Update Java

Dockerfile

@@ -1,14 +1,23 @@
+# Use a specific version of OpenJDK based on Debian ("bullseye" in this case)
 FROM --platform=$BUILDPLATFORM openjdk:22-ea-21-jdk-slim-bullseye AS builder
 
-RUN apt update && apt install gradle git && rm -rf /var/lib/apk/* /var/cache/apk/*
+# Replace 'apk' commands with 'apt-get' for Debian-based package management.
+# Install required packages such as 'git' and 'gradle'. Remember to update and clean up properly.
+RUN apt-get update && \
+    apt-get install -y gradle git && \
+    rm -rf /var/lib/apt/lists/*
 
 WORKDIR /mxids
 COPY . .
 RUN ./gradlew shadowJar
 
+# Second stage: Setup the runtime container
 FROM openjdk:22-ea-21-jdk-slim-bullseye
 
-RUN apt update && apt install bash && rm -rf /var/lib/apk/* /var/cache/apk/*
+# Again, switch to 'apt-get' for installing 'bash'. Clean up to keep the image size down.
+RUN apt-get update && \
+    apt-get install -y bash && \
+    rm -rf /var/lib/apt/lists/*
 
 VOLUME /etc/mxids
 VOLUME /var/mxids
@@ -19,8 +28,9 @@ ENV CONF_FILE_PATH="/etc/mxids/mxids.yaml"
 ENV SIGN_KEY_PATH="/var/mxids/sign.key"
 ENV SQLITE_DATABASE_PATH="/var/mxids/mxids.db"
 
-CMD [ "/start.sh" ]
-
-ADD src/docker/start.sh /start.sh
-ADD src/script/mxids /app/mxids
+# It's usually a good practice to use 'COPY' instead of 'ADD' for local files unless you need the extra capabilities of 'ADD' (like auto-extracting tar files).
+COPY src/docker/start.sh /start.sh
+COPY src/script/mxids /app/mxids
 COPY --from=builder /mxids/build/libs/mxids.jar /app/mxids.jar
+
+CMD ["/start.sh"]