flask python web app using docker in azure app service.
- Azure subscription and account
- python 3.6 - anaconda distribution
- Visual studio code
- Docker account
- azure sql server database
Replace this in webapp.py with your info
server = <database server>
database = <database name>
username = <user name>
password = <password
set RUNENV=local
conda create -n flask
conda activate flask
pip install -r requirements.txt
python webapp.py
Docker is useful for consistency in prod and local testing. This is also useful if you want to install additional softwares/drivers in azure app service.
steps
- Commands to test docker locally
docker build -f dockerfile --rm -t flaskwebapp:latest . docker run -p 5000:5000 --rm flaskwebapp docker ps docker stop
-
Commands to test docker locally
docker build -f dockerfile --rm -t flaskwebapp:latest . docker run -p 5000:5000 --rm flaskwebapp docker ps docker stop <CONTAINER ID> -
Login to registry instance (docker hub or ACR) in local machine
Tutorial : Azure container service
docker login --username <username> --password <password> <login server>
- Push docker image to azure container service
Follow tutorial: Azure container service
docker images
docker push krishancontainerregistry.azurecr.io/myrepo/flaskwebapp:v1
Right click. Run docker instance from the repo. I think it runs the docker instance in some shared resource. Use port 5000 Ping does not work in docker (ICMP packet discarded). Try using telnet
- Azure app service using Docker images
Followed tutorial : Sample tutorial using dockerhub. Push to azure container services instead of docker hub
Define entry port to docker using PORT application setting. PORT is necessary to tell azure which port to connect to docker.
If I change it to 3000, this happens in app service logs.
docker run -d -p 62348:3000 --name dockerflaskwebappkrishan_1 -e PORT=3000
- Visual studio code and docker azure app service Install docker extention.
Tutorial: Docker using visual studio code
ctrl+shift+P docker build
or docker build --rm -f "Dockerfile" -t krishancontainerregistry.azurecr.io/myrepo/flaskwebapp:v1 . Run docker image as a container instance: docker run --rm -it -p 5000:5000 krishancontainerregistry.azurecr.io/myrepo/flaskwebapp:v1
- How to redeploy?
Push docker image and restart app service.
SQL server works fine locally , but since azure app service for python and docker image used both are in Linux, additional drivers needed to be installed.
ODBC for ubuntu machine https://www.microsoft.com/en-us/sql-server/developer-get-started/python/ubuntu/step/2.html
For debian install mysql drivers
RUN curl https://packages.microsoft.com/keys/microsoft.asc | apt-key add - \
&& curl https://packages.microsoft.com/config/debian/9/prod.list > /etc/apt/sources.list.d/mssql-release.list \
&& apt-get update \
&& ACCEPT_EULA=Y apt-get install msodbcsql17 -y \
&& apt-get install unixodbc-dev
SQL Alachemy config instruction:
SQL server works fine using flask web server in local machine and docker. But once attached to UWSGI, it throws error
pyodbc.Error: ('IM004', "[IM004] [unixODBC][Driver Manager]Driver's SQLAllocHandle on SQL_HANDLE_HENV failed (0) (SQLDriverConnect)")
Related link: https://stackoverflow.com/questions/24444326/connecting-to-db2-databaseunixodbcdriver-managerdrivers-sqlallochandle-on
Fixed from uwsgi.ini remove
uid = 1000
Tutorial: Azure blob storage in python
Useful command to generate requirements.txt
pip freeze > requirements.txt
Folder structure is imprtant in python. Or it results in unexpected behaviour
Flask file structure demo https://scotch.io/tutorials/getting-started-with-flask-a-python-microframework