Alright, let’s talk about building a custom connector for a niche SaaS app in Sentinel. I’ve been through this ritual a few times now—usually after realizing the out-of-the-box connectors are either too broad or, more likely, non-existent for the tool my security team suddenly decided is critical. Spoiler: it’s never as smooth as the Microsoft docs suggest.
First, you’ll need to live in the Azure Resource Manager templates and Logic Apps designer. The general flow is: use the HTTP action in Logic Apps to call the SaaS app’s API, parse the JSON, map the relevant fields to Sentinel’s Common Information Model (CIM), and hope the rate limits don’t throttle you into oblivion. The real friction points I’ve hit:
* **Authentication quirks:** If your app uses something other than basic OAuth 2.0 (think API keys in headers, custom JWT flows), be prepared to write a small Azure Function just to handle the auth handshake. Logic Apps’ native HTTP action can get surprisingly finicky.
* **Pagination handling:** Most APIs paginate. Your connector needs to loop through pages, and if you’re not careful, you’ll burn through API calls or miss data. I’ve had to add delay timers and state-tracking variables to avoid hitting limits.
* **CIM mapping is a manual chore:** Translating the app’s unique field names (e.g., `external_threat_score`) to something Sentinel understands isn’t automated. You’ll be manually mapping fields in the Logic App, which is error-prone and tedious.
The biggest gotcha? Maintenance. That niche SaaS app will update its API (maybe twice a year if you’re unlucky), and your elegant Logic App will break. There’s no alert for this—you’ll just notice a gap in your logs. So you’re now on the hook for monitoring the monitor.
I’m curious if anyone else has built connectors for less common apps—like a Deel or a Jamf—and whether you’ve found a more sustainable pattern than the official “HTTP -> Parse JSON -> For each -> Transform” loop. Is anyone using the Azure Functions route exclusively for more control, or is the overhead not worth it?
You've precisely identified the technical friction points. From a procurement and vendor management standpoint, this is where the true Total Cost of Ownership for a niche SaaS app becomes visible. The development hours you're describing for auth workarounds and pagination logic are a direct cost, often unaccounted for during the initial vendor selection.
My team formalizes this risk by including specific API connectivity requirements in the Request for Proposal stage. We mandate that vendors provide a detailed API specification document covering authentication method, rate limits, pagination strategy, and error handling. If their API lacks standard OAuth 2.0 or clear pagination tokens, we score them lower and factor in the anticipated integration surcharge.
This often reveals that a "best-of-breed" niche tool with a poor API can be more expensive than a slightly less optimal tool with a robust, well-documented integration surface. The security team's critical need must be balanced against the operational burden you're now shouldering. Have you considered pushing back on the vendor for better API support, using these development hurdles as a business case?
PPro
The real question is, why are we in the Logic Apps designer to begin with? Every time someone builds a bespoke connector for a "critical" niche app, you're signing up to maintain a fragile, undocumented pipeline. It's technical debt with a fancy Azure logo.
The pain you describe with auth and pagination is the vendor's problem, not your engineering team's to solve. If their API is that clunky, the app probably isn't mature enough to be in your security stack. But here we are, writing custom functions because someone didn't want to challenge the requirement.
Yeah, the HTTP action in Logic Apps is clunky for anything beyond a simple GET. That handshake function you mentioned becomes a mini-app to manage.
Ever tried running this whole flow in a container instead? A small go binary handling the auth and pagination, scheduled as a K8s cron job, can be way more predictable than Logic Apps state management. Push to a queue and let something else handle the CIM mapping.
The vendor's bad API becomes your problem to containerize, which is at least a portable kind of debt.
yaml all the things