Create a Custom Output Format

Introduction

Prowler can generate outputs in multiple formats, allowing users to customize the way findings are presented. This is particularly useful when integrating Prowler with third-party tools, creating specialized reports, or simply tailoring the data to meet specific requirements. A custom output format gives you the flexibility to extract and display only the most relevant information in the way you need it.

Prowler organizes its outputs in the /lib/outputs directory. Each format (e.g., JSON, CSV, HTML) is implemented as a Python class.
Outputs are generated based on findings collected during a scan. Each finding is represented as a structured dictionary containing details like resource IDs, severities, descriptions, and more.
Consult the Prowler Developer Guide to understand how Prowler works and the way that you can create it with the desired output!
Identify the best approach for the specific output you’re targeting.

Steps to Create a Custom Output Format

Schema

Output Class:

The class must inherit from Output. Review the Output Class.
Create a class that encapsulates attributes and methods for the output. The following is the code for the CSV class:

class CSV(Output):
    def transform(self, findings: List[Finding]) -> None:
        """Transforms the findings into the CSV format.

        Args:
            findings (list[Finding]): a list of Finding objects

        """
    ...

Transform Method:

This method will transform the findings provided by Prowler to a specific format. The following is the code for the transform method for the CSV class:

def transform(self, findings: List[Finding]) -> None:
    """Transforms the findings into the CSV format.

    Args:
        findings (list[Finding]): a list of Finding objects

    """
    try:
        for finding in findings:
            finding_dict = {}
            finding_dict["AUTH_METHOD"] = finding.auth_method
            finding_dict["TIMESTAMP"] = finding.timestamp
            finding_dict["ACCOUNT_UID"] = finding.account_uid
            finding_dict["ACCOUNT_NAME"] = finding.account_name
            finding_dict["ACCOUNT_EMAIL"] = finding.account_email
            finding_dict["ACCOUNT_ORGANIZATION_UID"] = (
                finding.account_organization_uid
            )
            finding_dict["ACCOUNT_ORGANIZATION_NAME"] = (
                finding.account_organization_name
            )
            finding_dict["ACCOUNT_TAGS"] = unroll_dict(
                finding.account_tags, separator=":"
            )
            finding_dict["FINDING_UID"] = finding.uid
            finding_dict["PROVIDER"] = finding.metadata.Provider
            finding_dict["CHECK_ID"] = finding.metadata.CheckID
            finding_dict["CHECK_TITLE"] = finding.metadata.CheckTitle
            finding_dict["CHECK_TYPE"] = unroll_list(finding.metadata.CheckType)
            finding_dict["STATUS"] = finding.status.value
            finding_dict["STATUS_EXTENDED"] = finding.status_extended
            finding_dict["MUTED"] = finding.muted
            finding_dict["SERVICE_NAME"] = finding.metadata.ServiceName
            finding_dict["SUBSERVICE_NAME"] = finding.metadata.SubServiceName
            finding_dict["SEVERITY"] = finding.metadata.Severity.value
            finding_dict["RESOURCE_TYPE"] = finding.metadata.ResourceType
            finding_dict["RESOURCE_UID"] = finding.resource_uid
            finding_dict["RESOURCE_NAME"] = finding.resource_name
            finding_dict["RESOURCE_DETAILS"] = finding.resource_details
            finding_dict["RESOURCE_TAGS"] = unroll_dict(finding.resource_tags)
            finding_dict["PARTITION"] = finding.partition
            finding_dict["REGION"] = finding.region
            finding_dict["DESCRIPTION"] = finding.metadata.Description
            finding_dict["RISK"] = finding.metadata.Risk
            finding_dict["RELATED_URL"] = finding.metadata.RelatedUrl
            finding_dict["REMEDIATION_RECOMMENDATION_TEXT"] = (
                finding.metadata.Remediation.Recommendation.Text
            )
            finding_dict["REMEDIATION_RECOMMENDATION_URL"] = (
                finding.metadata.Remediation.Recommendation.Url
            )
            finding_dict["REMEDIATION_CODE_NATIVEIAC"] = (
                finding.metadata.Remediation.Code.NativeIaC
            )
            finding_dict["REMEDIATION_CODE_TERRAFORM"] = (
                finding.metadata.Remediation.Code.Terraform
            )
            finding_dict["REMEDIATION_CODE_CLI"] = (
                finding.metadata.Remediation.Code.CLI
            )
            finding_dict["REMEDIATION_CODE_OTHER"] = (
                finding.metadata.Remediation.Code.Other
            )
            finding_dict["COMPLIANCE"] = unroll_dict(
                finding.compliance, separator=": "
            )
            finding_dict["CATEGORIES"] = unroll_list(finding.metadata.Categories)
            finding_dict["DEPENDS_ON"] = unroll_list(finding.metadata.DependsOn)
            finding_dict["RELATED_TO"] = unroll_list(finding.metadata.RelatedTo)
            finding_dict["NOTES"] = finding.metadata.Notes
            finding_dict["PROWLER_VERSION"] = finding.prowler_version
            self._data.append(finding_dict)
    except Exception as error:
        logger.error(
            f"{error.__class__.__name__}[{error.__traceback__.tb_lineno}]: {error}"
        )

Batch Write Data To File Method:

This method will write the modeled object to a file. The following is the code for the batch_write_data_to_file method for the CSV class:

def batch_write_data_to_file(self) -> None:
    """Writes the findings to a file using the CSV format using the `Output._file_descriptor`."""
    try:
        if (
            getattr(self, "_file_descriptor", None)
            and not self._file_descriptor.closed
            and self._data
        ):
            csv_writer = DictWriter(
                self._file_descriptor,
                fieldnames=self._data[0].keys(),
                delimiter=";",
            )
            csv_writer.writeheader()
            for finding in self._data:
                csv_writer.writerow(finding)
            self._file_descriptor.close()
    except Exception as error:
        logger.error(
            f"{error.__class__.__name__}[{error.__traceback__.tb_lineno}]: {error}"
        )

Integration With The Current Code

Once that the desired output format is created it has to be integrated with Prowler. Take a look at the the usage from the current supported output in order to add the new one. Here is an example of the CSV output creation inside prowler code:

if mode == "csv":
    csv_output = CSV(
        findings=finding_outputs,
        create_file_descriptor=True,
        file_path=f"{filename}{csv_file_suffix}",
    )
    generated_outputs["regular"].append(csv_output)
    # Write CSV Finding Object to file
    csv_output.batch_write_data_to_file()

Testing

Verify that Prowler’s findings are accurately writed in the desired output format.
Simulate edge cases to ensure robust error handling.

Documentation

Provide clear, detailed documentation for your output:
- Setup instructions, including any required dependencies.
- Configuration details.
- Example use cases and troubleshooting tips.
Good documentation ensures maintainability and simplifies onboarding for new users.

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