Remove sources-api-go Dependency for On-Prem Deployments

[ELK4N4]

Overview

This PR removes the dependency on sources-api-go for on-prem deployments by eliminating the application type lookup and configuring the housekeeper to work directly with Koku's Kafka events.

Motivation

As part of the migration to make Koku the single source of truth for sources:

• ros-ocp-backend previously made a REST call to sources-api-go at startup to get the cost-management application type ID
• This is no longer necessary since Koku now publishes source deletion events directly
• Simplifies the on-prem architecture by removing inter-service dependencies

Changes

Modified Files

File	Changes
internal/config/config.go	Added ONPREM configuration flag
internal/services/housekeeper/sourcesCleaner.go	Modified to skip application type filtering when ONPREM is enabled

Key Changes

1. New ONPREM Configuration Flag

Added ONPREM environment variable to the config:

// config.go
ONPREM bool

2. Simplified Sources Cleaner

When ONPREM=true:

• Skips the REST call to sources-api-go to fetch application type ID
• Uses a constant application type ID (0) for cost-management
• Still filters Kafka events by Application_type_id == 0

Application Type ID

For on-prem deployments, the application type ID is hardcoded to 0 (constant OnPremCostAppID). This is consistent with Koku, which publishes Kafka events with Application_type_id: 0. The housekeeper still filters events by application type ID, but uses the hardcoded value 0 instead of fetching it from sources-api-go.

Before (cloud mode):

1. On startup: GET /api/sources/v1.0/application_types?filter[name][eq]=/insights/platform/cost-management
2. Store application_type_id from response
3. On Kafka event: Filter by application_type_id

After (on-prem mode):

1. On startup: Set cost_app_id = 0 (constant)
2. On Kafka event: Filter by Application_type_id == 0

Configuration

Set the following environment variable to enable on-prem mode:

ONPREM=true

Testing

• Verified housekeeper correctly processes Kafka events from Koku
• Tested cluster cleanup when sources are deleted
• Confirmed no REST calls to sources-api-go when ONPREM is enabled

Related PRs

• koku: Enables Sources API and publishes Kafka events on source deletion
• cost-helm-chart: Helm chart updates to configure ONPREM flag for ros-ocp-backend