AWS: 2. Getting the deployent files to an EC2 instance

In the previous post I created the base image with the requisite services (e.g. IIS, WebDeploy etc) for the simple API service.

Instead of logging into each EC2 instance and installing the application, it would be really nice if I can simply deploy the application on VM on start up. I can then deploy many VMs with the application with little manual intervention.

In this port I am going to do just that!

Moving the deployment files to Simple Storage Service (S3)

The S3 is a highly available and highly durable object storage service on AWS platform. The AWS platform itself use S3 as a backing (e.g. log files, backups).

The first step is to create a bucket and upload the files to this bucket. I have called this bucket "simpleapistartup". I can simply use the "Upload" button to upload the files to the bucket.

The WebDeploy packages uploaded to S3

Copying the installation files from S3 to EC2 instance

The files in the S3 bucket needs to be copied to the EC2 instance on startup. In order to copy the files, the EC2 instance must have access to the bucket. The recommended solution for accessing the bucket from EC2 instance is to create an Identity and Access Management (IAM) role and associate the role with the EC2 instance. The IAM roles allow AWS resources access to other resources without having to explicitly provide access or secret keys.

The IAM role can only be associated with an EC2 instance at launch time and not when it is in running state.

I have created the role "S3ApiDeployment" that has full access to S3 and associated it with the new instance.

Associating the role when launching a new EC2 instance

The next step is to provide the initialisation script to download the files from S3 to the C:\Deployment folder in the EC2 instance.

The AWS Command Line Interface (CLI)

The AWS CLI is a command line based interface for developing scripts to execute against the AWS Platform.

The first step is to download the AWS CLI from here. There are multiple flavours and I have chosen the CLI for Windows. Once installed I can execute commands such as the following to access S3.

• aws s3 ls - lists all the buckets from S3

The plan is to run a script at VM boot time to download the files from S3. The following script copies the "simpleapistartup" bucket content including subdirectories to c:\Deployment folder.

• aws s3 cp s3://simpleapistartup/ c://deployment/ --recursive

EC2 User data

The installation script is passed to the an EC2 instance through Instance User data. The User data is set during an EC2 provisioning stage. See the following screen capture.

Setting initialisation script through User data

It is important that "As Text" radio button is selected because the content is base64 encoded when transferring to EC2.

The AWS CLI script needs to be wrapped in "<script>" or "<powershell>" tags. See the following.


I decided to use "<powershell>" tag because I plan to include Powershell commandlets in the future.

OK!, this is enough for this post. In the next post I will launch an EC2 instance which will run the above script to copy the deployment files from S3.

References:

• Setting Instance User data