Docker command can t connect to Docker daemon

Question

I want to make a move to Docker  so I ve just started to mess around with it  I ve installed Docker on a VirtualBox Ubuntu 15 10  Wily Werewolf  installation and as suggested here I then tried running a basic nginx Docker image     docker run --name mynginx1 -P -d nginx Cannot connect to the Docker daemon  Is the docker daemon running on this host    So I checked out whether Docker was running     sudo service docker status   docker service - Docker Application Container Engine    Loaded  loaded   lib systemd system docker service  enabled  vendor preset  enabled     Active  active  running  since vr 2015-11-06 08 41 48 CET  15min ago      Docs  https   docs docker com  Main PID  7542  docker     CGroup   system slice docker service             -7542  usr bin docker daemon -H fd     nov 06 08 41 47 kramer65-VirtualBox systemd 1   Starting Docker Application Container Engine    nov 06 08 41 47 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 47 900410966 01 00  level info msg  API    ock  nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 033514149 01 00  level info msg  Fire   lse  nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 141594321 01 00  level info msg  Defa   ess  nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 416294436 01 00  level warning msg  Y   it   nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 565507576 01 00  level info msg  Load   rt   nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 567907022 01 00  level info msg  Load   ne   nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 567945214 01 00  level info msg  Daem   ion  nov 06 08 41 48 kramer65-VirtualBox docker 7542   time  2015-11-06T08 41 48 567969891 01 00  level info msg  Dock    9 0 nov 06 08 41 48 kramer65-VirtualBox systemd 1   Started Docker Application Container Engine  Hint  Some lines were ellipsized  use -l to show in full    This suggests that the Docker daemon is actually already running  but to be sure I just started the Docker daemon manually     sudo docker daemon INFO 0000  API listen on  var run docker sock            INFO 0000   graphdriver  using prior storage driver  aufs   INFO 0000  Firewalld running  false                      INFO 0000  Default bridge  docker0  is assigned with an IP address XXX XX X X XX  Daemon option --bip can be used to set a preferred IP address  WARN 0000  Your kernel does not support swap memory limit   INFO 0000  Loading containers  start                      INFO 0000  Loading containers  done                      INFO 0000  Daemon has completed initialization           INFO 0000  Docker daemon                                 commit 76d6bc9 execdriver native-0 2 graphdriver aufs version 1 9 0   I then tried running the image again  but with the same result     docker run --name mynginx1 -P -d nginx Cannot connect to the Docker daemon  Is the docker daemon running on this host    I tried sudo ing the command  but to no avail  What am I doing wrong here

User · Answer

Try to use  sudo  with the command you are running

User · Answer

For Ubuntu  Happened with me when I updated docker  You need to unmask the service and socket and then restart the service  Following worked for me   systemctl unmask docker service systemctl unmask docker socket systemctl start docker service   What happend behind the scenes systemd also has the ability to mark a unit as completely unstartable  automatically or manually  by linking it to  dev null  This is called masking the unit  and is possible with the mask command   sudo systemctl mask docker service   You can check the list of masked services using   sudo systemctl list-unit-files     To enable auto manual start of service you need to unmask it using   sudo sytemctl unmask docker service   Now the service will be enabled as shown below

User · Answer

I had the same problem  Been struggling for two days to solve it   It only worked when I did    According to Docker s Tutorial  you need to add the Docker key if not already added using     sudo wget -qO- https   get docker com gpg   sudo apt-key add - Then make sure you grant docker privileges to yourself using     sudo usermod -aG docker  USER   Hope this helps you too

User · Answer

Tested in Ubuntu 16 04    Create the docker group and add your user to the docker group groupadd docker usermod -aG docker  USER newgrp docker    Configure docker service to be exposed mkdir -p  etc systemd system docker service d echo -e   Service  nExecStart  nExecStart  usr bin dockerd -H fd    -H tcp   0 0 0 0 2376   gt  gt   etc systemd system docker service d override conf    restart service systemctl daemon-reload service docker restart

User · Answer

After install everything and start the service  try close your terminal and open it again  then try pull your image  Edit  I also had this issue again  if the solution above won t worked  try this solution that is the command bellow  sudo mv  var lib docker network files   tmp dn-bak     Considerations  If command above works you probably are with network docker problems  anyway this resolves it  to confirm that  see the log with the command bellow  tail -5f  var log upstart docker log   If the output have something like that  FATA 0000  Error starting daemon  Error initializing network controller  could not delete the default bridge network  network bridge has active endpoints   var run docker sock is up   You really are with network problems  however I do not know yet if the next time you restart update  2 months no issue again  your OS will get this problem again and if it is a bug or installation problem  My docker version  Client   Version       1 9 1  API version   1 21  Go version    go1 4 2  Git commit    a34a1d5  Built         Fri Nov 20 13 12 04 UTC 2015  OS Arch       linux amd64  Server   Version       1 9 1  API version   1 21  Go version    go1 4 2  Git commit    a34a1d5  Built         Fri Nov 20 13 12 04 UTC 2015  OS Arch       linux amd64

User · Answer

This question is currently number 3 on a Google search   After doing some research into solving this problem on my Linux system I thought I would write this answer   The original post states the problem is on Ubuntu but I also experienced the issue using Fedora   With that in mind  here is what I did to fix the problem    On Fedora 22  Installing Docker     gt  curl -fsSL https   get docker com    sh   After installing Docker   A user needs to be added to the docker group     gt  sudo usermod -aG docker   The docker daemon needs to be started    gt  sudo service docker start   You can set the daemon to start at boot    gt  sudo chkconfig docker on   You can verify the docker service is running    gt  service docker status   And one last final check    gt  docker run hello-world

User · Answer

After installing docker on Ubuntu  I ran the following command   sudo service docker start   Have you tried it

User · Answer

I was able to fix that by running the following command  sudo mv  var lib dpkg info docker-ce   tmp

User · Answer

Had the same issue and what worked for me was  Checking the ownership of  var run docker sock   ls -l  var run docker sock   If you re not the owner then change ownership with the command  sudo chown  your-username   var run docker sock   Then you can go ahead and try executing the docker commands hassle-free  D

User · Answer

As docker binds to a  unix socket which is owned by root while starting up  using  sudo  along with the docker commands will work

User · Answer

I have faced same error on Amazon EC2 instance  The issue got fixed after restarting the instance

User · Answer

For Ubuntu 16 04  Inside file  lib systemd system docker service change   ExecStart  usr bin dockerd fd      with   ExecStart  usr bin dockerd -H tcp   0 0 0 0 2375   Inside file  etc init d docker change   DOCKER OPTS    with   DOCKER OPTS  -H tcp   0 0 0 0 2375    and then restart your computer

User · Answer

note to self  I get the error from the question s title when I forget to run docker command with sudo   sudo docker run       Ubuntu 15 10

User · Answer

Add the user to the docker group   Add the docker group if it doesn t already exist   sudo groupadd docker Add the connected user    USER   to the docker group   sudo gpasswd -a   USER  docker Restart the Docker daemon   sudo service docker restart Either do a newgrp docker or log out in to activate the changes to groups

User · Answer

I also had the same issue  The problem was in sockets allocated to docker-daemon and docker-client  First  permission was not set for the docker-client on docker sock You can set it using  sudo usermod -aG docker  USER  Then check your bash file where the docker-client is running  For me it was on 0 0 0 0 2375  while docker-daemon was running on unix socket  It was set in the configuration file of dockerd   Just comment the bash-line and it ll work fine  But if you want to make it work on TCP port instead of unix socket  change the configuration file of dockerd and set it on 0 0 0 0 2375 and keep the line in bash as it is if present or set it to 0 0 0 0 2375

User · Answer

I have same issue while running docker   you can run commands as sudo user   sudo docker    your command here

User · Answer

For the ones who already tried restarting your machine  unsetting the environment variable DOCKER HOST as told in the docker env documentation and all the rest just try to go with the   sudo service docker restart   Only this did the trick for me even after restarting the machine

User · Answer

Giving non-root access - from docker Add the docker group if it doesn t already exist    sudo groupadd docker  Add the connected user  quot   USER  quot  to the docker group  Change the user name to match your preferred user  You may have to logout and log back in again for this to take effect    sudo gpasswd -a   USER  docker  Restart the Docker daemon    sudo service docker restart

User · Answer

Perhaps this will help someone  as the error message is extremely unhelpful  and I had gone through all of the standard permission steps numerous times to no avail   Docker occasionally leaves ghost environment variables in place that block access  despite your system otherwise being correctly set up  The following shell commands may make it accessible again  if you have had it running at one point and it just stopped cooperating after a reboot   unset DOCKER HOST unset DOCKER TLS VERIFY unset DOCKER TLS PATH docker ps   I had a previously working docker install  and after rebooting my laptop it simply refused to work  Was correctly added to the docker user group  had the correct permissions on the socket  etc  but could still not run docker login  docker run      etc  This fixed it for me  Unfortunately I have to run this on each reboot  This is mentioned on a couple of github issues also as a workaround  although it seems like a bug that this is a persistent barrier to correct operation of Docker  note  I am on Arch Linux  not OSX  but this was the same issue for me

User · Answer

Add current user to docker group   sudo usermod -aG docker   whoami

User · Answer

Usually  the following command does the trick   sudo service docker restart   This  instead of docker start for the cases where Docker seems to already be running    If that works then  as suggested and in another answer and on this GitHub issue  if you haven t added yourself in the docker group do it by running   sudo usermod -aG docker  lt your-username gt     And you re most likely good to go     As for anybody else bumping into this  in some OS s docker doesn t start right after you install it and  as a result  the same can t connect to daemon message appears  In this case you can first verify that Docker is indeed not running by checking the status of your docker service by executing   sudo service docker status   If the output looks something like  docker stop waiting instead of docker start running  process 15378 then it obviously means Docker is not active  In this case make sure you start it with   sudo service docker start   And  as before  you ll most likely be good to go

User · Answer

You need to add your current user to the docker group as follows   sudo usermod -aG docker   whoami    then logout  amp  login again into the system or restart the system  test by docker version  for further info how to install docker-engine follow docker documentation

User · Answer

For OSX    After opening docker and starting the  default  machine via the Quickstart Terminal  https   docs docker com engine installation mac    you try docker commands and get this  can t connect to docker daemon  message  it turns out you need some env variables set   eval    docker-machine env default    Then try it out with docker run hello-world to see if everything is peachy

User · Answer

enter as root  sudo su  and try this   unset DOCKER HOST docker run --name mynginx1 -P -d nginx   I ve the same problem here  and the docker command only worked running as root  and also with this DOCKER HOST empty  PS  also beware that the correct and official way to install on Ubuntu is to use their apt repositories  even on 15 10   not with that  wget  thing

[linux] Docker command can't connect to Docker daemon

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