Temporal Workflow Versioning

Guidance for safely updating workflows while maintaining compatibility with running executions.

Why Versioning Matters

Temporal replays workflow history to reconstruct state. If workflow code changes, replay may fail with non-determinism errors. Versioning ensures:

• Running workflows complete successfully
• New workflows use updated logic
• Safe rollback if issues occur

GetVersion API

The primary tool for workflow versioning.

Basic Usage

func MyWorkflow(ctx workflow.Context, input Input) error {
    // Introduce a version branch
    v := workflow.GetVersion(ctx, "change-id", workflow.DefaultVersion, 1)

    if v == workflow.DefaultVersion {
        // Original logic (for workflows started before change)
        err := oldBehavior(ctx)
    } else {
        // New logic (v == 1, for new workflows)
        err := newBehavior(ctx)
    }

    return err
}

Parameters

Parameter	Description
ctx	Workflow context
changeID	Unique identifier for this change point
minSupported	Minimum version to support (usually DefaultVersion)
maxSupported	Current version number

Version Numbers

• workflow.DefaultVersion (-1): Original code before any versioning
• 1, 2, 3, ...: Incremental version numbers

Common Scenarios

Adding New Activity

func OrderWorkflow(ctx workflow.Context, order Order) error {
    // Original activities
    err := workflow.ExecuteActivity(ctx, ValidateOrder, order).Get(ctx, nil)
    if err != nil {
        return err
    }

    // Version gate for new activity
    v := workflow.GetVersion(ctx, "add-fraud-check", workflow.DefaultVersion, 1)
    if v >= 1 {
        // New: Add fraud check for new workflows
        err = workflow.ExecuteActivity(ctx, CheckFraud, order).Get(ctx, nil)
        if err != nil {
            return err
        }
    }

    // Continue with rest of workflow
    err = workflow.ExecuteActivity(ctx, ProcessPayment, order).Get(ctx, nil)
    return err
}

Removing Activity

func OrderWorkflow(ctx workflow.Context, order Order) error {
    v := workflow.GetVersion(ctx, "remove-legacy-check", workflow.DefaultVersion, 1)

    if v == workflow.DefaultVersion {
        // Old: Keep legacy activity for existing workflows
        workflow.ExecuteActivity(ctx, LegacyCheck, order).Get(ctx, nil)
    }
    // New workflows (v >= 1) skip the legacy check

    // Continue with workflow
    return workflow.ExecuteActivity(ctx, ProcessOrder, order).Get(ctx, nil)
}

Changing Activity Parameters

func OrderWorkflow(ctx workflow.Context, order Order) error {
    v := workflow.GetVersion(ctx, "new-shipping-params", workflow.DefaultVersion, 1)

    var shippingResult ShippingResult
    if v == workflow.DefaultVersion {
        // Old parameter format
        err := workflow.ExecuteActivity(ctx, ShipOrder, order.ID).Get(ctx, &shippingResult)
    } else {
        // New parameter format with more data
        input := ShippingInput{
            OrderID:  order.ID,
            Priority: order.Priority,
            Address:  order.ShippingAddress,
        }
        err := workflow.ExecuteActivity(ctx, ShipOrderV2, input).Get(ctx, &shippingResult)
    }

    return err
}

Multiple Versions

func OrderWorkflow(ctx workflow.Context, order Order) error {
    v := workflow.GetVersion(ctx, "payment-flow", workflow.DefaultVersion, 2)

    switch v {
    case workflow.DefaultVersion:
        // Original: single payment call
        return processPaymentV1(ctx, order)
    case 1:
        // V1: Added retry logic
        return processPaymentV2(ctx, order)
    default:
        // V2 (current): Added fraud check
        return processPaymentV3(ctx, order)
    }
}

Deployment Strategy

Safe Deployment Process

1. Add version gates before deployment
2. Deploy workers with new code
3. Monitor for non-determinism errors
4. Let old workflows complete naturally
5. Clean up version gates after all old workflows finish

Deployment Timeline

Day 0: Deploy code with GetVersion
        - New workflows: use new logic
        - Old workflows: use old logic

Day 1-N: Old workflows complete naturally
         Monitor for issues

Day N+1: Once all old workflows done:
         - Remove version gates
         - Simplify to new logic only

Monitoring During Rollout

# Watch for non-determinism errors
sum(rate(temporal_workflow_task_execution_failed_total{failure_reason="NonDeterminismError"}[5m]))

# Track workflow completions by version
# (requires custom search attributes)

Workflow Reset

Alternative to versioning for fixing stuck workflows.

When to Use Reset

• Workflow stuck due to bug
• Need to retry from specific point
• Cannot wait for natural completion

Reset Commands

# Reset to specific event
temporal workflow reset \
  --workflow-id <id> \
  --event-id 10 \
  --reason "Reset after bug fix"

# Reset to last workflow task
temporal workflow reset \
  --workflow-id <id> \
  --type LastWorkflowTask \
  --reason "Retry last decision"

# Reset to first workflow task
temporal workflow reset \
  --workflow-id <id> \
  --type FirstWorkflowTask \
  --reason "Start over"

# Batch reset multiple workflows
temporal workflow reset-batch \
  --query "WorkflowType='OrderWorkflow' AND ExecutionStatus='Running'" \
  --type LastWorkflowTask \
  --reason "Batch reset for bug fix"

Reset Types

Type	Description	Use Case
FirstWorkflowTask	Restart from beginning	Complete redo
LastWorkflowTask	Redo last decision	Recent bug
--event-id N	Reset to specific event	Targeted retry

Best Practices

Version Gate Naming

Use descriptive, unique change IDs:

// GOOD: Descriptive and unique
workflow.GetVersion(ctx, "add-fraud-check-2024-01", ...)
workflow.GetVersion(ctx, "payment-retry-logic", ...)
workflow.GetVersion(ctx, "shipping-v2-params", ...)

// BAD: Generic or reused
workflow.GetVersion(ctx, "change1", ...)
workflow.GetVersion(ctx, "fix", ...)

Cleanup Strategy

After all old workflows complete:

// Before cleanup (versioned)
func OrderWorkflow(ctx workflow.Context, order Order) error {
    v := workflow.GetVersion(ctx, "add-validation", workflow.DefaultVersion, 1)
    if v >= 1 {
        validate(ctx, order)
    }
    return process(ctx, order)
}

// After cleanup (simplified)
func OrderWorkflow(ctx workflow.Context, order Order) error {
    validate(ctx, order)  // Now always runs
    return process(ctx, order)
}

Testing Versions

Test both old and new paths:

func TestOrderWorkflow_NewVersion(t *testing.T) {
    env := s.NewTestWorkflowEnvironment()
    // Test new logic
    env.ExecuteWorkflow(OrderWorkflow, testOrder)
    // Assert new behavior
}

func TestOrderWorkflow_ReplayOldHistory(t *testing.T) {
    replayer := worker.NewWorkflowReplayer()
    replayer.RegisterWorkflow(OrderWorkflow)
    // Replay with old history
    err := replayer.ReplayWorkflowHistoryFromJSONFile(nil, "old_history.json")
    require.NoError(t, err)
}

Anti-Patterns

Don't Change Version IDs

// WRONG: Changing ID breaks replay
// v1 code
workflow.GetVersion(ctx, "my-change", ...)
// v2 code - BROKEN
workflow.GetVersion(ctx, "my-change-v2", ...)  // Different ID!

// RIGHT: Keep same ID, increment version
// v1 code
workflow.GetVersion(ctx, "my-change", DefaultVersion, 1)
// v2 code
workflow.GetVersion(ctx, "my-change", DefaultVersion, 2)  // Same ID

Don't Lower maxSupported

// WRONG: Lowering version breaks existing workflows
// v1 code
workflow.GetVersion(ctx, "change", DefaultVersion, 2)
// v2 code - BROKEN
workflow.GetVersion(ctx, "change", DefaultVersion, 1)  // Lowered!

// RIGHT: Only increase versions
workflow.GetVersion(ctx, "change", DefaultVersion, 3)

Additional Resources

Reference Files

For detailed versioning patterns, consult:

• references/version-patterns.md - Advanced versioning scenarios
• references/migration-guide.md - Large-scale migration strategies