Docker Containers and Storage Overview

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Questions and Answers

What occurs to changes in a container's state that are not stored in persistent storage when the container is removed?

Changes are transferred to another running container.

Changes remain intact for future use.

Changes are saved to a temporary filesystem.

Changes disappear permanently. (correct)

Which of the following statements is true regarding tmpfs storage in containers?

Tmpfs data is permanently stored and accessible after stopping a container.

Tmpfs data is written to the host’s memory and deleted when the container stops. (correct)

Tmpfs storage is always more reliable than Docker volumes.

Tmpfs storage can be shared among containers running on any operating system.

What is a primary characteristic of Docker containers regarding isolation?

Containers are well isolated from each other and the host machine. (correct)

Containers can easily access each other's storage and network configurations.

Containers have complete access to the host's file system.

Containers do not support networking capabilities.

What does the mount flag do when creating a tmpfs volume?

<p>It supports multiple options during container startup. (A)</p> Signup and view all the answers

What role do storage plugins play in Docker?

<p>They map storage from the host to external sources like storage arrays. (A)</p> Signup and view all the answers

Flashcards

What is a Docker container?

A runnable instance of a Docker image. Containers can be created, started, stopped, moved, or deleted using the Docker API or CLI. They can be connected to networks, have storage attached, and can even be used to create new images.

Describe tmpfs in Docker

A temporary storage option in Docker that uses the host's memory. Data is deleted when the container stops, making it ideal for sensitive data that shouldn't persist. However, containers can't share tmpfs space unless they are running on Linux.

What is a Docker volume?

A persistent storage method in Docker that allows data to be shared between containers. Data is stored outside of the container's filesystem, ensuring it survives container restarts. You can create, mount, and manage Docker volumes.

What is a bind mount in Docker?

A method of connecting a container to a specific directory on the host machine. Any data changed in the mount point will be reflected in the host's filesystem, allowing for easy sharing of data and configurations.

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What are storage plugins in Docker?

Plugins that allow Docker to connect to external storage platforms. These plugins map storage from the host to external sources, like storage arrays or appliances.

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Study Notes

Containers

Containers are runnable instances of images.
Docker API or CLI manages creation, starting, stopping, moving, and deleting containers.
Containers can connect to multiple networks, attach storage, or create new images.
By default, containers are isolated from other containers and the host machine.
Users can adjust container isolation levels for network, storage, and other subsystems.
A container's definition stems from its image and configuration options.
Removed container changes (non-persistent) are lost.

Storage

Temporary Filesystems (tmpfs)

tmpfs is a non-permanent storage option.
Data is written directly to host memory and deleted when the container stops.
Useful for sensitive data needing no permanent storage.
Containers can't share tmpfs space unless on a Linux OS.
tmpfs and mount flags are used during creation.
mount is newer, supporting various startup options.
Temporary filesystems are stored in RAM (or swap) and not on the host or container.

Storage Plugins

Storage plugins connect to external storage platforms.
Plugins map host storage to external sources (arrays, appliances).
A list of storage plugins is available on the Docker Plugins page.

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Description

This quiz covers essential concepts related to Docker containers and storage mechanisms, including temporary filesystems like tmpfs. Understand how containers function, their isolation levels, and the management of ephemeral data. Test your knowledge on creating and handling Docker containers efficiently.