In docker swarm mode you can list nodes with docker node ls. If you want to assign a label to each node you can use the below command to update node labels. For example you can assign a key=value pair like role=storage to one of your node listed with the first command:

docker node update --label-add role=storage YOUR_HOSTNAME

Read more here:
- https://docs.docker.com/engine/swarm/manage-nodes/#update-a-node

The great thing about this labeling is in docker compose file that you can tell docker which server should get deployed on which server (node):

deploy:
   replicas: 4
   placement:
     constraints:
       - node.labels.role == storage

NOTE: role is something that we ourselves have been defined. You can define your own as requirements vary.


#docker #node #swarm #label #role

#java #js #java_script #kim

https://github.com/mher/flower

#celery #flower #celery_monitoring

پیروزی ایران بر مراکش رو خدمت تمامی فوتبال دوستان و ایران دوستان تبریک میگم. به امید موفقیتهای بیشتر

🇮🇷🇮🇷🇮🇷🇮🇷🇮🇷

این موضوع نسبتا بی ربط به بحث کانال رو دوستان لطفا بخونند و تحمل کنند، پیشاپیش عذر خواهی میکنم:

علی کریمی:

تا یک ماه چیزی نخریم؛ هر چیزی که گرون شده.تا دست "دلال و دزدا" ببره از این مملکت

If you have worked with htop you would definitely love Glance, an advanced real time system monitoring tool for Linux.

When you run it in linux you would see IO, CPU, RAM, Network bandwidth, latest system errors, etc in one glance! When you run it it displays the heaviest process on top by default. Read about its UI, installation, etc here:

- https://www.tecmint.com/glances-an-advanced-real-time-system-monitoring-tool-for-linux/

#linux #htop #glance

You can use Grafana to display your OS metrics. You can use its API endpoints to get data in JSON or XML and moreover it provides a web UI for you to take look at the graphs.

By default when you install nginX on Linux a logrotate config file will be created in /etc/logrotate.d/nginx. Sometimes you may see that after a while logs inside of nginX access log is empty and it is logged into the file usually named access.log.1. This error happens when a process cannot close its file handler and has to write into access.log.1.

If you take a look at the config rotation of nginX you will see a part called postrotate that run a command, for nginx it is as below:

postrotate
     invoke-rc.d nginx rotate >/dev/null 2>&1
 endscript

If you run the command between postrotate and endscript it may gives the below error:

invoke-rc.d: action rotate is unknown, but proceeding anyway.
 invoke-rc.d: policy-rc.d denied execution of rotate.

Just remove a file related to i-MSCP:

rm /usr/sbin/policy-rc.d

NOTE: Or if you want to be safe rename it to something else.


Now you can run invoke-rc.d command and you should see a result like below:

[ ok ] Re-opening nginx log files: nginx.

Now every log will be directed to its file not it_file_name.log.1, and file handlers are closed safely.

#nginx #policy_rc #invoke_rc #log_rotate #rotate

There are times that you noway but getting data from a third part library and that library has rate limit on their endpoints. For example I have recently used geopy python library to get latitude and longitude by giving city name to the function:

from geopy.geocoders import Nominatim

 city_name = 'Tehran'
 geolocator = Nominatim()
 location = geolocator.geocode(city_name)
 print location.latitude, location.longitude

This library by default sends its requests to https://nominatim.openstreetmap.org/search to get geo location data. It's rate limit is 1 request per second. To circumvent these problems and limitations use redis to cache results in your server and read cached result from your own system:

self.redis.hset(city_name, 'lat', lat)
 self.redis.hset(city_name, 'long', longitude)

Now read from cache in case it exists:

if self.redis.hexists(city_name, 'lat'):
     location = self.redis.hgetall(city_name)

Make sure to put sleep(1) when reading from Nominatim in order to by pass its limitation.


NOTE: instead of Nominatim other 3rd parties can be used.

#python #geopy #geo #latitude #longitude #Nominatim #redis #hset #geocoders

#programmer_jokes #fun

Apply new basic license on Kibana:

You need to download the license first:
- https://register.elastic.co/xpack_register


The license is a json file that can be applied by cURL, first go to your server where elasticsearch is running and then:

curl -XPUT 'http://172.16.133.102:9200/_xpack/license' -H "Content-Type: application/json" -d @license.json

NOTE: license.json is the file that should be present beside from where you are issuing the cURL command.

#kibana #curl #license #elasticsearch

space=$(df -k / | tail -1 | awk '{print $4}')
 echo "free disk space is $space"

 if [ $space -lt 510000 ]
 then
   echo $(date) + " - Purge elasticsearch indexes..."
   curl -X DELETE "http://localhost:9200/your_index_name_*"
   echo ''
 else
   echo $(date) + " - disk space seems OK"
 fi

Put this in a crontab and you are good to go.

#linux #sysadmin #bash #script #df #elasticsearch #es

tail command in Linux is used to see content of a file from the end. It is usually used for checking log files in server. The interesting thing about tail is that you can use this command to get the last line. So in a bash script if you want to get last row of the below output:

root@server:~# ls -l
 total 24
 -rw-r--r-- 1 root root  291 May 26 05:19 es_queries
 -rw-r--r-- 1 root root 1198 Jun 19 10:34 users.json
 -rwxr-xr-x 1 root root  272 Jun 19 11:22 monitor_disk_space.sh
 -rwxr-xr-x 1 root root  433 Jun 19 10:00 another_script.sh

You would do:

root@server:~# ls -l | tail -1
 -rwxr-xr-x 1 root root  433 Jun 19 10:00 another_script.sh

That's why we have used this command in the previous post on df -k /.

#bash #tail #script #ls

Have you ever wanted to syntax highlight text area with specific content in it? Let's say it contains json data. We also need to have
code folding (+/- in front of objects to collapse them). The tool that can be used for this purpose is codeMirror:
- https://codemirror.net/index.html

One of the things that I want to note here is that textarea wont get updated when you enter data in codeMirror field. For that you need to call save() method of codeMirror like below:

var myEditor = CodeMirror.fromTextArea(page_content, {
     lineNumbers: true,
     mode: "markdown",
     lineWrapping: true,
     lineNumbers:false,
     indentWithTabs: true
 });

 function updateTextArea() {
     myEditor.save();
 }
 myEditor.on('change', updateTextArea);

Download all the demos from github:
- https://github.com/codemirror/codemirror


Instead of myEditor change you can update textarea on form submit.

#syntax_highlighting #syntax #codeMirror #code_folding

#programmer_jokes #fun

pyflame, a fantastic python profiler that uses linux ptrace system call to collect profiling information. It gives you a graph to see where you have messed things up!

One of the great great great things about this library is that you can attach it to a currently running process to profile it. A command like below will do the job:

# Attach to PID 12345 and profile it for 1 second
 pyflame -p 12345

Code and installation can be found in github:
- https://github.com/uber/pyflame

Read more about it:
- https://pyflame.readthedocs.io/en/latest/

#python #pyflame #profiler

In debian linux you can check a directory size by du -h -d 1, BUT in CentOS it is a little bit different:

du -sh /path/to/dir/*

#linux #du #centos #centos #debian

#programmer_jokes #fun