Debugpy unable to start Flask server

[TopeltR]

Environment data

• debugpy version: 1.6.7
• OS and version: macOS Ventura 13.2.1
• Python version (& distribution if applicable, e.g. Anaconda): 3.10.11
• Using VS Code or Visual Studio: VS Code
• Flask version: 2.3.2

Actual behaviour

When using a startup command to run a Flask server with debugpy and code reloading like this:
FLASK_DEBUG=true FLASK_ENV=development python3 -m debugpy --listen 0.0.0.0:5678 -m flask run

debugpy raises a RuntimeException:

Details

* Debug mode: on
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
* Running on http://127.0.0.1:5000
Press CTRL+C to quit
* Restarting with watchdog (fsevents)
Traceback (most recent call last):
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/_vendored/pydevd/pydevd.py", line 3489, in <module>
  main()
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/_vendored/pydevd/pydevd.py", line 3482, in main
  globals = debugger.run(setup['file'], None, None, is_module)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/_vendored/pydevd/pydevd.py", line 2510, in run
  return self._exec(is_module, entry_point_fn, module_name, file, globals, locals)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/_vendored/pydevd/pydevd.py", line 2528, in _exec
  globals = pydevd_runpy._run_module_as_main(module_name, alter_argv=False)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_runpy.py", line 238, in _run_module_as_main
  return _run_code(code, main_globals, None,
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_runpy.py", line 124, in _run_code
  exec(code, run_globals)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/__main__.py", line 39, in <module>
  cli.main()
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/server/cli.py", line 430, in main
  run()
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/server/cli.py", line 302, in run_module
  start_debugging(argv_0)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/server/cli.py", line 256, in start_debugging
  debugpy.listen(options.address)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/public_api.py", line 31, in wrapper
  return wrapped(*args, **kwargs)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/server/api.py", line 143, in debug
  log.reraise_exception("{0}() failed:", func.__name__, level="info")
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/server/api.py", line 141, in debug
  return func(address, settrace_kwargs, **kwargs)
File "/home/topeltr/Documents/Github/example-application/venv/lib/python3.10/site-packages/debugpy/server/api.py", line 262, in listen
  raise RuntimeError(str(endpoints["error"]))
RuntimeError: Can't listen for client connections: [Errno 48] Address already in use

I looked a bit more into the problem and it seems that a change in Werkzeug causes this. sys.orig_argv passes the entire command to the reloader i.e. python3 -m debugpy --listen 0.0.0.0:5678 -m flask run - which leads to a second instance of debugpy being started without shutting down the previous one causing the traceback from debugpy side. I already raised an issue on the Werkzeug side and they signalled that it should be handled on the debugpy side.

Expected behaviour

No RuntimeError emitted and Debugpy can start a Flask server with code reloading.

Steps to reproduce:

1. Use versions mentioned in the environments section
2. Run minimal Flask app (example here)

[jaredannis]

i am having same issue, in my docker compose:

command: python -m debugpy --listen 0.0.0.0:5666 -m flask run --host=0.0.0.0

gets error:

RuntimeError: Can't listen for client connections: [Errno 98] Address already in use

setting flask to --no-reload lets the app load, but i am losing functionality

i am able to get it to work if explicitly set these versions:
werkzeug==2.2.2
flask==2.2.2
debugpy==1.6.3

[srh-sloan]

We are also experiencing exactly this problem. Is there any update on when it will be fixed please?

[sebastienpires]

Same issue here - we start losing the ability to debug if we upgrade any Python3.10 application to Werkzeug 2.3.0.

[int19h]

Note that you can disable the Flask reloader by using --no-reload without disabling other Flask debugging features.

[yezhengli-Mr9]

Are you following https://code.visualstudio.com/docs/containers/docker-compose for python with docker-compose? Not able to debug in vscode same way as pycharm in j2eeexpert2015/flask_docker#1 although feel I need to debug in vscode j2eeexpert2015/springbootdebug#1 due to the fact I need to run docker-compose up under sudo su.

For https://code.visualstudio.com/docs/containers/docker-compose and utilizing sample code https://github.com/j2eeexpert2015/flask_docker, I finish following steps:

1. On the Debug tab, choose the Configuration dropdown, choose New Configuration, choose Python, and select the Remote Attach configuration template. Result in following launch.json:

 {
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Remote Attach",
            "type": "python",
            "request": "attach",
            "connect": {
                "host": "localhost",
                "port": 5678
            },
            "pathMappings": [
                {
                    "localRoot": "${workspaceFolder}",
                    "remoteRoot": "."
                }
            ],
            "justMyCode": true
        }
    ]
}

2. copydocker-compose.yaml https://github.com/j2eeexpert2015/flask_docker/blob/587dc48e1a563226e5fd1ac63e82243590649f5c/docker-compose.yml#L4-L8 as docker-compose.debug.yaml and add into ``docker-compose.debug.yaml` as following

version: "2"
services:
  app:
    build: ./app
++  command: ["sh", "-c", "pip install debugpy -t /tmp && python /tmp/debugpy --wait-for-client --listen 0.0.0.0:5678 app.py runserver 0.0.0.0:5000 --nothreading --noreload"]
    links:
      - db
    ports:
      - "5000:5000"
++    - 5678:5678

  db:
    image: mysql:5.7
    ports:
      - "32000:3306"
    environment:
      MYSQL_ROOT_PASSWORD: root
    volumes:
      - ./db:/docker-entrypoint-initdb.d/:ro

3. Add RUN pip install debugpy to DockerFile just in case https://github.com/j2eeexpert2015/flask_docker/blob/587dc48e1a563226e5fd1ac63e82243590649f5c/app/Dockerfile#L10-L11

  COPY app.py /app
++RUN pip install debugpy 
  CMD python app.py

4. Add breakpoint in same as video tutorial
   

5. Right-click on the docker-compose.debug.yml file and choose Compose Up:

Executing task: docker compose -f "docker-compose.debug.yml" up -d --build 

[+] Building 0.6s (11/11) FINISHED                                                                                                                          docker:default
 => [app internal] load .dockerignore                                                                                                                                 0.0s
 => => transferring context: 2B                                                                                                                                       0.0s
 => [app internal] load build definition from Dockerfile                                                                                                              0.0s
 => => transferring dockerfile: 206B                                                                                                                                  0.0s
 => [app internal] load metadata for docker.io/library/python:3.6                                                                                                     0.4s
 => [app 1/6] FROM docker.io/library/python:3.6@sha256:f8652afaf88c25f0d22354d547d892591067aa4026a7fa9a6819df9f300af6fc                                               0.0s
 => [app internal] load build context                                                                                                                                 0.0s
 => => transferring context: 63B                                                                                                                                      0.0s
 => CACHED [app 2/6] WORKDIR /app                                                                                                                                     0.0s
 => CACHED [app 3/6] COPY requirements.txt /app                                                                                                                       0.0s
 => CACHED [app 4/6] RUN pip install -r requirements.txt                                                                                                              0.0s
 => CACHED [app 5/6] COPY app.py /app                                                                                                                                 0.0s
 => CACHED [app 6/6] RUN pip install debugpy                                                                                                                          0.0s
 => [app] exporting to image                                                                                                                                          0.0s
 => => exporting layers                                                                                                                                               0.0s
 => => writing image sha256:6f77b8fe1a24179a7ee1f8450ecf30f33a8a2d01cb8523fbe1891679882967eb                                                                          0.0s
 => => naming to docker.io/library/flask_docker-app                                                                                                                   0.0s
[+] Running 3/3
 ✔ Network flask_docker_default  Created                                                                                                                              0.1s 
 ✔ Container flask_docker-db-1   Started                                                                                                                              0.1s 
 ✔ Container flask_docker-app-1  Started                                                                                                                              0.1s 
 *  Terminal will be reused by tasks, press any key to close it. 

or docker-compose up in terminal (similar to Java Debugging in Docker: How to Use VS Code and Docker Compose with sample code https://github.com/j2eeexpert2015/springbootdebug)

docker-compose up
Creating network "flask_docker_default" with the default driver
Creating flask_docker_db_1 ... done
Creating flask_docker_app_1 ... done
Attaching to flask_docker_db_1, flask_docker_app_1
db_1   | 2024-01-01 22:32:02+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.44-1.el7 started.
db_1   | 2024-01-01 22:32:02+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
db_1   | 2024-01-01 22:32:02+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.44-1.el7 started.
db_1   | 2024-01-01 22:32:02+00:00 [Note] [Entrypoint]: Initializing database files
db_1   | 2024-01-01T22:32:02.961535Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
db_1   | 2024-01-01T22:32:03.211579Z 0 [Warning] InnoDB: New log files created, LSN=45790
db_1   | 2024-01-01T22:32:03.271596Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
db_1   | 2024-01-01T22:32:03.342051Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 9614249d-a8f5-11ee-afd7-0242ac140002.
db_1   | 2024-01-01T22:32:03.348199Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
db_1   | 2024-01-01T22:32:03.465054Z 0 [Warning] A deprecated TLS version TLSv1 is enabled. Please use TLSv1.2 or higher.
db_1   | 2024-01-01T22:32:03.465064Z 0 [Warning] A deprecated TLS version TLSv1.1 is enabled. Please use TLSv1.2 or higher.
db_1   | 2024-01-01T22:32:03.465341Z 0 [Warning] CA certificate ca.pem is self signed.
db_1   | 2024-01-01T22:32:03.471705Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.
app_1  | Collecting debugpy
app_1  |   Using cached debugpy-1.5.1-cp36-cp36m-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (1.9 MB)
app_1  | Installing collected packages: debugpy
app_1  | Successfully installed debugpy-1.5.1
app_1  | WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
app_1  | WARNING: You are using pip version 21.2.4; however, version 21.3.1 is available.
app_1  | You should consider upgrading via the '/usr/local/bin/python -m pip install --upgrade pip' command.
db_1   | 2024-01-01 22:32:07+00:00 [Note] [Entrypoint]: Database files initialized
db_1   | 2024-01-01 22:32:07+00:00 [Note] [Entrypoint]: Starting temporary server
db_1   | 2024-01-01 22:32:08+00:00 [Note] [Entrypoint]: Waiting for server startup
db_1   | 2024-01-01T22:32:08.159998Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
db_1   | 2024-01-01T22:32:08.160922Z 0 [Note] mysqld (mysqld 5.7.44) starting as process 124 ...
db_1   | 2024-01-01T22:32:08.162816Z 0 [Note] InnoDB: PUNCH HOLE support available
db_1   | 2024-01-01T22:32:08.162833Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
db_1   | 2024-01-01T22:32:08.162835Z 0 [Note] InnoDB: Uses event mutexes
db_1   | 2024-01-01T22:32:08.162838Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
db_1   | 2024-01-01T22:32:08.162839Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.13
db_1   | 2024-01-01T22:32:08.162840Z 0 [Note] InnoDB: Using Linux native AIO
db_1   | 2024-01-01T22:32:08.163000Z 0 [Note] InnoDB: Number of pools: 1
db_1   | 2024-01-01T22:32:08.163069Z 0 [Note] InnoDB: Using CPU crc32 instructions
db_1   | 2024-01-01T22:32:08.164143Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
db_1   | 2024-01-01T22:32:08.167973Z 0 [Note] InnoDB: Completed initialization of buffer pool
db_1   | 2024-01-01T22:32:08.169052Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
db_1   | 2024-01-01T22:32:08.180233Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
db_1   | 2024-01-01T22:32:08.197763Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
db_1   | 2024-01-01T22:32:08.197808Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
db_1   | 2024-01-01T22:32:08.213086Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
db_1   | 2024-01-01T22:32:08.213443Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
db_1   | 2024-01-01T22:32:08.213447Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
db_1   | 2024-01-01T22:32:08.213703Z 0 [Note] InnoDB: 5.7.44 started; log sequence number 2768291
db_1   | 2024-01-01T22:32:08.213814Z 0 [Note] InnoDB: Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
db_1   | 2024-01-01T22:32:08.213934Z 0 [Note] Plugin 'FEDERATED' is disabled.
db_1   | 2024-01-01T22:32:08.214805Z 0 [Note] InnoDB: Buffer pool(s) load completed at 240101 22:32:08
db_1   | 2024-01-01T22:32:08.217155Z 0 [Note] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
db_1   | 2024-01-01T22:32:08.217161Z 0 [Note] Skipping generation of SSL certificates as certificate files are present in data directory.
db_1   | 2024-01-01T22:32:08.217163Z 0 [Warning] A deprecated TLS version TLSv1 is enabled. Please use TLSv1.2 or higher.
db_1   | 2024-01-01T22:32:08.217164Z 0 [Warning] A deprecated TLS version TLSv1.1 is enabled. Please use TLSv1.2 or higher.
db_1   | 2024-01-01T22:32:08.217463Z 0 [Warning] CA certificate ca.pem is self signed.
db_1   | 2024-01-01T22:32:08.217481Z 0 [Note] Skipping generation of RSA key pair as key files are present in data directory.
db_1   | 2024-01-01T22:32:08.223329Z 0 [Warning] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
db_1   | 2024-01-01T22:32:08.226573Z 0 [Note] Event Scheduler: Loaded 0 events
db_1   | 2024-01-01T22:32:08.226696Z 0 [Note] mysqld: ready for connections.
db_1   | Version: '5.7.44'  socket: '/var/run/mysqld/mysqld.sock'  port: 0  MySQL Community Server (GPL)
db_1   | 2024-01-01 22:32:09+00:00 [Note] [Entrypoint]: Temporary server started.
db_1   | '/var/lib/mysql/mysql.sock' -> '/var/run/mysqld/mysqld.sock'
db_1   | 2024-01-01T22:32:09.026098Z 3 [Note] InnoDB: Stopping purge
db_1   | 2024-01-01T22:32:09.046927Z 3 [Note] InnoDB: Resuming purge
db_1   | 2024-01-01T22:32:09.052902Z 3 [Note] InnoDB: Stopping purge
db_1   | 2024-01-01T22:32:09.064590Z 3 [Note] InnoDB: Resuming purge
db_1   | 2024-01-01T22:32:09.070887Z 3 [Note] InnoDB: Stopping purge
db_1   | 2024-01-01T22:32:09.082701Z 3 [Note] InnoDB: Resuming purge
db_1   | 2024-01-01T22:32:09.089075Z 3 [Note] InnoDB: Stopping purge
db_1   | 2024-01-01T22:32:09.101439Z 3 [Note] InnoDB: Resuming purge
db_1   | Warning: Unable to load '/usr/share/zoneinfo/iso3166.tab' as time zone. Skipping it.
db_1   | Warning: Unable to load '/usr/share/zoneinfo/leapseconds' as time zone. Skipping it.
db_1   | Warning: Unable to load '/usr/share/zoneinfo/tzdata.zi' as time zone. Skipping it.
db_1   | Warning: Unable to load '/usr/share/zoneinfo/zone.tab' as time zone. Skipping it.
db_1   | Warning: Unable to load '/usr/share/zoneinfo/zone1970.tab' as time zone. Skipping it.
db_1   | 
db_1   | 2024-01-01 22:32:10+00:00 [Note] [Entrypoint]: /usr/local/bin/docker-entrypoint.sh: running /docker-entrypoint-initdb.d/init.sql
db_1   | 
db_1   | 
db_1   | 2024-01-01 22:32:10+00:00 [Note] [Entrypoint]: Stopping temporary server
db_1   | 2024-01-01T22:32:10.153423Z 0 [Note] Giving 0 client threads a chance to die gracefully
db_1   | 2024-01-01T22:32:10.153437Z 0 [Note] Shutting down slave threads
db_1   | 2024-01-01T22:32:10.153440Z 0 [Note] Forcefully disconnecting 0 remaining clients
db_1   | 2024-01-01T22:32:10.153443Z 0 [Note] Event Scheduler: Purging the queue. 0 events
db_1   | 2024-01-01T22:32:10.153465Z 0 [Note] Binlog end
db_1   | 2024-01-01T22:32:10.160297Z 0 [Note] Shutting down plugin 'ngram'
db_1   | 2024-01-01T22:32:10.160311Z 0 [Note] Shutting down plugin 'partition'
db_1   | 2024-01-01T22:32:10.160313Z 0 [Note] Shutting down plugin 'BLACKHOLE'
db_1   | 2024-01-01T22:32:10.160315Z 0 [Note] Shutting down plugin 'ARCHIVE'
db_1   | 2024-01-01T22:32:10.160317Z 0 [Note] Shutting down plugin 'PERFORMANCE_SCHEMA'
db_1   | 2024-01-01T22:32:10.160338Z 0 [Note] Shutting down plugin 'MRG_MYISAM'
db_1   | 2024-01-01T22:32:10.160340Z 0 [Note] Shutting down plugin 'MyISAM'
db_1   | 2024-01-01T22:32:10.160351Z 0 [Note] Shutting down plugin 'INNODB_SYS_VIRTUAL'
db_1   | 2024-01-01T22:32:10.160353Z 0 [Note] Shutting down plugin 'INNODB_SYS_DATAFILES'
db_1   | 2024-01-01T22:32:10.160355Z 0 [Note] Shutting down plugin 'INNODB_SYS_TABLESPACES'
db_1   | 2024-01-01T22:32:10.160356Z 0 [Note] Shutting down plugin 'INNODB_SYS_FOREIGN_COLS'
db_1   | 2024-01-01T22:32:10.160357Z 0 [Note] Shutting down plugin 'INNODB_SYS_FOREIGN'
db_1   | 2024-01-01T22:32:10.160358Z 0 [Note] Shutting down plugin 'INNODB_SYS_FIELDS'
db_1   | 2024-01-01T22:32:10.160360Z 0 [Note] Shutting down plugin 'INNODB_SYS_COLUMNS'
db_1   | 2024-01-01T22:32:10.160361Z 0 [Note] Shutting down plugin 'INNODB_SYS_INDEXES'
db_1   | 2024-01-01T22:32:10.160361Z 0 [Note] Shutting down plugin 'INNODB_SYS_TABLESTATS'
db_1   | 2024-01-01T22:32:10.160362Z 0 [Note] Shutting down plugin 'INNODB_SYS_TABLES'
db_1   | 2024-01-01T22:32:10.160364Z 0 [Note] Shutting down plugin 'INNODB_FT_INDEX_TABLE'
db_1   | 2024-01-01T22:32:10.160364Z 0 [Note] Shutting down plugin 'INNODB_FT_INDEX_CACHE'
db_1   | 2024-01-01T22:32:10.160365Z 0 [Note] Shutting down plugin 'INNODB_FT_CONFIG'
db_1   | 2024-01-01T22:32:10.160366Z 0 [Note] Shutting down plugin 'INNODB_FT_BEING_DELETED'
db_1   | 2024-01-01T22:32:10.160367Z 0 [Note] Shutting down plugin 'INNODB_FT_DELETED'
db_1   | 2024-01-01T22:32:10.160368Z 0 [Note] Shutting down plugin 'INNODB_FT_DEFAULT_STOPWORD'
db_1   | 2024-01-01T22:32:10.160369Z 0 [Note] Shutting down plugin 'INNODB_METRICS'
db_1   | 2024-01-01T22:32:10.160370Z 0 [Note] Shutting down plugin 'INNODB_TEMP_TABLE_INFO'
db_1   | 2024-01-01T22:32:10.160371Z 0 [Note] Shutting down plugin 'INNODB_BUFFER_POOL_STATS'
db_1   | 2024-01-01T22:32:10.160372Z 0 [Note] Shutting down plugin 'INNODB_BUFFER_PAGE_LRU'
db_1   | 2024-01-01T22:32:10.160373Z 0 [Note] Shutting down plugin 'INNODB_BUFFER_PAGE'
db_1   | 2024-01-01T22:32:10.160374Z 0 [Note] Shutting down plugin 'INNODB_CMP_PER_INDEX_RESET'
db_1   | 2024-01-01T22:32:10.160376Z 0 [Note] Shutting down plugin 'INNODB_CMP_PER_INDEX'
db_1   | 2024-01-01T22:32:10.160377Z 0 [Note] Shutting down plugin 'INNODB_CMPMEM_RESET'
db_1   | 2024-01-01T22:32:10.160378Z 0 [Note] Shutting down plugin 'INNODB_CMPMEM'
db_1   | 2024-01-01T22:32:10.160379Z 0 [Note] Shutting down plugin 'INNODB_CMP_RESET'
db_1   | 2024-01-01T22:32:10.160380Z 0 [Note] Shutting down plugin 'INNODB_CMP'
db_1   | 2024-01-01T22:32:10.160381Z 0 [Note] Shutting down plugin 'INNODB_LOCK_WAITS'
db_1   | 2024-01-01T22:32:10.160382Z 0 [Note] Shutting down plugin 'INNODB_LOCKS'
db_1   | 2024-01-01T22:32:10.160383Z 0 [Note] Shutting down plugin 'INNODB_TRX'
db_1   | 2024-01-01T22:32:10.160384Z 0 [Note] Shutting down plugin 'InnoDB'
db_1   | 2024-01-01T22:32:10.160442Z 0 [Note] InnoDB: FTS optimize thread exiting.
db_1   | 2024-01-01T22:32:10.160555Z 0 [Note] InnoDB: Starting shutdown...
db_1   | 2024-01-01T22:32:10.260733Z 0 [Note] InnoDB: Dumping buffer pool(s) to /var/lib/mysql/ib_buffer_pool
db_1   | 2024-01-01T22:32:10.260877Z 0 [Note] InnoDB: Buffer pool(s) dump completed at 240101 22:32:10
db_1   | 2024-01-01T22:32:11.290973Z 0 [Note] InnoDB: Shutdown completed; log sequence number 12227086
db_1   | 2024-01-01T22:32:11.292015Z 0 [Note] InnoDB: Removed temporary tablespace data file: "ibtmp1"
db_1   | 2024-01-01T22:32:11.292035Z 0 [Note] Shutting down plugin 'MEMORY'
db_1   | 2024-01-01T22:32:11.292038Z 0 [Note] Shutting down plugin 'CSV'
db_1   | 2024-01-01T22:32:11.292040Z 0 [Note] Shutting down plugin 'sha256_password'
db_1   | 2024-01-01T22:32:11.292040Z 0 [Note] Shutting down plugin 'mysql_native_password'
db_1   | 2024-01-01T22:32:11.292114Z 0 [Note] Shutting down plugin 'binlog'
db_1   | 2024-01-01T22:32:11.293093Z 0 [Note] mysqld: Shutdown complete
db_1   | 
db_1   | 2024-01-01 22:32:12+00:00 [Note] [Entrypoint]: Temporary server stopped
db_1   | 
db_1   | 2024-01-01 22:32:12+00:00 [Note] [Entrypoint]: MySQL init process done. Ready for start up.
db_1   | 
db_1   | 2024-01-01T22:32:12.320317Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
db_1   | 2024-01-01T22:32:12.324342Z 0 [Note] mysqld (mysqld 5.7.44) starting as process 1 ...
db_1   | 2024-01-01T22:32:12.327188Z 0 [Note] InnoDB: PUNCH HOLE support available
db_1   | 2024-01-01T22:32:12.327210Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
db_1   | 2024-01-01T22:32:12.327214Z 0 [Note] InnoDB: Uses event mutexes
db_1   | 2024-01-01T22:32:12.327216Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
db_1   | 2024-01-01T22:32:12.327220Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.13
db_1   | 2024-01-01T22:32:12.327221Z 0 [Note] InnoDB: Using Linux native AIO
db_1   | 2024-01-01T22:32:12.327466Z 0 [Note] InnoDB: Number of pools: 1
db_1   | 2024-01-01T22:32:12.327563Z 0 [Note] InnoDB: Using CPU crc32 instructions
db_1   | 2024-01-01T22:32:12.328833Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
db_1   | 2024-01-01T22:32:12.343717Z 0 [Note] InnoDB: Completed initialization of buffer pool
db_1   | 2024-01-01T22:32:12.345509Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
db_1   | 2024-01-01T22:32:12.365297Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
db_1   | 2024-01-01T22:32:12.384479Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
db_1   | 2024-01-01T22:32:12.384535Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
db_1   | 2024-01-01T22:32:12.403458Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
db_1   | 2024-01-01T22:32:12.404061Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
db_1   | 2024-01-01T22:32:12.404070Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
db_1   | 2024-01-01T22:32:12.404452Z 0 [Note] InnoDB: 5.7.44 started; log sequence number 12227086
db_1   | 2024-01-01T22:32:12.404571Z 0 [Note] InnoDB: Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
db_1   | 2024-01-01T22:32:12.404810Z 0 [Note] Plugin 'FEDERATED' is disabled.
db_1   | 2024-01-01T22:32:12.407917Z 0 [Note] InnoDB: Buffer pool(s) load completed at 240101 22:32:12
db_1   | 2024-01-01T22:32:12.409841Z 0 [Note] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
db_1   | 2024-01-01T22:32:12.409855Z 0 [Note] Skipping generation of SSL certificates as certificate files are present in data directory.
db_1   | 2024-01-01T22:32:12.409858Z 0 [Warning] A deprecated TLS version TLSv1 is enabled. Please use TLSv1.2 or higher.
db_1   | 2024-01-01T22:32:12.409859Z 0 [Warning] A deprecated TLS version TLSv1.1 is enabled. Please use TLSv1.2 or higher.
db_1   | 2024-01-01T22:32:12.410374Z 0 [Warning] CA certificate ca.pem is self signed.
db_1   | 2024-01-01T22:32:12.410410Z 0 [Note] Skipping generation of RSA key pair as key files are present in data directory.
db_1   | 2024-01-01T22:32:12.410708Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
db_1   | 2024-01-01T22:32:12.410743Z 0 [Note] IPv6 is available.
db_1   | 2024-01-01T22:32:12.410754Z 0 [Note]   - '::' resolves to '::';
db_1   | 2024-01-01T22:32:12.410772Z 0 [Note] Server socket created on IP: '::'.
db_1   | 2024-01-01T22:32:12.416621Z 0 [Warning] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
db_1   | 2024-01-01T22:32:12.421924Z 0 [Note] Event Scheduler: Loaded 0 events
db_1   | 2024-01-01T22:32:12.422097Z 0 [Note] mysqld: ready for connections.
db_1   | Version: '5.7.44'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server (GPL)

7. hit F5 with the Python: Remote Attach launch configuration selected.
8. Open browser and go to localhost:5000

While localhost:5000 in the browser smoothly returns

{"get_employees": [{"Employee1": "Developer"}, {"Employee2": "HR"}]}`

the breakpoint turns from red to hollow circle and never get hit

[yezhengli-Mr9]

Submit issue #1491

[stevefoga]

Did anybody ever find a workaround for this?

[Keith-CPlus]

Any other workaround for this? Other than bumping down werkzeug and flask versions?

[lukaspiatkowski]

I've got a workaround, but you have to use debugpy API instead of the CLI. Just find the place in your code before you call run(... , use_reloader=True) on your flask app and add:

if (
    # The WERKZEUG_RUN_MAIN is set to true when running the subprocess for
    # reloading, we want to start debugpy only once during the first
    # invocation and never during reloads.
    os.environ.get("WERKZEUG_RUN_MAIN") != "true"
):
    import debugpy

    debugpy.listen(("0.0.0.0", 5678))
    debugpy.wait_for_client()

This will start debugpy only for the first original invocation of your app and not for the subsequent reload invocations. The WERKZEUG_RUN_MAIN env variable is set by Werkezeug itself and is used to identify if this is the reloadable subprocess.