Container docker-jpwshd-debian

tldr : Quickstart

Clone repo

1. cd into your development directory
2. git clone git@github.com:jwesemann/docker-jpwshd.git
3. cd docker-jpwshd

Build docker image weseit/pwshd

1. cd devdir/
2. Look into Dockerfile (amd64) or Dockerfile-armv8 (armv8) and update the URL of the wget-command to point to the latest powershell package available.
3. Start the build script for your current architecture, e.g. ./dobuild.sh for amd64
4. Check output and resulting image: docker image ls shoud give you one line containing weseit/pwshd

Run container with persistent data-directories

1. ./run.sh
2. ctrl-c to interrupt the tail -f
3. ./log.sh to show container log output. Or use your vaforite management tool.

Data location

• All my docker containers use a directory datadir/ as a base config directory.
• This container uses datadir/workdir/ which is mounted at runtime into the container as /root/workdir/
• Running script can be found in datadir/workdir/JMonitor.ps1
• Datafile with recorded ping-values is located @ datadir/workdir/JMonitor.csv

Overview

This small framework can be used to start (looping) Powershell-Scripts in a well defined unix server environment acting as "server daemons".

It uses a debian Docker-image from Microsoft Powershell team with additional German locales to start a script (default or configured by environment variable). Please visit https://hub.docker.com/_/microsoft-powershell for more information about these Docker-images.

To make this implementation run on ARM devices like the Raspberyy PI-4 (my development environment) I added 2nd Dockerfile-armv8 which is not dependent on the Microsoft Docker image anymore but only on the official Debian image debian:latest. It will install powershell into /root/powershell and run /root/powershell/pwsh . Please visit https://hub.docker.com/_/debian to get more information on the used Debian image.

The included script JMonitor.ps1 periodically pings (ICMP request) a well defined webserver and writes the times needed into a CSV-file. Any pre-existing files will be reused (not overwritten) and the output data will be appended to the CSV-file.

In general this Dockerfile and the underlying simple scripts should run in several environments : Windows 10/11 native, Windows 10/11 WSL Ubuntu 20.04, Synology DSM718+, Kali-Linux native . I plan to extend this to be an multi-architecture docker image for my Raspberry 3/4 but need some learning how to achieve this.

Startup-Hook

The startup-hook is an implicite one. A standard Powershell profile Microsoft.PowerShell_profile.ps1 will be copied into the default directory /home/root/.config/powershell during image-building based on the Dockerfile).

It checks environment variable PWSHSCRIPTFILE and directory /root/workdir which should be mounted into the container from the docker host to decide which specific Powershell-script will be started as the main looping script.

The shell-code within this script makes sure that the main functional loop will only be started if no other instance of a pwsh-process is already running within its container. This behavior makes it possible to attach an interactive terminal using powershell as its shell into the running conatiner for debugging purposes.

Files in devdir

• Dockerfile : Create image script for amd64based machines
• dobuild.sh : Starts the docker build sequence based on debian:stable-slim for amd64 based machines.
• Dockerfile_armv8 : based on Debians docker image. Will add Powershell with own install routines. So no dependency on Microsoft docker repo anymore.
• dobuild-armv8.sh : Starts the docker build sequence based on debian:stable-slim for armv8based machines.
• Microsoft.PowerShell_profile.ps1 : Powershell autostart-script containing the main startup-logic. Needs to be placed in /root/.config/powershellto start automatically.
• JStandard.ps1 : small Powershell-script which will be copied from the image into workdir and being started if no valid combination to run from the environment-variable and directory-content is found. Will just show a short info message and exit. If this script is being used the container-restart-policy should be set to --restart=on-failure:3 to avoid endless restart tries.
• JMonitor.ps1 : The initial payload-script I wrote for my client PC to monitor ICMP-performance of my internet connection. It is based on a much older NT-CMD version. Target of this project was to make this functionality available in docker on my different servers (Synology NAS 718+, Raspberry Pi, Windows) to run 24/7/365 independently from my client workstation. I already collected > 1 million data points giving me an interesting overview over the behavior and quality of the internet line and the reliability of my internal network (router / NAS downtimes)
• Currently missing in this repo: My private reporting MS-Excel sheet using the CSV as a database input and showing the graphical output. I plan to use the CSV to learn about Grafana/InfluxDB later if I find some time. But for now Excel does the job. A demo output can be found at this screenshoot .