Golang Archives - Philipp's Tech Blog

Jun 20 / 2021
3

elastictl: Import, export, re-shard and performance-test Elasticsearch indices

For my work, I work a lot with Elasticsearch. Elasticsearch is pretty famous by now, so I doubt that it needs an introduction. But if you happen to not know what it is: it’s a document store with unique search capabilities, and incredible scalability.

Despite its incredible features though, it has its rough edges. And no, I don’t mean the horrific query language (honestly, who thought that was a good idea?). I mean the fact that without external tools it’s quite impossible to import, export, copy, move or re-shard an Elasticsearch index. Indices are very final, unfortunately.

This is quite often very inconvenient if you have a growing index for which each Elasticsearch shard is outgrowing its recommended size (2 billion documents). Or even if you have the opposite problem: if you have an ES cluster that has too many shards (~800 shards per host is the recommendation I think), because you have too many indices.

This is why I wrote elastictl: elastictl is a simple tool to import/export Elasticsearch indices into a file, and/or reshard an index. In this short post, I’ll show a few examples of how it can be used.

Dec 17 / 2020
Comments Off on Snippet 0x0F: Recursive search/replace tool “re”

Code Snippets, Programming

Snippet 0x0F: Recursive search/replace tool “re”

Two and a half years ago, I wrote my first Go program. I wanted to learn another language, and Go looked like a ton of fun: straight forward, easy to learn, and a static binary with no runtime shenanigans. I picked a project and I started hacking. Looking back, the code I wrote is a little cringy, but not terrible. I’d surely do things differently these days, now that I have more Go experience. But we all start somewhere.

However, the tool that I wrote, a recursive search/replace tool which I intelligently dubbed re, is actually incredibly useful: to my own surprise, I use it every day. I haven’t made a single modification to it in all that time (until today for this post). And since I’m in the sharing mood today, I thought I’d share it with the millions of people (cough) that come here every day. Ha!

Dec 13 / 2020
Comments Off on Go: Calculating public key hashes for public key pinning in curl

Scripting, Security

Go: Calculating public key hashes for public key pinning in curl

Something occurred to me the other day. This is my blog, and that means I can write about whatever I want. Now you may think that’s totally obvious, but it’s not. For the longest time I wouldn’t blog about anything that I didn’t deem blog-worthy. Small things, like “this is a cool function I found” or “I learned this thing today”, were not blog-worthy in my mind for some reason.

Well today I am changing that. I like writing, but not necessarily so much that I always want to write a super long post. Sometimes, things should be short. Like this one.

So in this super short post I’m gonna show you a cool thing I figured out: How to calculate the the value that curls --pinnedpubkey option needs in Go.

Jul 22 / 2019
Comments Off on Deduplicating NTFS file systems (fsdup)

Programming

Deduplicating NTFS file systems (fsdup)

At my work, we store hundreds of thousands of block-level backups for our customers. Since our customer base is mostly Windows focused, most of these backups are copies of NTFS file systems. As of today, we’re not performing any data deduplication on these backups, which is pretty crazy considering that how well you’d think a Windows OS will probably dedup.

So I started on a journey to attempt to dedup NTFS. This blog post briefly describes my journey and thoughts, but also introduces a tool called fsdup I developed as part of a 3 week proof-of-concept. Please note that while the tool works, it’s highly experimental and should not be used in production!