You may have come across this message when you tried to run an executable from Dockerfile. In this article, you will learn how to resolve this error with the help of Systemd. To run an executable from Dockerfile, you must remove the “/” from ENTRYPOINT/CMD. Then, make sure that the ENTRYPOINT/CMD in the Dockerfile calls a bash script.
exec user process in Dockerfile
This issue has several possible causes. One of them is that you have not changed the dockerfile since the issue first occurred. You need to rebuild the docker image if this is the case. The make buildx command rebuilds the docker image if you have not done so yet. It also requires the docker buildx feature to be enabled. Otherwise, you might get an exec format error.
exec user process in Systemd
Whenever you invoke a user process from Systemd, you’ll get an error message saying ‘exec user process in Systemd failed to start’. The cause of this error is probably the absence of the user specified in the systemd.conf file. To solve this issue, you need to use the DynamicUser= facility, which dynamically allocates and releases a user/group name. Systemd’s default user/group is root, and user processes are managed by the root instance of systemd-user. If you want to run user services of other users, you can use the DynamicUser= facility, which is applied at boot time and during package installation.
If you get this error, it means that the systemd filesystems list is not updated to the latest kernel version. Systemd uses the kernel version for its list of filesystems, so it will likely be out of date by the time the process is created. You can see what filesystems are currently available on your system by running the systemd-analyze(1) command.
If the main process is not a daemon, you can use the “exec user process in Systemd” option. It will prevent the systemd service from failing if it can’t get its main PID. This option will not work for services that have Type=forking and PIDFile=. In these cases, the main PID is always known, so guessing will only produce wrong results if your service has multiple processes. Failure detection and automatic restart of services won’t work reliably without a main PID.
When a user process fails to start, you can resolve the problem by modifying the environment variables. The environment variables are passed by the user service manager to the processes. The system manager will pass the environment variables to all user processes. You can also use the truncate-path option, which is only useful for units where only one process is running at a time. This option is useful for services that use only one ExecStart, ExecStartPost, and ExecStop=.
If the exec command is used with the type of service, the result will depend on the type. For example, if the service is a systemd service, the process that is invoked must be a service process. ExecStartPre or ExecStopPost command may be used to restart the service, but they may not be able to start the process.
If you use the cgroup v2 command, you can avoid this problem. RHEL and CentOS 7 do not support this feature. For other operating systems, you can install the latest systemd version or update the cgroup configuration. If you’re running a Systemd based operating system, you can use loginctl to set a lingering mode. It will prevent the user process from being killed. Alternatively, if you’re using Systemd to manage a network server, you can log out as root to continue working.