Docker is an excellent technology used by almost all companies around the globe. This tutorial will explain how to pull your first container using Docker. We will be pulling a hello-world docker image from dockerhub. To follow along, I assume Docker is installed and running in your system.
Docker hello world example
Hello-world is the basic image, and the Docker community manages it. Hello, the world image will not create any container; it will just display the output, which shows your docker installation is OK.
Let’s proceed further and pull the hello-world image from dockerhub
Docker pull hello-world
Type the docker pull command to pull the hello-world image from the dockerhub
docker pull hello-world Using default tag: latest latest: Pulling from library/hello-world Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c Status: Image is up to date for hello-world:latest docker.io/library/hello-world:latest
If you wish to know more information about what docker pull does, please follow this link
Run the below command to verify if the images pull successfully
docker images REPOSITORY TAG IMAGE ID CREATED SIZE hello-world latest d1165f221234 3 months ago 13.3kB
docker images command will list the images that are present in your local system
Docker run hello-world
The docker run command starts the docker container from the docker image. Let’s run the hello-world image and verify the output:
docker run hello-world
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/excellent; if you are getting above output, your hello-world containers are running as expected.
Docker hello-world github
You can visit the Docker hello-world github page to learn more about how this hello-world dockerfile has been written.
The hello-world docker image supports various architectures like amd64,arm32v7,arm32v5 arm64v8, windows-amd64, etc. The hello-world github page has a dockerfile for all the supported architecture.
Docker hello-world windows
Docker is a containerization platform that will perform the same irrespective of where you are installing the image. So to spin up a hello-world docker for windows, we have to follow the same steps we have followed for any other os version.
You can follow this link to install Docker on windows. Once the Docker is successfully installed, you can type the below command to pull the hello-world docker image from the github
docker run hello-world
You would get the below output if your docker installation were proper.
docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete
Digest: sha256:cc15c5b292d8525effc0f89cb299f1804f3a725c8d05e158653a563f15e4f685
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
Docker Hello-world Nginx
In the above session, we have seen how to pull the basic Hello-world docker image from the dockerhub, which is basically used to verify if your docker installation is working as expected.
Now it’s time to move further and pull the Nginx image from the dockerhub. Nginx image is another basic hello-world image that developer uses extensively.
Type the below command to pull the nginx image
docker pull nginx Using default tag: latest latest: Pulling from library/nginx a2abf6c4d29d: Pull complete f3409a9a9e73: Pull complete 9919a6cbae9c: Pull complete fc1ce43285d7: Pull complete 1f01ab499216: Pull complete 13cfaf79ff6d: Pull complete Digest: sha256:366e9f1ddebdb844044c2fafd13b75271a9f620819370f8971220c2b330a9254 Status: Downloaded newer image for nginx:latest docker.io/library/nginx:latest
Now type the below command to run the nginx image
docker run --name my_nginx -d -p 8081:80 nginx:latest 0b1cd7ba9cd2b5933f749b62d6d5e633f20266a1a5876843f87d8eec1009217c
Goto localhost:8081 to access the nginx UI.
A more detailed explanation of the nginx image can be found here
Hello world python docker image
So far, we have understood how to build the docker image, which is readily available in the dockerhub.In this session, we will understand how to build a python docker image from scratch.
To create a custom docker image. create a folder name python-hello-world
mkdir python-hello-world
Now create a dockerfile and paste the below content
FROM python:3.7 ADD helloworld.py / CMD [ "python", "./helloworld.py"]
Dockerfile Explanation:
- we have used python:3.7 as a base image
- In the second step, we copied the helloworld.py file to the / directory.
- finally, in the last step, we are running the helloworld.py file
You can check my other blogs to fully understand how to write a dockerfile and the essential things that need to be taken care of while writing one.
Now, Create another file, helloworld.py, and paste the below content
print("Hello from Naive-skill")verify if the python-hello-world folder contains the below files
dockerfile helloworld.py
Build the docker image by typing the below command
docker build --tag python-hello-world . Sending build context to Docker daemon 3.072kB Step 1/3 : FROM python:3.7 3.7: Pulling from library/python 0e29546d541c: Pull complete 9b829c73b52b: Pull complete cb5b7ae36172: Pull complete 6494e4811622: Pull complete 6f9f74896dfa: Pull complete fcb6d5f7c986: Pull complete 7a72d131c196: Pull complete c4221d178521: Pull complete 71d5c5b5a91f: Pull complete Digest: sha256:d9abbc0737ff8d23a546859c85903f1b8235a1495a405d5a47cbc55747f27b20 Status: Downloaded newer image for python:3.7 ---> ad37de9b03ef Step 2/3 : ADD helloworld.py / ---> ae8f839bb059 Step 3/3 : CMD [ "python", "./helloworld.py"] ---> Running in 305cdb634f91 Removing intermediate container 305cdb634f91 ---> 9d426cc74961 Successfully built 9d426cc74961 Successfully tagged python-hello-world:latest Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them
Now run the docker image by typing the below command
docker run python-hello-world Hello from Naive-skill
Conclusion
In this blog, we have understood the hello-world docker file and explored nginx and python hello-world images. I hope you liked this basic docker hello-world tutorial. Feel free to ask your valuable questions in the comments section below.
