Creating a Docker Image for your Application

This is the recommended workflow for creating your own Docker image for your application:

  1. Write a Dockerfile for your application.
  2. Build the image with docker build command.
  3. Host your Docker image on a registry.
  4. Pull and run the image on the target machine.

Write the Dockerfile

Docker builds images automatically by reading the instructions from a Dockerfile. It is a text file that contains all commands needed to build a given image.

In the following example, we will build and run the Hello ZED tutorial application in a container.

First let’s prepare the host with the code:

$ git clone https://github.com/stereolabs/zed-examples.git
$ cd zed-examples/tutorials/tutorial\ 1\ -\ hello\ ZED/

Open a text editor and create a new Dockerfile with the following content:

# Specify the parent image from which we build
FROM stereolabs/zed:3.7-gl-devel-cuda11.4-ubuntu20.04

# Set the working directory
WORKDIR /app

# Copy files from your host to your current working directory
COPY cpp hello_zed_src

# Build the application with cmake
RUN mkdir /app/hello_zed_src/build && cd /app/hello_zed_src/build && \
    cmake -DCMAKE_LIBRARY_PATH=/usr/local/cuda/lib64/stubs \
      -DCMAKE_CXX_FLAGS="-Wl,--allow-shlib-undefined" .. && \
    make

# Run the application
CMD ["/app/hello_zed_src/build/ZED_Tutorial_1"]

We provide some extra arguments to CMake to ensure that CMake and GCC can find all the required CUDA libraries. We also tell the compiler to allow linking even if there are undefined symbols from libraries such as nvcuvid that are not yet available. These will be available at runtime using NVIDIA container toolkit.

For more information on writing dockerfiles, check Dockerfile reference documentation.

Build your Docker Image

Now that you have created a Dockerfile, it’s time to build your image using the docker build command.

$ docker build -t hellozed:v1 .

Tips: On NVIDIA Jetson, we recommend building your Jetson Docker Container on x86 host, and running it on the target Jetson to avoid long compilation time on boards such as Jetson Nano.

Test your Image

Let’s start the container based on the new image we created using the docker run command.

$ docker run -it --gpus all -e NVIDIA_DRIVER_CAPABILITIES=all --privileged hellozed:v1

On Jetson or older Docker versions, use these arguments:

$ docker run -it --runtime nvidia --privileged hellozed:v1

You should now see the output of the terminal.

$ docker run -it --gpus all --privileged hellozed:v1
    Hello! This is my serial number: 23468248

Optimize your Image Size

Docker images can get very large and become a problem when pulling over the network or pushing on devices with limited storage (such as Jetson Nano). Here are a few advice to keep your image size small:

  • Minimize the number of RUN commands. Each command adds a layer to the image, so consolidating the number of RUN can reduce the number of layers in the final image. Note that layers are designed to be reusable, and will not be pushed or pulled if they didn’t change.

  • Use --no-install-recommends when installing packages with apt-get install to disable installation of optional packages and save disk space.

  • Remove tarballs or other archive files that were copied during the installation. Each layer is added on top of the others, so files that were not removed in a given RUN step will be present in the final image even if they are removed in a later RUN step.

  • Similarly, clean package lists that are downloaded with apt-get update by removing /var/lib/apt/lists/* in the same RUN step.

  • Create separate images for development and production. Production images should not include all of the libraries and dependencies pulled in by the build.

  • Use multi-stage builds (see Docker docs) and push only your prod image.

RUN apt-get update -y && \
    apt-get autoremove -y && \
    apt-get install --no-install-recommends lsb-release && \
    tar -xvf archive.tar.gz &&\
    rm -rf /var/lib/apt/lists/* && \
    rm -rf archive.tar.gz

RUN apt-get update
RUN apt-get autoremove -y
RUN apt-get install lsb-release
RUN tar -xvf archive.tar.gz

Host your Docker Image

Now that you have created your image, you need to share it on a registry so it can be downloaded and run on any destination machine. A registry is a stateless, server-side application that stores and lets you distribute Docker images.

Use Docker Hub Registry

By default, Docker provides an official free-to-use registry, DockerHub, where you can push and pull your images. For example at Stereolabs, the ZED SDK Docker images are built automatically by a public Gitlab CI job and pushed to Stereolabs DockerHub repository.

There are situations where you will not want your image to be publicly available. In this case, you need to create your own private Docker Registry. You can get private repos from Docker, or from many other third-party providers.

Use Local Registry Server

For local development, if your host and target machines are on the same network, you can setup a local registry server and push your images there.

For more information on deploying your own registry server, please refer to Docker docs.

Save and Load Images as Files

Lastly it is also possible to export and load your Docker image as a file.

To export a Docker image simply use :

# Saving can take some time depending on the image size
$ docker save hellozed:v1 -o hellozed_v1.tar

On the destination machine, simply load the Docker image using :

$ docker load -i hellozed_v1.tar

cc967c529ced: Loading layer [==================================================>]  65.57MB/65.57MB
2c6ac8e5063e: Loading layer [==================================================>]  991.2kB/991.2kB
6c01b5a53aac: Loading layer [==================================================>]  15.87kB/15.87kB
e0b3afb09dc3: Loading layer [==================================================>]  3.072kB/3.072kB
37b9a4b22186: Loading layer [==================================================>]   17.1MB/17.1MB
dd841c774a30: Loading layer [==================================================>]  29.22MB/29.22MB
52ad947270f1: Loading layer [==================================================>]  3.072kB/3.072kB
4e3516398cef: Loading layer [==================================================>]  793.6MB/793.6MB
582ab80c9f26: Loading layer [==================================================>]  1.394GB/1.394GB
85fd2f8b4dc8: Loading layer [==================================================>]  3.727GB/3.727GB
d5bd3dceedb5: Loading layer [==================================================>]  222.1MB/222.1MB
f6b7ec875383: Loading layer [==================================================>]  2.048kB/2.048kB
eef68a3e44c4: Loading layer [==================================================>]  11.78kB/11.78kB
2b29f57c8c23: Loading layer [==================================================>]  930.3kB/930.3kB
Loaded image: hellozed:v1

Next Steps

At this point, you have successfully created a Docker image for the “Hello ZED” application and learnt how to host and share it.

Let’s learn now how to Run and Build Jetson Docker Containers on x86 to speed up development and deployment on embedded boards such as Jetson Nano, without needing cross compilation.

If you are not planning to use a Jetson board, you can learn how to use OpenCV with ZED in a Docker container or you can learn how to use the robotics framework ROS in a Docker container.