Page 6 of 10

Install and run Metabase

October 18, 2021 / abhijit

Metabase is a data analyzer and visualizer tool which can connect to many types of databases.

It can do some smart analysis as well as let you write proper SQL queries to create charts and graphs.

Metabase is a Java application which can be run directly. Conversely, it can also be run via Docker.

Compile fossil on Ubuntu Linux

September 25, 2021 / abhijit

Recently, I had to build fossil from source on Ubuntu because I needed to make a change to the source code.

It required a number of dependencies which is expected to be installed.

They are –
gcc (obviously!)
zlib1g and zlib1g-dev
tcl-dev
tk
libssl
libssl-dev

error while running rake task – “Don’t know how to build task”

September 5, 2021 / abhijit

The default method to pass arguments to Rake tasks is to give the parameters in square brackets –

desc 'Method #1: Use the default rake way to add two numbers and log the result'
task :add, [:num1, :num] do |t, args|
  puts args[:num1].to_i + args[:num].to_i
end

Reference: 4 ways to pass arguments to a Rake task

$ rake add[1,2]
# => 3

However, I would rather pass the arguments like this –

$ rake add 1 2
# => 3

Setup up READ_ONLY users on Postgres

August 28, 2021 / abhijit

To grant access to users for only viewing a database (i.e. no INESRTs or CREATE or UPDATE access) there are certain conditions.

First, access should be only allowed through ssh.

Second, the ssh user should not be able to get into a shell directly.

And finally, the database should restrict access to that particular user with relevant permissions.

We all strive for safety, prosperity, comfort, long life, and dullness.
Aldo Leopold

PM2 – the best process manager

June 22, 2021 / abhijit

In the past, on my server I’ve installed Fossil, Syncthing, Bitwarden, Inlets. All these require some form of Process Management. These programs / processes / services need to be always running, so they are restarted in case they get terminated. Also, on a system restart these need to start up automatically.

I’ve mostly used Systemd or Supervisor to all these things.

However, I recently came across PM2 and I was really blown out of my mind as to how simple it was to set it up.

Upgrading Wallabag from 2.3 to 2.4

June 20, 2021 / abhijit

I had upgraded PHP from 7.2 to 7.3 on my server and suddenly Wallabag stopped working!

I got some weird error like –

PHP Fatal error: Allowed memory size of 134217728 bytes exhausted

I guessed it had something to do with the PHP upgrade. So, I decided to upgrade Wallabag as well.

That’s when the problems started!

Simplest JavaScript & CSS minifier – YUI Compressor

June 20, 2021 / abhijit

I was looking for a simple JavaScript / CSS minifier. Essentially, a program which will

minify – remove empty lines
obfuscate – shorten variable names

There are many online tools available of course. Of the new ones, Parcel was the best. However, the resulting files had some extraneous code which I could do without.

Then I remembered about YUI Compressor, which I think is one of the first ones introduced many, many years ago.

Ruby Tips 1

June 8, 2021 / abhijit

There are numerous tips in Ruby but I seem to keep forgetting them and having to search for them every time. So high time I started documenting them out.

This one I learnt from 10 Tips & Tricks from Drifting Ruby. I’m only going to keep to Ruby specific ones.

SQLite load test for concurrent transactions using JMeter and JDBC Connection

June 6, 2021 / abhijit

I came across this article via a Hacker News post. This mentioned that SQLite was able to handle –

400 write transactions per second, and thousands of reads

I’ve recently started implementing applications with SQLite and with journal_mode set to WAL so that multiple concurrent writes could be done. However, I was curious to confirm the concurrent transactions number.

Earlier, I have used SQLite for development but usually on production we would face challenges with the notorious Database is locked error, we would move to Postgres or MySQL. However, I’ve always felt that for 90% of the applications we create don’t require these and was keen to back it up with numbers.

So, I decided to use Apache JMeter to try load testing a sample application.