What is AWS Application Load Balancer ? | Instructions to setup Application Load Balancer

This video teaches you what is ALB, how to set up and use an application load balancer in AWS, We will see step by step setup of the application load balancer. You will learn what is target group in AWS ALB, how to configure path-based routing rules.

Subscribe: https://www.youtube.com/c/JavaHomeCloud/featured 

#aws 

What is GEEK

Buddha Community

Dotnet Script: Run C# Scripts From The .NET CLI

dotnet script

Run C# scripts from the .NET CLI, define NuGet packages inline and edit/debug them in VS Code - all of that with full language services support from OmniSharp.

NuGet Packages

Name	Version	Framework(s)
dotnet-script (global tool)		net6.0, net5.0, netcoreapp3.1
Dotnet.Script (CLI as Nuget)		net6.0, net5.0, netcoreapp3.1
Dotnet.Script.Core		netcoreapp3.1 , netstandard2.0
Dotnet.Script.DependencyModel		netstandard2.0
Dotnet.Script.DependencyModel.Nuget		netstandard2.0

Installing

Prerequisites

The only thing we need to install is .NET Core 3.1 or .NET 5.0 SDK.

.NET Core Global Tool

.NET Core 2.1 introduced the concept of global tools meaning that you can install dotnet-script using nothing but the .NET CLI.

dotnet tool install -g dotnet-script

You can invoke the tool using the following command: dotnet-script
Tool 'dotnet-script' (version '0.22.0') was successfully installed.

The advantage of this approach is that you can use the same command for installation across all platforms. .NET Core SDK also supports viewing a list of installed tools and their uninstallation.

dotnet tool list -g

Package Id         Version      Commands
---------------------------------------------
dotnet-script      0.22.0       dotnet-script

dotnet tool uninstall dotnet-script -g

Tool 'dotnet-script' (version '0.22.0') was successfully uninstalled.

Windows

choco install dotnet.script

We also provide a PowerShell script for installation.

(new-object Net.WebClient).DownloadString("https://raw.githubusercontent.com/filipw/dotnet-script/master/install/install.ps1") | iex

Linux and Mac

curl -s https://raw.githubusercontent.com/filipw/dotnet-script/master/install/install.sh | bash

If permission is denied we can try with sudo

curl -s https://raw.githubusercontent.com/filipw/dotnet-script/master/install/install.sh | sudo bash

Docker

A Dockerfile for running dotnet-script in a Linux container is available. Build:

cd build
docker build -t dotnet-script -f Dockerfile ..

And run:

docker run -it dotnet-script --version

Github

You can manually download all the releases in zip format from the GitHub releases page.

Usage

Our typical helloworld.csx might look like this:

Console.WriteLine("Hello world!");

That is all it takes and we can execute the script. Args are accessible via the global Args array.

dotnet script helloworld.csx

Scaffolding

Simply create a folder somewhere on your system and issue the following command.

dotnet script init

This will create main.csx along with the launch configuration needed to debug the script in VS Code.

.
├── .vscode
│   └── launch.json
├── main.csx
└── omnisharp.json

We can also initialize a folder using a custom filename.

dotnet script init custom.csx

Instead of main.csx which is the default, we now have a file named custom.csx.

.
├── .vscode
│   └── launch.json
├── custom.csx
└── omnisharp.json

Note: Executing dotnet script init inside a folder that already contains one or more script files will not create the main.csx file.

Running scripts

Scripts can be executed directly from the shell as if they were executables.

foo.csx arg1 arg2 arg3

OSX/Linux

Just like all scripts, on OSX/Linux you need to have a #! and mark the file as executable via chmod +x foo.csx. If you use dotnet script init to create your csx it will automatically have the #! directive and be marked as executable.

The OSX/Linux shebang directive should be #!/usr/bin/env dotnet-script

#!/usr/bin/env dotnet-script
Console.WriteLine("Hello world");

You can execute your script using dotnet script or dotnet-script, which allows you to pass arguments to control your script execution more.

foo.csx arg1 arg2 arg3
dotnet script foo.csx -- arg1 arg2 arg3
dotnet-script foo.csx -- arg1 arg2 arg3

Passing arguments to scripts

All arguments after -- are passed to the script in the following way:

dotnet script foo.csx -- arg1 arg2 arg3

Then you can access the arguments in the script context using the global Args collection:

foreach (var arg in Args)
{
    Console.WriteLine(arg);
}

All arguments before -- are processed by dotnet script. For example, the following command-line

dotnet script -d foo.csx -- -d

will pass the -d before -- to dotnet script and enable the debug mode whereas the -d after -- is passed to script for its own interpretation of the argument.

NuGet Packages

dotnet script has built-in support for referencing NuGet packages directly from within the script.

#r "nuget: AutoMapper, 6.1.0"

Note: Omnisharp needs to be restarted after adding a new package reference

Package Sources

We can define package sources using a NuGet.Config file in the script root folder. In addition to being used during execution of the script, it will also be used by OmniSharp that provides language services for packages resolved from these package sources.

As an alternative to maintaining a local NuGet.Config file we can define these package sources globally either at the user level or at the computer level as described in Configuring NuGet Behaviour

It is also possible to specify packages sources when executing the script.

dotnet script foo.csx -s https://SomePackageSource

Multiple packages sources can be specified like this:

dotnet script foo.csx -s https://SomePackageSource -s https://AnotherPackageSource

Creating DLLs or Exes from a CSX file

Dotnet-Script can create a standalone executable or DLL for your script.

Switch	Long switch	description
-o	--output	Directory where the published executable should be placed. Defaults to a 'publish' folder in the current directory.
-n	--name	The name for the generated DLL (executable not supported at this time). Defaults to the name of the script.
	--dll	Publish to a .dll instead of an executable.
-c	--configuration	Configuration to use for publishing the script [Release/Debug]. Default is "Debug"
-d	--debug	Enables debug output.
-r	--runtime	The runtime used when publishing the self contained executable. Defaults to your current runtime.

The executable you can run directly independent of dotnet install, while the DLL can be run using the dotnet CLI like this:

dotnet script exec {path_to_dll} -- arg1 arg2

Caching

We provide two types of caching, the dependency cache and the execution cache which is explained in detail below. In order for any of these caches to be enabled, it is required that all NuGet package references are specified using an exact version number. The reason for this constraint is that we need to make sure that we don't execute a script with a stale dependency graph.

Dependency Cache

In order to resolve the dependencies for a script, a dotnet restore is executed under the hood to produce a project.assets.json file from which we can figure out all the dependencies we need to add to the compilation. This is an out-of-process operation and represents a significant overhead to the script execution. So this cache works by looking at all the dependencies specified in the script(s) either in the form of NuGet package references or assembly file references. If these dependencies matches the dependencies from the last script execution, we skip the restore and read the dependencies from the already generated project.assets.json file. If any of the dependencies has changed, we must restore again to obtain the new dependency graph.

Execution cache

In order to execute a script it needs to be compiled first and since that is a CPU and time consuming operation, we make sure that we only compile when the source code has changed. This works by creating a SHA256 hash from all the script files involved in the execution. This hash is written to a temporary location along with the DLL that represents the result of the script compilation. When a script is executed the hash is computed and compared with the hash from the previous compilation. If they match there is no need to recompile and we run from the already compiled DLL. If the hashes don't match, the cache is invalidated and we recompile.

You can override this automatic caching by passing --no-cache flag, which will bypass both caches and cause dependency resolution and script compilation to happen every time we execute the script.

Cache Location

The temporary location used for caches is a sub-directory named dotnet-script under (in order of priority):

1. The path specified for the value of the environment variable named DOTNET_SCRIPT_CACHE_LOCATION, if defined and value is not empty.
2. Linux distributions only: $XDG_CACHE_HOME if defined otherwise $HOME/.cache
3. macOS only: ~/Library/Caches
4. The value returned by Path.GetTempPath for the platform.

 

Debugging

The days of debugging scripts using Console.WriteLine are over. One major feature of dotnet script is the ability to debug scripts directly in VS Code. Just set a breakpoint anywhere in your script file(s) and hit F5(start debugging)

Script Packages

Script packages are a way of organizing reusable scripts into NuGet packages that can be consumed by other scripts. This means that we now can leverage scripting infrastructure without the need for any kind of bootstrapping.

Creating a script package

A script package is just a regular NuGet package that contains script files inside the content or contentFiles folder.

The following example shows how the scripts are laid out inside the NuGet package according to the standard convention .

└── contentFiles
    └── csx
        └── netstandard2.0
            └── main.csx

This example contains just the main.csx file in the root folder, but packages may have multiple script files either in the root folder or in subfolders below the root folder.

When loading a script package we will look for an entry point script to be loaded. This entry point script is identified by one of the following.

• A script called main.csx in the root folder
• A single script file in the root folder

If the entry point script cannot be determined, we will simply load all the scripts files in the package.

The advantage with using an entry point script is that we can control loading other scripts from the package.

Consuming a script package

To consume a script package all we need to do specify the NuGet package in the #loaddirective.

The following example loads the simple-targets package that contains script files to be included in our script.

#load "nuget:simple-targets-csx, 6.0.0"

using static SimpleTargets;
var targets = new TargetDictionary();

targets.Add("default", () => Console.WriteLine("Hello, world!"));

Run(Args, targets);

Note: Debugging also works for script packages so that we can easily step into the scripts that are brought in using the #load directive.

Remote Scripts

Scripts don't actually have to exist locally on the machine. We can also execute scripts that are made available on an http(s) endpoint.

This means that we can create a Gist on Github and execute it just by providing the URL to the Gist.

This Gist contains a script that prints out "Hello World"

We can execute the script like this

dotnet script https://gist.githubusercontent.com/seesharper/5d6859509ea8364a1fdf66bbf5b7923d/raw/0a32bac2c3ea807f9379a38e251d93e39c8131cb/HelloWorld.csx

That is a pretty long URL, so why don't make it a TinyURL like this:

dotnet script https://tinyurl.com/y8cda9zt

Script Location

A pretty common scenario is that we have logic that is relative to the script path. We don't want to require the user to be in a certain directory for these paths to resolve correctly so here is how to provide the script path and the script folder regardless of the current working directory.

public static string GetScriptPath([CallerFilePath] string path = null) => path;
public static string GetScriptFolder([CallerFilePath] string path = null) => Path.GetDirectoryName(path);

Tip: Put these methods as top level methods in a separate script file and #load that file wherever access to the script path and/or folder is needed.

REPL

This release contains a C# REPL (Read-Evaluate-Print-Loop). The REPL mode ("interactive mode") is started by executing dotnet-script without any arguments.

The interactive mode allows you to supply individual C# code blocks and have them executed as soon as you press Enter. The REPL is configured with the same default set of assembly references and using statements as regular CSX script execution.

Basic usage

Once dotnet-script starts you will see a prompt for input. You can start typing C# code there.

~$ dotnet script
> var x = 1;
> x+x
2

If you submit an unterminated expression into the REPL (no ; at the end), it will be evaluated and the result will be serialized using a formatter and printed in the output. This is a bit more interesting than just calling ToString() on the object, because it attempts to capture the actual structure of the object. For example:

~$ dotnet script
> var x = new List<string>();
> x.Add("foo");
> x
List<string>(1) { "foo" }
> x.Add("bar");
> x
List<string>(2) { "foo", "bar" }
>

Inline Nuget packages

REPL also supports inline Nuget packages - meaning the Nuget packages can be installed into the REPL from within the REPL. This is done via our #r and #load from Nuget support and uses identical syntax.

~$ dotnet script
> #r "nuget: Automapper, 6.1.1"
> using AutoMapper;
> typeof(MapperConfiguration)
[AutoMapper.MapperConfiguration]
> #load "nuget: simple-targets-csx, 6.0.0";
> using static SimpleTargets;
> typeof(TargetDictionary)
[Submission#0+SimpleTargets+TargetDictionary]

Multiline mode

Using Roslyn syntax parsing, we also support multiline REPL mode. This means that if you have an uncompleted code block and press Enter, we will automatically enter the multiline mode. The mode is indicated by the * character. This is particularly useful for declaring classes and other more complex constructs.

~$ dotnet script
> class Foo {
* public string Bar {get; set;}
* }
> var foo = new Foo();

REPL commands

Aside from the regular C# script code, you can invoke the following commands (directives) from within the REPL:

Command	Description
#load	Load a script into the REPL (same as #load usage in CSX)
#r	Load an assembly into the REPL (same as #r usage in CSX)
#reset	Reset the REPL back to initial state (without restarting it)
#cls	Clear the console screen without resetting the REPL state
#exit	Exits the REPL

Seeding REPL with a script

You can execute a CSX script and, at the end of it, drop yourself into the context of the REPL. This way, the REPL becomes "seeded" with your code - all the classes, methods or variables are available in the REPL context. This is achieved by running a script with an -i flag.

For example, given the following CSX script:

var msg = "Hello World";
Console.WriteLine(msg);

When you run this with the -i flag, Hello World is printed, REPL starts and msg variable is available in the REPL context.

~$ dotnet script foo.csx -i
Hello World
>

You can also seed the REPL from inside the REPL - at any point - by invoking a #load directive pointed at a specific file. For example:

~$ dotnet script
> #load "foo.csx"
Hello World
>

Piping

The following example shows how we can pipe data in and out of a script.

The UpperCase.csx script simply converts the standard input to upper case and writes it back out to standard output.

using (var streamReader = new StreamReader(Console.OpenStandardInput()))
{
    Write(streamReader.ReadToEnd().ToUpper());
}

We can now simply pipe the output from one command into our script like this.

echo "This is some text" | dotnet script UpperCase.csx
THIS IS SOME TEXT

Debugging

The first thing we need to do add the following to the launch.config file that allows VS Code to debug a running process.

{
    "name": ".NET Core Attach",
    "type": "coreclr",
    "request": "attach",
    "processId": "${command:pickProcess}"
}

To debug this script we need a way to attach the debugger in VS Code and the simplest thing we can do here is to wait for the debugger to attach by adding this method somewhere.

public static void WaitForDebugger()
{
    Console.WriteLine("Attach Debugger (VS Code)");
    while(!Debugger.IsAttached)
    {
    }
}

To debug the script when executing it from the command line we can do something like

WaitForDebugger();
using (var streamReader = new StreamReader(Console.OpenStandardInput()))
{
    Write(streamReader.ReadToEnd().ToUpper()); // <- SET BREAKPOINT HERE
}

Now when we run the script from the command line we will get

$ echo "This is some text" | dotnet script UpperCase.csx
Attach Debugger (VS Code)

This now gives us a chance to attach the debugger before stepping into the script and from VS Code, select the .NET Core Attach debugger and pick the process that represents the executing script.

Once that is done we should see our breakpoint being hit.

Configuration(Debug/Release)

By default, scripts will be compiled using the debug configuration. This is to ensure that we can debug a script in VS Code as well as attaching a debugger for long running scripts.

There are however situations where we might need to execute a script that is compiled with the release configuration. For instance, running benchmarks using BenchmarkDotNet is not possible unless the script is compiled with the release configuration.

We can specify this when executing the script.

dotnet script foo.csx -c release

 

Nullable reference types

Starting from version 0.50.0, dotnet-script supports .Net Core 3.0 and all the C# 8 features. The way we deal with nullable references types in dotnet-script is that we turn every warning related to nullable reference types into compiler errors. This means every warning between CS8600 and CS8655 are treated as an error when compiling the script.

Nullable references types are turned off by default and the way we enable it is using the #nullable enable compiler directive. This means that existing scripts will continue to work, but we can now opt-in on this new feature.

#!/usr/bin/env dotnet-script

#nullable enable

string name = null;

Trying to execute the script will result in the following error

main.csx(5,15): error CS8625: Cannot convert null literal to non-nullable reference type.

We will also see this when working with scripts in VS Code under the problems panel.

Download Details:
Author: filipw
Source Code: https://github.com/filipw/dotnet-script
License: MIT License

#dotnet  #aspdotnet  #csharp 

Introducing AWS Gateway Load Balancer

Last year, we launched Virtual Private Cloud (VPC) Ingress Routing to allow routing of all incoming and outgoing traffic to/from an Internet Gateway (IGW) or Virtual Private Gateway (VGW) to the Elastic Network Interface of a specific Amazon Elastic Compute Cloud (EC2) instance. With VPC Ingress Routing, you can now configure your VPC to send all traffic to an EC2 instance that typically runs network security tools to inspect or to block suspicious network traffic or to perform any other network traffic inspection before relaying the traffic to other EC2 instances.

While that makes it easy to add an appliance into the network, ensuring high availability and scalability remains a challenge. Customers have to either over-provision appliances to handle peak load and high availability, or they have to manually scale up and down the appliances based on traffic, or use other ancillary tools – all of which increases operational overhead and costs.

#aws marketplace #aws partner network #aws #aws gateway load balancer

AWS Application Load Balancer vs. NGINX Plus

In August 2016, Amazon Web Services (AWS) introduced Application Load Balancer for Layer 7 load balancing of HTTP and HTTPS traffic. The new product added several features missing from AWS’s existing Layer 4 and Layer 7 load balancer, Elastic Load Balancer, which was officially renamed Classic Load Balancer.

A year later, AWS launched Network Load Balancer for improved Layer 4 load balancing, so the set of choices for users running highly available, scalable applications on AWS includes:

• NGINX Open Source and NGINX Plus
• Classic Load Balancer
• Application Load Balancer (ALB)
• Network Load Balancer (NLB)

In this post, we review ALB’s features and compare its pricing and features to NGINX Open Source and NGINX Plus.

Notes –

• The information about supported features is accurate as of July 2020, but is subject to change.
• For a direct comparison of NGINX Plus and Classic Load Balancer (formerly Elastic Load Balancer or ELB), as well as information on using them together, see our previous blog post.
• For information on using NLB for a high‑availability NGINX Plus deployment, see our previous blog post.

Features In Application Load Balancer

ALB, like Classic Load Balancer or NLB, is tightly integrated into AWS. Amazon describes it as a Layer 7 load balancer – though it does not provide the full breadth of features, tuning, and direct control that a standalone Layer 7 reverse proxy and load balancer can offer.

ALB provides the following features that are missing from Classic Load Balancer:

• Content‑based routing. ALB supports content‑based routing based on the request URL, Host header, and fields in the request that include standard and custom HTTP headers and methods, query parameters, and source IP address. (See “Benefits of migrating from a Classic Load Balancer” in the ALB documentation.)
• Support for container‑based applications. ALB improves on the existing support for containers hosted on Amazon’s EC2 Container Service (ECS).
• More metrics. You can collect metrics on a per‑microservice basis.
• WebSocket support. ALB supports persistent TCP connections between a client and server.
• HTTP/2 support. ALB supports HTTP/2, a superior alternative when delivering content secured by SSL/TLS.

(For a complete feature comparison of ALB and Classic Load Balancer, see “Product comparisons” in the AWS documentation.)

ALB was a significant update for AWS users who had struggled with Classic Load Balancer’s limited feature set, and it went some way towards addressing the requirements of sophisticated users who need to be able to secure, optimize, and control the traffic to their web applications. However, it still does not provide all the capabilities of dedicated reverse proxies (such as NGINX) and load balancers (such as NGINX Plus).

#load balancing #elastic load balancing (elb) #amazon web services #aws

How To Unite AWS KMS with Serverless Application Model (SAM)

The Basics

AWS KMS is a Key Management Service that let you create Cryptographic keys that you can use to encrypt and decrypt data and also other keys. You can read more about it here.

Important points about Keys

Please note that the customer master keys(CMK) generated can only be used to encrypt small amount of data like passwords, RSA key. You can use AWS KMS CMKs to generate, encrypt, and decrypt data keys. However, AWS KMS does not store, manage, or track your data keys, or perform cryptographic operations with data keys.

You must use and manage data keys outside of AWS KMS. KMS API uses AWS KMS CMK in the encryption operations and they cannot accept more than 4 KB (4096 bytes) of data. To encrypt application data, use the server-side encryption features of an AWS service, or a client-side encryption library, such as the AWS Encryption SDK or the Amazon S3 encryption client.

Scenario

We want to create signup and login forms for a website.

Passwords should be encrypted and stored in DynamoDB database.

What do we need?

1. KMS key to encrypt and decrypt data
2. DynamoDB table to store password.
3. Lambda functions & APIs to process Login and Sign up forms.
4. Sign up/ Login forms in HTML.

Lets Implement it as Serverless Application Model (SAM)!

Lets first create the Key that we will use to encrypt and decrypt password.

KmsKey:
    Type: AWS::KMS::Key
    Properties: 
      Description: CMK for encrypting and decrypting
      KeyPolicy:
        Version: '2012-10-17'
        Id: key-default-1
        Statement:
        - Sid: Enable IAM User Permissions
          Effect: Allow
          Principal:
            AWS: !Sub arn:aws:iam::${AWS::AccountId}:root
          Action: kms:*
          Resource: '*'
        - Sid: Allow administration of the key
          Effect: Allow
          Principal:
            AWS: !Sub arn:aws:iam::${AWS::AccountId}:user/${KeyAdmin}
          Action:
          - kms:Create*
          - kms:Describe*
          - kms:Enable*
          - kms:List*
          - kms:Put*
          - kms:Update*
          - kms:Revoke*
          - kms:Disable*
          - kms:Get*
          - kms:Delete*
          - kms:ScheduleKeyDeletion
          - kms:CancelKeyDeletion
          Resource: '*'
        - Sid: Allow use of the key
          Effect: Allow
          Principal:
            AWS: !Sub arn:aws:iam::${AWS::AccountId}:user/${KeyUser}
          Action:
          - kms:DescribeKey
          - kms:Encrypt
          - kms:Decrypt
          - kms:ReEncrypt*
          - kms:GenerateDataKey
          - kms:GenerateDataKeyWithoutPlaintext
          Resource: '*'

The important thing in above snippet is the KeyPolicy. KMS requires a Key Administrator and Key User. As a best practice your Key Administrator and Key User should be 2 separate user in your Organisation. We are allowing all permissions to the root users.

So if your key Administrator leaves the organisation, the root user will be able to delete this key. As you can see **KeyAdmin **can manage the key but not use it and KeyUser can only use the key. ${KeyAdmin} and **${KeyUser} **are parameters in the SAM template.

You would be asked to provide values for these parameters during SAM Deploy.

#aws #serverless #aws-sam #aws-key-management-service #aws-certification #aws-api-gateway #tutorial-for-beginners #aws-blogs

How to Create A Simple Application Load Balancer in AWS

Hi all, today we are going to create a simple application load balancer in AWS. We will be going to use 2 windows server to achieve this. Our both windows server will be located in two different Availability zones(AZs).

Creating Ec2 Instances on AWS

First we have to create 2 servers(Windows Server) in two different Availability Zones. I have created it in us-east-1a and us-east-1b as shown in below image

Install a Remote Desktop Client

I am using Linux Based Personal System so if you are using in the same way please follow this step else if you are using windows in your personal system you can download the rdp(remote desktop file) file and connect using that only.

Before connecting using rdp file you have to upload your key.

on the same screen as above image click on Get password

Now browse your pem file and decrypt your password. Save it somewhere

Configure local Server

Now, we are going to configure our web server and then add our html file in it.

Click on Server Manager located on task bar

Click on add roles and features

Now, click on next until the below image appears. Choose web server(iis) on select server roles window.

Click on Add Features then click on next and finally install it.

Close it once it has been installed.

Creating Web Page

Now we will be going to create a simple web page(index.html).

Go to File Explorer -> Local Disk(C) -> Inetpub -> wwwroot

There you will find two files. Delete both of them and then create on text file on same location.

Feed something on that page which will be shown on internet.

Save the file with name index.html

Creating Target Group for Load Balancer

Now, before creating Load Balancer we have to create our target group first. We will be going to use target of type “instance”

Name your target group. And let other field as it is.

Finally register your targets

Creating Application Load Balancer

Now, we will be doing our final step.

Select Application Load balancer. Name your ALB. Fill details such as internet facing, ipv4 , target group name, protocol(i am using only http), Availability zones(where your instances are located), Security group

 

After it gets provisioned and all targets are healthy you can finally test it.

Copy of application load balancer dns and paste it over browser. refresh it after some time. random refreshing will balance its load to our two servers.

Conclusion

In this blog we have created a simple application load balancer using two windows server located in different AZs(Availability Zones). We have configured our web server and created web page on both servers. We have created Target group and finally application load balancer to balance the load to our both servers.

Visit https://docs.aws.amazon.com/elasticloadbalancing/latest/application/introduction.html for more details.

Visit https://blog.knoldus.com/technology/aws/ for more blogs on AWS

Original article source at: https://blog.knoldus.com/

#aws #application #load