Dev Ops – Page 7 – My Point of View

What’s a Reverse Proxy

If you’re like me, the word “proxy” is an overloaded term. In different contexts, the word proxy means something different to different people. In this case, I’m talking about a server that’s an intermediary between the caller and the receiver of a networking call (usually HTTP or similar). Before you can understand a reverse proxy, let’s talk about forward proxies (or proxy servers, as you might be familiar with).

A proxy server is a server that takes requests and re-executes the call to the Internet (or intranet) on behalf of the original caller. This can be used for caching requests to improve speed of execution or for filtering content (as well as other reasons). In Figure 1, you can see a typical proxy server diagram.

A reverse proxy is very much like a proxy server, but, not too surprisingly, in reverse. Instead of intercepting calls going outside the Internet/intranet, a reverse proxy intercepts calls from the outside and forwards them to local servers. Often the proxy server is the only accessible server in this scenario. If you look at Figure 2, you can see that all calls come into the reverse proxy. Often the caller has no idea that there’s a reverse proxy.

Now that you have a general idea of what a reverse proxy is, let’s talk about the why of reverse proxies.

Do I Need a Reverse Proxy?

Many projects have no need for a reverse proxy. You should learn about them anyway, because it’s another arrow in your development quiver to use when you need it. The use-case for using a reverse proxy is fairly well defined. The reverse proxy can be used in microservice scenarios where you don’t want individual clients to know about the naming or topology of your data center.

Reverse proxies are not only helpful in those microservices projects. Here are some other reasons to use a reverse proxy:

Service gatekeeping
Load balancing
SSL termination
Security
URL writing

Although you might want to use a reverse proxy for all of these reasons, you don’t need all of these services. Use a reverse proxy in the way your application works. You can use reverse proxies as a product (e.g., CloudFlare) or built into your own projects.

The most obvious use-case for many of you reading this article is to use a reverse proxy to provide an API gateway for microservices. A reverse proxy can expose a server that represents a single surface area for requests. The details of how the service is implemented and where the actual service resides are made opaque to the actual clients. This is what I call service aggregation. In this case, a reverse proxy is used to accept calls from clients and then pass them off to the underlying service (or cluster of services). This allows you to change the composition of the microservice without breaking clients.

Here is the list of reverse proxies;

Traefik Labs

YARP – Yet Another Proxy – Microsoft open source

For YARP, you can read more here on code magazine

You can read more about Microservices here;

Delete a local git branch

How to delete a Test_Branch.

Switch to some other branch and delete Test_Branch, as follows:

$ git checkout master
$ git branch -d Test_Branch

If above command gives you error – The branch 'Test_Branch' is not fully merged. If you are sure you want to delete it and still you want to delete it, then you can force delete it using -D instead of -d, as:

$ git branch -D Test_Branch

To delete Test_Branch from remote as well, execute:

git push origin --delete Test_Branch

Check the link for more info.

Standard Practice to Create Repository

A standard practice to create repository should always be;

Main branch should always have a .gitignore and readme file.
Create a working branch from main
Develop feature in your working branch
Before committing, do a merge from remote main to working branch and resolve any conflicts in working branch. This will help you to get team changes merged into your working branch.
Commit your changes. Create a PR and you are done.

I hope this will help.

How to add gitignore file in existing solution using Visual Studio

Stop tracking the files that should be ignored in Git

How to add gitignore file in existing solution using Visual Studio

Recently I came across an issue where existing projects were showing .vs folder checked-in and being tracked. Developers were having code conflict problems and were not able to create PR request.

Here is the work around to add gitignore file in existing solution using Visual Studio.

Remove .vs folder from main branch and working branch. If there are PR policy in place, disable that for fixing this. After .vs folder removal, enable PR policy.

Open Visual Studio and make sure it’s connected to Git branch. Click on Git->Settings.

This will add gitignore file in the root of project folder. Switch to Git changes window in your working branch and commit / sync your changes.

Now we need to stop tracking all .vs folder changes that’s been created on developer machines to build and run the project. Use these magic commands, one time only;

git rm -r –cached .
git add .
git commit -am “remove ignored files”

For added piece of mind, sync your main branch and do a merge from main branch to work branch locally. Resolve any cache files and conflicts. You might need to run above three command again.

After this, Create PR and it should merge with main branch. This will take your pain away.

I hope this will help.

Standard Practice to Create Repository

Stop tracking the files that should be ignored in Git

create virtual machine from existing windows 10 pc

Recently my ages old laptop started acting funny. I am assuming it might die soon. Before getting a new laptop I needed to crate a VHD of my old laptop for any reference.

The native tool from Microsoft to create VHD is Disk2vhd. This will create virtual machine and disk that can be attached in Hyper-V running in a separate machine. Here is the link;

https://docs.microsoft.com/en-us/sysinternals/downloads/disk2vhd

Here is the installation instruction of this VHD inside Hyper-V.

First of all create a new generation 2 VM that we’ll use with our new VHDX we created using Disk2VHD. Don’t create a new vdhx but select to use an existing one and point it to the one we just created with Disk2VHD. Rename it if needed to something more suitable.

Don’t boot the VM but add a DVD and attach the Windows Server ISO of the version your vhdx contains to the DVD.

Move the DVD to the top of the boot order I firmware.

he VM will boot to the DVD when you hit a key.

Select your language and keyboard layoout when asked and the don’t install or upgrade the OS but boot

Type diskpart and list the disks. Select the disk we need (the OS disk, the only one here) and list the volumes. You can see that volume 3 off 99MB is RAW. That’s not supposed to be that way. So let’s fix this by creating boot loader directory structure, repair the boot record by creating the boot sector & copy the needed boot files into it.

Type:

select volume 3

assign drive letter L:

FORMAT FS=FAT32 LABEL=”BOOT”

That’s it we can now us that 99MB volume to make our disk bootable to windows again. Type Exit to leave diskpart.

So now we have a formatted boot partition we can create the need folder structure and fix the boot record and configure our UEFI bootloader

Switch to the L: volume

create efi\microsoft\boot folder structure for the bootloader as show below with the md command(make directory)

Type: bootrec /fixboot to create the bootrecord

Type: bcdboot C:\Windows /l en-us /s l: /f ALL

This creates the BCD store & copies the boot files from the windows system directory

Just click Continue to exit and continue to Windows Server 2019. Remember to eject DVD drive.

.. and voila, your new VM has now booted.