What is Docker? - Definition & Meaning

Definition

Docker is an open-source platform for building, distributing, and running applications in containers. A container packages an application with all its dependencies into an isolated, portable unit that works consistently across any environment — from a developer laptop to a production server.

Technical explanation

Docker uses OS-level virtualization via Linux namespaces (for isolation) and cgroups (for resource limitation) to create lightweight containers that share the host system's kernel. Unlike virtual machines, a container doesn't have its own operating system, allowing them to start in milliseconds with minimal overhead. Core concepts include: Dockerfile (a recipe for building a container image), Docker Image (a read-only template with the application and dependencies), Docker Container (a running instance of an image), Docker Registry (e.g., Docker Hub for storing and sharing images), and Docker Compose (a tool for defining and running multi-container applications via a YAML file). Docker Compose is particularly useful for complex stacks: you define the chatbot application, database, vector database, and reverse proxy as services in a docker-compose.yml file and start everything with a single command. Volumes are used for persistent data storage, networks for communication between containers, and health checks for automatic monitoring.

How OpenClaw Installeren applies this

OpenClaw Installeren uses Docker and Docker Compose as the foundation for every AI assistant deployment. The complete chatbot stack — application, database, vector database, and optionally Ollama for local LLMs — is defined in a docker-compose.yml file and runs as isolated containers on your VPS. This makes updates simple (pull new image and restart), ensures reproducibility, and simplifies troubleshooting.

Practical examples

• An AI chatbot stack running three containers via Docker Compose: the Node.js chatbot application, a PostgreSQL database with pgvector for embeddings, and an Nginx reverse proxy for SSL termination.
• A developer reproducing the exact production environment locally with "docker compose up," so bugs occurring on the server can also be reproduced and fixed locally.
• A team automatically building a new Docker image on every code change via a CI/CD pipeline, pushing it to Docker Hub, and automatically deploying it to the production VPS.

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