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Deployment DevOps Learning Weekly

Weekly: Migration

The past week has been extremely exciting and nerve-wrecking. My team has finally completed the migration from on-premise to the cloud. It’s the first time that I’ve done anything like this and I’m blessed to have someone senior to lead us through the migration period.

ps: I wrote but forgot to post so this was actually 2-3 weeks ago

I’m a part of the MyCareersFutureSG team, so our users are the working population of Singapore, and we host hundreds of thousands of job postings, so there are definitely some challenge in migrating the data.

It’s the first time that I’ve handled such huge amounts of data when migrating across platform and the validation and verification process is really scary, especially when we couldn’t get the two checksum to match. It’s also the first time that I’ve done multiple Kubernetes cluster base image upgrade rollover. There were multiple occasions where we were scared that the cluster will completely crash but it managed to survive the transition.

Let me sum up the things I’ve learnt over the migration.

  • When faced with large amount of data, divide and conquer. Split data into smaller subsets so that you have enough resource to compute.
  • When rolling nodes, having two separate auto scaling groups will allow you to test the new image before rolling every single node.
  • If you want to tweak the ASG itself, detach all the nodes first so that you will have an “unmanaged” cluster, then no matter what you do to the existing ASG, at least your cluster will still stay up.
  • When your database tells you that the checksum doesn’t match, make sure that when you dump the data, it’s in the right collation, or right encoding format
  • Point your error pages at a static provider like S3, because if you point it at some live resource, there’s a chance that a mis-configuration will show an ugly 503 message. (something that happened briefly for us)
  • Data less than 100GB is somewhat reasonable to migrate over the internet these days
  • Running checksum hash on thousands and thousands files is quite computationally and memory intensive, provision enough resources for it.

Overall, the migration actually went over quite well and we completed ahead of time. Of course, the testing afterwards is where we find bugs that we have never found before because it’s the first time in years that so many eyes are on the system at the same time.

The smoothness is also thanks to the team who has carefully planned the steps required to migrate the data over, as well as setup streaming backups to the new infrastructure so that half of the data is already in place and we just need to verify that the streamed data is bit perfect.

Since it’s been a couple of weeks since this happened, I realize that I am lucky to be blessed with the opportunity to do something like this. Cause I’ve just caught up with my friends and most of the times, their job scopes don’t really allow them to do something that far out of scope. Which… depending on your stage of life it could be viewed as a pro/con. I’m definitely viewing this 4 day migration effort over a public holiday weekend as positive cause it’s something not everyone can experience so early on in their career!

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Learning Thoughts Weekly

Weekly: Google Analytics and building habits

Well, skipping the things that I had to do, one of the fun things that I’ve been exploring is Google Analytics. I’ve heard so much about it, and we actually used it in my current team (just that I haven’t really worked on this portion yet).

Went through the GA For Beginners course and it actually gives me a nice little certificate of completion. So that’s nice. I’m bringing this up because I want to experiment with it, which means that I’ve integrated it with this blog, as well as my landing page. Hopefully I can get some kind of metric at the end of the month. Unless the visitors of my sites are all bots, which would be a little disheartening.

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Development Learning Weekly

Weekly: MySQL benchmarking

Been busy with work and life that did not have the time to explore new things. Or maybe I did just that I forgot. Either way, the plan for the weekends is to explore Caddy as an automated way for me to deploy my portfolio/landing page, either that or cheating and using Netlify instead. The current flow I’m using relies on Ansible to deploy the page, which is a little bit manual in a sense. Hoping to change that.

We started doing benchmarking on our DB because one of our search queries has been slowing down significantly lately, and it’s affecting our user experience. In order to optimize the performance, we need a way of measuring the changes that we were going to implement.

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DevOps Keyboard Learning Weekly

Weekly: AWS and Keyboards

As I am helping another team part time to setup some infra on AWS, I felt my fundamental AWS knowledge being tested all over again. I’ve gotten so used to doing the more “tricky/complex” things that when starting from fresh, got tripped up by some basic setup.

  • Internet facing ELB must have public subnet associated
  • As long as the each AZ has a public subnet associated, the ELB will be able to route to the AZ
  • Public subnets must have IGW, NAT not counted
  • NAT instance must be created in a subnet which has IGW
  • ELB does not need to be in the same subnet as Target Group to route to it
  • ELB needs at least a /27 subnet
  • ELB reserves 8 IP in the subnet for autoscaling
  • NLB does not load balance cross-zone by default
  • ALB load balance cross-zone by default
  • Smallest subnet in AWS is /28
  • OpenVPN Access Server needs EIP
  • OpenVPN Access Server needs to setup through SSH first

While I wasn’t the one who setup the bulk on the networking, I wasn’t able to quickly pinpoint the exact reason why I was unable to get connectivity for the VPN that I was setting up. Just proves that there are some fundamental concepts that I need brushing up on.

On happier news, I finally bought/receive the lube for my future keyboard. Over the weekends I decided to try lubing my current Filco TKL keyboard without disassembly to see how it works/feels.

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Keyboard Learning Weekly

Weekly: diving deeper into keyboards

This week I finally made the plunge into the slightly deeper end of the mechanical keyboard community. I made the pre-order for Drop’s Ctrl Keyboard (Halo True switches). Total damage after shipping: 201.05 USD.

It’s my first step into the custom keyboard modding community. I was contemplating for the longest time if I should build a totally custom keyboard from scratch from sites like kbdfans for example. But the high cost of entry and the fear of screwing up made me decide to go for a semi-custom route instead.

However, while waiting for the keyboard to come, I decided to do some slight modifications to my Filco keyboard to see if I could improve the feel and sound of it.

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DevOps Learning Thoughts Weekly

Weekly: It has been a week?

The past week has been pretty hectic changing between roles as a dev and ops, helping out with other projects till 2-3am every day has really taken its toll and I feel old.

Unsurprisingly, I haven’t been able to really work on any of my own projects but I did learn something interesting that I wish to write about.

Recently facing an issue on Gitlab CI pipeline, where I want to run integration/regression tests on the latest docker build. However, since each image is meant to be production ready, it means that it will be ran as a non-root user. Which means that it will restrict what the user can do when the container starts. Here’s why this problem has caused me such a headache.

Beware, below is really more of a rant about the troubles I faced.

Categories
Learning Weekly

Weekly: Fixed images not loading on blog

This blog has went down twice in the past week. Which seems rather unstable. But I always have to keep in mind that it’s a $1 web host after all.

That 86 mins downtime right there ¯\_(ツ)_/¯
Averaging 1 second for response time, not great but not terrible

I know this because I use this service called uptimerobot which is a freemium service that can help you keep track of your services uptime. I’ve been using it for the past couple of years but I don’t think I’ve ever mentioned on this blog. It’s great because it will send you email notifications when it’s unable to reach your site!

It’s interesting that when I was self-hosting it, it only ever went down for 2 mins over 6,500 thousand hours. It’s a bit insane when I think about how far tech has came.

The logs only shows so far back on the free plan

Not sure if anyone noticed but the images has not been loading consistently on the blog, it was due to the image optimiser + caching + CloudFlare. Decided to simplify everything by relying on WordPress’s Jetpack CDN to load my images instead and it’s loading pretty much instantly now!

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Learning Weekly

Weekly: Circuit Breaker

It has been 3 weeks since Singapore went into Circuit Breaker mode, which is pretty much a semi lock down situation. Been working from home a month or more now and I’m slowly getting really bored of the stay home lifestyle.

That said, I am thankful that I’m in the line of profession that allows me to WFH without much issue and business still goes on as usual. On brighter side of things, mentioned that I bought a new NAS last week, and it arrived this week. It’s definitely a huge upgrade over my old WD MyBookLiveDuo. (2 bay NAS). I remember that when I bought it over 7 years ago, it was the most expensive purchase in my life.

Synology DS918+

Why did I get something that was released in 2018? Well, because the new refresh for it was $200+ more and the only advantage was that it has an extra drive bay. I heard that there will be a new edition for this probably this year or next, but based on the past 5 years or so, there’s really not much performance improvements to expect from a NAS.

The configuration I ended up with was

  • Ram: 4GB
  • Drives: 4 X 6TB WD Reds
  • Cache: None (TBD)
  • Raid: SHR2 (similar to RAID6)
  • Usable space: 10.5TB
  • Network: 2 X 1gbps bonded
Categories
Development Learning Weekly

Weekly: SG calculator

This is a side project that I’ve been working with my friend since last year but haven’t gotten many hours into it because … procrastination. But hey we finally have a MVP deployed onto Netlify and for the rare few people who somehow stumbled upon my blog, this is something you can check out.

TLDR; this is a quick calculator online designed to answer complicated questions regarding CPF and HDB (tbd).

https://sg-calculator.netlify.app

Even though I call it MVP it’s really still an early alpha and we’re still trying to figure things out and add more features to it. So there’s a high chance that things will just break from time to time.

Inception

We decided to work on this because planning for finance and housing in Singapore is quite a pain. While there are many calculators online that can give you numbers that you’re looking for, nothing is as simple or specific as, “How much do I have to save to retire with XYZ sum at the age of N?”.

Categories
Learning Optimization Weekly

Weekly: New hosting provider!

Another attempt at reviving my blog after only 7 posts for the entire year. But I finally figured out what this blog can be used for.

So the history of my blog started with me just ranting about my thoughts and feelings, that was many many years ago when I first started blogging, there was barely any filter to the things that I wrote and it was a rant every single damn day. That changed when I became more concerned with privacy.

It started with writing my inner thoughts and feelings on a self-hosted WordPress instance inside of a VM, then that transitioned to pen and paper and I almost completely stopped blogging altogether. Last year, I made the choice start journaling on a very regular basis, using a journaling app called Journey. It was great! I wrote on a near daily basis and I felt like I have a better grasp of my life.

Then I started writing Medium articles to have a better reach to tech audiences, which was the original intent of this revamped blog in 2018. But this blog quickly died down cause it’s not easy to pump out articles like that quickly.

So what is the point of this blog then? This will be where I just spam/rant/note down the interesting things that I’ve done over the week, just purely tech related, because a lot of these thoughts and experiences have been omitted in my journal (it’s boring to write about those in a journal). I’ve set a goal of writing one per week, to consolidate the fun things that I’ve been up to.

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