AWS elastic beanstalk deploy always fails (uploading a zipfile) - python-3.x

Question

I upload a new version of my app as a zipfile and click deploy. Then the status changes to severe.
This is the error trace:
WARN
Environment health has transitioned from Info to Degraded. Command failed on all instances. Incorrect application version found on all instances. Expected version "Sample" (deployment 2). Application update failed 10 seconds ago and took 4 minutes.
ERROR
During an aborted deployment, some instances may have deployed the new application version. To ensure all instances are running the same version, re-deploy the appropriate application version.
ERROR
Failed to deploy application.
ERROR
Unsuccessful command execution on instance id(s) 'i------'. Aborting the operation.
ERROR
[Instance: i-002326d7ceeba0ea9] Command failed on instance. Return code:
1 Output: nginx: [emerg] no host in upstream ":80" in /etc/nginx/conf.d/elasticbeanstalk-nginx-docker-upstream.conf:
2 nginx: configuration file /etc/nginx/nginx.conf test failed Failed to start nginx, abort deployment.
Hook /opt/elasticbeanstalk/hooks/appdeploy/enact/01flip.sh failed.
For more detail, check /var/log/eb-activity.log using console or EB CLI.
ERROR
Failed to start nginx, abort deployment
/var/log/eb-activity.log
here are errors in this log:
[0mInstalling dependencies from Pipfile.lock (5e00f3)…
Failed to load paths: /bin/sh: 1: /root/.local/share/virtualenvs/app-lp47FrbD/bin/python: not found
...
[2020-05-29T01:51:24.746Z] INFO [11395] - [Application update v1.3.3-1#3/AppDeployStage1/AppDeployEnactHook/00run.sh] : Completed activity. Result:
jq: error (at <stdin>:1): Cannot iterate over null (null)
a2f568b1c255eb9e0fdc6ceebdd29b9ec64b9ab4481a3e1c5bcb11828b0ac526
[2020-05-29T01:51:24.747Z] INFO [11395] - [Application update v1.3.3-1#3/AppDeployStage1/AppDeployEnactHook/01flip.sh] : Starting activity...
[2020-05-29T01:51:26.099Z] INFO [11395] - [Application update v1.3.3-1#3/AppDeployStage1/AppDeployEnactHook/01flip.sh] : Activity execution failed, because: nginx: [emerg] no host in upstream ":80" in /etc/nginx/conf.d/elasticbeanstalk-nginx-docker-upstream.conf:2
nginx: configuration file /etc/nginx/nginx.conf test failed
Failed to start nginx, abort deployment (ElasticBeanstalk::ExternalInvocationError)
caused by: nginx: [emerg] no host in upstream ":80" in /etc/nginx/conf.d/elasticbeanstalk-nginx-docker-upstream.conf:2
nginx: configuration file /etc/nginx/nginx.conf test failed
Failed to start nginx, abort deployment (Executor::NonZeroExitStatus)
...
[2020-05-29T01:51:26.099Z] INFO [11395] - [Application update v1.3.3-1#3/AppDeployStage1/AppDeployEnactHook/01flip.sh] : Activity failed.
[2020-05-29T01:51:26.099Z] INFO [11395] - [Application update v1.3.3-1#3/AppDeployStage1/AppDeployEnactHook] : Activity failed.
[2020-05-29T01:51:26.099Z] INFO [11395] - [Application update v1.3.3-1#3/AppDeployStage1] : Activity failed.
[2020-05-29T01:51:26.100Z] INFO [11395] - [Application update v1.3.3-1#3] : Completed activity. Result:
Application update - Command CMD-AppDeploy failed
The inability to deploy has been consistent for this environment, after several attempts, even reverting to an older version.

Answer 1

Afterwards, I resolved this by isolating the code and error messages using a local docker image with the zipfile. Running the code on my machine outside of docker did NOT reveal any problems, because the pip / pipenv part was missing some depdendency.
Steps for local docker testing:
WITHIN a docker container:
docker system prune
Go to the folder with Dockerfile
docker image build -t <app_name>:<version_number> .
TO run locally:
(docker rm <app_name> first, if you've already got a stopped container with the same name from prior testing)
docker container run --publish 80:80 --name <app_name> myapp:1.0
NOTE:
this won't let you test AWS functions that require environment variables, such as ~.aws credentials because they're not inside the image.
(but you could add them with your Dockerfile)
Once the docker container is running, you'll see (I saw) error messages that were not there when testing locally, because they were caused by a missing package dependency and a pipenv error.