I installed Docker in my machine where I have Ubuntu OS. When I run:

sudo docker run hello-world

All is ok, but I want to hide the sudo command to make the command shorter. If I write the command without sudo

docker run hello-world

That displays the following:

docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.35/containers/create: dial unix /var/run/docker.sock: connect: permission denied. See 'docker run --help'.

The same happens when I try to run:

docker-compose up

How can I resolve this?

To fix that issue, I searched where is my docker and docker-compose installed. In my case, docker was installed in /usr/bin/docker and docker-compose was installed in /usr/local/bin/docker-compose path. Then, I write this in my terminal:

To docker:

sudo chmod +x /usr/bin/docker

To docker-compose:

sudo chmod +x /usr/local/bin/docker-compose

Now I don't need write in my commands docker the word sudo

/***********************************************************************/

ERRATA:

The best solution of this issue was commented by @mkasberg. I quote comment:

That might work, you might run into issues down the road. Also, it's a security vulnerability. You'd be better off just adding yourself to the docker group, as the docs say. sudo groupadd docker, sudo usermod -aG docker $USER. Docs: https://docs.docker.com/install/linux/linux-postinstall/

If you want to run docker as non-root user then you need to add it to the docker group.

1. Create the docker group if it does not exist

$ sudo groupadd docker

1. Add your user to the docker group.

$ sudo usermod -aG docker $USER

1. Log in to the new docker group (to avoid having to log out / log in again; but if not enough, try to reboot):

$ newgrp docker

1. Check if docker can be run without root

$ docker run hello-world

Reboot if still got error

$ reboot

Warning

The docker group grants privileges equivalent to the root user. For details on how this impacts security in your system, see Docker Daemon Attack Surface..

Taken from the docker official documentation: manage-docker-as-a-non-root-user

After an upgrade I got the permission denied. Doing the steps of 'mkb' post install steps don't have change anything because my user was already in the 'docker' group; I retry-it twice any way without success.

After an search hour this following solution finaly worked :

sudo chmod 666 /var/run/docker.sock

Solution came from Olshansk.

Look like the upgrade have recreate the socket without enough permission for the 'docker' group.

Problems

This hard chmod open security hole and after each reboot, this error start again and again and you have to re-execute the above command each time. I want a solution once and for all. For that you have two problems :

• 1 ) Problem with SystemD : The socket will be create only with owner 'root' and group 'root'.

  You can check this first problem with this command :

  ls -l /lib/systemd/system/docker.socket
  

  If every this is good, you should see 'root/docker' not 'root/root'.

• 2 ) Problem with graphical Login : https://superuser.com/questions/1348196/why-my-linux-account-only-belongs-to-one-group

  You can check this second problem with this command :

  groups
  

  If everything is correct you should see the docker group in the list. If not try the command

  sudo su $USER -c groups
  

  if you see then the docker group it is because of the bug.

Solutions

If you manage to to get a workaround for the graphical login, this should do the job :

sudo chgrp docker /lib/systemd/system/docker.socket
sudo chmod g+w /lib/systemd/system/docker.socket

But If you can't manage this bug, a not so bad solution could be this :

sudo chgrp $USER /lib/systemd/system/docker.socket
sudo chmod g+w /lib/systemd/system/docker.socket

This work because you are in a graphical environnement and probably the only user on your computer. In both case you need a reboot (or sudo chmod 666 /var/run/docker.sock)

lightdm and kwallet ship with a bug that seems to not pass the supplementary groups at login. To solve this, I also, beside sudo usermod -aG docker $USER, had to comment out

auth optional pam_kwallet.so
auth optional pam_kwallet5.so

to

#auth optional pam_kwallet.so
#auth optional pam_kwallet5.so

in /etc/pam.d/lightdm before rebooting, for the docker-group to actually have effect.

bug: https://bugs.launchpad.net/lightdm/+bug/1781418 and here: https://bugzilla.redhat.com/show_bug.cgi?id=1581495

1. Add current user to docker group

sudo usermod -aG docker $USER

1. Change the permissions of docker socket to be able to connect to the docker daemon /var/run/docker.sock

sudo chmod 660 /var/run/docker.sock

1. Add docker group

$ sudo groupadd docker

1. Add your current user to docker group

$ sudo usermod -aG docker $USER

1. Switch session to docker group

$ newgrp - docker

1. Run an example to test

$ docker run hello-world

use this command

sudo usermod -aG docker $USER

then restart your computer this worked for me.

I solve this error with the command :

$ sudo chmod 666 /var/run/docker.sock

Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.40/images/json: dial unix /var/run/docker.sock: connect: permission denied

sudo chmod 666 /var/run/docker.sock

This fix my problem.

Seriously guys. Do not add Docker in your groups or modify the socket posix (without a hardening SELinux), it's a simple way to make a root privesc. Just add an alias in your .bashrc. It's simpler and safer as: alias dc='sudo docker'.

sudo chmod 666 /var/run/docker.sock

this helped me while I was getting error even to log in to the docker. But now this works completely fine in my system.

After Docker Installation on Centos. While running below command I got below error.

[centos@aiops-dev-cassandra3 ~]$ docker run hello-world
docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.soc k/v1.40/containers/create: dial unix /var/run/docker.sock: connect: permission denied.
See 'docker run --help'.

Change Group and Permission for docker.socket

[centos@aiops-dev-cassandra3 ~]$ ls -l /lib/systemd/system/docker.socket
-rw-r--r--. 1 root root 197 Nov 13 07:25 /lib/systemd/system/docker.socket
[centos@aiops-dev-cassandra3 ~]$ sudo chgrp docker /lib/systemd/system/docker.socket
[centos@aiops-dev-cassandra3 ~]$ sudo chmod 666 /var/run/docker.sock
[centos@aiops-dev-cassandra3 ~]$ ls -lrth /var/run/docker.sock
srw-rw-rw-. 1 root docker 0 Nov 20 11:59 /var/run/docker.sock
[centos@aiops-dev-cassandra3 ~]$

Verify by using below docker command

[centos@aiops-dev-cassandra3 ~]$ docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
1b930d010525: Pull complete
Digest: sha256:c3b4ada4687bbaa170745b3e4dd8ac3f194ca95b2d0518b417fb47e5879d9b5f
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/get-started/

[centos@aiops-dev-cassandra3 ~]$

You can always try Manage Docker as a non-root user paragraph in the https://docs.docker.com/install/linux/linux-postinstall/ docs.

After doing this also if the problem persists then you can run the following command to solve it:

sudo chmod 666 /var/run/docker.sock

you can follow these steps and this will work for you:

1. create a docker group sudo groupadd docker

2. add your user to this group sudo usermod -aG docker $USER

3. list the groups to make sure that docker group created successfully by running this command groups

4. run the following command also to change the session for docker group newgrp docker

5. change the group ownership for file docker.socksudo chown root:docker /var/run/docker.sock

6. change the ownership for .docker directory sudo chown "$USER":"$USER" /home/"$USER"/.docker -R

7. finally sudo chmod g+rwx "$HOME/.docker" -R

After that test you can run docker ps -a

After you installed docker, created 'docker' group and added user to it, edit docker service unit file:

sudo nano /usr/lib/systemd/system/docker.service

Add two lines into the section [Service]:

SupplementaryGroups=docker    
ExecStartPost=/bin/chmod 666 /var/run/docker.sock

Save the file (Ctrl-X, y, Enter)

Run and enable the Docker service:

sudo systemctl daemon-reload
sudo systemctl start docker
sudo systemctl enable docker

Just open terminal and type this command

sudo chmod 666 /var/run/docker.sock

Rebooting the machine worked for me.

$ reboot

I ran into a similar problem as well, but where the container I wanted to create needed to mount /var/run/docker.sock as a volume (Portainer Agent), while running it all under a different namespace. Normally a container does not care about which namespace it is started in -- that is sort of the point -- but since access was made from a different namespace, this had to be circumvented.

Adding --userns=host to the run command for the container enabled it to use the attain the correct permissions.

Quite a specific use case, but after more research hours than I want to admit I just thought I should share it with the world if someone else ends up in this situation :)

A simple hack is to execute as a "Super User".

To access the super user or root user, follow:

At user@computer:

$sudo su

After you enter your password, you'll be at root@computer:

$docker run hello-world

It is definitely not the case the question was about, but as it is the first search result while googling the error message, I'll leave it here.

First of all, check if docker service is running using the following command:

systemctl status docker.service

If it is not running, try starting it:

sudo systemctl start docker.service

... and check the status again:

systemctl status docker.service

If it has not started, investigate the reason. Probably, you have modified a config file and made an error (like I did while modifying /etc/docker/daemon.json)

It only requires the changes in permission of sock file.

sudo chmod 666 /var/run/docker.sock

this will work definitely.

This work for me:

Get inside the container and modify the file's ACL

sudo usermod -aG docker $USER
sudo setfacl --modify user:$USER:rw /var/run/docker.sock

It's a better solution than use chmod.

We always forget about ACLs . See setfacl.

sudo setfacl -m user:$USER:rw /var/run/docker.sock`**

The Docker daemon binds to a Unix socket instead of a TCP port. By default that Unix socket is owned by the user root and other users can only access it using sudo. The Docker daemon always runs as the root user.

If you don’t want to preface the docker command with sudo, create a Unix group called docker and add users to it. When the Docker daemon starts, it creates a Unix socket accessible by members of the docker group.

To create the docker group and add your user:

1. Create the docker group

   sudo groupadd docker
   

2. Add your user to the docker group

   sudo usermod -aG docker $USER
   

3. Log out and log back in so that your group membership is re-evaluated.

   If testing on a virtual machine, it may be necessary to restart the virtual machine for changes to take effect.

   On a desktop Linux environment such as X Windows, log out of your session completely and then log back in.

   On Linux, you can also run the following command to activate the changes to groups:

   newgrp docker 
   

4. Verify that you can run docker commands without sudo. The below command downloads a test image and runs it in a container. When the container runs, it prints an informational message and exits

   docker run hello-world
   

If you initially ran Docker CLI commands using sudo before adding your user to the docker group, you may see the following error, which indicates that your ~/.docker/ directory was created with incorrect permissions due to the sudo commands.

WARNING: Error loading config file: /home/user/.docker/config.json -
stat /home/user/.docker/config.json: permission denied

To fix this problem, either remove the ~/.docker/ directory (it is recreated automatically, but any custom settings are lost), or change its ownership and permissions using the following commands:

sudo chown "$USER":"$USER" /home/"$USER"/.docker -R

sudo chmod g+rwx "$HOME/.docker" -R

All other post installation steps for docker on linux can be found here https://docs.docker.com/engine/install/linux-postinstall/

i try this commend with sudo commend and it was ok.sudo docker pull hello-world or sudo docker run hello-world

Fix Docker Issue: (Permission denied)

• Create the docker group if it does not exist: sudo groupadd docker

• See number of super users in the available system: grep -Po '^sudo.+:\K.*$' /etc/group

• Export the user in linux command shell: export USER=demoUser

• Add user to the docker group: sudo usermod -aG docker $USER

• Run the following command/ Login or logout: newgrp docker

• Check if docker runs ok or not: docker run hello-world

• Reboot if you still get an error: reboot

If it does not work, run this command:

sudo chmod 660 /var/run/docker.sock

The most straightforward solution is to type

sudo chmod 640 /var/run/docker.sock every time you boot your machine. However, this method defeats any system security that may be in place and opens up the Docker socket to everybody. If this is acceptable to you -e.g.: the only user of your machine- then use it.

Nevertheless, it will be required every time you boot your machine, you can make it run with booting by adding

start on startup
task
exec chmod 640 /var/run/docker.sock

to the /etc/init/docker-chmod.conf file.

ubuntu 21.04 systemd socket ownership

Let me preface, this was a perfectly suitable solution for me during local development and I got here searching for ubuntu docker permission error so i'll just leave this here.

I didn't own the unix socket, so I chowned it.

sudo chown $(whoami):$(whoami) /var/run/docker.sock

Another, more permanent solution for your dev environment, is to modify the user ownership of the unix socket creation. This will give your user the ownership, so it'll stick between restarts:

sudo nano /etc/systemd/system/sockets.target.wants/docker.socket

docker.socket:

[Unit]
Description=Docker Socket for the API

[Socket]
ListenStream=/var/run/docker.sock
SocketMode=0660
SocketUser=YOUR_USERNAME_HERE
SocketGroup=docker

[Install]
WantedBy=sockets.target

In the Linux environment, after installing docker and docker-compose reboot is required for work docker better to avoid this issue

$ sudo systemctl restart docker

I tried all the described methods and nothing helped to solve the problem. The solution was to use the --use-drivers parameter when running selenoid and selenoid-ui. Below is the full listing of my Dockerfile.

FROM selenoid/chrome
USER root
RUN apt-get update
RUN apt-get -y install docker.io
RUN curl -s https://aerokube.com/cm/bash | bash
RUN ./cm selenoid start --vnc --use-drivers
RUN ./cm selenoid-ui start --use-drivers
EXPOSE 4444 8080
CMD ["-conf", "/etc/selenoid/browsers.json", "-video-output-dir", "/opt/selenoid/video/"]

In my case it was the process itself (CI server agent) that was trying to run a docker command wasn't able to run it, but when I tried to run same command from within the same user it worked.

Restarting the daemon that runs CI server agent solved the problem.

The reason why command wasn't working from within agent before is because the agent was running before I installed docker and granted docker group permissions, and agent process used cached old permissions and was failing. Restarting the process dropped the cache and make things work out.

If creating a docker group and adding your user to it doesn't work (the best solution, described in the previous answers), then this one is the second best alternative:

sudo chown $USER /var/run/docker.sock 

What it does is changing the ownership of the docker.sock file to your user.

Note: It's a really bad practice to use chmod 666, because it gives permissions to practically everyone to access and modify the docker.sock file.

As a shortest answer for linux user ->

Simply try any command as super user with "sudo"

Eg:- sudo docker-compose up

Below command helped me

run this if linux

sudo chmod 666 /var/run/docker.sock

Adding answer here for future reference: (This is the cause and what solved it for my use case)

This happens when your Unix user account lacks permission to interact with the socket that exposes the Docker API. Adding yourself to the docker group is the best practice way to resolve this problem:

$ sudo usermod -aG docker $USER

You'll need to open a new shell window or logout and back in again for this change to take effect.

Source

If the user was already in the 'docker' group; try to give permission to /var/run/docker.sock file sudo chmod 666 /var/run/docker.sock it will work

Docker already created a guide to Run the Docker daemon as a non-root user (Rootless mode).

Rootless mode allows running the Docker daemon and containers as a non-root user to mitigate potential vulnerabilities in the daemon and the container runtime.

You just need the check permissions for this file /var/run/docker.sock it should be 666 chmod 666 /var/run/docker.sock