Author: Sidharth Khattri

Stream a file to AWS S3 using Akka Streams (via Alpakka) in Play Framework

In this blog post we’ll see how a file can be streamed from a client (eg: browser) to Amazon S3 (AWS S3) using Alpakka’s AWS S3 connector. Aplakka provides various Akka Stream connectors, integration patterns and data transformations for integration use cases. The example in this blog post uses Play Framework to provide a user interface to submit a file from a web page directly to Continue Reading

Using Microsoft SQL Server with Scala Slick

This blog post shows simple CRUD operations on Microsoft SQL Server using Scala Slick version 3.2.3. You might be thinking what’s really great about it? Duh! But until Scala Slick 3.2.x was released, using commercial databases was within the horizon of an additional closed source package know as Slick Extensions which supported Slick drivers for following databases Oracle IBM DB2 Microsoft SQL Server   Library Continue Reading

NGINX – Understanding and Setting up a reverse proxy server

Let’s start by understanding what a reverse proxy server means and then I’ll lay down the steps for setting up such a server using our beloved NGINX. A reverse proxy server is one which helps in directing client requests to other (usually backend) servers or to multiple applications hosted on the same server on different ports. You can think of it as an abstraction layer Continue Reading

Change AWS EC2 Instance Key Pair without stopping the Instance

If you landed on this blog post then I guess you might be looking for a way to change the Key pair associated with your AWS EC2 Instance without stopping the instance or you’re just following our blog posts 🙂 Either way, I’ll try to explain the easiest way to do just that in this blog post. Let’s start by creating a new Key pair Continue Reading

Streaming data from PostgreSQL using Akka Streams and Slick in Play Framework

In this blog post I’ll try to explain the process wherein you can stream data directly from PostgreSQL database using Scala Slick (which is Scala’s database access/query library) and Akka Streams (which is an implementation of Reactive Streams specification on top of Akka toolkit) in Play Framework. The process is going to be pretty straightforward in terms of implementation where data is read from one Continue Reading

NGINX – Redirecting HTTP to HTTPS

Using HTTPS is highly recommended and I cannot stop when explaining the benefits of using it! Also something which is more important is to make sure when HTTPS is setup it is ensured that all traffic via HTTP is blocked in a way that it is redirected to HTTPS. This can be easily achieved by giving NGINX the following set of instructions in the virtual Continue Reading

NGINX – Load Balancing your application made easy

Often there are requirements to load balance your application in order to scale out and make your application more performant and NGINX can be used to do just that! It can distribute your traffic to several application servers. There are several load balancing methods available in NGINX which are round robin – wherein the requests are distributed in a round-robin fashion least connected – request Continue Reading

NGINX – Redirecting traffic between www and non-www domain

Just in case you ever wondered whether the re-routing from www to non-www or non-www to www domain is possible using NGINX then you bet it is! In fact it is very simple and can be done using the following steps 1. Redirecting from www to non-www Setup a initial virtual server block to point your domain to your content, a simple example would look something Continue Reading

NGINX – Restrict access to Geographical Locations using GeoIP module

In this post I’ll try to explain how NGINX GeoIP module can be used to restrict access to your web-portal/website only to a specific geographical region. Begin by verifying NGINX GeoIP module is installed on the server which can be done via nginx -V if you can see –with-http_geoip_module in the output you are ready to use the GeoIP database with NGINX but if not you Continue Reading

NGINX – Disable direct access (via http and https) to a website using IP address

For the requirements wherein direct access to a website using IP address has to be disabled/blocked, following steps can be followed To disable/block direct access to IP for port 80 create a new or add to an existing (as required) server configurations as follows server { listen 80 default_server; server_name _; return 404; } where _ catches all the domain names pointing to your server’s Continue Reading

NGINX – Easiest way to setup SSL using .pfx files

I’ll try to explain the easiest way to use a .pfx file that can be used to install SSL on NGINX. We’ll start by extracting the CRT file using openssl with the following command openssl pkcs12 -in ./YOUR-PFX-FILE.pfx -clcerts -nokeys -out domain.crt Followed by extracting the private key with the following command openssl pkcs12 -in ./YOUR-PFX-FILE.pfx -nocerts -nodes -out domain.rsa

Introduction to Nginx

Hi all, Knoldus organized a 30 min session on 3rd March 2017 at 4:50 PM. The topic was Introduction to Nginx. Session slides are shared in this blog post and you can post any questions related to the slides in the comment section below 🙂

Akka Persistence Event Sourcing

This presentation covers a brief introduction to 1) how event sourcing works (commands, domain events, event logs) 2) DDD (domain driven design) 3) CQRS (command query responsibility segregation) 4) how event sourced architecture can be useful 5) akka persistence as a tool for event sourcing   Watch the video session:

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