Install daemontools in CentOS 7

Install daemontools in CentOS 7

Daemontools is a tool used to manage Unix services. It provides a set of tools to manage a series of user processes. After a process is down for some reason, daemontools automatically restarts the process.

Note:

The managed process cannot run in the form of daemon. For example, nginx. conf must disable daemon and daemon off;
Do not create any directory in/service/./service/only stores some symbol links.
You only need to complete the installation/configuration steps.
Install

$ mkdir  ~/tools$ cd /tools$ wget http://cr.yp.to/daemontools/daemontools-0.76.tar.gz$ tar xvzf daemontools-0.76.tar.gz$ cd admin/daemontools-0.76$ package/install

If an error occurs during installation

/Usr/bin/ld: errno: TLS defini tion in/lib/libc. so.6 section. tbss mismatches non-TLS reference in envdir. o will admin/daemontools-0.76/src/error. in h, replace extern int errno with # include <errno. h>

After the installation is complete, two directories,/service/command, will be created.

Start daemontools

Daemontools is a set of service management tools. The svscanboot tool is used to start the svscan tool. Run the following command to start svscanboot:

# /command/svscanboot &

You can also set boot startup. For more information, see

After the process is started, view the process and find that the sub-process of svscan as svscanboot is running

# ps -ef|grep svs  root      9134  9072  0 04:05 pts/2    00:00:00 /bin/sh /command/svscanbootroot      9136  9134  0 04:05 pts/2    00:00:00 svscan /service

Configuration

After svscanboot is started, the corresponding svscan process is started. The parameter/service/is the directory for managing the configuration file.

Create the services Directory, for example

# mkdir -p /opt/svc/{nginx, tornado}

Create a run script in the services Directory (the name must be run and the permission is 755), such as the nginx directory

# Touch/opt/svc/nginx/run & chmod 755/opt/svc/nginx/run # cat/opt/svc/nginx/run #! /Bin/shexec/home/vagrant/nginx/sbin/nginx # start the process command

Create a symbol link. After creation, daemontools automatically starts the nginx process.

#ln -s /opt/svc/nginx/  /service/ #ln -s /opt/svc/tornado/  /service/ # pstree -a  -p 9134svscanboot,9134 /command/svscanboot  |-readproctitle,9137 service errors:...  `-svscan,913      6 /service      |-supervise,9138 nginx      |   `-nginx,913       9      |       `-nginx,9140               `-supervise,9164      tornado          `-python,9165 /home/vagrant/tornado/main.py

Svscanboot is responsible for starting the svscan service and managing the supervise process. The specific customer processes are managed in a unified manner through the supervise process.

Now nginx and tornado are managed by daemontool. Try to kill the tornado application process.

root@precise32:/service# kill 9165root@precise32:/service# !psps -ef|grep torroot          9164  9136  0 04:06 pts/2    00:00:00 supervise tornadoroot          9181  9164  2 04:09 pts/2    00:00:00 python /home/vagrant/tornado/main.py

As you can see, although the tornado application is manually killed, the daemontool automatically restarts the application.

Common commands

Start the managed process (no svc command is required after configuration)

Svc-u/service/nginx/(if nginx fails after startup, daemontools will automatically restart nginx)

Shut down the managed process (daemontools supervise process is not disabled)

svc -d /service/nginx/

View service status

svstat /service/nginx/

Remove service

Rm/service/nginx # Remove soft connection svc-dx/opt/svc/nginx/

Pouting

Q: What should I do if the daemontools process crashes ??
A: Check the document and manually kill the svscanboot/svscan/supervisor process?

The above content from http://linbo.github.io/2013/02/24/daemontools

Some modifications are required on CentOS 7 as follows:

Cut 'n' paste fromhttp: // www.productionmonkeys.net/guides/qmail-server/daemontools

CentOS 7 uses systemd

Create a new file/etc/systemd/system/daemontools. service, with the startup code in it:
Create a file/etc/systemd/system/daemontools. service with the following content:

[Unit]Description=daemontools Start superviseAfter=getty.target[Service]Type=simpleUser=rootGroup=rootRestart=alwaysExecStart=/command/svscanboot /dev/ttyS0TimeoutSec=0[Install]WantedBy=multi-user.target

Start the service. Start the service:

Systemctl start daemontools. service

Test that it is running, Test whether to run:

Systemctl status daemontools. service

Enable it to start at boot:

Systemctl enable daemontools. service