[CI] Trim docker image build context: exclude Maven target/, drop pip cache

docker/build.sh

@@ -81,6 +81,17 @@ if [ "$SEDONA_VERSION" = "latest" ]; then
 
     # The compilation must take place outside Docker to avoid unnecessary maven packages
     mvn clean install -DskipTests -Dspark="${SEDONA_SPARK_VERSION}" -Dscala=2.13
+else
+    # When building against a published Sedona version, install-sedona.sh
+    # downloads the shaded JAR from Maven Central inside the container and
+    # never reads spark-shaded/target/. Any stale Maven artifacts in the
+    # local tree would still be pulled into the build context by the
+    # `COPY ./spark-shaded/` step, ship in the published manifest, and add
+    # to every pull's download size — even though the dockerfile's trailing
+    # `RUN rm -rf ${SEDONA_HOME}` deletes them from the runtime filesystem.
+    # apache/sedona:1.9.0 hit this regression and shipped 1.1 GB heavier than
+    # 1.8.1 (4.03 GB vs 2.97 GB compressed) for exactly this reason.
+    rm -rf spark-shaded/target python/build python/dist
 fi
 
 # -- Building the image

docker/sedona-docker.dockerfile

@@ -43,14 +43,14 @@ ENV PYTHONPATH=${SPARK_HOME}/python
 # Set up OS libraries and PySpark
 RUN apt-get update
 RUN apt-get install -y openjdk-17-jdk-headless curl python3-pip maven
-RUN pip3 install pipenv --break-system-packages
+RUN pip3 install --no-cache-dir pipenv --break-system-packages
 COPY ./docker/install-spark.sh ${SEDONA_HOME}/docker/
 RUN chmod +x ${SEDONA_HOME}/docker/install-spark.sh
 RUN ${SEDONA_HOME}/docker/install-spark.sh ${spark_version} ${hadoop_s3_version} ${aws_sdk_version}
 
 # Install Python dependencies
 COPY docker/requirements.txt /opt/requirements.txt
-RUN pip3 install -r /opt/requirements.txt --break-system-packages
+RUN pip3 install --no-cache-dir -r /opt/requirements.txt --break-system-packages
 
 
 # Copy local compiled jars and python code to the docker environment

docker/sedona-docker.dockerfile.dockerignore

@@ -7,3 +7,16 @@
 !docs/usecases/**
 !python/**
 !spark-shaded/**
+
+# Re-exclude Python build artifacts and pyc caches so a tree that has
+# had `python -m build` run against it does not balloon the COPY layers.
+# Note: `**/target/` is intentionally NOT excluded here because the
+# build.sh `latest` mode runs `mvn clean install -DskipTests` and then
+# install-sedona.sh inside the image copies the freshly-built shaded
+# JAR from `${SEDONA_HOME}/spark-shaded/target/`. Stale Maven `target/`
+# directories from a prior local build are cleaned up by build.sh
+# (non-latest branch) instead — see docker/build.sh.
+python/build/
+python/dist/
+**/*.egg-info/
+**/__pycache__/