AWS Lambda 502 after deploy dev - django

Question

This is my first time with serverless aka AWS lambda.
Here is my directory tree 1st and 2nd level
$ tree -L 2
.
├── README.md
├── Visualization_Sarit
│   ├── BA_Read0DDataPlot1DGraph.py
│   ├── CC_ReadNew2DDataPlotLineGraph.py
│   ├── ModulesInterfaceTASK.py
│   ├── Visualization.docx
│   ├── Visualization.xlsx
│   └── inHT6Ms302
├── apps
│   ├── advanced_cases
│   ├── commons
│   ├── control_params
│   ├── device_params
│   ├── heating_params
│   ├── plasma_params
│   ├── plasma_species
│   ├── results
│   ├── scenarios
│   └── transport_params
├── experiments.py
├── f1
│   ├── README.md
│   ├── package-lock.json
│   ├── package.json
│   ├── public
│   └── src
├── ht6m
│   ├── __init__.py
│   ├── __pycache__
│   ├── api_urls.py
│   ├── celery.py
│   ├── db_routers.py
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
├── manage.py
├── media
├── requirements.in
├── requirements.txt
├── static
├── static_files
├── templates
│   ├── __init__.py
│   └── hello.html
└── zappa_settings.json
Here is my settings
settings.py
DEBUG = True
ALLOWED_HOSTS = ['*']
# Application definition
INSTALLED_APPS = [
'django_celery_results',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django_extensions',
'django_rq',
'django_filters',
'corsheaders',
'rest_framework',
'apps.advanced_cases',
'apps.commons',
'apps.control_params',
'apps.device_params',
'apps.heating_params',
'apps.plasma_params',
'apps.plasma_species',
'apps.results',
'apps.scenarios',
'apps.transport_params',
]
MIDDLEWARE = [
'corsheaders.middleware.CorsMiddleware',
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
]
zappa_settings.json
{
"dev": {
"django_settings": "ht6m.settings",
"profile_name": "aegon",
"project_name": "ht6minterface",
"runtime": "python3.7",
"s3_bucket": "zappa-20j5uvs5p",
"aws_region": "ap-southeast-1"
}
}
Deployment went smooth and suddenly raises 502
$ zappa deploy dev
Calling deploy for stage dev..
Creating ht6minterface-dev-ZappaLambdaExecutionRole IAM Role..
Creating zappa-permissions policy on ht6minterface-dev-ZappaLambdaExecutionRole IAM Role.
Downloading and installing dependencies..
- psycopg2-binary==2.8.2: Downloading
100%|█████████████████████████████████████████████████████████████████████████████████████| 2.94M/2.94M [00:01<00:00, 1.95MB/s]
- greenlet==0.4.15: Downloading
100%|██████████████████████████████████████████████████████████████████████████████████████| 42.4K/42.4K [00:00<00:00, 492KB/s]
- gevent==1.4.0: Downloading
100%|█████████████████████████████████████████████████████████████████████████████████████| 5.44M/5.44M [00:01<00:00, 5.01MB/s]
- cffi==1.12.3: Downloading
100%|███████████████████████████████████████████████████████████████████████████████████████| 431K/431K [00:00<00:00, 1.48MB/s]
- sqlite==python3: Using precompiled lambda package
'python3.7'
Packaging project as zip.
Uploading ht6minterface-dev-1559645572.zip (42.2MiB)..
100%|█████████████████████████████████████████████████████████████████████████████████████| 44.2M/44.2M [00:22<00:00, 1.96MB/s]
Scheduling..
Scheduled ht6minterface-dev-zappa-keep-warm-handler.keep_warm_callback with expression rate(4 minutes)!
Uploading ht6minterface-dev-template-1559645689.json (1.6KiB)..
100%|█████████████████████████████████████████████████████████████████████████████████████| 1.65K/1.65K [00:00<00:00, 17.7KB/s]
Waiting for stack ht6minterface-dev to create (this can take a bit)..
100%|███████████████████████████████████████████████████████████████████████████████████████████| 4/4 [00:16<00:00, 5.44s/res]
Deploying API Gateway..
Error: Warning! Status check on the deployed lambda failed. A GET request to '/' yielded a 502 response code.
I don't see any error in the zappa tail
$ zappa tail
Calling tail for stage dev..
[1559645713491] Instancing..
  File "<frozen importlib._bootstrap>", line 965, in _find_and_load_unlockededdule
[1559645730278] [DEBUG] 2019-06-04T10:55:30.278Z 466c2217-3fd7-4a2e-b97c-732866c5df54 Zappa Event: {'time': '2019-06-04T10:54:50Z', 'detail-type': 'Scheduled Event', 'source': 'aws.events', 'account': '530403937392', 'region': 'ap-southeast-1', 'detail': {}, 'version': '0', 'resources': ['arn:aws:events:ap-southeast-1:530403937392:rule/ht6minterface-dev-zappa-keep-warm-handler.keep_warm_callback'], 'id': 'c2ccca98-e69a-2f19-c398-4d123d24956c', 'kwargs': {}}
[1559645730279] [DEBUG] 2019-06-04T10:55:30.279Z 466c2217-3fd7-4a2e-b97c-732866c5df54 Zappa Event: {}
[1559645731280]
[1559645970227] [DEBUG] 2019-06-04T10:59:30.227Z ad604f41-5692-47b0-8e49-894f52afc56f Zappa Event: {'time': '2019-06-04T10:58:50Z', 'detail-type': 'Scheduled Event', 'source': 'aws.events', 'account': '530403937392', 'region': 'ap-southeast-1', 'detail': {}, 'version': '0', 'resources': ['arn:aws:events:ap-southeast-1:530403937392:rule/ht6minterface-dev-zappa-keep-warm-handler.keep_warm_callback'], 'id': '166fb665-ec39-526e-6ccb-47f1d8f083d3', 'kwargs': {}}
[1559645970227] [DEBUG] 2019-06-04T10:59:30.227Z ad604f41-5692-47b0-8e49-894f52afc56f Zappa Event: {}
[1559645971229]
Where am I wrong?

Answer 1

You're getting 502 because once deployed with API gateway, API gateway requires a very specific response from the Lambda, otherwise it will throw you a Malformed Lambda proxy response aka 502.
As mentioned in the documentation, you should make sure your Lambda is returning a response in the following structure (this must be a JSON):
{
"isBase64Encoded": true|false,
"statusCode": httpStatusCode,
"headers": { "headerName": "headerValue", ... },
"body": "..."
}

Answer 2

Move the apps according to jonvaughan
Another reference
Here is my working directory structure
$ tree -L 2
.
├── README.md
├── Visualization_Sarit
│   ├── BA_Read0DDataPlot1DGraph.py
│   ├── CC_ReadNew2DDataPlotLineGraph.py
│   ├── ModulesInterfaceTASK.py
│   ├── Visualization.docx
│   ├── Visualization.xlsx
│   └── inHT6Ms302
├── __init__.py
├── __pycache__
│   ├── api_urls.cpython-36.pyc
│   ├── celery_ht6m.cpython-36.pyc
│   ├── db_routers.cpython-36.pyc
│   ├── settings.cpython-36.pyc
│   ├── urls.cpython-36.pyc
│   └── wsgi.cpython-36.pyc
├── api_urls.py
├── apps
│   ├── __init__.py
│   ├── __pycache__
│   ├── advanced_cases
│   ├── commons
│   ├── control_params
│   ├── device_params
│   ├── heating_params
│   ├── plasma_params
│   ├── plasma_species
│   ├── results
│   ├── scenarios
│   └── transport_params
├── celery_ht6m.py
├── db_routers.py
├── experiments.py
├── f1
│   ├── README.md
│   ├── package-lock.json
│   ├── package.json
│   ├── public
│   └── src
├── manage.py
├── media
├── requirements.in
├── requirements.txt
├── settings.py
├── static
├── static_files
├── templates
│   ├── __init__.py
│   └── hello.html
├── urls.py
├── wsgi.py
└── zappa_settings.json