Building Containers

HCC2 applications are deployed using Docker containers. The following sections give a brief overview of this process. For more detailed descriptions of Docker, refer to Docker.com.

Example Dockerfile

In your development environment, run the following command:

cd $HOME/restapi_sample_interface

Edit the file Dockerfile. Configure this file to accommodate your specific app requirements.

The following Dockerfile is built for this app example.

# Build stage
FROM qratehcc2sdk.azurecr.io/python:3.12-slim-2024-04-19-debugbuild AS builder-image  
# Creates a non-root user with an explicit UID and adds permission to access the /app folder
# For more info, refer to https://aka.ms/vscode-docker-dotnet-configure-containers
RUN useradd -d /app -M -s /sbin/nologin -u 5678 -U appuser
USER appuser:appuser

FROM base AS slim
# Environment variable needed for read-only filesystem
ENV COMPlus_EnableDiagnostics=0

WORKDIR /app
COPY requirements.txt .
RUN pip3 install -r requirements.txt && pip3 install typing-extensions --upgrade

RUN mkdir classes/ & \
mkdir config/ & \
mkdir lib/ & \
mkdir data/ & 

COPY --chown=appuser:appuser *.py ./ 
COPY --chown=appuser:appuser config/ config/
COPY --chown=appuser:appuser classes/ classes/
COPY --chown=appuser:appuser lib/ lib/
COPY --chown=appuser:appuser data/ data/

COPY --chown=appuser:appuser entry_point.sh .
RUN chmod +x entry_point.sh
USER root:root
RUN install -o appuser -g appuser -d -m 0755 /tmp
RUN install -o appuser -g appuser -d -m 0755 /app/config
USER appuser:appuser
ENTRYPOINT ["./entry_point.sh"]

LABEL org.opencontainers.image.authors="NGRTU Team <ngrtuteam@sensiaglobal.com>" \
      org.opencontainers.image.vendor="Sensia Global" \
      org.opencontainers.image.url="https://www.sensiaglobal.com/" \
      org.opencontainers.image.license="Propietary" \
      com.sensiaglobal.image.artifacts.source="sensia-edge-docker-dev"

Creating Images Locally (Docker Desktop)

The Docker build command is used to build a Docker image. If a filename is not provided, the Dockerfile for the current path is used:

docker build . -t <<name>>/<<app name>>:<<tag>>

To use an alternative Docker file, enter the following:

docker build . -f <<filename>> -t <<name>>/<<app name>>:<<tag>>

where:

• <<app name>> is your app name (in this example, courseapp). Make sure yours is unique, e.g., <initials>_<app>_<version>
• <<tag>> is the tag you assign to this container for use in later stages.
• <<filename>> is the name of the Docker file. The default is 'Dockerfile'.
• --no-cache can be added to the Docker build command to recreate the image several times. It ensures that Docker does not use any cached layers during the build process, and that each build step retrieves the latest versions of dependencies and avoids potential inconsistencies.

sudo docker image ls

Building From Visual Studio 2022

You can build your Docker image from Windows using Visual Studio if you desire. The prerequisites are:

• Visual Studio
• WSL v2 with Ubuntu
• Docker Desktop

To build a Visual Studio HCC2 application:

1. Build and compile your C# application, testing as required with a Modbus server simulator (to replicate a HCC2) or a physical HCC2 device.

2. Add Docker support to your project OR build your own Dockerfile.

3. From WSL, navigate to your project folder (in the /mnt/<<windows path>>)

4. Run the Docker build command as described above.

   sudo docker build . -t <<name>>/<<app name>>:<<tag>>