Linux - Docker Not Installed or Running Error

This issue can occur if Docker is not installed or if the user is not added to the Docker group. 

Check if Docker is installed. 

Run the following command:

docker info

Sample output:

Client:
 Context: default
 Debug mode: false
 Servers:
  default:
    Host: localhost
    Engine:
      Version: 20.10.14
      API version: 1.44
      Go version: go1.17.15
      Git commit: 8668127
      Built: Thu Apr 1 06:02:55 2021
      OS/Arch: linux/amd64
      Experimental: false
    Kernel: 5.15.0-52-generic
    Operating System: Ubuntu 22.04.1 LTS
    Total Memory: 31.8GiB
    CPUs: 8

If you see this output, Docker is installed, but the user may not be added to the Docker group.

Check if the user is in the Docker group. 

Run the following command:

grep -i docker /etc/group

Sample output:

docker:x:999:root,$USER1,$USER2,etc

1️⃣ Verify if your username is listed. 

If not, add the user to the Docker group.

Add user to the Docker group:

sudo usermod -aG docker $USER

Example

sudo usermod -aG docker Michael

2️⃣ Verify the user is added by re-running the group check:

grep -i docker /etc/group

The output should now include your username, e.g.:

docker:x:999:root,michael

3️⃣ Reboot the server.

sudo reboot

4️⃣Restart Docker.

sudo systemctl restart docker

Now run docker info once again to validate. If you're still experiencing issues, you may need a fresh install of the docker application.