Dockerfile

• A Dockerfile is a text file that contains instructions for building a Docker image.

• The instructions in a Dockerfile tell Docker how to create a containerized application.

• Dockerfile instructions include things like copying files, running commands, and setting environment variables.

• Once a Dockerfile is created, it can be used to build a Docker image using the docker build command.

• The Docker image created from a Dockerfile can be used to create and run Docker containers on any machine that supports Docker.

  

  [Here docker file holds the instructions, when we do a docker build for this docker file, the image gets created]

  Advantages:

• Consistent environments: ensures that all team members are working in the same environment, reducing issues caused by differences in system configuration and software versions.

• Resource efficiency: uses fewer resources than traditional virtual machines, allowing for multiple containers to run on the same machine without impacting performance.

• Scalability: makes it easy to scale applications up or down as needed, saving resources and reducing costs.

• Portability: can be run on any machine that supports Docker, making it easy to move applications between different environments and cloud providers.

• Security: provides a secure runtime environment for applications, reducing the risk of security vulnerabilities and providing tools for scanning images for security vulnerabilities and configuring security settings for containers.

  Why should we use the docker file?

• Improved productivity: With Docker and Dockerfiles, developers can quickly build and test applications in a consistent environment, without having to worry about differences in system configurations. This can save time and improve productivity.

• Reduced risk: Docker makes it easy to deploy applications to different environments, such as development, testing, and production, without having to worry about differences in system configurations. This can help reduce the risk of deployment errors and improve the quality of the final product.

• Cost savings: Docker containers use fewer resources than traditional virtual machines, which can help reduce infrastructure costs. Docker also makes it easy to scale applications up or down as needed, which can help save resources and reduce costs.

• Portability: Docker containers are portable and can be run on any machine that supports Docker. This makes it easy to move applications between different environments and cloud providers, which can help reduce vendor lock-in and make it easier to switch providers.

• Security: Docker provides a secure runtime environment for applications, which helps reduce the risk of security vulnerabilities. Docker also provides tools for scanning images for security vulnerabilities and configuring security settings for containers.

Tasks:

1. Create a Dockerfile for a simple web application
   step 1: create a folder and a file in it, where the file doesn't contain any extensions.

   

   

   

   

   step 2: Creating base image ubuntu [add instructions in the docker file as shown below and use cat command to display contents]

   

2. Build the image using the Dockerfile and run the container

   step 1: Build a docker file to create an image, and -t is used for the tag

   

   step 2: Display images

   

   step 3: Run the image to create a container

   

   step 4: Type docker ps command to see your running container

   

3. Verify that the application is working as expected by accessing it in a web browser

   

4. Push the image to a public or private repository (e.g. Docker Hub )

   use these below commands to push into the repo
   step 1: login to docker using docker login command

   

   step 2: Create a New Tag for a Docker Image using docker tag Command

   

   [The above command is tagging the Docker image named "mynginx" with tag "1" with a new name "vrishnishreevb/mynginx" and tag "1". This will create a new image with the name "vrishnishreevb/mynginx" and tag "1", which is a copy of the original image "mynginx:1"]

   step 3: Now push into the docker registry as shown below

   

   [This command pushes the Docker image named "vrishnishreevb/mynginx" with tag "1" to a Docker registry]

   Now, browse the docker hub and check the repositories

   

Thank you so much for reading.

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