Radish Logic - Developer Blog

CloudFormation: How to solve Circular Dependency between an Elastic IP and an EC2 Instance

When writing a CloudFormation Template that needs to use the value of an Elastic IP to a file inside an EC2 Instance, you will most likely encounter a Circular dependency between resources error.

I encountered this when configuring OpenSwan IPSec VPN in CloudFormation.

You can try the CloudFormation template below to see the error above.

CloudFormation Template with Circular Dependency Error

Parameters:
  AmazonLinux2AMIID:
    Type: AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>
    Default: /aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2

  KeyName:
    Type: AWS::EC2::KeyPair::KeyName

Resources:
  ElasticIP:
    Type: 'AWS::EC2::EIP'
    Properties:
      Domain: vpc
      InstanceId: !Ref EC2Instance
  
  EC2Instance:
    Type: AWS::EC2::Instance
    Properties: 
      ImageId: !Ref AmazonLinux2AMIID
      InstanceType: t2.micro
      KeyName: !Ref KeyName
      UserData: 
        Fn::Base64:
          !Sub |
            #!/bin/bash -ex
            echo "${ElasticIP}" >> /EIPAddress.txt

How to install ChefDK in Amazon Linux 2

The ChefDK is a package that includes everything you need to start using Chef. You will need this if you want to develop using chef.

Since I always use Amazon Web Services (AWS) EC2, I tend to choose Amazon Linux 2 even for projects using Chef.

Below is a step-by-step tutorial on how to install ChefDK in an EC2 instance running Amazon Linux 2.

Installation via shell commands

SSH to your Amazon Linux 2 EC2 Instance and run the command below.

curl https://omnitruck.chef.io/install.sh | sudo bash -s -- -c current -P chefdk

This will install the latest version of ChefDK.

For production systems we should specify the specific version of ChefDK or else this will install the version. To do this we need to add the -v option in the end of the command.

Below is an example where we install ChefDK version 4.7.73.

curl https://omnitruck.chef.io/install.sh | sudo bash -s -- -c current -P chefdk -v 4.7.73

Next is to check if chef was installed properly. Go to the Verification section of this post.

Installation via ChefDK Download Page

Go to https://downloads.chef.io/chefdk.

You may select your desired version for ChefDK. Default is the latest stable version.

Copy the URL for the latest version of Red Hat Enterprise Linux.

How to install Active Directory Administration Tools in Windows Server

If you need Active Directory Users and Computers on your Windows Server, you need to install Active Directory Administration Tools.

The walk through below will also install other AD Administration Tools like DNS configuration and optional if you want to install Group Policy Management.

Tutorial below have been tested in Windows Server 2016, Windows Server 2019 and Amazon Workspaces Windows 10.

I learned the steps below when I was configuring Amazon Workspaces Windows 10 to do Active Directory Administration. I was avoiding to RDP to the AD Domain Controller to lessen the impact when I make adjustments that is why I needed the Active Directory Management Tools inside my Amazon Workspace.

Note: It is best if your Windows Server is already joined to an Active Directory Domain.

Step-by-step Instruction to Install Active Directory Administration Tools

Click on Start Menu and click Server Manager.

On Server Manager click Add roles and features.

EC2 with IAM Role: CloudFormation Sample Template

Creating an EC2 Instance with an IAM Role is easy when you do it via the AWS Console but doing this with CloudFormation is not as direct. You will need an Instance Profile to connect an EC2 with an IAM Role.

TL;DR: See the CloudFormation Template below.

How to get the AWS Account ID in Lambda Python

There are use cases where the need to get the AWS Account ID of the Lambda Function during runtime is required. I thought it was easy as getting the AWS Region but it was not. Luckily there is a way to get it, use the step-by-step instructions below.

To get the AWS Account ID where the Lambda Function is running use the code below.

def lambda_handler(event, context):

    aws_account_id = context.invoked_function_arn.split(":")[4]

    print(aws_account_id)

How does the code work?

The context object that is being passed to the lambda_handler function provides different methods and properties about the lambda function, like invocation and execution environment.

Grafana monitoring for AWS CloudWatch via EC2 IAM Role

Grafana is an open source software to create visualization of time-series data. This can graph AWS CloudWatch Metrics too.

As a security best practice when using Grafana on an EC2 Instance it is recommended to use an IAM Role. Using a credentials file may expose access to your AWS Account if ever other people gain access to your Grafana Server.

Follow the step-by-step instructions below on how to attach an IAM Role to your Grafana EC2 Instance and set Grafana to access CloudWatch.

Creation of IAM Role for Grafana EC2 Instance

Create an IAM policy with the below permission in JSON. Name this GrafanaAccessPolicy.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowReadingMetricsFromCloudWatch",
      "Effect": "Allow",
      "Action": [
        "cloudwatch:DescribeAlarmsForMetric",
        "cloudwatch:ListMetrics",
        "cloudwatch:GetMetricStatistics",
        "cloudwatch:GetMetricData"
      ],
      "Resource": "*"
    },
    {
      "Sid": "AllowReadingTagsInstancesRegionsFromEC2",
      "Effect": "Allow",
      "Action": ["ec2:DescribeTags", "ec2:DescribeInstances", "ec2:DescribeRegions"],
      "Resource": "*"
    },
    {
      "Sid": "AllowReadingResourcesForTags",
      "Effect": "Allow",
      "Action": "tag:GetResources",
      "Resource": "*"
    }
  ]
}

Then create an IAM Role with the following properties.

Trusted Entity Type	`EC2`
Policies	`GrafanaAccessPolicy`
Role name	`GrafanaAccessRole`

How to install Grafana on EC2 Amazon Linux 2

Grafana is an open source software that specializes in creating graphs and visualizations for users to easily understand the time-series data.

On this step-by-step guide, we will be launching an EC2 Instance with Amazon Linux 2 as the operating system, then install and run Grafana.

EC2 Instance Setup

Launch an EC2 Instance using the Amazon Linux 2 AMI.

For reference here are the settings of my EC2 Instance.

AMI	Amazon Linux 2
Instance Type	t2.micro (free tier) or t3a.nano (cheapest)
Storage	8GB General Purpose SSD (gp2)
Tags	Key: Name Value: Grafana-Server
Security Group	See below (EC2 Security Group Setup)

Note: This post is about installing Grafana on Amazon Linux 2. Launching an EC2 Instance will not be discussed here.

EC2 Security Group Setup

For the EC2 Instance Security Group I opened SSH (22) and default Grafana port (3000) to the internet (0.0.0.0/0).

How to check if your Windows 10 is 64-bit or 32-bit

When selecting a program installer to download it usually has 2 options: 64-bit installer or 32-bit installer. How do I know which one to download?

TL;DR – click here for instructions.

Nowadays, websites can know which version of Windows you are running and would only give you one link to download the installer. Sometimes, it is not that easy like how I installed Visual Studio Code for all Users in Windows which gave me lots of options, Windows, Linux, Mac, 32-bit or 64-bit versions.

It is important to download the correct version of the installer or else it might not work correctly with your system.

To see what architecture your Windows Operating System is running, see the different ways below.

3 ways to check if your Windows Architecture is 64-bit or 32-bit

Via Graphical User Interface (with screenshots)

To check if your running a Windows 64-bit or 32-bit, right-click on the Start Button (Window button on the lower left of your screen) or on your keyboard click Window+X.

Then click System.

This will open a Settings window that shows details about your computer.

Installing Visual Studio Code for All Users in Windows

I am trying to install Visual Studio Code for all users in Windows but it always installs for a single user. Is there a way to install it one time and it is installed for all users?

Yes, there is a way to install Visual Studio Code for all users in Windows.

TL;DR – Download the System Installer here and install.

The Problem

Visiting the website of Visual Studio Code (code.visualstudio.com) and pressing Download for Windows will download the installer for a single user in Windows.

What if you have multiple users in your Windows computer like me? I have a different User Accounts for different projects and different use cases. I had to install for different users.

Follow the tutorial below to install Visual Studio Code for all Users.