Docker in 100 Seconds
What is Docker?
- Docker: A tool to package software into containers that run reliably in any environment.
Understanding Containers
- Container: A lightweight, standalone, executable package of software that includes everything needed to run it: code, runtime, system tools, libraries, and settings.
- Purpose: Ensures software behaves the same regardless of where it is run.
Containers vs. Virtual Machines (VMs)
- Virtual Machine:
- Hardware is simulated.
- Runs a full operating system (OS).
- Bulky and slow due to the overhead of running multiple OS.
- Container:
- Only virtualizes the OS, not the hardware.
- Multiple containers share the same OS kernel.
- More efficient and faster than VMs.
Key Components of Docker
- Dockerfile:
- Acts like DNA: code that tells Docker how to build an image.
- Starts with a base image (e.g., Ubuntu).
- Image:
- A snapshot of software along with all its dependencies.
- Immutable.
- Used to create containers.
- Container:
- The actual running instance of the image in the real world.
Creating a Docker Image
- Dockerfile:
- Use
FROM to start from an existing template like Ubuntu.
- Use
RUN to install dependencies.
- Set environment variables.
- Define a default command to execute when the container starts.
- Building the Image:
- Command:
docker build
- Builds the image layer by layer.
- Running the Container:
- Command:
docker run
- Starts the container from the built image.
Advantages of Docker
- Portability: Run containers on multiple machines, clouds, on-premises, etc., reliably.
- Efficiency: Faster startup and better resource utilization compared to VMs.
Conclusion
- Docker simplifies application deployment and scaling.
- Stay tuned for more content on Docker.
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