If you have ever happened to execute some complex scripts using the cron system you were inevitable to discover the Linux environment was different than the login or ssh shell. The different environment tends to lead to a missing or different PATH environment! Here is what happens with podman starting a container from a cron script:
time="2020-04-19T20:45:20Z" level=error msg="Error adding network: failed to locate iptables: exec: \"iptables\": executable file not found in $PATH" time="2020-04-19T20:45:20Z" level=error msg="Error while adding pod to CNI network \"podman\": failed to locate iptables: exec: \"iptables\": executable file not found in $PATH" Error: unable to start container "onedrive-cli": error configuring network namespace for container d297cf80db20441d4258a1acc7d810444795d1ca8730ab242d9fe8a13eaa697d: failed to locate iptables: exec: "iptables": executable file not found in $PATH
The iptables executable is missing because the PATH variable is different than the login or ssh shell one. Executing the commands or the script under ssh or login will result in no error and a proper podman (docker) execution!
A similar problem could have happened with another software trying to execute iptables or another tool, which is not found in the cron’s PATH environment because cron’s environment is very limited and
To ensure the PATH is like the user’s (root) environment just source the “profile” or “.bashrc” file of the current user before the execution of the script or in the first lines of it.
This would do the trick.
. /etc/profile
Or user’s custom
. ~/.bashrc
Or the default OS bashrc
. /etc/bashrc
The dot may be replaced by “source”:
source /etc/bashrc
All (environment) variables will be available after the source command.
Here is the difference:
The environment without the sourcing profile/bashrc file:
LANG=en_US.UTF-8 XDG_SESSION_ID=19118 USER=root PWD=/root HOME=/root SHELL=/bin/sh SHLVL=1 LOGNAME=root DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus XDG_RUNTIME_DIR=/run/user/0 PATH=/usr/bin:/bin _=/usr/bin/env
Sourcing the “/etc/profile” file:
LANG=en_US.UTF-8 HISTCONTROL=ignoredups HOSTNAME=srv.example.com XDG_SESSION_ID=19165 USER=root PWD=/root HOME=/root MAIL=/var/spool/mail/root SHELL=/bin/bash SHLVL=1 LOGNAME=root DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus XDG_RUNTIME_DIR=/run/user/0 PATH=/usr/local/sbin:/usr/sbin:/usr/bin:/bin HISTSIZE=1000 LESSOPEN=||/usr/bin/lesspipe.sh %s _=/usr/bin/env
Multiple additional envrinment varibles, which could be important for user’s scripts executed by the cron.
And in CentOS 8 the iptables happens to be in “/usr/sbin/iptables” – a path /usr/sbin not included in the default cron environment PATH variable!
Of course, the PATH environment may be edited in the cron scheduler with crontab (by just setting the PATH with a path) till the next path missing in it and included in the user’s path! It’s just better to ensure the two environments are the same every time by sourcing the environment configuration file such as /etc/profile or user’s bashrc (or the default on in /etc/bashrc?).