note-to-self://hans.anderson
Posts helping me remember how to do something I don't do often enough to remember. Or, that have enough steps in a particular order that I need to remember. Hopefully, they may help you, too.
April 28, 2025
How to Intercept Sockets Using Playwright
Intercept sockets using playwright with dev console trick.
ReadApril 28, 2025
Kubernetes CoreDNS Notes
Some notes to help me remember some Kubernetes items: Core DNS handles all of the DNS internally. If it's not in CoreDNS then it checks the external network. ClusterIP means it's only accessible...
ReadApril 28, 2025
Run Owasp Zap in a Docker container
Run as daemon mode: Desktop UI: Then go to http://localhost:8080/zap. Use https://host.docker.internal to hit https://local..com Baseline scan: Full scan: Find container's IP: Use...
ReadApril 23, 2025
Writing to stdout/stderr in Docker / Kubernetes
Recently I was testing some log aggregation, and I needed to write data to stdout/stderr so that the logging agent could send them to the aggregator. Here's a snippet of code to run that for awhile...
ReadApril 23, 2025
Check Whether an AWS VPC is Being Used
If you need to check whether a VPC is being used -- you do not want to delete a VPC if it is being used, you can double-check it with this command:
ReadMarch 10, 2025
Cloudflare API Example in bash/curl
Cloudflare API Example in bash/curl. This particular script was a proof-of-concept to disable a cache rule.
ReadJanuary 25, 2025
ARP in Networking
ARP (Address Resolution Protocol) is a fundamental networking protocol. It translates IP addresses into their corresponding MAC address.
Find your network interface:
ifconfig...
January 19, 2025
Promises in Three Languages
Three ways to handle concurrent API requests that resolve when all are done, but can run concurrently. In other words, if you have three requests and takes 2 seconds, takes 1 second takes 2...
ReadJanuary 19, 2025
Concurrency vs Parallelism
As always: This is for my own understanding. Please don't assume it is 100% correct. Concurrency is handling multiple tasks during the same time. Parallelism is actually doing tasks at the same...
ReadJanuary 18, 2025
Things to Know About Concurrency
Things to know about Concurrency: Why it's important: Devops involves working with systems that might involve multiple processes, threads, or containers running concurrently. Understanding basic...
ReadJanuary 18, 2025
The `awk` Command
To determine whether a website is using only IPv6 or if it supports both IPv4 and IPv6 (dual stack), you can do: If only the IPv6 ping is successful, the site might not support IPv4. If...
ReadJanuary 17, 2025
Bring a Git Subfolder and History to New Repo
Bring a git subfolder and it's history over to start a new repo: https://docs.github.com/en/get-started/using-git/splitting-a-subfolder-out-into-a-new-repository I did this for a repo and it was...
ReadJanuary 12, 2025
Wireshark
Here's some notes on Wireshark, especially filtering results. You need to set an environment variable in a terminal, AND open the browser from that terminal: Then, you need to tell Wireshark...
ReadDecember 29, 2024
Kubernetes ConfigMap Values
Extract a Specific Key from a ConfigMap: You can use jq or yq to parse JSON or YAML output to get specific values. For example, to get the value of a specific key in a...
December 21, 2024
Command to Find a Command's Shared Libraries
Command to find out what shared libraries an executable needs: ldd /bin/bash eg
When I created a chroot test, I copied /bin/bash and then did the ldd, and it was not...
December 21, 2024
Command to Find a Command's Apt Package
Sometimes I type a command in linux and it's not found. I try to install it and it's not found. Often it will say what package you need to install, but when it doesn't it's usually something...
ReadDecember 21, 2024
Python Instance Types
Python's gettype or instanceof is isinstance().
isinstance() can be used to check for a variety of object types in Python. Here are some common...
December 21, 2024
Endianness and Hex Editor Values
Type "foobar" (no quotes) into a text file, open in a hex editor. 'b' will be hex '62' which translated to dec is '98', which is the ascii code for the letter 'b'. B's ascii code is 66, so the hex...
ReadDecember 21, 2024
Signal Handling in Three Languages
Signal processing in three scripting languages: Run: Run: Run:
ReadDecember 21, 2024
Hexidecimal Math
Note: this is not the "word" abc123. This is the number abc123 as represented in hexidecimal.
Each "place" is 16^<place>.
So abc123:
a...
December 7, 2024
Docker RUN v ADD v COPY
I was wondering why we needed specific commands like COPY, instead of just RUN cp file1 file2. Research, and a colleague, says there are two reasons:
Basically,...
December 7, 2024
Docker Image Layers
Each instruction in a Dockerfile (like RUN, COPY, or ADD) creates a new layer. These layers are stacked on top of each other to form a complete...
December 7, 2024
Docker RUN v CMD v ENTRYPOINT
RUN - (buildtime) during image build, lines in a bash script to install everything for the image. Most Dockerfiles will have many of these. Each one creates a docker layer. It's a good idea to...
ReadDecember 3, 2024
Kubernetes Control Plane
Control Plane is a group of components to run the cluster; Data Plane is everything that is actually the app and things supporting the app. It's like the Control Plane is the OS and the Data Plane is...
ReadNovember 23, 2024
Add a Kubernetes Cluster Context
This is for my own understanding. Please don't assume it is 100% correct.
Each cluster provider will have some sort of kubeconfig command so you can add a context locally, for whatever...
November 23, 2024
View Your Current a Kubernetes `kubectl` Cluster Context on the CLI
When I first started using git many years ago, you would be working pretty blind on the command line (and I don't know of any GUI tools at the beginning). So, to make sure you didn't...
November 23, 2024
VSCode keybindings.json file
My keybindings.json file, mostly for backup purposes:
Note: on a Mac, these are in ~/Library/Application Support/Code/User/keybindings.json
November 23, 2024
Install a Kubernetes Ingress
This is for my own understanding. It might be wrong but reflects my current understanding.
(using kind)
This setup maps ports 80 and 443 from localhost to the ingress. It's like...
November 23, 2024
Difference Between Kubernetes yaml and Helm Chart
This is for my own understanding. Please don't assume it is 100% correct. A helm chart is an abstraction that allows you to group multiple k8s configuration files into one package and deploy...
ReadNovember 23, 2024
Kubernetes Helm Releases
This is for my own understanding. Please don't assume it is 100% correct. When releasing with helm, the release name typically stays the same when you then upgrade a Helm chart. The release name...
ReadNovember 14, 2024
Kubernetes `Rollout`
In k8s, you don't "deploy", you "rollout". But, you don't "rollout" either. You either apply a deployment (or do it through helm, preferably), or kubectl create deployment <name>....
November 13, 2024
Kubernetes Scaling
CA - Cluster Autoscaling. VPA - Vertical Pod Autoscaling. HPA - Horizontal Pod Autoscaling. To me, using VPA/HPA alone can’t be much cost savings. At best, it can rearrange the resources you are...
ReadNovember 13, 2024
Kubernetes Helm Basics
This is for my own understanding. It might be wrong but reflects my current understanding. Helm is a package manager and templater. It stores whatever info it has about the configuration in the...
ReadNovember 13, 2024
Kubernetes Cluster Management
This reflects how I currently understand this, and may be incorrect: kops: create k8s clusters that you manage yourself, on whatever provider (AWS, Azure, etc) eksctl: create k8s clusters managed...
ReadNovember 6, 2024
How to Find What Resource to List for `kind:`
When creating an application in kubernetes, there are a lot of values for the kind: field. This is how to find those, and explain them so you know what values should be there.
Example:...
November 4, 2024
VSCode *.code-workspace file
An example of a <something>.code-workspace file, mostly for backup purposes:
October 31, 2024
VSCode settings.json file
My settings.json file as of 2024-10-31, mostly for backup purposes:
Note: on a Mac, these are in ~/Library/Application Support/Code/User/settings.json
October 31, 2024
VSCode Tips and Snippet
Open any compatible file: To open a file that isn't in a workspace into a new window instead. I like this when it's just a random file I want to edit, not part of a project.
ReadOctober 30, 2024
The `awk` Command
Has some crossover abilities but really shines with displaying or translating column data. Example usage: Find something in a file, then display the first two columns: Output data in a more...
ReadOctober 25, 2024
Kubernetes Namespace v Context
This SO answer really helped.
Essentially, a context is just a way to set the namespace on the client side when running kubectl so that you don't have to type out the namespace part of...
October 25, 2024
Why You Need an HPA for Every Container
HPA = Horizontal Pod Autoscaler. POD You need to configure resource request values for all of your containers in Kubernetes because HPA makes scaling decisions based on those values. It makes those...
ReadOctober 10, 2024
State Software Design Pattern
The State Design Pattern is a behavioral design pattern that allows an object to change its behavior when its internal state changes. This pattern is particularly useful when an object needs to...
ReadOctober 9, 2024
PHP Storm Ideavim File
Note: Need to restart PHP Storm after any change to take effect.
I couldn't get the Action(<action>) syntax working but the :action <action> works fine....
October 9, 2024
RBAC, ABAC, Roles & Permissions
Roles vs Permissions Set permissions to roles and assign roles to users. Don't assign permissions directly to users. Create a permission, like "can view page". Assign that permission to a role,...
ReadOctober 8, 2024
AWS Policy Elements
Some elements of an AWS policy include: SID (optional): Statement ID used to identify the purpose of the policy statement, especially with a policy with multiple statements. Version: There are only...
ReadOctober 8, 2024
Package Managers
Here’s a detailed table summarizing popular package managers and their key features, along with links to their official resources: Package Manager Software Ecosystem Versioning...
ReadOctober 7, 2024
Kubernetes Hierarchy
Hierarchy: Cluster (parent) --- Nodes Group (collection of machines) ----- Node (machines) ------- Pods (workload units on nodes) --------- Containers (running applications) Think of the Node as...
ReadSeptember 29, 2024
Examples of Abstraction in the Real World
The reason we can even use things in this modern world is because of abstraction. No single person could know how everything we use on a daily basis works, much less how they were made in the first...
ReadMay 25, 2024
xargs tips
XARGS things to remember
xargs -p will show the command
find . -name "foo" -print0 | xargs -0 (<<< print0 null, xarg uses null instead of space, in case file...
May 24, 2024
Code Coverage VSCode With PHPUnit
Need: Get some code coverage up for unit tests in vscode. PHPUnit can handle outputting the necessary coverage information. Coverage Gutters can read the outputting coverage file (in xml). I'm...
ReadMay 18, 2024
Redis client commands I want to remember
In laravel local, while devving vendor/bin/sail redis redis-cli (command, container, client)
In forge/prod:
Delete keys based on a part:
May 18, 2024
SOLID Progamming Principles
The Principles: Single Responsibility - the class should do one thing and thus would only have one stakeholder with a reason to change it. A class that handles a report. Two things can change: the...
ReadMay 18, 2024
Big O Notation
Used to analyze worst-case (usually) complexity to check resource requirements for runtime as inputs increase. Not about the hardware, etc. High level view. How long: time complexity. Memory...
ReadMay 17, 2024
Brew (homebrew) commands and tips
Homebrew/brew MacOSX:
Mac with M1/M3/M4: arch -arm64 brew install
May 13, 2024
Mocking in Unit Tests
In testing a specific class, you mock it's dependencies to make sure that class calls the dependency correctly.
Mock the dependency.
shouldReceive - declare what should be called...
April 30, 2024
Networking
In the subnet 192.168.1.0/30, the available addresses are as follows:
CIDR Notation: /30 indicates that the first 30 bits of the IP address are the network portion, leaving 2 bits for...
February 4, 2024
How to do an SQL Delete based on a Join
I'm mostly used to simple deletes using where clauses, but I know a DBA who prefers to use joins. To get more familiar, I've been doing simple stuff like that. The syntax between MS-SQL and MySQL is...
ReadFebruary 1, 2024
A Simple PHP Benchmarking function
I recently needed to find where some performance issues were and didn't have the time to download and figure out any real-life tools, but this basic system helped. I could just sprinkle...
ReadJanuary 31, 2024
MySQL - Find What Tables Have a Column Name
How to find out what tables in a MySQL database have a specific column, by name.
ReadJanuary 17, 2024
How to Generate a Laravel API Token using Artisan Tinker
Generate a basic Laravel users.api_token:
ReadDecember 23, 2023
How to disable warning that MacOSX switched to zsh
To avoid this message: Add this to ~/.bashrc: From Stackoverflow
ReadDecember 21, 2023
Binary Math
Binary math is base 2. Our normal everyday numbering system is a base 10.
Instead of 10 numbers (0-9), you can only have a value of 0 or 1.
Take 00101101 = (0 * 2^7) + (0 * 2^6)...
June 18, 2023
Reminder about PHP TS vs NTS
From PHP Documentation: Thread Safety means that binary can work in a multithreaded webserver context, such as Apache 2 on Windows. Thread Safety works by creating a local storage copy in each...
ReadMay 7, 2023
Useful Git Snippets
Pull without going thru all the SSL self-signed BS but also not permanently overriding it. I used this a few times on a client network with a self-signed cert in the chain but no time to update the...
ReadMarch 17, 2023
Find, based on Time
GAME. CHANGER. newerBt is “birth time” where newerCt is “change time” which doesn’t find things being copied around. WOOHOO!!! (newermt!)...
ReadDecember 21, 2022
Bitwise Operators
If both binary numbers have a 1 in the same place, it's a 1. If one place has a 1 and one place has a 0, in & you keep the...
December 8, 2022
Basic but Useful SSL Expiration Date checker
At an old job, every now and then we'd have a fire drill because, despite it being a large, capable organization, no one seems to track when an SSL cert expires. So, I created this little script to...
ReadNovember 18, 2022
Finding Your Public IP Address
How to find IP of my router (public IP). There is no way to do it with ifconfig, etc. That will only show local network stuff, and the internal network apparently doesn't know what it's public IP...
ReadOctober 30, 2022
Javascript Promises, Async and Await
As always: This is for my own understanding. Please don't assume it is 100% correct.
await pauses the execution of an async function until the awaited promise resolves...
February 27, 2022
Update Internet Information Server (IIS) Fast CGI Timeout
When debugging on Windows using Internet Information Server, if I took too long to step through what I was debugging, it would time out and I'd have to start over. Talk about anxiety! Lol. This...
ReadJanuary 2, 2022
Quick and Dirty API endpoint testing using devtools console.
Sometimes I'd be on a client network, without access to tools like Postman. But, I'd want to test and endpoint to see what's what. So, a little hackery with the devtools console and I'm good:...
ReadDecember 21, 2021
Null and the Null Byte
The null keyword vs a null byte. They are not the same.
Null Keyword:
Represents the absence of a value.
Used in various programming languages to indicate a variable has...
August 17, 2021
Fix Git/Apache/Curl Self-Signed Cert issue
This is mainly a reminder to myself about how to do this, and the link to Matt Ferderer's website with the real instructions: Real Instructions Notes: Apache curl:...
ReadFebruary 8, 2021
Install an SSL Cert in Apache
openssl pkcs12 -in domain.com.pfx -out domain.com.pem -nodes openssl rsa -in domain.com.pem -out domain.com.cert.key openssl x509 -in domain.com.pem -out domain.com.cert.crt Assuming copy those...
ReadFebruary 8, 2021
SQL Snippets to Remember
Row Number Over: Find Duplicates: To determine if there is a duplicate:
ReadDecember 23, 2020
Setting up DNS for your AWS S3 static web site
Target Audience This post is aimed at relatively capable web/devops. People like me. I’m not going to remember everything, so I’ll probably re-read this myself in a few months or a year when I...
ReadDecember 23, 2020
Setting up an AWS S3 bucket for your static web site
Target Audience This post is aimed at relatively capable web/dev ops. People like me. I’ll probably re-read this myself in a few months or a year when I forget how to go about this. “Static...
ReadDecember 23, 2020
WordPress-to-static using wget mirror functionality and AWS S3
I like using WordPress. I’ve used it, AEM, Jekyll, a version of Laravel-as-CMS (currently Jigsaw and a lot of custom built code (in the early days). I don’t like how WordPress seems to be a main...
ReadDecember 23, 2020
Note to Self - Using AWS Client’s S3 Sync
This is pretty easy to do. If you use homebrew on a mac, open a terminal and type:
brew install awscli
I’m assuming that you can to apt-get install awscli on Linux, as...
April 30, 2020
Loosely Coupled
Examples of "Loosely Coupled" in the real world. Restaurant Kitchen: Think of a restaurant where chefs specialize in different types of cuisine (e.g., Italian, Chinese, Mexican). Each chef can...
ReadOctober 8, 2017
Horizontal v Vertical Scaling
Horizontal scaling = Adding more houses 🏠 🏠 🏠 (More servers or machines) Vertical scaling = Adding more rooms 🛏️ 🛏️ 🛏️ to existing houses (More resources like CPU or RAM to...
Read