Explore various situations not found in Docker

Docker is a popular containerization platform that allows users to quickly create, deploy and run applications. However, sometimes you may run into some issues, such as not being able to find something in Docker. This may be confusing because you may already have the required components installed.

In this article, we will explore various situations that are not found in Docker and how to solve them.

Problem 1: Docker image not found

When you want to run an image in Docker, you may encounter the following error:

docker: Error response from daemon: manifest for <image> not found</image>

or:

docker: Error response from daemon: repository <image> not found: does not exist or no pull access</image>

This means that Docker cannot find the required image. This can be due to the following reasons:

1. Mirror does not exist: The image you are looking for simply does not exist.
2. Address error: The mirror address you used may be incorrect. Please make sure you are using the correct address.
3. Insufficient access rights: You may not have sufficient access rights to access the required image. If this is a private image, you need to use the correct credentials to access it.

Solution:

1. Make sure the image you are looking for actually exists.
2. Please check whether your mirror address is correct.

3. If this is a private image, please make sure you have sufficient permissions to access it. You can log in using the following command:

   docker login

Issue 2: Container not found

When you try to find the container using the following command:

docker ps

You may receive the following error:

docker: Error response from daemon: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?.

This means that the Docker daemon is not running.

Solution:

1. Check if the Docker service is running:

   systemctl status docker

2. If the service is not running, use the following Command to start it:

   systemctl start docker

Problem 3: Docker network not found

Docker containers usually communicate with each other over the network. If you can't find something in the Docker network, you may encounter the following error:

Get http://my-container:8080: dial tcp: lookup my-container on <dns>: no such host</dns>

This means that Docker cannot resolve the container's hostname.

Solution:

1. Make sure your container has joined a Docker network. You can use the following command to check:

   docker network ls

2. If your container has not joined the network yet, please use the following command to add it to the network:

   docker network connect <network> <container></container></network>

   Where, <network></network> is the name of the network you want to add the container to, and <container></container> is the name or ID of the container you want to add to the network.

3. If your container still cannot resolve the hostname, please check that your DNS configuration is correct. You can use the following command to view the DNS configuration of the container:

   docker exec <container> cat /etc/resolv.conf</container>

   If this file is empty or wrong, configure the correct DNS server in the container.

Question 4: Docker data volume not found

When you try to view the Docker data volume using the following command:

docker volume ls

You may If you see an empty list, it means you don't have any data volumes.

Solution:

1. Make sure you have created at least one data volume. You can use the following command to create a data volume:

   docker volume create <name></name>

   where <name></name> is the name you want to specify for the data volume.

2. If you have created a data volume, make sure it is properly bound to the container. You can use the following command to check the binding status of the container:

   docker inspect <container> | grep Volumes</container>

   If this command returns blank, your data volume is not bound correctly.

Conclusion

It’s not uncommon to not find something in Docker. Typically this is caused by misconfiguration or issues with the Docker environment. In this article, we discuss various scenarios in which images, containers, networks, and volumes are not found in Docker and provide solutions to related issues. By following these steps, you should be able to resolve any issues you encounter with Docker.

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