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How to Interact with AWS CLI from a Batch Script

Amazon Web Services (AWS) provides the AWS Command Line Interface (AWS CLI), a unified tool to manage your AWS services. From downloading files from S3 to spinning up EC2 instances, the AWS CLI can be completely controlled via Windows Batch scripts, allowing you to orchestrate cloud operations natively from your local environment.

In this guide, we will demonstrate how to authenticate and execute common AWS CLI commands directly from a Batch script.

Setup: AWS CLI Configuration​

Before running a script, you must configure your credentials. Unlike Azure which relies heavily on Service Principals in scripts, AWS CLI relies heavily on pre-configured profiles.

  1. Install the AWS CLI for Windows.
  2. Open your command prompt and run: aws configure (or aws configure --profile myProfile).
  3. Enter your AWS Access Key ID, Secret Access Key, Region, and Output format (typically json or text).

Implementation Script​

@echo off
setlocal enabledelayedexpansion

:: 1. Define AWS Profile and Region
set "awsProfile=default"
set "awsRegion=us-east-1"

:: 2. Verify AWS CLI is installed
where aws >nul 2>nul
if !errorlevel! neq 0 (
    echo [ERROR] AWS CLI is not installed or not in PATH.
    pause
    exit /b 1
)

echo Verifying AWS Identity...
:: Command: Get Caller Identity
call aws sts get-caller-identity --profile "%awsProfile%" >nul 2>nul
if !errorlevel! neq 0 (
    echo [ERROR] Authentication failed. Check your credentials.
    pause
    exit /b 1
)
echo [OK] Identity verified.
echo.

:: 3. Example: List all S3 Buckets
echo --- S3 BUCKETS ---
call aws s3 ls --profile "%awsProfile%"
if !errorlevel! neq 0 (
    echo [ERROR] Failed to list S3 buckets.
    pause
    exit /b 1
)
echo.

:: 4. Example: Upload a local file to S3
set "localFile=C:\Backups\Database.bak"
set "s3Bucket=s3://my-company-backup-bucket/daily/"

if exist "%localFile%" (
    echo Uploading "%localFile%" to %s3Bucket%...
    call aws s3 cp "%localFile%" "%s3Bucket%" --profile "%awsProfile%"
    if !errorlevel! neq 0 (
        echo [ERROR] Failed to upload "%localFile%" to S3.
        pause
        exit /b 1
    )
    echo [OK] Upload complete.
) else (
    echo [SKIP] Upload skipped, file "%localFile%" not found.
)

:: 5. Example: Querying EC2 Instances (JSON Parsing)
echo.
echo --- EC2 INSTANCES (Running^) ---
:: Use --output text or table for easy Batch reading
call aws ec2 describe-instances --filters "Name=instance-state-name,Values=running" --query "Reservations[*].Instances[*].[InstanceId, PublicIpAddress]" --output table --profile "%awsProfile%" --region "%awsRegion%"
if !errorlevel! neq 0 (
    echo [ERROR] Failed to query EC2 instances.
    pause
    exit /b 1
)

echo.
echo [SUCCESS] AWS Operations Complete!

endlocal
pause
exit /b 0

Parsing AWS Output into Batch Variables​

A common requirement is extracting a specific piece of information, like an Instance IP or an S3 Object URL, and saving it to a variable for the next step of the script. The AWS CLI supports the --query parameter (which uses JMESPath), and outputting as text makes FOR /F loops perfectly suited to read the result.

@echo off
setlocal enabledelayedexpansion

set "bucketName=my-public-assets"

:: Get the total size of all objects in a bucket
set "totalSizeBytes="
for /f "tokens=*" %%A in ('call aws s3api list-objects --bucket "%bucketName%" --query "[sum(Contents[].Size)]" --output text 2^>nul') do set "totalSizeBytes=%%A"

if not defined totalSizeBytes (
    echo [ERROR] Failed to retrieve bucket size for "%bucketName%".
    pause
    exit /b 1
)

echo Bucket "%bucketName%" consumes !totalSizeBytes! bytes.

endlocal
pause
exit /b 0

Why Interact with AWS CLI from Batch?​

  1. Automated Offsite Backups: Using aws s3 sync inside a scheduled Batch script to push local directories to Amazon S3 incrementally.
  2. Environment Orchestration: A script that automatically starts a development EC2 instance (aws ec2 start-instances), waits 30 seconds, and then SSHs into it.
  3. Cross-Cloud Operations: A script that pulls data from Azure, processes it locally, and pushes the result to an AWS Glue job.

Important Considerations​

  1. Use call: Similar to the Azure CLI, aws commands on Windows are sometimes routed through batch wrappers. Using call aws s3 ls ensures your script doesn't unexpectedly terminate after the first AWS command executes.
  2. Credential Security: The aws configure command stores your credentials plaintext in ~/.aws/credentials. If running on a shared server, ensure only the authorized Service Account has read access to this file. Alternatively, use IAM Roles if running the script directly on an EC2 instance.
  3. Output Formats: By default, AWS CLI outputs detailed JSON. Use --output text or --output table when interacting with Batch to avoid the nightmare of parsing multi-line JSON natively.

Conclusion​

Interfacing with the AWS CLI brings the full power of Amazon Web Services to your local Windows automation. By utilizing configured profiles, the call command, and text-based output formatting, you can construct elegant Batch scripts that provision cloud resources, sync terabytes of data, and manage massive EC2 fleets with a single double-click.

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