flask + docker + remote debugging: Debug adapter process has terminated unexpectedly

Environment data

• VS Code version: 1.27.2
• Extension version (available under the Extensions sidebar): 2018.8.0
• OS and version: Debian 9.5 - Kernel 4.9.0-8-amd64
• Python version (& distribution if applicable, e.g. Anaconda): 3.6.5
• Type of virtual environment used (N/A | venv | virtualenv | conda | …): none
• Relevant/affected Python packages and their versions: Flask 0.12.2, ptvsd 3.0.0
• App running in actual Docker

Actual behavior

Remote Debugger does not attach to the flask app running in a docker container on localhost

Expected behavior

Remote Debugger attaches to the flask app running in a docker container on localhost. Worked on VS Code < 1.27

Steps to reproduce:

1. Start docker containers on local machine
2. webapp is waiting for remote debugger to connect
3. VS Code debugger does not attach

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

No Output

notificationsAlerts.ts:41 Debug adapter process has terminated unexpectedly
t.onDidNotificationChange @ notificationsAlerts.ts:41
(anonymous) @ notificationsAlerts.ts:27
e.fire @ event.ts:140
t.notify @ notifications.ts:113
t.error @ notificationService.ts:52
t.onDebugAdapterExit @ rawDebugSession.ts:529
(anonymous) @ rawDebugSession.ts:169
e.fire @ event.ts:140
(anonymous) @ debugAdapter.ts:305
emitTwo @ events.js:126
emit @ events.js:214
__dirname.ChildProcess._handle.onexit @ internal/child_process.js:198

----------------------------------------------------------

[Extension Host] Python Extension: Error in debugger Banner Error: Missing required @injectable annotation in: Random.
	at getTargets (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/planning/reflection_utils.js:20:15)
	at Object.getDependencies (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/planning/reflection_utils.js:11:19)
	at /home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/planning/planner.js:106:51
	at Array.forEach (<anonymous>)
	at _createSubRequests (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/planning/planner.js:94:20)
	at Object.plan (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/planning/planner.js:129:9)
	at /home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/container/container.js:316:37
	at Container._get (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/container/container.js:309:44)
	at Container.get (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/node_modules/inversify/lib/container/container.js:228:21)
	at ServiceContainer.get (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/ioc/container.js:28:89)
	at DebuggerBanner.<anonymous> (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:163:55)
	at Generator.next (<anonymous>)
	at /home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:18:71
	at new Promise (<anonymous>)
	at __awaiter (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:14:12)
	at DebuggerBanner.getDebuggerLaunchThresholdCounter (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:158:16)
	at DebuggerBanner.<anonymous> (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:135:22)
	at Generator.next (<anonymous>)
	at /home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:18:71
	at new Promise (<anonymous>)
	at __awaiter (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:14:12)
	at DebuggerBanner.passedThreshold (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:133:16)
	at DebuggerBanner.<anonymous> (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:72:30)
	at Generator.next (<anonymous>)
	at /home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:18:71
	at new Promise (<anonymous>)
	at __awaiter (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:14:12)
	at DebuggerBanner.shouldShow (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:68:16)
	at DebuggerBanner.<anonymous> (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:188:37)
	at Generator.next (<anonymous>)
	at fulfilled (/home/lars/.vscode/extensions/ms-python.python-2018.8.0/out/client/debugger/banner.js:15:58)
	at <anonymous>

debug.log

10:19:47 AM, 9/17/2018
Started @ Mon Sep 17 2018 10:19:47 GMT+0200 (CEST)
From Client:
Content-Length: 313

{"command":"initialize","arguments":{"clientID":"vscode","clientName":"Visual Studio Code","adapterID":"python","pathFormat":"path","linesStartAt1":true,"columnsStartAt1":true,"supportsVariableType":true,"supportsVariablePaging":true,"supportsRunInTerminalRequest":true,"locale":"en-us"},"type":"request","seq":1}
To Client:
Content-Length: 653

{"seq":1,"type":"response","request_seq":1,"command":"initialize","success":true,"body":{"supportsExceptionInfoRequest":true,"supportsConfigurationDoneRequest":true,"supportsConditionalBreakpoints":true,"supportsSetVariable":true,"supportsExceptionOptions":true,"supportsEvaluateForHovers":true,"supportsModulesRequest":true,"supportsValueFormattingOptions":true,"supportsHitConditionalBreakpoints":true,"supportsSetExpression":true,"supportsLogPoints":true,"supportTerminateDebuggee":true,"exceptionBreakpointFilters":[{"filter":"raised","label":"Raised Exceptions","default":false},{"filter":"uncaught","label":"Uncaught Exceptions","default":true}]}}
From Client:
Content-Length: 385

{"command":"attach","arguments":{"name":"Attach (to Docker)","logToFile":true,"type":"python","request":"attach","pathMappings":[{"localRoot":"/home/lars/dev/MWScan-Portal/web/flask/","remoteRoot":"/home/flask/app/web/flask/"}],"port":3000,"host":"127.0.0.1","debugOptions":["RedirectOutput","UnixClient"],"__sessionId":"1d2e5bbc-f18a-4460-b9f9-1e934f2ac312"},"type":"request","seq":2}
To Client:
Content-Length: 385


To Client:
{"command":"attach","arguments":{"name":"Attach (to Docker)","logToFile":true,"type":"python","request":"attach","pathMappings":[{"localRoot":"/home/lars/dev/MWScan-Portal/web/flask/","remoteRoot":"/home/flask/app/web/flask/"}],"port":3000,"host":"127.0.0.1","debugOptions":["RedirectOutput","UnixClient"],"__sessionId":"1d2e5bbc-f18a-4460-b9f9-1e934f2ac312"},"type":"request","seq":2}
To Client:
Content-Length: 313


To Client:
{"command":"initialize","arguments":{"clientID":"vscode","clientName":"Visual Studio Code","adapterID":"python","pathFormat":"path","linesStartAt1":true,"columnsStartAt1":true,"supportsVariableType":true,"supportsVariablePaging":true,"supportsRunInTerminalRequest":true,"locale":"en-us"},"type":"request","seq":1}
To Client:
PTVSDBG
Socket End
check and shutdown
shutdown
Sending Terminated Event
To Client:
Content-Length: 45


To Client:
{"seq":0,"type":"event","event":"terminated"}
Shutting down debug session
disposing

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Attach (to Docker)",
            "logToFile": true,
            "type": "python",
            "request": "attach",
            "pathMappings": [
                {
                    "localRoot": "${workspaceRoot}/web/flask/",
                    "remoteRoot": "/home/flask/app/web/flask/",
                }
            ],
            "port": 3000,
            "host": "localhost",
        },
    ]

docker-compose.yml

version: '2'

services:
 web:
   build:
     context: ./web
   depends_on:
     - postgres
   ports:
     - "5000:5000"
     - "3000:3000"
   environment:
     - FLASK_APP=flask/app.py
   volumes:
     - ./web/:/home/flask/app/web/
     - ./samples/:/samples
   command: flask run --host=0.0.0.0 --no-debugger --no-reload

app.py

import ptvsd

try:
    ptvsd.enable_attach(address=('0.0.0.0', 3000), secret=None)
    ptvsd.wait_for_attach()
except Exception as ex:
    print('Not working: ')

telnet 127.0.0.1 3000 (on developer machine)

lars@laptop:/$ telnet 127.0.0.1 3000
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
PTVSDBG

[Brice187]

After removing the secret ptvsd works as expected with 2018.8.0, thank you

[DonJayamanne]

@Brice187 Please ensure you are using the latest version of PTVSD in the docker container. It looks like you don’t have it at your end, the new version doesn’t require the secret in the enable_attach method.

Once done, please get back to us.