mirror of https://github.com/docker/docs.git
116 lines
4.4 KiB
Markdown
116 lines
4.4 KiB
Markdown
---
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title: Persist container data
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keywords: get started, quick start, intro, concepts
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description: Learn how to persist container data
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---
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This walkthrough shows you how to persist data between containers. To better understand some concepts in this walkthrough, complete the [Run multi-container applications](./multi-container-apps.md) walkthrough first.
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Docker isolates all content, code, and data in a container from your local filesystem. When you delete a container, Docker deletes all the content within that container.
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Sometimes, you may want to persist the data that a container generates. To do this, you can use volumes.
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{{< include "guides-get-docker.md" >}}
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## Step 1: Get the sample application
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If you have git, you can clone the repository for the sample application. Otherwise, you can download the sample application. Choose one of the following options.
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{{< tabs >}}
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{{< tab name="Clone with git" >}}
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Use the following command in a terminal to clone the sample application repository.
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```console
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$ git clone https://github.com/docker/multi-container-app
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```
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{{< /tab >}}
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{{< tab name="Download" >}}
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Download the source and extract it.
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{{< button url="https://github.com/docker/multi-container-app/archive/refs/heads/main.zip" text="Download the source" >}}
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{{< /tab >}}
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{{< /tabs >}}
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## Step 2: Add a volume to persist data
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To persist data after you delete a container, use a volume. A volume is a location in your local filesystem, automatically managed by Docker Desktop.
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To add a volume to this project, open the `compose.yaml` file in a code or text editor, and then uncomment the following lines.
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```yaml
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todo-database:
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# ...
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volumes:
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- database:/data/db
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# ...
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volumes:
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database:
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```
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The `volumes` element that is nested under `todo-database` tells Compose to mount the volume named `database` to `/data/db` in the container for the todo-database service.
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The top-level `volumes` element defines and configures a volume named `database` that can be used by any of the services in the Compose file.
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## Step 3: Run the application
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To run the multi-container application, open a terminal and run the following commands. Replace `/path/to/multi-container-app/` with the path to your application's directory.
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{{< include "open-terminal.md" >}}
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```console
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$ cd /path/to/multi-container-app/
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```
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```console
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$ docker compose up -d
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```
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## Step 4: View the frontend and add todos
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In the **Containers** tab of Docker Desktop, you should now have an application stack with two containers running (the todo-app, and todo-database).
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To view the frontend and add todos:
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1. In Docker Desktop, expand the application stack in **Containers**.
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2. Select the link to port **3000** in the **Port(s)** column or open [http://localhost:3000](http://localhost:3000).
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3. Add some todo tasks in the frontend.
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## Step 5: Delete the application stack and run new containers
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Now, no matter how often you delete and recreate the containers, Docker Desktop persists your data and it's accessible to any container on your system by mounting the `database` volume. Docker Desktop looks for the `database` volume and creates it if it doesn't exist.
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To delete the application stack:
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1. Open the **Containers** tab of Docker Desktop
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2. Select the Delete icon next to your application stack.
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After you delete the application stack, follow the steps from [Step 3: Run the
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application](#step-3-run-the-application) to run the application again. Note
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that when you delete the containers and run them again, Docker Desktop persists any todos that you created.
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## Summary
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In this walkthrough, you persisted data between containers using a volume. You can use this to persist and share data among isolated and ephemeral containers.
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Related information:
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- Deep dive into [volumes](../../storage/volumes.md)
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- Learn about using volumes in Compose in the [Compose file reference](../../compose/compose-file/_index.md)
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- Explore using volumes via the CLI in the [docker volume CLI reference](../../reference/cli/docker/volume/create.md) and [Docker run reference](/reference/run/)
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## Next steps
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Continue to the next walkthrough to learn how you can access a local directory from a container.
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{{< button url="./access-local-folder.md" text="Access a local folder" >}}
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