I would like to periodically trigger a remote bash script. How this needs to work is that a 3rd party application will connect to a CentOS 7 system on a specific TCP port and send a short text message. SSH is not an option because of the 3rd party application.
When the message is received it needs to pass the IP address to the bash script. I would like the bash script to run and then go dormant until the next message. I would prefer not to write a daemon. I just want to keep this simple.
These messages may come a few times per week or less. We had this running on using xinetd but not sure exactly how to make this work with systemd.
Here is what I have so far:
/etc/systemd/systemfoo.service
[Unit]
Description=Foo Service
After=network.target foo.socket
Requires=foo.socket
[Service]
Type=oneshot
ExecStart=/bin/bash /opt/foo/foo.sh
TimeoutStopSec=5
[Install]
WantedBy=multi-user.target
/etc/systemd/systemfoo.socket
[Unit]
Description=Foo Socket
PartOf=foo.service
[Socket]
ListenStream=127.0.0.1:7780
[Install]
WantedBy=sockets.target
/opt/foo/foo.sh
#!/bin/bash
# Not sure how to get IP
logger -t FOO "Connection received:"
# Do some action
This is what I see in the log:
Jul 10 17:29:32 localhost systemd: Listening on Foo Socket.
Jul 10 17:29:32 localhost systemd: Starting Foo Socket.
Jul 10 17:29:32 localhost systemd: Started Foo Service.
Jul 10 17:29:32 localhost systemd: Starting Foo Service...
Jul 10 17:29:32 localhost FOO: Connection received
Jul 10 17:29:53 localhost systemd: Started Session 4 of user vagrant.
Jul 10 17:29:53 localhost systemd-logind: New session 4 of user vagrant.
Jul 10 17:29:53 localhost systemd: Starting Session 4 of user vagrant.
Jul 10 17:29:56 localhost su: (to root) vagrant on pts/1
Jul 10 17:30:11 localhost systemd: Started Foo Service.
Jul 10 17:30:11 localhost systemd: Starting Foo Service...
Jul 10 17:30:11 localhost FOO: Connection received
Jul 10 17:30:11 localhost systemd: Started Foo Service.
Jul 10 17:30:11 localhost systemd: Starting Foo Service...
Jul 10 17:30:11 localhost FOO: Connection received
Jul 10 17:30:11 localhost systemd: Started Foo Service.
Jul 10 17:30:11 localhost systemd: Starting Foo Service...
Jul 10 17:30:11 localhost FOO: Connection received
Jul 10 17:30:11 localhost systemd: Started Foo Service.
Jul 10 17:30:11 localhost systemd: Starting Foo Service...
Jul 10 17:30:11 localhost FOO: Connection received
Jul 10 17:30:11 localhost systemd: Started Foo Service.
Jul 10 17:30:11 localhost systemd: Starting Foo Service...
Jul 10 17:30:11 localhost FOO: Connection received
Jul 10 17:30:11 localhost systemd: start request repeated too quickly for foo.service
Jul 10 17:30:11 localhost systemd: Failed to start Foo Service.
Jul 10 17:30:11 localhost systemd: Unit foo.socket entered failed state.
Jul 10 17:30:11 localhost systemd: Unit foo.service entered failed state.
Jul 10 17:30:11 localhost systemd: foo.service failed.
Any suggestions on how to make systemd run the script once and then wait for the next message before running it again?
For testing I'm just running:
echo "Hello" | nc 127.0.0.1 7780
Updated Working Configuration
/etc/systemd/[email protected] Note the @.
[Unit]
Description=Foo Service
After=network.target systemfoo.socket
Requires=systemfoo.socket
[Service]
Type=oneshot
ExecStart=/bin/bash /opt/foo/foo.sh
TimeoutStopSec=5
[Install]
WantedBy=multi-user.target
/etc/systemd/systemfoo.socket
[Unit]
Description=Foo Socket
[email protected]
[Socket]
ListenStream=127.0.0.1:7780
Accept=Yes
[Install]
WantedBy=sockets.target
/opt/foo/foo.sh
#!/bin/bash
# Not sure how to get IP
logger -t FOO "Connection received: $REMOTE_ADDR $REMOTE_PORT"
# Do some action
Required to load the configuration into systemd:
systemctl enable systemfoo.socket
systemctl start systemfoo.socket
