free web page counters

Docker image vs container: What are the main differences?

Sedang Trending 3 minggu yang lalu

Jan 21, 2025

Aris S.

6min Read

 What are nan main differences?

Images and containers are basal concepts successful Docker that are intimately related and activity hand-in-hand. Since some are utilized for deploying package efficiently, immoderate users mightiness not understand what sets them apart.

In this tutorial, you will study nan main differences betwixt a Docker image vs container. We will comparison them successful respective aspects, including mutability, lifecycle, and applications successful deployment.

What is simply a Docker container?

A instrumentality successful Docker is an isolated virtual situation that runs independently. It packs each components required to tally an application, including dependencies, libraries, and code.

Think of a Docker instrumentality arsenic an flat portion wrong a building. It contains each nan basal accommodation for nan tenant to unrecorded independently of their neighbors, which are nan runtime, libraries, and code.

For example, an online shop exertion mightiness dwell of respective services, specified arsenic nan beforehand end, backmost end, and database. These components each usage different tools, programs, and code.

You tin battalion each work successful a instrumentality pinch its required components. This enables nan services to tally independently contempt being hosted connected nan aforesaid host, allowing you to easy negociate and modify them.

What is simply a Docker image?

A Docker image contains instructions connected really to build a container, including nan required components and root code. It lets you easy group up a accordant situation and support compatibility crossed aggregate systems.

If Docker containers are flat units wrong a building, Docker images service arsenic nan level plan. It specifies nan components required to build nan room and nan furnishings needed for nan tenant to unrecorded comfortably.

You tin build aggregate containers from nan aforesaid image, each pinch identical application, components, and configuration.

Key differences betwixt Docker images and containers

After exploring nan wide meaning of Docker images and containers, let’s spot really they disagree successful respective cardinal aspects.

Mutability

Already built Docker images are read-only, meaning users can’t alteration nan configuration to build nan container. For example, you can’t adhd a caller package package aliases edit already-specified dependencies.

To modify nan configuration, you must make a caller Docker image from a Dockerfile, a human-readable matter successful which you constitute nan basal components and instructions to create containers.

Pro tip

Developers besides usage Dockerfile to widen existing images by adding a caller furniture of instruction aliases program. Instead of penning a Dockerfile from scratch to create a caller image, you tin download an existing 1 from a registry for illustration Docker Hub, which we will explicate successful nan Storage conception later.

Meanwhile, a Docker instrumentality is editable astatine runtime. You tin alteration nan exertion code, adhd a caller program, aliases edit configuration files freely without affecting different container.

Lifecycle

During nan exertion deployment process, Docker images and containers spell done different phases. However, nan lifecycle phases tin disagree depending connected your project’s guidance policy.

Here’s an illustration of a Docker image’s lifecycle:

  • Creation the creation shape is wherever you build a Docker image lawsuit from a Dockerfile. 
  • Tagging and versioning – developers explanation each Docker image to find which instrumentality it builds and its iteration. 
  • Pruning – developers will delete aged Docker images and switch them pinch caller ones from a caller Dockerfile. 

Meanwhile, a Docker container’s lifecycle mightiness look arsenic follows:

  • Creation – nan developers build nan instrumentality from a Docker image.
  • Running – nan instrumentality starts and actively executes its process.
  • Paused/unpaused – nan administrators halt aliases resume nan instrumentality operation. 
  • Stopped – nan instrumentality stops aft completing its process, and you tin restart it later. 
  • Deleted – nan instrumentality nary longer exists, meaning you must recreate it from nan image.

Images typically stay successful retention agelong aft creation for type power and reuse. However, you mightiness yet remove Docker images to free up retention abstraction aliases cleanable up your environment.

Meanwhile, containers thin to person a shorter lifecycle arsenic developers often recreate, stop, and delete them passim nan exertion improvement process.

Storage

In summation to nan section strategy and big server, images are stored successful a backstage aliases nationalist Docker registry. This centralized retention enables users to prevention images and stock them pinch their team.

You tin usage nan official Docker Hub registry, utilize third-party services from unreality providers, aliases self-host nan shop connected a virtual backstage server platform for illustration nan 1 from Hostinger.

Meanwhile, you tin only shop Docker containers connected nan big system. To stock and archive them successful different locations, you must usage their images.

Most celebrated images connected Docker Hub

Portability

Docker image’s portability intends you tin easy store, share, and reuse it connected different systems. Meanwhile, you can’t move containers by default and must carrier them arsenic images.

You tin move images and build containers connected immoderate strategy that supports Docker. However, owed to configuration differences, containers mightiness behave otherwise connected different machine.

Commands

Docker provides different command-line utilities to interact pinch images and containers. Here are commands for Docker image:

  • docker build – creates a Docker image from a Dockerfile.
  • docker propulsion – downloads an image from a Docker registry.
  • docker push – uploads a section image to a registry.
  • docker images – lists each locally disposable images.
  • docker rmi – removes an image from nan section system.
  • docker tag – adds a caller tag to an image for versioning.

Meanwhile, managing containers uses nan pursuing commands:

  • docker run – creates and starts a instrumentality from an image.
  • docker ps – lists each moving containers.
  • docker exec – runs a bid wrong a moving container.
  • docker stop – stops a moving container.
  • docker start – starts a stopped container.
  • docker rm – removes a stopped container.
  • docker logs – prints logs from a moving aliases stopped container.

Usage successful improvement and production

During development, you usage Docker images to group up and replicate nan testing area connected different machines. It is particularly adjuvant successful a squad situation since members don’t request to instal each constituent manually.

Images’ portability and consistency besides thief streamline deployment. Since you tin battalion your exertion and its components into a azygous image, you tin quickly push your task into accumulation environments without having to hole nan dependencies.

Meanwhile, Docker containers successful improvement supply an isolated situation wherever developers tin freely trial changes. It prevents modifications from affecting different services and minimizes nan consequence of conflicts betwixt components.

In production, Docker containers fto you big your exertion utilizing aggregate redundant nodes, which optimize assets utilization and work availability. You tin besides deploy your task arsenic microservices and debar vendor lock-in by distributing containers connected different systems.

When to usage Docker images and containers?

In a real-world scenario, you will ever usage some Docker images and containers since they activity hand-in-hand. However, you mightiness utilize them astatine different stages of your development.

At nan opening of your development, you will usage Docker images to battalion your exertion and its components. You will besides usage them to group up nan situation connected different machines and way improvement iteration.

Meanwhile, Docker containers are useful successful nan accumulation phase, during which your exertion is already running. You tin besides usage them to standard your task up aliases down by managing each environment.

We urge checking our tutorial connected creating a Docker container to study much astir nan improvement series successful real-world applications.

Conclusion

A Docker instrumentality is an isolated situation that houses your exertion and its components. A Docker image is an instruction for building a instrumentality and installing nan required software.

Docker image is immutable, meaning users can’t modify it and must create a caller 1 from a Dockerfile to alteration its configuration. Conversely, you tin customize a container, for illustration adding a caller programme aliases editing code.

Docker images tin beryllium easy moved betwixt systems, stored successful a centralized registry, and person a longer lifecycle. Containers, meanwhile, tin only beryllium transported arsenic images, reside connected nan big server, and are often recreated passim development.

You tin usage Docker images to easy group up accordant environments connected aggregate systems, whether for testing aliases collaboration. Meanwhile, containers tally your exertion connected nan big server during deployment.

Docker image vs instrumentality FAQ

What’s nan main quality betwixt a Docker image and a container?

A Docker instrumentality is an isolated situation for an application, arsenic good arsenic its dependencies, libraries, and different required resources. Meanwhile, a Docker image is an instruction for building a container, including nan components to install. They are fundamentally nan aforesaid but service different purposes successful deployment.

Is a Dockerfile an image?

A Dockerfile is simply a matter record containing nan instructions and configuration to build an image. To create an image, you must make a caller Dockerfile and adhd basal components for illustration libraries and packages. Then, you tally nan Docker motor to build nan image.

Can Docker containers beryllium without images?

No, building Docker containers requires images arsenic they specify nan configuration instructions and required components. Docker images, however, tin beryllium without a Dockerfile since you tin download them from a registry for illustration Docker Hub.

Author

Aris is simply a Content Writer specializing successful Linux and WordPress development. He has a passion for networking, front-end web development, and server administration. By combining his IT and penning experience, Aris creates contented that helps group easy understand analyzable method topics to commencement their online journey. Follow him connected LinkedIn.