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Approval Request Workflow — HTTP-Triggered Auto-Approval Logic App

Article · Azure Logic Apps · Workflow Definition Language (schema 2016-06-01) · Content version 1.0.0.0

Overview

This Logic App implements an automated approval-routing workflow for expense or purchase requests. It exposes an HTTP endpoint that accepts approval requests, evaluates the requested amount against a configurable approval threshold, and returns an immediate synchronous decision:

• Requests below the threshold are auto-approved and acknowledged with an HTTP 200 OK response.
• Requests at or above the threshold are flagged for manual review and acknowledged with an HTTP 202 Accepted response.

Because both outcomes respond synchronously to the caller, this workflow functions as a lightweight approval decision API that upstream systems (forms, ticketing tools, procurement apps) can call directly.

Workflow architecture

Execution flow:

HTTP POST received
      │
      ▼
Initialize ApprovalThreshold = 5000
      │
      ▼
amount < ApprovalThreshold ?
      │
  ┌───┴────┐
 Yes       No
  │         │
  ▼         ▼
200 OK    202 Accepted
auto-     pending-
approved  manual-review

Trigger: When an approval request is received

The workflow starts with a Request trigger (type: Request, kind: Http), which provisions a callable HTTPS endpoint when the Logic App is saved. The trigger activates whenever an external system sends an HTTP POST to the generated endpoint URL.

The trigger enforces a JSON request schema to validate and type the incoming payload:

{
  "type": "object",
  "properties": {
    "requestId":      { "type": "string" },
    "requesterEmail": { "type": "string" },
    "amount":         { "type": "number" },
    "costCenter":     { "type": "string" }
  },
  "required": ["requestId", "requesterEmail", "amount"]
}

Defining the schema on the trigger makes the payload properties available as strongly-typed dynamic content (for example, triggerBody()?['amount']) in downstream actions.

Example request:

POST https://<logic-app-endpoint> HTTP/1.1
Content-Type: application/json

{
  "requestId": "REQ-2026-0042",
  "requesterEmail": "jdoe@contoso.com",
  "amount": 3200,
  "costCenter": "CC-1180"
}

For more information, see Receive and respond to inbound HTTPS calls in Azure Logic Apps.

Actions

1. Initialize_approval_threshold

Type: InitializeVariable · Runs after: trigger

This action declares an integer variable that defines the auto-approval cutoff:

{
  "variables": [
    {
      "name": "ApprovalThreshold",
      "type": "integer",
      "value": 5000
    }
  ]
}

Centralizing the threshold in a variable, rather than hard-coding it inside the condition expression, keeps the business rule in a single, easily maintained location. See Store and manage values by using variables in Azure Logic Apps.

2. Check_if_auto_approval_applies

Type: If (Condition) · Runs after: Initialize_approval_threshold (Succeeded)

This control action evaluates whether the requested amount qualifies for automatic approval:

{
  "and": [
    {
      "less": [
        "@triggerBody()?['amount']",
        "@variables('ApprovalThreshold')"
      ]
    }
  ]
}

The expression compares the amount property from the trigger payload against the ApprovalThreshold variable using the less operator — the condition is true when amount < 5000. The ? operator (triggerBody()?['amount']) performs a null-safe property access, preventing a runtime failure if the property is absent.

For expression reference, see Reference guide to workflow expression functions in Azure Logic Apps and Add conditions to control workflow actions.

True branch: Respond_approved

When the amount is under the threshold, the workflow returns an immediate approval:

{
  "statusCode": 200,
  "headers": { "Content-Type": "application/json" },
  "body": {
    "requestId": "@triggerBody()?['requestId']",
    "status": "auto-approved",
    "reviewedBy": "system"
  }
}

The response echoes the caller's requestId for correlation, sets status to auto-approved, and attributes the decision to system — providing a clear audit signal that no human reviewer was involved.

False (else) branch: Respond_pending_review

When the amount meets or exceeds the threshold, the workflow defers the decision:

{
  "statusCode": 202,
  "headers": { "Content-Type": "application/json" },
  "body": {
    "requestId": "@triggerBody()?['requestId']",
    "status": "pending-manual-review",
    "reason": "Amount exceeds auto-approval threshold"
  }
}

The 202 Accepted status code is semantically appropriate here: the request has been received and accepted for processing, but the final outcome (manual review) is not yet complete. The reason field tells the caller why automatic approval did not apply.

Both branches use the native Response action; see Receive and respond to inbound HTTPS calls in Azure Logic Apps.

Parameters and connections

The definition declares a single standard parameter:

The absence of managed connections means this Logic App has no external service dependencies, no connection authentication to maintain, and minimal failure surface.

Response summary

Purpose and functionality

This workflow encapsulates a common enterprise pattern: threshold-based approval triage. Its value lies in removing low-risk requests from human review queues while guaranteeing that high-value requests receive scrutiny. Typical integration scenarios include:

• A procurement or expense form that calls this endpoint on submission and displays the decision to the requester in real time.
• A ticketing system that routes tickets to an approvals queue only when the workflow returns 202.
• A parent Logic App or Power Automate flow that uses this workflow as a reusable decision component.

Extension considerations: the boundary condition is worth noting — an amount of exactly 5000 routes to manual review because the comparison uses less rather than lessOrEquals. Natural next steps for a production implementation include sourcing ApprovalThreshold from Azure App Configuration or a workflow parameter instead of a hard-coded value, adding a notification action (for example, Office 365 Outlook or Microsoft Teams) in the else branch to alert reviewers, and persisting decisions to a data store for audit history.

Additional resources

• What is Azure Logic Apps?
• Schema reference for Workflow Definition Language
• Receive and respond to inbound HTTPS calls
• Add conditions to control workflow actions
• Store and manage values by using variables
• Workflow expression functions reference