Using Logic Apps Consumption

Azure Logic Apps Consumption Best Practices

Overview

Azure Logic Apps Consumption is a multitenant, pay-per-execution integration platform. Success requires loosely coupled architecture, idempotent design, and defensive error handling. This skill covers Code View (JSON) conventions and production-ready patterns.

When to Use

• Building new Logic Apps Consumption workflows
• Reviewing or refactoring existing workflows
• Debugging performance or reliability issues
• Planning CI/CD deployment pipelines

Not for: Logic Apps Standard (single-tenant) - different patterns apply.

Architecture Patterns

Loosely Coupled Design

Source System → Service Bus → Logic App (Enrich/Route) → Service Bus → Logic App (Transform) → Destination

Benefits:

• Parallel execution - independent components scale separately
• Isolated failures - one component failure doesn't cascade
• Independent deployment - update modules without full redeploy
• Focused testing - unit test each workflow separately

Rule: One workflow per integration concern. Avoid monolithic workflows handling multiple protocols or systems.

Idempotent Operations

Same message processed multiple times must yield identical results:

• Use Upsert (update or insert) instead of always INSERT
• Generate deterministic IDs that remain consistent across retries
• Implement message deduplication at Service Bus level

Code View (JSON) Best Practices

Schema Reference

{
  "$schema": "https://schema.management.azure.com/schemas/2016-06-01/Microsoft.Logic.json",
  "contentVersion": "1.0.0.0"
}

Structure Order

1. Parameters (environment-specific values)
2. Triggers
3. Actions
4. Outputs

Parameters for Environment Abstraction

"parameters": {
  "environment": { "type": "String", "defaultValue": "dev" },
  "apiEndpoint": { "type": "String" },
  "connectionString": { "type": "SecureString" }
}

Use SecureString/SecureObject for credentials - masked in logs and history.

Meaningful Action Names

// ❌ BAD
"HTTP": { ... },
"Compose_2": { ... },
"For_each_3": { ... }

// ✅ GOOD
"Get_Customer_Details": { ... },
"Transform_To_Canonical_Format": { ... },
"Process_Each_Order_Line": { ... }

Run-After Configuration

"Send_Error_Notification": {
  "runAfter": {
    "Process_Order": ["Failed", "TimedOut"]
  }
}

Statuses: Succeeded, Failed, Skipped, TimedOut

Error Handling

Retry Policies

"retryPolicy": {
  "type": "Exponential",
  "count": 4,
  "interval": "PT7S",
  "minimumInterval": "PT5S",
  "maximumInterval": "PT1H"
}

Scope-Based Error Handling

┌─ Scope: Process_Order ─────────────────┐
│  Get_Order → Validate → Transform      │
└────────────────────────────────────────┘
         │
         ├── [Succeeded] → Send_Confirmation
         └── [Failed] → Log_Error → Send_Alert

Group related actions in Scope, then use runAfter on scope status.

Terminate Action

"Terminate_With_Error": {
  "type": "Terminate",
  "inputs": {
    "runStatus": "Failed",
    "runError": {
      "code": "ValidationFailed",
      "message": "@{variables('errorMessage')}"
    }
  }
}

Performance Optimization

Limits (Consumption)

Optimization Techniques

1. Avoid nested loops - each iteration persists state to storage
2. Filter before looping - reduce iterations with @take(), @skip(), conditions
3. Use chunking for large messages (>100MB)
4. Debatch at trigger - split array into individual runs
5. Limit concurrency on For Each (default: 20, max: 50)

"For_each": {
  "type": "Foreach",
  "runtimeConfiguration": {
    "concurrency": { "repetitions": 10 }
  }
}

Trigger Optimization

"triggers": {
  "When_messages_available": {
    "recurrence": {
      "frequency": "Minute",
      "interval": 3
    },
    "splitOn": "@triggerBody()",
    "runtimeConfiguration": {
      "concurrency": { "runs": 25 }
    }
  }
}

splitOn debatches arrays into parallel runs.

Security Best Practices

Authentication

1. Managed Identity (preferred) - no credentials to manage
2. Azure Key Vault for secrets - reference via @parameters('keyVaultSecret')
3. OAuth 2.0 for external APIs

Network Security

• Private endpoints for internal resources
• IP restrictions on HTTP triggers
• Access keys for trigger URLs (regenerate periodically)

Data Protection

• Use Secure Inputs/Outputs on sensitive actions (masks in run history)
• Avoid logging PII in tracked properties
• Enable customer-managed keys for encryption at rest

"Get_Secret": {
  "type": "ApiConnection",
  "inputs": { ... },
  "runtimeConfiguration": {
    "secureData": {
      "properties": ["inputs", "outputs"]
    }
  }
}

Naming Conventions

Expressions & Functions

Common Patterns

// Null-safe property access
@coalesce(triggerBody()?['customer']?['name'], 'Unknown')

// Date formatting
@formatDateTime(utcNow(), 'yyyy-MM-dd')

// Conditional
@if(equals(variables('status'), 'active'), 'Process', 'Skip')

// Array operations
@length(body('Get_Items'))
@first(body('Get_Items'))
@union(variables('list1'), variables('list2'))

// String operations
@concat('Order-', variables('orderId'))
@replace(variables('text'), ' ', '-')
@split(variables('csv'), ',')

Expression Limits

• Max expression length: 8,192 characters
• Max nesting depth: 10 levels
• Avoid complex expressions in loops (evaluate once, store in variable)

Deployment (ARM Templates)

Template Structure

├── azuredeploy.json          # Main template
├── azuredeploy.parameters.dev.json
├── azuredeploy.parameters.prod.json
└── connectors/
    └── connections.json      # Shared connections

CI/CD Pipeline

# Azure DevOps example
stages:
  - stage: Deploy
    jobs:
      - job: DeployLogicApp
        steps:
          - task: AzureResourceManagerTemplateDeployment@3
            inputs:
              deploymentScope: 'Resource Group'
              templateLocation: 'Linked artifact'
              csmFile: 'azuredeploy.json'
              csmParametersFile: 'azuredeploy.parameters.$(env).json'

Connection Authorization

After deployment, connections require manual authorization or use:

• Managed Identity (auto-authorized)
• Service Principal with pre-configured consent

Monitoring & Diagnostics

Enable Diagnostic Settings

"diagnosticSettings": {
  "logs": [
    { "category": "WorkflowRuntime", "enabled": true },
    { "category": "IntegrationAccountTrackingEvents", "enabled": true }
  ],
  "metrics": [
    { "category": "AllMetrics", "enabled": true }
  ]
}

Key Metrics

• Runs Started/Succeeded/Failed
• Run Latency
• Action Latency
• Billable Action Executions

Tracked Properties

"Send_Order": {
  "trackedProperties": {
    "orderId": "@variables('orderId')",
    "customerName": "@body('Get_Customer')?['name']"
  }
}

Query in Log Analytics:

AzureDiagnostics
| where ResourceType == "WORKFLOWS"
| where trackedProperties_orderId_s == "12345"

Common Pitfalls

SetVariable Cannot Self-Reference

// ❌ FAILS - variable cannot reference itself
"Set_Counter": {
  "type": "SetVariable",
  "inputs": {
    "name": "counter",
    "value": "@add(variables('counter'), 1)"
  }
}

// ✅ WORKS - use intermediate variable or IncrementVariable
"Increment_Counter": {
  "type": "IncrementVariable",
  "inputs": {
    "name": "counter",
    "value": 1
  }
}

For non-numeric accumulation (strings, arrays):

// ❌ FAILS - cannot append to itself
"Append_To_List": {
  "type": "SetVariable",
  "inputs": {
    "name": "items",
    "value": "@union(variables('items'), array(body('Get_Item')))"
  }
}

// ✅ WORKS - use AppendToArrayVariable
"Append_Item": {
  "type": "AppendToArrayVariable",
  "inputs": {
    "name": "items",
    "value": "@body('Get_Item')"
  }
}

Variables Inside Parallel Branches

Variables set in parallel branches have race conditions - final value is unpredictable.

// ❌ DANGEROUS
┌─ Parallel ─────────────────────┐
│  Branch A: Set_Total = 100     │
│  Branch B: Set_Total = 200     │
└────────────────────────────────┘
// Total could be 100 OR 200

Solution: Use separate variables per branch, merge after parallel completes.

Compose vs Variable

Compose outputs are immutable and cheaper (no storage write).

Trigger Outputs in Loops

triggerBody() and triggerOutputs() are evaluated once at workflow start. Safe to use in loops without re-fetching.

Until Loop Gotchas

"Until_Complete": {
  "type": "Until",
  "expression": "@equals(variables('status'), 'Complete')",
  "limit": {
    "count": 60,
    "timeout": "PT1H"
  }
}

Pitfalls:

• Default limit is 60 iterations AND 1 hour - whichever hits first
• No built-in delay between iterations - add explicit Delay action
• Infinite loop protection exists but burns through action quota fast

HTTP Action Timeout

Default HTTP timeout is 100 seconds. Long-running APIs need async pattern:

"Call_Long_Running_API": {
  "type": "Http",
  "inputs": {
    "method": "POST",
    "uri": "...",
    "retryPolicy": { "type": "None" }
  },
  "operationOptions": "DisableAsyncPattern"
}

For truly long operations, use webhook pattern or polling with Until.

JSON Parse Failures

Parse JSON action fails silently on schema mismatch if properties are missing. Use:

// Make properties optional in schema
"properties": {
  "name": { "type": "string" },
  "email": { "type": ["string", "null"] }
}

Or use coalesce() after parsing:

@coalesce(body('Parse_JSON')?['email'], 'no-email@example.com')

Split On with Empty Arrays

splitOn on empty array = zero workflow runs (no error, no notification).

Add validation or use Service Bus dead-letter for empty payload scenarios.

Anti-Patterns to Avoid

Cost Optimization

Billing Model

• ~4,000 free actions/month
• Standard connectors: lower rate
• Enterprise connectors: higher rate
• Each action execution counts

Reduction Strategies

1. Trigger conditions - prevent unnecessary runs
2. Batch operations - 1 bulk call vs N individual calls
3. Remove unused connectors - eliminate authorization overhead
4. Audit regularly - disable/delete unused workflows

"triggers": {
  "When_email_arrives": {
    "conditions": [
      { "expression": "@contains(triggerBody()?['from'], '@important.com')" }
    ]
  }
}

Quick Reference

References

• Workflow Definition Language Schema
• Error Handling
• Limits and Configuration
• ARM Template Deployment