Configuration

After installing the plugin, you need to configure it with your AWS credentials and CloudFront distribution settings.

AWS Prerequisites

Before configuring the plugin, ensure you have:

AWS Account with CloudFront access
CloudFront Distribution configured for your WordPress site
IAM User or IAM Role with appropriate permissions

Required IAM Permissions

Create an IAM policy with these minimum permissions:

json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "cloudfront:CreateInvalidation",
                "cloudfront:GetInvalidation",
                "cloudfront:ListInvalidations"
            ],
            "Resource": "arn:aws:cloudfront::*:distribution/YOUR_DISTRIBUTION_ID"
        }
    ]
}

Configuration Methods

Method 1: EC2 Instance Role (Recommended for AWS EC2)

If your WordPress site is running on an EC2 instance, using an EC2 instance role is the most secure and recommended method. This approach eliminates the need to store AWS credentials in your application.

Prerequisites

EC2 Instance Role: Your EC2 instance must have an IAM role attached with the required CloudFront permissions
Instance Metadata Service: Ensure the instance metadata service is accessible (enabled by default)

Setting up EC2 Instance Role

Create IAM Role:
- Go to AWS IAM Console
- Create a new role with the "EC2" trusted entity
- Attach the following policy (or create a custom one):

json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "cloudfront:CreateInvalidation",
                "cloudfront:GetInvalidation",
                "cloudfront:ListInvalidations"
            ],
            "Resource": "arn:aws:cloudfront::*:distribution/YOUR_DISTRIBUTION_ID"
        }
    ]
}

Attach Role to EC2 Instance:
- Go to EC2 Console
- Select your instance
- Actions → Security → Modify IAM role
- Select the created role
Configure Plugin:
- Go to Settings > C3 CloudFront Cache
- Enter only the CloudFront Distribution ID
- Leave AWS credentials fields empty
- Click Save Changes

The plugin will automatically detect and use the EC2 instance role credentials.

Security Benefits

No credentials stored in application code or database
Automatic credential rotation
No risk of credential exposure
Follows AWS security best practices

Method 2: WordPress Admin Interface

Go to Settings > C3 CloudFront Cache
Fill in the required fields:
- CloudFront Distribution ID
- AWS Access Key ID
- AWS Secret Access Key
Click Save Changes

The plugin will test your credentials and save them securely in the WordPress options table.

Method 3: wp-config.php Constants (Advanced)

For enhanced security, you can define constants in your wp-config.php file:

php

// Add to wp-config.php (before the "That's all, stop editing!" line)
define( 'AWS_ACCESS_KEY_ID', 'your_access_key_here' );
define( 'AWS_SECRET_ACCESS_KEY', 'your_secret_key_here' );
define( 'C3_DISTRIBUTION_ID', 'your_cloudfront_distribution_id' );

For Different Hosting Environments

以下の設定は、Shared Hosting、VPS/Dedicated Server、Dockerなど、どの環境でも同じように使用できます：

php

// Add to wp-config.php
define( 'AWS_ACCESS_KEY_ID', 'your_access_key_here' );
define( 'AWS_SECRET_ACCESS_KEY', 'your_secret_key_here' );
define( 'C3_DISTRIBUTION_ID', 'your_cloudfront_distribution_id' );

Environment-Specific Considerations

AWS EC2: Strongly recommended to use EC2 instance roles for maximum security
Shared Hosting: Consider using the WordPress admin interface as file system access may be limited
VPS/Dedicated Server: Consider using environment variables for enhanced security
Docker: Consider using environment variables or IAM roles for containerized environments

Security Note

Using wp-config.php constants provides enhanced security by keeping credentials out of the database. However, the WordPress admin interface is perfectly suitable for most use cases and provides a user-friendly configuration experience.

Method 4: AWS Systems Manager / Secrets Manager

For enhanced security in production environments, you can use AWS Systems Manager Parameter Store or Secrets Manager to manage your credentials.

Using Parameter Store

Store credentials in Parameter Store and retrieve them programmatically:

php

add_filter('c3_credential', function($credentials) {
    try {
        $ssm = new Aws\Ssm\SsmClient(['version' => 'latest', 'region' => 'us-east-1']);
        $result = $ssm->getParameters([
            'Names' => ['/c3-cloudfront/aws-access-key', '/c3-cloudfront/aws-secret-key', '/c3-cloudfront/distribution-id'],
            'WithDecryption' => true
        ]);
        
        $params = [];
        foreach ($result['Parameters'] as $param) {
            $params[$param['Name']] = $param['Value'];
        }
        
        return [
            'key' => $params['/c3-cloudfront/aws-access-key'],
            'secret' => $params['/c3-cloudfront/aws-secret-key'],
            'distribution_id' => $params['/c3-cloudfront/distribution-id'],
            'timeout' => 30
        ];
    } catch (Exception $e) {
        error_log('C3 CloudFront: Failed to retrieve credentials from SSM: ' . $e->getMessage());
        return $credentials;
    }
});

Using Secrets Manager

Store credentials as a JSON secret and retrieve them:

php

add_filter('c3_credential', function($credentials) {
    try {
        $secretsManager = new Aws\SecretsManager\SecretsManagerClient(['version' => 'latest', 'region' => 'us-east-1']);
        $result = $secretsManager->getSecretValue(['SecretId' => 'c3-cloudfront-credentials']);
        $secret = json_decode($result['SecretString'], true);
        
        return [
            'key' => $secret['aws_access_key_id'],
            'secret' => $secret['aws_secret_access_key'],
            'distribution_id' => $secret['distribution_id'],
            'timeout' => 30
        ];
    } catch (Exception $e) {
        error_log('C3 CloudFront: Failed to retrieve credentials from Secrets Manager: ' . $e->getMessage());
        return $credentials;
    }
});

Security Note

Remember to configure appropriate IAM permissions for accessing Parameter Store or Secrets Manager, and use SecureString type for sensitive parameters.

Finding Your CloudFront Distribution ID

Log in to the AWS Console
Navigate to CloudFront
Find your distribution in the list
Copy the ID (e.g., E1234567890123)

Testing Configuration

After configuration, test that everything works:

Go to Settings > C3 CloudFront Cache
Click Manual Invalidation
Enter a test path (e.g., /)
Click Invalidate

If successful, you should see a confirmation message and the invalidation should appear in your CloudFront console.

WP-CLI Testing

You can also test configuration using WP-CLI:

bash

# Test configuration by flushing cache for a specific post
wp c3 flush 1

# Test full cache clear
wp c3 flush all

Advanced Configuration Options

Custom Invalidation Intervals

php

// Change invalidation interval (default: 1 minute)
add_filter('c3_invalidation_interval', function($interval_minutes) {
    return 5; // 5 minutes
});

// Change retry interval for failed invalidations (default: 1 minute)
add_filter('c3_invalidation_cron_interval', function($interval_minutes) {
    return 2; // 2 minutes
});

Invalidation Limits

php

// Change the number of paths per invalidation batch (default: 100)
add_filter('c3_invalidation_item_limits', function($limits) {
    return 300; // 300 paths per batch
});

Logging Configuration

php

// Enable comprehensive invalidation logging
add_filter('c3_log_invalidation_list', '__return_true');

// Enable cron job logging (legacy, use above for comprehensive logging)
add_filter('c3_log_cron_invalidation_task', '__return_true');

Troubleshooting Configuration

Common Issues

Invalid Credentials

Verify your AWS Access Key ID and Secret Access Key in the WordPress admin
Check that the IAM user has necessary permissions
Ensure credentials are properly URL-encoded if special characters are present
If using wp-config.php constants, verify they are correctly defined
For EC2 Instance Role: Verify the IAM role is attached to the instance and has the required CloudFront permissions

Distribution Not Found

Verify the CloudFront Distribution ID is correct
Ensure the distribution exists and is not deleted
Check that you're using the distribution ID, not the domain name

Permission Denied

Review IAM policy permissions
Ensure the policy is attached to the correct user/role
Check CloudFormation resource limits

Timeout Errors

Increase the C3_HTTP_TIMEOUT value
Check network connectivity to AWS services
Verify firewall settings allow outbound HTTPS traffic

For more troubleshooting help, see the Troubleshooting Guide.

Next Steps

With configuration complete, learn about basic usage and explore advanced features.

Configuration ​

AWS Prerequisites ​

Required IAM Permissions ​

Configuration Methods ​

Method 1: EC2 Instance Role (Recommended for AWS EC2) ​

Prerequisites ​

Setting up EC2 Instance Role ​

Method 2: WordPress Admin Interface ​

Method 3: wp-config.php Constants (Advanced) ​

For Different Hosting Environments ​

Method 4: AWS Systems Manager / Secrets Manager ​

Using Parameter Store ​

Using Secrets Manager ​

Finding Your CloudFront Distribution ID ​

Testing Configuration ​

WP-CLI Testing ​

Advanced Configuration Options ​

Custom Invalidation Intervals ​

Invalidation Limits ​

Logging Configuration ​

Troubleshooting Configuration ​

Common Issues ​

Next Steps ​