[CENTOS] I made a ready-to-use syslog server with Play with Docker

I want to create a server for verification with Docker

So I played with Play with Docker!

● What you need docker account Browser (Chrome recommended)

● What I made https://hub.docker.com/r/tt15/centos-syslog

Play with Docker operation

https://labs.play-with-docker.com

Log in to Play with Docker with a Docker account (like Chrome recommends) Press ** + ADD NEW INSTANCE ** to launch the Docker environment (IP address is automatically assigned, and instances can be pinged to the Internet) Type the Docker command on the screen on the right to build the environment.

docker.test

$ docker pull centos:centos7

centos7: Pulling from library/centos
ab5ef0e58194: Pull complete 
Digest: sha256:4a701376d03f6b39b8c2a8f4a8e499441b0d567f9ab9d58e4991de4472fb813c
Status: Downloaded newer image for centos:centos7
docker.io/library/centos:centos7

You can download the image on Docker Hub with docker pull.

• Note It's like "public user": "like a version called a tag".

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docker.test

$ docker run -it -d --privileged --name centos -p 514:514/udp centos:centos7 /sbin/init

484bc681a2d879c94ecabc8401756fee3828f5d16c9ed8dfffb3937d91506100

Launch the pulled image with docker run. By the way, you can check the image that is currently running with docker ps.

• Note -it is for tty If you do not enter -d, the following prompt will not appear --privileged is sudo-like If you do not give a descriptive name with --name, you can give it randomly Open the port used for syslog with -p Take the pulled image as an argument Run / sbin / init, otherwise you couldn't use the systemctl command to use later

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docker.test

$ docker exec -it centos /bin/bash

[root@484bc681a2d8 /]# 

You can execute commands on the image you are running with docker exec.

• Note I think that -it can be used for interactive processing using tty. .. You can type ls or cat in / bin / bash. By the way, you can return to the docker side with Ctrl + C.

CentOS operation

bash.rx

[root@484bc681a2d8 /]# yum -y install rsyslog
[root@484bc681a2d8 /]# yum -y install net-tools

After each execution, the state of dobadoba and download will appear. Install the required packages for syslogd. Also installed a command package to display CentOS network information. Used for later operation check. The rest is completed with minimal rsyslog settings.

• Note Net-tools seems to be deprecated and is deprecated. I couldn't use the alternative command ss and I used it because I'm used to netstat.

rsyslog.conf operation

bash.test

[root@484bc681a2d8 /]# vi /etc/rsyslog.conf

rsyslog.conf

# Provides UDP syslog reception
$ModLoad imudp
$UDPServerRun 514

# Provides TCP syslog reception
$ModLoad imtcp
$InputTCPServerRun 514

Since you have installed rsyslog, you should have rsyslog.conf. Since all the settings are commented out with #, delete the # in the above 4 places. In terms of vi, you can delete the character to the right of the cursor with x. To save, press the exc key, press:, and enter wq !.

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bash.rx

[root@484bc681a2d8 /]# systemctl restart rsyslog
[root@484bc681a2d8 /]# netstat -antup
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address   Foreign Address State PID/Program name    
tcp     0      0 0.0.0.0:514        0.0.0.0:*      LISTEN   879/rsyslogd        
tcp6    0      0 :::514             :::*           LISTEN   879/rsyslogd        
udp     0      0 0.0.0.0:514        0.0.0.0:*               879/rsyslogd        
udp6    0      0 :::514             :::*                    879/rsyslogd    

Restarting rsyslog will load the modified rsyslog.conf. You can display the TCP and UDP connection status with netstat -antup. You can see that rsyslog is running on port 514.

• Note -antup is written by combining the options of -a, -n ,,, respectively. -a is all -n is a number display -t is TCP -u is UDP -p is the process ID display

The receiver of rsyslog is now ready!

Verification

In the same flow as before, do another ** + ADD NEW INSTANCE ** and start rsyslog. Only the setting part of rsyslog.conf is different when starting up the sender!

bash.tx

[root@484bc681a2d8 /]# vi /etc/rsyslog.conf
*.info;mail.none;authpriv.none;cron.none* @192.168.0.1:514
*.info;mail.none;authpriv.none;cron.none* @@192.168.0.1:514

Add these two lines at the very end of rsyslog.conf. Don't forget to change the IP address to that of the real environment. Also restart after setting!

• Note @ Is UDP and @@ is TCP. ..

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bash.tx

[root@484bc681a2d8 /]# logger
test1
test2
test3

It seems that the sender can send the log with the logger command. It will be sent to / var / log / messages on the receiving side, so let's take a look.

bash.rx

[root@484bc681a2d8 /]# tail /var/log/messages
Mar 15 07:05:43 484bc681a2d8 root: test1
Mar 15 07:05:45 484bc681a2d8 root: test2
Mar 15 07:05:46 484bc681a2d8 root: test3

tail is a command to display from the last line of the text file. I can send it properly! !!

Impressions

With Play with Docker, it was easy because the sender and receiver could be created quickly! I'm grateful that it can be completed with just a browser. Even after 4 hours, you can pull docker from anywhere by pushing the image created on Docker Hub. (You can use docker login, docker tag, docker push)