create script to check for backwards compatibility

.github/workflows/maven.yml

@@ -22,11 +22,25 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up JDK 8
-        uses: actions/setup-java@v3
+        uses: actions/setup-java@v4
         with:
           java-version: '8'
           distribution: 'corretto'
       - name: Build with Maven
-        run: mvn -B package --file pom.xml -DskipITs
+        run: mvn -B package --file pom.xml -DskipITs
+
+  backwards-compatible-check:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 8
+        uses: actions/setup-java@v4
+        with:
+          java-version: '8'
+          distribution: 'corretto'
+      - name: Check backwards compatibility of changes
+        run: .github/scripts/backwards_compatibility_check.sh

.github/workflows/scripts/backwards_compatibility_check.sh

@@ -0,0 +1,103 @@
+#!/bin/bash
+
+TRUE=1
+FALSE=0
+KCL_MAVEN_DIR=~/.m2/repository/software/amazon/kinesis/amazon-kinesis-client
+
+REMOVED_METHODS_FLAG=$FALSE
+LATEST_VERSION=""
+LATEST_JAR=""
+CURRENT_VERSION=""
+CURRENT_JAR=""
+
+# Get the JAR from the latest version release on Maven.
+get_latest_jar() {
+  #  clear the directory so that the latest release will be the only version in the Maven directory after running mvn dependency:get
+  rm -rf "$KCL_MAVEN_DIR"
+  mvn -B dependency:get -Dartifact=software.amazon.kinesis:amazon-kinesis-client:LATEST
+  LATEST_VERSION=$(ls "$KCL_MAVEN_DIR" | grep '[0-9].[0-9].[0-9]')
+  LATEST_JAR=$KCL_MAVEN_DIR/$LATEST_VERSION/amazon-kinesis-client-$LATEST_VERSION.jar
+}
+
+# Get the JAR with the changes that need to be verified.
+get_current_jar() {
+  mvn -B install -DskipTests
+  CURRENT_VERSION=$(mvn -q  -Dexec.executable=echo -Dexec.args='${project.version}' --non-recursive exec:exec)
+  CURRENT_JAR=$KCL_MAVEN_DIR/$CURRENT_VERSION/amazon-kinesis-client-$CURRENT_VERSION.jar
+}
+
+# Skip classes with the KinesisClientInternalApi annotation. These classes are subject to breaking backwards compatibility.
+ignore_kinesis_client_internal_api() {
+  local current_class="$1"
+  local grep_internal_api_result=$(javap -v -classpath "$LATEST_JAR" "$current_class" | grep KinesisClientInternalApi)
+  if [[ "$grep_internal_api_result" != "" ]]
+  then
+    continue
+  fi
+}
+
+# Skip classes which are not public (e.g. package level). These classes will not break backwards compatibility.
+ignore_non_public_classes() {
+  local current_class="$1"
+  local class_definition=$(javap -classpath "$LATEST_JAR" "$current_class" | head -2 | tail -1)
+  if [[ "$class_definition" != *"public"* ]]
+  then
+    continue
+  fi
+}
+
+# Ignore methods that change from abstract to non-abstract (and vice versa) if the class is an interface.
+ignore_abstract_changes_in_interfaces(){
+  local current_class="$1"
+  local class_definition=$(javap -classpath "$LATEST_JAR" "$current_class" | head -2 | tail -1)
+  if [[ $class_definition == *"interface"* ]]
+  then
+    LATEST_METHODS=${latest_methods// abstract / }
+    CURRENT_METHODS=${current_methods// abstract / }
+  fi
+}
+
+# Checks if there are any methods in the latest version that were removed in the current version.
+find_removed_methods() {
+  echo "Checking if methods in current version (v$CURRENT_VERSION) were removed from latest version (v$LATEST_VERSION)"
+  local latest_classes=$(jar tf $LATEST_JAR | grep .class | tr / . |  sed 's/\.class$//' | sort)
+  for class in $latest_classes
+  do
+    ignore_kinesis_client_internal_api "$class"
+    ignore_non_public_classes "$class"
+
+    LATEST_METHODS=$(javap -classpath "$LATEST_JAR" "$class")
+    CURRENT_METHODS=$(javap -classpath "$CURRENT_JAR" "$class")
+
+    ignore_abstract_changes_in_interfaces "$class"
+
+    local removed_methods=$(diff <(echo "$latest_methods") <(echo "$current_methods") | grep '^<')
+
+    if [[ "$removed_methods" != "" ]]
+    then
+      REMOVED_METHODS_FLAG=$TRUE
+      echo "$class does not have method(s):"
+      echo "$removed_methods"
+    fi
+  done
+}
+
+get_backwards_compatible_result() {
+  if [[ $REMOVED_METHODS_FLAG == $TRUE ]]
+  then
+    echo "Current KCL version is not backwards compatible with version $LATEST_VERSION. See output above for removed packages/methods."
+    exit 1
+  else
+    echo "Current KCL version is backwards compatible with version $LATEST_VERSION."
+    exit 0
+  fi
+}
+
+main() {
+  get_latest_jar
+  get_current_jar
+  find_removed_methods
+  get_backwards_compatible_result
+}
+
+main