Understanding volume instructions in Docker
In Docker, we can create separate images, containers, and volumes. Whenever we start a container, we can mount the volume.
If we can do it manually in Docker, we can automate it through a build process using a file called Dockerfile.
This article will discuss building, creating, and mounting volumes in Docker via a Dockerfile.
Understanding the VOLUME instruction in Docker
When using Dockerfile, we use several instructions to automatically build single or multiple containers. An example of these instructions is the VOLUME instruction.
In the Dockerfile, it should look like this:
FROM ubuntu
RUN mkdir /samplevol
VOLUME /samplevol
However, some confusion arises when we try to enter the value of the VOLUME instruction in the Dockerfile. When using the VOLUME instruction, we need to understand that this is not where we indicate the location of the Docker volume outside the container.
Instead, the VOLUME instruction is where we tell the target where inside the container we are going to mount our external Docker volume when the container is already running.
If we remember, when we run a container we can use the --volume or -v parameter to mount a specific volume. However, this parameter has other uses as well.
For example, using the --volume parameter we can specify where the Docker volume should be mounted.
Example command:
$ docker run --volume=/volumesd:/samplevol sushi_bake
In the above command, the /volumesd directory is the location of the unmounted Docker volume. The /samplevol directory is where we will mount the Docker volume in the container we create and run.
Additionally, the **/samplevol** directory is the correct value for the VOLUME instruction in the Dockerfile.
Alternatively, we can avoid confusion by not adding the VOLUME instruction in the Dockerfile. If we do not add a mount point in the VOLUME instruction, Docker assigns a default location for the volume to be mounted.
This location is usually under /var/lib/docker/volumes .
For reprinting, please send an email to 1244347461@qq.com for approval. After obtaining the author's consent, kindly include the source as a link.
Related Articles
Get the IP address of the Docker container from the host using docker inspect
Publish Date：2025/03/26 Views：103 Category：Docker
-
Docker containers are not just for isolation—they are often used to manage processes that still need to communicate directly with each other. However, to communicate, you usually need to know the IP address of each container, which you ca
Solution to incorrect access log time when deploying Nginx in Docker
Publish Date：2025/03/26 Views：165 Category：Docker
-
In the process of operating the website, I never took the logs too seriously. Although logging was turned on, I never analyzed the logs carefully. Today, when I looked at the logs on a whim, I found that the recorded time was 8 hours less t
Docker deploys nginx php application
Publish Date：2025/03/26 Views：131 Category：Docker
-
I'm learning docker recently. I'm learning by building an nginx+php development environment example. Here I record the build process. First, give a docker-compose.yml deployment configuration file version: '3' services: nginx: container_nam
How to use Docker to image a Node.js web application
Publish Date：2025/03/26 Views：107 Category：Docker
-
Docker is a containerization platform that simplifies the packaging and execution of applications. Containers run as independent processes with their own file systems, but share the kernel of their host machine. Docker has attracted much at
Start a Bash terminal in a new Docker container
Publish Date：2025/03/26 Views：97 Category：Docker
-
Docker containers are a standard unit for packaging all the dependencies of an application, allowing us to easily run them in any environment. Containers have become very popular recently, and most developers now rely heavily on containers
Passing environment variables to containers in Docker
Publish Date：2025/03/26 Views：125 Category：Docker
-
This article will introduce how to pass environment variables to containers in Docker. Passing environment variables to containers in Docker using the -e and tags -env We will first see how to create environment variables and pass them to t
Install Docker using Homebrew
Publish Date：2025/03/26 Views：202 Category：Docker
-
There is no doubt that Docker containers have revolutionized the way we develop and deploy applications. They provide developers with the ability to package applications and dependencies in an isolated environment. Recently, we've seen wide
Enforce clean build of images in Docker
Publish Date：2025/03/26 Views：88 Category：Docker
-
This article discusses and demonstrates how to enforce clean builds of images in Docker. Building images in Docker We will use a simple Flask application to demonstrate this concept. my-app Create a app.py simple application named in the ho
Running a Docker instance from a Dockerfile
Publish Date：2025/03/26 Views：140 Category：Docker
-
Docker containers have undoubtedly become the standard unit for managing software and dependencies in different environments. When using real applications, you must create a docker file before building the container image of the application
