In the Ballerina Language how do I hot reload code via `bal run` without a server restart?

Question

I can run a development server locally via bal run and interact with my API via Swagger in VSCode (very nice!), however, it seems that I have to kill & restart the server to reflect code changes?

Is there a smarter way to automatically hot reload code changes & update the server?

I first-off expected the default behaviour to reflect code changes.

I then figured I could opt in via an option to bal run, but looking at bal run --help I didn't see any --debug or similar option?

Answer 1

Currently, there is no official support for this. But I sometimes use a shell script to do this.

#!/bin/bash

DIRECTORY_TO_WATCH="<package-directory>"    # provide the absolute directory

run_command() {
    # Get the previous jvm PID and kill it
    prevJPID=$(jps | grep '$_init' | awk '{print $1}')
    kill -9 $prevJPID >/dev/null 2>&1
    wait $prevJPID 2>/dev/null

    # Run the command in the background and get its PID and Jvm PID
    bal run $DIRECTORY_TO_WATCH &
    PID=$!
    sleep 2
    JPID=$(jps | grep '$_init' | awk '{print $1}')
    echo "PID of the command: $PID"
    echo "PID of jvm process: $JPID"
}

run_command

fswatch -0 $DIRECTORY_TO_WATCH | while IFS= read -r -d "" file; do
    if [[ "$file" == *.bal ]]; then
        echo "File changed $file"
        kill -9 $PID >/dev/null 2>&1
        wait $PID 2>/dev/null
        run_command
    fi
done

Here, you have to provide the absolute path for the DIRECTORY_TO_WATCH (e.g. "/Users/dulaj/Desktop/temp/servo").

Also, you have to give +x permission to the file. via the following command.

chmod +x <script-name>