Search results

Matches found for tag 'Docker': 8

Docker on Debian / Ubuntu not respecting ufw firewall settings exposing ports

9 December 2019 by Peter

Again another unexpected Docker issue. In a previous post I described why and how you must force Docker to use a subnet, to prevent sudden unexpected changes in the network with consequences like mail no longer working. This post is about Docker not respecting firewall settings, at least when running Debian / Ubuntu and ufw (Uncomplicated Firewall). Docker does not tell you this, and exposes ports, ...
Read more

Docker containers suddenly using 192.168.0.0/16 instead of 172.17.0.0/16: services lost

27 November 2019 Updated 27 November 2019 by Peter

I have an ISPConfig server with Docker applications. They use the host Postfix mail transfer agent (MTA) to deliver mail to the outside world. Before using the send mail function I have a check if Postfix can be accessed. This works fine. But suddenly mail was not sent. The log file contained error messages like: 2019-11-26 17:31:56,758 ERROR MailMessage - send_mail: self.error_message = sending message, ...
Read more

How to set the timezone when using the Python Alpine Docker image

13 November 2019 by Peter

While writing an application on my Docker platform I hit an unexpected problem, yes, another one ... This was the first time that I had to show the time on a page of a website running on Docker and it appeared that the time was UTC instead of local time. In the code I was just using the normal Python calls to get the time: import datetime ... now = datetime.datetime.now() hour = now.hour ...
Read more

ISPConfig: running a Python Flask Docker container as a jailed Shell User

18 October 2019 Updated 18 October 2019 by Peter

I run a server with ISPConfig with some 50 sites. The sites are static or PHP. I am developing Python Flask applications now and also want to run them on the ISPConfig server. You can create virtual environments on the ISPConfig server and run your application from here. But some time ago I have chosen to use Docker for development, staging and production. It takes time to set this up ...
Read more

Another captcha implementation for Flask and WTForms

4 July 2019 Updated 29 August 2019 by Peter

In the past I wrote a captcha in PHP to limit email newsletter sign ups, worked fine, in fact it is still in use today. You cannot really block spam registrations. There are registration robots but there are also people being paid a few bucks to flood your website with fake or troll accounts. That is the reality and we have to face it. And now there is also deeplearning that can be used to break our ...
Read more

Sending mail from a Docker container using ISPConfig3 host Postfix MTA

28 June 2019 Updated 31 August 2019 by Peter

In the endless number of problems you encounter, and solve, when starting to use new technology I was facing a new one: how to send email from my Python Docker app using the ISPConfig host MTA (Mail transfer Agent). I found there are two ways to do this: Send mail from our container to port 25 of the host where the MTA is listening on Write the mail file to a directory on the host and use a script ...
Read more

Reducing the size of a Python application Docker image using Python wheels

10 March 2019 Updated 30 August 2019 by Peter

When using docker we want the size of the docker image to be minimal. Why? Many reasons. Memory footprint is one especially when running many Python Flask websites on an ISPConfig3 server. Fortunately, from docker 17.05 we can use multistage builds. Using this we reduce our image size from 376MB to 211MB! Below are two images we can use: > docker images python 3.6-alpine 1837080c5e87 5 ...
Read more

Python Flask app on Docker in ISPConfig3 with Nginx - Part 1: Minimal app

13 February 2019 Updated 31 August 2019 by Peter

This is a post showing how to run a Flask app on ISPConfig3. Why? I have a VPS on the internet running Debian and ISPConfig3. It is running static sites and PHP sites. But now I also want to run my Flask python apps here. This way I can use the domain management I am used to and do not need an extra server for Python apps. This solution uses Docker to run the Flask app, printing 'Hello world', and ...
Read more