How to migrate docker container

1. The article from the provided URL explains how to migrate Docker containers, images, and volumes
from one server to another. Here's a summary of the steps outlined in the article:
1. Export Docker Containers
 Step 1: List all running containers using the command:
# docker ps
 Step 2: Commit the container to create an image:
# docker commit <container_id> <new_image_name>
 Step 3: Save the image as a tar file:
# docker save -o <image_name>.tar <new_image_name>
2. Transfer Docker Images
 Step 1: Use scp or any file transfer method to move the tar file to the new server:
# scp <image_name>.tar user@new_server:/path/to/destination
 Step 2: On the new server, load the image from the tar file:
# docker load -i <image_name>.tar
3. Export Docker Volumes
 Step 1: Identify the volumes associated with the container:
# docker inspect -f '{{ .Mounts }}' <container_id>
 Step 2: Create a backup of the volume data:
# docker run --rm -v <volume_name>:/volume -v $(pwd):/backup busybox tar cvf
/backup/<volume_name>.tar /volume
 Step 3: Transfer the volume tar file to the new server using scp:
# scp <volume_name>.tar user@new_server:/path/to/destination
4. Import Docker Volumes on the New Server
 Step 1: Create a new volume on the new server:
# docker volume create <new_volume_name>
 Step 2: Restore the volume data from the tar file:
# docker run --rm -v <new_volume_name>:/volume -v $(pwd):/backup busybox tar xvf
/backup/<volume_name>.tar -C /volume
5. Recreate Containers on the New Server
 Step 1: Use the loaded image and restored volume to recreate the container:
# docker run -d --name <new_container_name> -v <new_volume_name>:/path/to/volume
<new_image_name>

2. 6. Verify the Migration
 Step 1: Check if the container is running:
# docker ps
 Step 2: Verify the data inside the container and volume to ensure everything is intact.
Additional Tips:
 Network Configuration: If your containers rely on specific network configurations, ensure
those are replicated on the new server.
 Environment Variables: If your containers use environment variables, make sure to pass
them correctly when recreating the container.
By following these steps, you can successfully migrate Docker containers, images, and volumes from
one server to another. The article provides a detailed guide with commands to ensure a smooth
transition.
Uploading a Docker image to a Docker repository (such as Docker Hub or a private registry) involves
several steps, including committing a container to an image, tagging the image, and pushing it to the
repository. Below are the detailed steps:
Step 1: Commit a Container to an Image
If you have a running container and want to create an image from it, use the docker
commit command.
1. List running containers:
# docker ps
Note the CONTAINER ID of the container you want to commit.
2. Commit the container to an image:
# docker commit <container_id> <image_name>:<tag>
 Replace <container_id> with the ID of your container.
 Replace <image_name> with the name you want to give the image.
 Replace <tag> with a version or tag (e.g., v1, latest).
Example:
# docker commit abc1234 my-custom-image:latest
3. Verify the image:
# docker images
You should see your newly created image in the list.

3. Step 2: Tag the Image for the Repository
Before uploading, you need to tag the image with the repository name (e.g., Docker Hub
username/repository).
1. Tag the image:
# docker tag <image_name>:<tag> <dockerhub_username>/<repository_name>:<tag>
 Replace <dockerhub_username> with your Docker Hub username.
 Replace <repository_name> with the name of the repository.
 Replace <tag> with the desired tag (e.g., latest).
Example:
# docker tag my-custom-image:latest karthidkk123/my-repo:latest
2. Verify the tagged image:
# docker images
You should see the newly tagged image.
Step 3: Log in to Docker Hub
To upload the image, you need to log in to Docker Hub (or your private registry).
1. Log in to Docker Hub:
# docker login
 Enter your Docker Hub username and password when prompted.
Step 4: Push the Image to the Repository
Once logged in, you can push the tagged image to the repository.
1. Push the image:
# docker push <dockerhub_username>/<repository_name>:<tag>
Example:
# docker push karthidkk123/my-repo:latest
2. Verify the upload:
 Go to Docker Hub (https://hub.docker.com/) and log in.
 Navigate to your repository to confirm that the image has been uploaded.

4. Step 5: Pull the Image on Another Machine
To use the uploaded image on another machine, you can pull it from the repository.
1. Log in to Docker Hub (if not already logged in):
# docker login
2. Pull the image:
# docker pull <dockerhub_username>/<repository_name>:<tag>
Example:
# docker pull karthidkk123/my-repo:latest
3. Run the container:
# docker run -d <dockerhub_username>/<repository_name>:<tag>
Summary of Commands
Here’s a quick summary of the commands used:
# Commit a container to an image
docker commit <container_id> <image_name>:<tag>
# Tag the image for the repository
docker tag <image_name>:<tag> <dockerhub_username>/<repository_name>:<tag>
# Log in to Docker Hub
docker login
# Push the image to the repository
docker push <dockerhub_username>/<repository_name>:<tag>
# Pull the image on another machine
docker pull <dockerhub_username>/<repository_name>:<tag>
By following these steps, you can upload a Docker image to a repository and share it with others or
use it across different machines.