Parameterise versions into Dockerfile

Use build arguments for the base image and plugin version in the
Dockerfile so that the Dockerfile does not need to be edited every time
we update versions

.github/workflows/dockerhub.yml

@@ -22,6 +22,16 @@ jobs:
 
       - name: Build with Maven
         run: mvn -B package --file pom.xml
+
+      - name: Detect OpenSearch Version
+        id: opensearch
+        run: |
+          echo version=$(mvn -q -Dexec.executable=echo -Dexec.args='${opensearch.version}' --non-recursive exec:exec) >> $GITHUB_OUTPUT
+
+      - name: Detect Plugin Version
+        id: plugin
+        run: |
+          echo version=$(mvn -q -Dexec.executable=echo -Dexec.args='${project.version}' --non-recursive exec:exec) >> $GITHUB_OUTPUT
       
       - name: Log in to Docker Hub
         uses: docker/login-action@f4ef78c080cd8ba55a85445d5b36e214a81df20a
@@ -53,4 +63,7 @@ jobs:
           context: .
           file: ./Dockerfile
           tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
+          labels: ${{ steps.meta.outputs.labels }}
+          build-args: |
+            OPENSEARCH_VERSION=${{ steps.opensearch.outputs.version }}
+            PLUGIN_VERSION=${{ steps.plugin.outputs.version }}

Dockerfile

@@ -1,3 +1,5 @@
-FROM opensearchproject/opensearch:2.9.0
-COPY target/releases/SynonymsPlugin-2.9.0.0.zip /tmp
-RUN /usr/share/opensearch/bin/opensearch-plugin install --batch file:///tmp/SynonymsPlugin-2.9.0.0.zip
+ARG OPENSEARCH_VERSION
+FROM opensearchproject/opensearch:${OPENSEARCH_VERSION}
+ARG PLUGIN_VERSION
+COPY target/releases/SynonymsPlugin-${PLUGIN_VERSION}.zip /tmp
+RUN /usr/share/opensearch/bin/opensearch-plugin install --batch file:///tmp/SynonymsPlugin-${PLUGIN_VERSION}.zip