs-${SCANNER_VERSION}.tgz" -C dist --strip-components 1
+rm -f "spotbugs-${SCANNER_VERSION}.tgz"
 
 # Install FindSecBugs for use as a SpotBugs plugin
-mkdir -p /fsb; \
-  cd /fsb; \
-  curl -LO "https://github.com/find-sec-bugs/find-sec-bugs/releases/download/version-${FINDSECBUGS_VERSION}/findsecbugs-cli-${FINDSECBUGS_VERSION}.zip"; \
-  unzip -n "findsecbugs-cli-${FINDSECBUGS_VERSION}.zip"; \
-  rm -f "findsecbugs-cli-${FINDSECBUGS_VERSION}.zip"; \
-  mv "lib/findsecbugs-plugin-${FINDSECBUGS_VERSION}.jar" lib/findsecbugs-plugin.jar
+mkdir -p /fsb
+cd /fsb
+curl -LO "https://github.com/find-sec-bugs/find-sec-bugs/releases/download/version-${FINDSECBUGS_VERSION}/findsecbugs-cli-${FINDSECBUGS_VERSION}.zip"
+unzip -n "findsecbugs-cli-${FINDSECBUGS_VERSION}.zip"
+rm -f "findsecbugs-cli-${FINDSECBUGS_VERSION}.zip"
+mv "lib/findsecbugs-plugin-${FINDSECBUGS_VERSION}.jar" lib/findsecbugs-plugin.jar
 
 echo ["$(date "+%H:%M:%S")"] "==> Beginning cleanup…"