When you see the "WARNING! Using --password via the CLI is insecure" message in Docker, it's not just being overly cautious. The warning exists because passing passwords directly in the command line exposes them in:

• Shell history files (~/.bash_history)
• Process listings (visible via commands like ps)
• Any logging systems that might capture command output

Here's how to properly authenticate with ECR without triggering the warning:

aws ecr get-login-password | docker login --username AWS --password-stdin https://$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.us-east-1.amazonaws.com

This approach:

1. Generates the temporary ECR password securely
2. Pipes it directly to Docker without exposing it in the command line
3. Works in CI/CD pipelines and automated scripts

For a complete build and push workflow:

#!/bin/bash

# Authenticate with ECR
ECR_REGISTRY=$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.us-east-1.amazonaws.com
aws ecr get-login-password | docker login --username AWS --password-stdin $ECR_REGISTRY

# Build and push
docker build -t my-app .
docker tag my-app:latest $ECR_REGISTRY/my-app:latest
docker push $ECR_REGISTRY/my-app:latest

For cross-region deployments, you'll need to specify the region explicitly:

REGION=eu-west-1
ECR_REGISTRY=$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.$REGION.amazonaws.com
aws ecr get-login-password --region $REGION | docker login --username AWS --password-stdin $ECR_REGISTRY

While --password-stdin solves the immediate warning, consider these additional security measures:

• Use AWS IAM roles instead of access keys when possible
• Implement least-privilege permissions for your CI/CD system
• Rotate credentials regularly
• Consider using temporary session tokens for enhanced security

If you encounter authentication failures:

1. Verify your AWS credentials are properly configured (aws configure)
2. Check that the IAM user has ecr:GetAuthorizationToken permissions
3. Ensure your Docker daemon is running
4. Confirm the AWS region matches your ECR repository's region

When working with Amazon Elastic Container Registry (ECR), many developers encounter the warning "WARNING! Using --password via the CLI is insecure. Use --password-stdin." when executing commands like:

docker login -u AWS -p "$(aws ecr get-login-password)" \
"https://$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.us-east-1.amazonaws.com"

This warning appears because passing passwords directly via command-line arguments can expose them in shell history or process listings. The Docker team recommends using the --password-stdin flag for improved security.

Here's the proper way to authenticate with ECR without triggering security warnings:

aws ecr get-login-password | docker login \
--username AWS \
--password-stdin \
"https://$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.us-east-1.amazonaws.com"

For automation scripts or CI/CD pipelines, consider these implementations:

#!/bin/bash

# Get ECR login details
ECR_REGISTRY="$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.us-east-1.amazonaws.com"
ECR_PASSWORD=$(aws ecr get-login-password)

# Secure login
echo "$ECR_PASSWORD" | docker login --username AWS --password-stdin "$ECR_REGISTRY"

# Verify login
if [ $? -eq 0 ]; then
    echo "Successfully logged in to ECR"
else
    echo "Failed to authenticate with ECR" >&2
    exit 1
fi

For enhanced security, you might want to handle temporary credentials:

#!/bin/bash

# Set AWS region
export AWS_DEFAULT_REGION=us-east-1

# Get temporary credentials (if using assumed roles)
aws sts get-caller-identity &> /dev/null || {
    echo "AWS credentials not valid" >&2
    exit 1
}

# ECR login with proper credential validation
ECR_REGISTRY=$(aws sts get-caller-identity --query 'Account' --output text).dkr.ecr.$AWS_DEFAULT_REGION.amazonaws.com
aws ecr get-login-password --region $AWS_DEFAULT_REGION | \
docker login --username AWS --password-stdin $ECR_REGISTRY

If you encounter problems:

• Ensure your AWS CLI is configured with proper credentials
• Verify your IAM user has ecr:GetAuthorizationToken permissions
• Check that your AWS region matches your ECR repository's region
• For assumed roles, confirm the session hasn't expired