This tutorial guides you to resolve errors Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root ? and Could not open lock file /var/lib/dpkg/lock-frontend – open (13: Permission denied) when you are trying to install softwares in your docker container.
Error: Unable to acquire the dpkg frontend lock, are you root ?
Let’s use standard docker ubuntu image for our example. The below docker run command will result in error because non-root user are not allowed to install software in the docker container. Let’s see how to install required softwares in the docker container.
$ docker run -d ubuntu apt-get update && apt-get install -y openssh-server && /usr/sbin/sshd -D 701462bd115bbdba023ec9908f5d889737c6faa2670db3482a307a7be3019a80 ******************************************************************************** You are running apt-get inside of Cloud Shell. Note that your Cloud Shell machine is ephemeral and no system-wide change will persist beyond session end. To suppress this warning, create an empty ~/.cloudshell/no-apt-get-warning file. The command will automatically proceed in 5 seconds or on any key. Visit https://cloud.google.com/shell/help for more information. ******************************************************************************** E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied) E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?
First, run the following docker command which will start bash session with root user. Then in the bash prompt run apt-get commands as shown.
$ docker run -it ubuntu bash //bash session [email protected]:/# apt-get update && apt-get install -y openssh-server ------- ------- Creating config file /etc/ssh/sshd_config with new version Creating SSH2 RSA key; this may take some time ... 3072 SHA256:TfRXuNvNIZXYKb6mEQYfsdPlw+hbsAFRpFZf0+h407c [email protected] (RSA) Creating SSH2 ECDSA key; this may take some time ... 256 SHA256:P8/CM7WpDygPx0A8fcZXyCmhSdYORqg0jS10C8Oh6hM [email protected] (ECDSA) Creating SSH2 ED25519 key; this may take some time ... 256 SHA256:J+z0EYlWJ5UvRAGHCN2Zp2I+O2mO51QGYaehZNYTz98 [email protected] (ED25519) Created symlink /etc/systemd/system/sshd.service → /lib/systemd/system/ssh.service. Created symlink /etc/systemd/system/multi-user.target.wants/ssh.service → /lib/systemd/system/ssh.service. invoke-rc.d: could not determine current runlevel invoke-rc.d: policy-rc.d denied execution of start. Setting up python3-chardet (3.0.4-4build1) ... Setting up python3-requests (2.22.0-2ubuntu1) ... Setting up networkd-dispatcher (2.0.1-1) ... Created symlink /etc/systemd/system/multi-user.target.wants/networkd-dispatcher.service → /lib/systemd/system/networkd-dispatcher.service. Setting up ssh-import-id (5.10-0ubuntu1) ... Attempting to convert /etc/ssh/ssh_import_id Processing triggers for systemd (245.4-4ubuntu3.2) ... Processing triggers for libc-bin (2.31-0ubuntu9) ... Processing triggers for ca-certificates (20190110ubuntu1.1) ... Updating certificates in /etc/ssl/certs... 0 added, 0 removed; done. Running hooks in /etc/ca-certificates/update.d... done.
Next, run the following commands to make necessary changes in the softwares installed and in the container’s file system.
[email protected]:/# mkdir /var/run/sshd [email protected]:/# adduser admin Adding user `admin' ... Adding new group `admin' (1000) ... Adding new user `admin' (1000) with group `admin' ... Creating home directory `/home/admin' ... Copying files from `/etc/skel' ... New password: Retype new password: passwd: password updated successfully Changing the user information for admin Enter the new value, or press ENTER for the default Full Name : Admin Room Number : 1 Work Phone : 1234567890 Home Phone : 2345678901 Other : Is the information correct? [Y/n] y [email protected]:/# usermod -aG sudo admin [email protected]:/# sed '[email protected]\s*required\s*[email protected] optional [email protected]' -i /etc/pam.d/sshd [email protected]:/# echo 'export NOTVISIBLE="in users profile"' >> ~/.bashrc [email protected]:/# echo "export VISIBLE=now" >> /etc/profile [email protected]:/# exit exit
Once you are done with the required changes, you can create a copy image (ubuntu_sshd) of your modified container with the following docker commit command.
$ docker commit `docker ps -lq` ubuntu_sshd sha256:a382afed9966e53c09d76b095e79342613d5a65c68725374895537fe6295ea24 $ docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu_sshd latest a382afed9966 10 seconds ago 222MB ubuntu latest 1e4467b07108 10 days ago 73.9MB
Now, you can use new image and run docker instance using the following command. This command will start new container and run sshd daemon in the container.
$ docker run -d -p 2222:22 ubuntu_sshd /bin/bash -c "/usr/sbin/sshd -D" a574cef96dfc4b15f907d5315bdd060ef7365b7dcfd700ad7a73a4d3b1e3ac3c $ docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a574cef96dfc ubuntu_sshd "/bin/bash -c '/usr/…" 5 minutes ago Up 5 minutes 0.0.0.0:2222->22/tcp pensive_agnesi 35ef2af2110d ubuntu "bash" 16 minutes ago Exited (0) 8 minutes ago laughing_nobel
Finally, you can SSH in to your docker container using the following command.
$ ssh [email protected] -p 2222 The authenticity of host '[localhost]:2222 ([127.0.0.1]:2222)' can't be established. ECDSA key fingerprint is SHA256:P8/CM7WpDygPx0A8fcZXyCmhSdYORqg0jS10C8Oh6hM. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '[localhost]:2222' (ECDSA) to the list of known hosts. [email protected]'s password: Welcome to Ubuntu 20.04 LTS (GNU/Linux 4.19.112+ x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/advantage This system has been minimized by removing packages and content that are not required on a system that users do not log into. To restore this content, you can run the 'unminimize' command. The programs included with the Ubuntu system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. [email protected]:~$
Once you SSH in to docker container with non-root user (admin) as shown above, then you can install any softwares using non root user as well and you should not see those errors.
Hope it helped 🙂
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