Alerting on file descriptor usage

This story was originally posted at https://blog.hadenes.io/post/prometheus-alerting-rule-for-redis-clients/

Recently, a customer auto scaling farm got out of hand due to a misconfiguration on their end, which led to Redis maximum number of connections to be exceeded, leading to a lot of requests failing.

Curiously, they were way below the default maximum number of clients of 10000.

After some digging up, it turns out that each client needs one file descriptor (well, that would have been easy to guess…), so they failed when they reached the default nofile limit of 1024.

The Redis documentation states the following:

In Redis 2.6 this limit…

Originally published at https://blog.hadenes.io on March 16, 2021.

In this post, we are going to compare the differences in effectiveness, from a computation and energy consumption perspective, between SystemD Timers and in-code loops for executing infinite loops.

We’ll focus specifically on Linux, since features such as timerfd are only available on it, although similar implementations exist for BSD and OSX such as kqueue.

The inspiration of this post came from this StackOverflow thread.

The case for SystemD Timers

Pros

timerfd

SystemD makes use of the Linux Kernel’s timerfd timers, a POSIX timer alternative that is more event-loop friendly, since it notifies time expiration via file descriptors (hence…


Ensuring the team is in good morale and mentally and physically healthy

This story was originally posted at https://blog.hadenes.io/post/health-check/

What is it?

The health check cycle is meant to ensure the team is in good morale and mentally and physically healthy.

The health check must held between a “checked” and a “checker”.

The “checked” can be any employee, in any area.

The “checker” must be a neutral party, that is, someone that is not on the same vertical as the “checked”. This person must also be someone as close to upper management as possible, or a side role with power to change things, like HR.

So that a connection can be formed on a personal…


Uma Jornada ao Coração

This story was originally posted at https://blog.hadenes.io/post/a-natureza-e-o-homem/

A masculinidade toxica se refere aos estereotipos nocivos e restritivos que a sociedade atribui ao sexo masculino.

Ela tambem se refere ao modo com o qual os homens lidam com tais pressoes.

A masculinidade toxico e fruto de um conjunto de mitos que a sociedade transmite aos garotos e aos homens sobre o que significa ser um “homem de verdade”.

O homem que nao segue esses dogmas poe em duvida seu valor e sua identidade enquanto homem.

Essas pressoes levam a relacionamentos abusivos, agressividade, violencia e toda sorte de maleficios para aqueles ao redor do homem.

Mas e ao proprio homem?

Video

Slides

A Natureza e o Homem — Uma Jornada ao Coracao de Henrique Gonçalves


Giving experts structure

This story was originally posted at https://blog.hadenes.io/post/the-role-of-the-leader-when-experts-talk/

When leading a high performance, highly skilled team, a leader may find themselves in a situation where their ability to input on the subject being discussed is limited.

It’s also possible that a leader may wish to get some distance from the discussion in order to empower it’s participants and allow them to reach consensus without resorting to the leader’s approval.

Whether the case, the leader doesn’t have to give input on the matter per se in order to help the team achieve a consensus.

Creative Deviation

Given a complicated situation, when all experts gather…


Don’t Ask a Crowd to Take an Action

This story was originally posted at https://blog.hadenes.io/post/retrospective-dynamics-make-a-wish/

When assigning a task, a leader can’t just tell “do this” without giving proper context and structure.

While you may sometimes get away with assigning overly abstract tasks to senior members, as they have a great deal of experience to support them, it’s always important to clearly communicate what needs to be done and why, while setting the right expectation as to the outcome and deadline.

This is Leadership 101, but it doesn’t end here.

Don’t Ask a Crowd to Take an Action

It’s common for a task to be given to a team, without giving any single individual responsibility for…


A fairy grants you a wish — how do you know it came true?

This story was originally posted at https://blog.hadenes.io/post/retrospective-dynamics-make-a-wish/

The Dynamic

Source: Lydia Grawunder & Sebastian Nachtigall

Imagine that a magic and bright fairy gives you one wish to solve the biggest issue on your team overnight.

What do you ask her?

When you arrive at work the next day, you immediately spot the difference.

What changed?

How it Works

Give participants 2 minutes to silently ponder the following question:

“A fairy grants you a wish that will fix your biggest problem at work overnight. What do you wish for?”

Follow up with:

“You come to work the next morning. You can tell, that the fairy has…


Handling a sensitive topic

This story was originally posted at https://blog.hadenes.io/post/on-salary-ceilings/

Salary ceilings are a sensitive topic.

While they may be driven by real, fair business limitations, they nonetheless put a block on the evolution of brilliant employees, and may lead to them leaving for greener pastures.

We may work for love, but we all have basic needs that need to be supplied, and unless you run a charity, you can’t expect people to work for you for less than what they deserve.

Here are some ideas on how to deal with that, and also some points of attention.

Lateral Movement

Encourage lateral movement for anyone…


Soft Skills are a must

This story was originally posted at https://blog.hadenes.io/post/why-management-ladders-should-start-higher/

A manager needs to have certain soft skills that put them on a place where a certain maturity is needed.

A manager needs to be able to communicate well, must have a solid emotional stability and be able to solve conflicts.

As an engineer, you are often expected to, at the beginning of the ladder, meet certain expectations around mentoring, assistance in recruiting/interviewing/on-boarding, comprehension of the domain and business context of your team, and the ability to give relevant feedbacks.

Those skills are the bare minimum for any manager.

The management ladder starts…


This story was originally posted at https://blog.hadenes.io/post/fun-with-shells/

This is part of a series of articles meant to guide newcomers and professionals alike on important security topics, and sometimes questions from certifications like CEH will be used as the initial instigator to the article. Topics vary from the very basic to the really advanced stuff.

We are in no way associated with EC Council or any other group or company, and the only purpose of this series is to sum up our study group learnings.

A shell is basically the command line interface you are likely to use on a daily…

Kamus Hadenes

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