Download Hello World Docker Image

Using Codefresh pipelines

Hello world Python Flask application Dockerized. Contribute to shekhargulati/python-flask-docker-hello-world development by creating an account on GitHub.

  • Sep 19, 2017 To find out more about a Docker image, run docker image inspect alpine. In the demo above, you used the docker image pull command to download the alpine image. When you executed the command docker container run hello-world, it also did a docker image pull behind the scenes to download the hello-world image.
  • $ g -o hello hello.cpp $./hello Hello, Red Hat Developer Program World! For more information, see the GNU C Compiler section of the Red Hat Developer Toolset 7 User Guide. Docker-formatted container images.
  • Jun 29, 2020 Once you know which image you’d like to install, you can use the following command to instruct Docker to download the desired software. Just as an example, we’ll install the hello-world package which can be used to make sure that Docker is able to download and run images successfully. $ docker pull hello-world.

Codefresh can work with Go projects of any version using built-in modules or any other dependency mechanism.

The example golang project

You can see the example project at https://github.com/codefresh-contrib/golang-sample-app. The repository contains a simple Golang web application including unit tests. There are 3 Dockerfiles available:

  • Simple Dockerfile (with old Go version that requires GOPATH building)
  • Dockerfile with Go modules (optimized for Docker caching)
  • Multi-stage Dockerfile (with Go modules and unit tests)

Let’s see these workflows in order.

Simple Docker image pipeline

The most simple pipeline that you can create is just two steps. A clone step to fetch the code and a build step to create a Docker image.

codefresh.yml

Once you run this pipeline Codefresh will create a Docker image for the Golang application:

The big advantage of this workflow is that the Dockerfile you use can define any Go version and dependency tool. As long as the Dockerfile is self-contained (i.e. it compiles GO on its own), the pipeline will work as expected.

In the example application, the simple (unoptimized) Dockerfile has an old Go version that still requires GOPATH folders.

Dockerfile

Run unit tests as part of the pipeline

If you want to run Go specific steps in your pipeline, you can use freestyle steps with any GO image that you want. If your GO application is using GO modules, this is even easier as you don’t need to place the application into a specific GOPATH compliant directory first.

This pipeline is running unit tests as a separate step and then builds the docker image.

codefresh.yml

If the unit tests fail, then the docker image will never be created (Codefresh automatically stops a pipeline when there is an error).

Notice that in this case we have added module support in the Go application. The new Dockerfile is the following:

Dockerfile

The Dockerfile will also automatically take advantage of the Codefresh distributed docker cache.

Create a multi-stage Docker image for GO

Download Hello World Docker Image

Especially with Go applications, the recommended way to create Docker images is with multi-stage builds. This makes the resulting Docker image as compact as possible.

You can also embed unit tests in the Docker creation process, which guarantee the correctness of image (integration tests are best kept in the pipeline).

Image

Hello World Movie

Here is the new Dockerfile:

Dockerfile

Codefresh has native support for multi-stage builds. The pipeline is the same as the first one with just two steps.

codefresh.yml

You should see a much smaller Docker image at the end.

Viewing Docker images

World

If you look at your Docker registry dashboard created the advantages of the multi-stage build are very clear:

We recommend using Go modules and multi-stage builds in your Go projects.

Hello World Anime

What to read next

We will see here how to install Docker on Windows and how to create a Java hello world in Docker .

Download and install Docker

To install Docker on Windows you must first download Docker from this URLhttps://docs.docker.com/compose/insta

Choosing the option Get Docker Desktop for Windows true the option to download
https://docs.docker.com/docker-for-windows/install/

It will ask you to register with your ID and password. If you don’t have one, you must create your account.

Once you have login you will see the button for downloading the installer.

After starting the downloaded file, the installer will ask you if you prefer to use Docker with a Windows or Linux software.The best option is Linux. This can be changed later.Chosen this will begin the unpacking of Docker

Once the installation is finished, open Docker Desktop to start docker and let it run.

You will see the docker icon in the notification area.There you can enter with your ID and password and set general docker settings.The default options are sufficient for this example.

Now you can check your Docker installation.Open a cmd terminal, PowerShell or CMD, and check typing:

How to create a hello world with Docker

From Windows CMD terminal run this:

This will download a hello world sample container from the docker hub and execute it.

You can execute this container later like this:

docker run hello-world

How to create your first docker file

Download Hello World Docker Image

Download Hello World Docker Image For Windows 10

Let’s see now how to create your first dockerfile.A dockerfile is a file with instructions for Docker to create a container that we can execute with the configuration and software we need.We are going to create a docker with a Linux image and run a hello world in java.

First create your HelloWorld in Java, compile and run it.

Download Hello World Docker Image

Then create your dockerfile file with the following instructions

Let’s analyze this dockerfile file:

    • FROM * alpine: latest - This instruction does add an Alpine linux to our docker. Alpine linux is a linux that weighs just about 5MB
    • ADD * HelloWorld.class HelloWorld.class - We add the file HelloWorld.class to our image with the same original name.
    • RUN * apk –update add openjdk8-jre - Install java *, specifically an openjdk to our docker image.
    • ENTRYPOINT * [“java”, “-Djava.security.egd = file: / dev /./ urandom”, “HelloWorld”] - Will execute our HelloWorld code.

How to run your first dockerfile

Now we build a dockerfile to create our image.Here we say make a dockerfile build with the name docker-hello-world and the tag (tag) latest

Now execute:

We will see our image created and available to be used.

Now we can run docker with this image and see the result.

Conclusion

You have seen here how to install Docker and verify that it is correctly installed.You have also created your first dockerfile to run a hello world made in Java inside the container.

Download Hello World Docker Images

We have seen some basic commands:

  • docker build command: to create a docker image.
  • docker run command: to execute a docker image.
  • docker images command: to see the created docker images.

You can see this code in:
https://github.com/gustavopeiretti/docker-hello-world-java-example
https://gitlab.com/gustavopeiretti/docker-hello-world-java-example

Download Hello World Docker Image File

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