FN – Page 2 – My 'wiki'

Python dependencies on project level

31/03/2020 FN Comments 0 Comment

Since I started work with Python, I struggled with dependencies on a project level. I was aware of requirements.txt file, but handling it became very difficult for multiple projects. Fortunately I found very handy tool called pipreqs which generages a project level requirements.txt file using one command. Installation

pip3 install pipreqs

1	pip3 install pipreqs

Usage Just go into your project directory and run

pipreqs

pipreqs

and install inside target environment

pip3 install -r requirements.txt

1	pip3 install -r requirements.txt

Sometimes it does on work on 100 %, but it can save a lot of…

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ls -la output explanation

28/03/2020 FN Comments 0 Comment

Show files ls Will provide basic overview of files and folders present in the directory

fniko@server:~$ ls
some_folder

1 2	fniko@server:~$ ls some_folder

Show files with details ls -l With file / folder details

fniko@server:~$ ls -l
total 4
drwxrwxr-x 3 fniko fniko 4096 Mar 28 00:45 some_folder

fniko@server:~$ ls -l

total 4

drwxrwxr-x 3 fniko fniko 4096 Mar 28 00:45 some_folder

Show hidden files ls -la Will show hidden files with . prefix

fniko@server:~$ ls -la
total 76
drwxr-xr-x 8 fniko fniko  4096 Mar 28 01:23 .
drwxr-xr-x 4 root  root   4096 Mar 25 10:32 ..
-rw------- 1 fniko fniko  5422 Mar 28 00:03 .bash_history
-rw-r--r-- 1 fniko fniko   220 Mar 25 10:32 .bash_logout
-rw-r--r-- 1 fniko fniko  3771 Mar 28 01:23 .bashrc
drwx------ 3 fniko fniko  4096 Mar 25 11:07 .cache
drwx------ 3 fniko fniko  4096 Mar 27 16:28 .config
drwx------ 3 fniko fniko  4096 Mar 25 10:35 .gnupg
drwx------ 5 fniko fniko  4096 Mar 28 00:29 .local
-rw------- 1 fniko fniko    64 Mar 26 12:30 .mysql_history
-rw-r--r-- 1 fniko fniko   807 Mar 25 10:32 .profile
-rw------- 1 fniko fniko     0 Mar 27 15:53 .python_history
-rw-rw-r-- 1 fniko fniko    75 Mar 25 10:53 .selected_editor
drwxr-xr-x 2 root  root   4096 Mar 25 10:34 .ssh
-rw------- 1 fniko fniko 16048 Mar 28 01:23 .viminfo
drwxrwxr-x 3 fniko fniko  4096 Mar 28 00:45 some_folder

fniko@server:~$ ls -la

total 76

drwxr-xr-x 8 fniko fniko 4096 Mar 28 01:23 .

drwxr-xr-x 4 root root 4096 Mar 25 10:32 ..

-rw------- 1 fniko fniko 5422 Mar 28 00:03 .bash_history

-rw-r--r-- 1 fniko fniko 220 Mar 25 10:32 .bash_logout

-rw-r--r-- 1 fniko fniko 3771 Mar 28 01:23 .bashrc

drwx------ 3 fniko fniko 4096 Mar 25 11:07 .cache

drwx------ 3 fniko fniko 4096 Mar 27 16:28 .config

drwx------ 3 fniko fniko 4096 Mar 25 10:35 .gnupg

drwx------ 5 fniko fniko 4096 Mar 28 00:29 .local

-rw------- 1 fniko fniko 64 Mar 26 12:30 .mysql_history

-rw-r--r-- 1 fniko fniko 807 Mar 25 10:32 .profile

-rw------- 1 fniko fniko 0 Mar 27 15:53 .python_history

-rw-rw-r-- 1 fniko fniko 75 Mar 25 10:53 .selected_editor

drwxr-xr-x 2 root root 4096 Mar 25 10:34 .ssh

-rw------- 1 fniko fniko 16048 Mar 28 01:23 .viminfo

drwxrwxr-x 3 fniko fniko 4096 Mar 28 00:45 some_folder

Output exmplanation

┌───────────── '-' for file, 'd' for dictionary, 'l' for symlink
│   ┌───────── permissions for 'user' - 'group' - 'others'
│   │       ┌─ number of links
│   │       │   ┌───────────── owner
│   │       │   │        ┌──── owner group
│   │       │   │        │                 ┌──────────── file size in bytes                 
│   │       │   │        │                 |        ┌─── last modification time
│   │       │   │        │                 |        |         ┌─── file name
|   |       |   |        |                 |        |         | 
|   |       |   |        |                 |        |         | 
-rw-r-----  1 syslog    adm             399687 Mar 28 01:08 syslog

┌───────────── '-' for file, 'd' for dictionary, 'l' for symlink

│ ┌───────── permissions for 'user' - 'group' - 'others'

│ │ ┌─ number of links

│ │ │ ┌───────────── owner

│ │ │ │ ┌──── owner group

│ │ │ │ │ ┌──────────── file size in bytes

│ │ │ │ │ | ┌─── last modification time

│ │ │ │ │ | | ┌─── file name

| | | | | | | |

-rw-r----- 1 syslog adm 399687 Mar 28 01:08 syslog

Bonus Running this command will add alias ll to run ls -la where this shortcut is not present yet.

echo alias ll='ls -la --color=auto' >> ~/.bashrc

1	echo alias ll='ls -la --color=auto' >> ~/.bashrc

Connecting the Raspberry Pi Zero W/WH to WiFi

19/03/2020 FN Comments 0 Comment

Recently I bought a Raspberry Pi Zero WH, and I wanted to connect it to my WiFi, but first 5 guides from Google were not working well, so I wanted to share the approach I used using raspi-config. 0. Get ready Raspbian on the Pi And connect to it using ethernet or plug in the monitor to it via HDMI. 1. Get ready SSH You can do this using sudo raspi-config (5. Interfacing options/P2 SSH) or using

sudo systemctl enable ssh
sudo systemctl start ssh

1 2	sudo systemctl enable ssh sudo systemctl start ssh

Default credentials…

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Kubernetes and Sealed Secrets (Kubernetes)

21/01/2020 FN Comments 0 Comment

PROBLEM: I would like to share my secrets to git SOLUTION: Use the Sealed Secretes (Installing kubeseal) Kubeseal is the CLI tool to manage sealed secret, is you are using macOS, you should use brew:

brew install kubeseal

1	brew install kubeseal

On (ubuntu based) linux you should be fine using:

wget https://github.com/bitnami-labs/sealed-secrets/releases/download/v0.9.6/kubeseal-linux-amd64 -O kubeseal
sudo install -m 755 kubeseal /usr/local/bin/kubeseal && rm kubeseal

1 2	wget https://github.com/bitnami-labs/sealed-secrets/releases/download/v0.9.6/kubeseal-linux-amd64 -O kubeseal sudo install -m 755 kubeseal /usr/local/bin/kubeseal && rm kubeseal

Creating a secret There are different ways how to create a secret, I am using direct input (–from-literal) or direct YAML efinition. I will show both. Let’s assume I am deploying some application which will…

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Display apps and occupied ports (Linux)

08/10/2019 FN Comments 0 Comment

PROBLEM: My app is not starting, because port is already in use! SOLUTION: Find it and kill it 🙂 netstat -tulpn Will provide nice table with all info you migh like, truncated outpus below:

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.1:9770          0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:5940          0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      -

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name

tcp 0 0 127.0.0.1:9770 0.0.0.0:* LISTEN -

tcp 0 0 127.0.0.1:5940 0.0.0.0:* LISTEN -

tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN -

sudo ss -tulpn More fresh, more detailed (i like it more than netstat)

Netid          State            Recv-Q           Send-Q                       Local Address:Port                        Peer Address:Port                                                                           
udp            UNCONN           0                0                              224.0.0.251:5353                             0.0.0.0:*               users:(("chrome",pid=3222,fd=260))                             
udp            UNCONN           0                0                              224.0.0.251:5353                             0.0.0.0:*               users:(("chrome",pid=3269,fd=131))

Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port

udp UNCONN 0 0 224.0.0.251:5353 0.0.0.0:* users:(("chrome",pid=3222,fd=260))

udp UNCONN 0 0 224.0.0.251:5353 0.0.0.0:* users:(("chrome",pid=3269,fd=131))

Now you can find what is “eating” your ports and you are able to debug errors 🙂 Note: If you cannot see the PID, use sudo to execute the command

Resize swap in Ubuntu 18.04 and later (Linux)

12/09/2019 FN Comments 2 comments

PROBLEM: My swap is too small 🙁 SOLUTION: Disable, resize and enable swap again! 1. Disable swap

sudo swapoff -a

1	sudo swapoff -a

2. Resize swap With goal of 2 GB (1 GB * 2)

sudo dd if=/dev/zero of=/swapfile bs=1G count=2

1	sudo dd if=/dev/zero of=/swapfile bs=1G count=2

Where: if – input file of – output file bs – block size count – block multiplier Note: If you get error: dd: memory exhausted by input buffer of size 1073741824 bytes (1.0 GiB) just try to change the bs to MB and increase the count size

sudo dd if=/dev/zero of=/swapfile bs=1M count=2000

1	sudo dd if=/dev/zero of=/swapfile bs=1M count=2000

3. Make…

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Permanently exporting environment variables using direnv (Linux)

06/09/2019 FN Comments 0 Comment

PROBLEM: I use some variables (credentials) so often, but I don’t like exporting them each time SOLUTION: Start using direnv! Direnv should be already present in your system You can check the same on the direnv website (here), if is not, you can always build it from binary. Hook direnv into shell Add this line on the end of your .bashrc file (if you are using bash)

eval "$(direnv hook bash)"

1	eval "$(direnv hook bash)"

Create .envrc file And put all variables you would like to have accesible…

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Ports in Kubernetes Services (Kubernetes)

27/08/2019 FN Comments 0 Comment

Just a quick reminder how ports definition in k8s services works. Service definition example below, just forgot all but port definition and take a closer look. NodePort

apiVersion: v1
kind: Service
metadata:
  name: client-node-port
spec:
  type: NodePort
  ports:
    - port: 3050
      targetPort: 3000
      nodePort: 31515
  selector:
    component: web

apiVersion: v1

kind: Service

metadata:

name: client-node-port

spec:

type: NodePort

ports:

- port: 3050

targetPort: 3000

nodePort: 31515

selector:

component: web

We can see port definition 3 times (it’s array and you can use as many of them as open ports you need): port, targetPort and nodePort. Why 3 ports? If you are familiar with Docker (Swarm) you would expect only 2, right…? NodePort port : other pod/service inside our cluster can access…

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Port forward to access applications in cluster (Kubernetes)

26/08/2019 FN Comments 0 Comment

PROBLEM: Cannot access pods in my k8s deployment for testing SOLUTION: Use very simple port-forward method Find your destination Decide what do you want to access. Port forward works on services, pods, deployments or even replicaSets. The syntax is very simple.

kubctl port-forward pod-name local-port:destination-port

1	kubctl port-forward pod-name local-port:destination-port

Which leads to example like this:

kubectl port-forward my-pod-name 1000:3000

1	kubectl port-forward my-pod-name 1000:3000

You can see your app through port 1000 on your local machine (working on the port 3000 on remote). Bear in mind, you are connecting directly to the service/pod/whatever, so use the…

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Create permanent command alias (Linux)

26/08/2019 FN Comments 0 Comment

PROBLEM: My set up aliases are not persistent after reboot SOLUTION: Write them to ~/.bashrc Edit ~/.bashrc Using sudo

sudo nano ~/.bashrc

1	sudo nano ~/.bashrc

Add as many aliases as you wish! Separe by new line. I prefer adding them on the beginning of the file so I can find them quickly.

alias ll="ls -l"
alias cls="clear"

1 2	alias ll="ls -l" alias cls="clear"