# Progressive Delivery Enhancements ## Overview Progressive Delivery Enhancements transforms the existing progressive delivery system into a fully automated, metrics-driven deployment platform. This enhancement provides metric-driven canary automation, feature flag integration, automatic traffic percentage calculation based on error rates, and sophisticated rollout strategies. This is a best-in-class implementation inspired by Argo Rollouts, Flagger, and modern GitOps practices, tailored for non-Kubernetes environments. --- ## Design Principles 1. **Metrics-Driven Decisions**: All traffic shifts based on objective data 2. **Fail-Fast, Recover-Faster**: Detect issues early, rollback automatically 3. **Gradual Risk Exposure**: Minimize blast radius through incremental rollouts 4. **Feature-Aware Deployments**: Coordinate releases with feature flags 5. **Traffic Engineering**: Fine-grained control over request routing 6. **Full Observability**: Every decision traceable and auditable --- ## Architecture ### Component Overview ``` ┌────────────────────────────────────────────────────────────────────────┐ │ Progressive Delivery System │ ├────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌──────────────────┐ ┌───────────────────┐ ┌─────────────────┐ │ │ │ RolloutController│───▶│ MetricsAnalyzer │───▶│ TrafficManager │ │ │ │ │ │ │ │ │ │ │ └──────────────────┘ └───────────────────┘ └─────────────────┘ │ │ │ │ │ │ │ ▼ ▼ ▼ │ │ ┌──────────────────┐ ┌───────────────────┐ ┌─────────────────┐ │ │ │ CanaryController │ │ FeatureFlagBridge │ │ LoadBalancer │ │ │ │ │ │ │ │ Integrations │ │ │ └──────────────────┘ └───────────────────┘ └─────────────────┘ │ │ │ │ │ │ │ ▼ ▼ ▼ │ │ ┌──────────────────┐ ┌───────────────────┐ ┌─────────────────┐ │ │ │ BlueGreenManager │ │ ExperimentEngine │ │ RollbackTrigger │ │ │ │ │ │ │ │ │ │ │ └──────────────────┘ └───────────────────┘ └─────────────────┘ │ │ │ └────────────────────────────────────────────────────────────────────────┘ ``` ### Key Components #### 1. RolloutController Orchestrates progressive rollout execution: ```csharp public sealed class RolloutController { public async Task StartRolloutAsync( RolloutConfig config, CancellationToken ct) { var session = new RolloutSession { Id = Guid.NewGuid(), ReleaseId = config.ReleaseId, EnvironmentId = config.EnvironmentId, Strategy = config.Strategy, StartedAt = _timeProvider.GetUtcNow(), Status = RolloutStatus.Initializing }; await _sessionStore.SaveAsync(session, ct); // Initialize based on strategy session = config.Strategy.Type switch { RolloutStrategyType.Canary => await InitializeCanaryAsync(session, config, ct), RolloutStrategyType.BlueGreen => await InitializeBlueGreenAsync(session, config, ct), RolloutStrategyType.Linear => await InitializeLinearAsync(session, config, ct), RolloutStrategyType.Exponential => await InitializeExponentialAsync(session, config, ct), _ => throw new UnsupportedStrategyException(config.Strategy.Type) }; // Start the rollout loop _ = RunRolloutLoopAsync(session, ct); return session; } private async Task RunRolloutLoopAsync( RolloutSession session, CancellationToken ct) { try { while (!ct.IsCancellationRequested && !session.IsTerminal) { session = await _sessionStore.GetAsync(session.Id, ct); // Check for manual pause if (session.Status == RolloutStatus.Paused) { await Task.Delay(TimeSpan.FromSeconds(5), ct); continue; } // Analyze current metrics var analysis = await _metricsAnalyzer.AnalyzeAsync(session, ct); // Make advancement decision var decision = await DecideNextActionAsync(session, analysis, ct); // Execute decision session = await ExecuteDecisionAsync(session, decision, ct); // Wait for observation period if (decision.Action == RolloutAction.Advance) { await Task.Delay(session.CurrentStage.ObservationPeriod, ct); } } } catch (Exception ex) { _logger.LogError(ex, "Rollout loop failed for session {SessionId}", session.Id); await FailRolloutAsync(session, ex.Message, ct); } } private async Task DecideNextActionAsync( RolloutSession session, MetricsAnalysis analysis, CancellationToken ct) { var decision = new RolloutDecision { SessionId = session.Id, DecidedAt = _timeProvider.GetUtcNow(), Analysis = analysis }; // Check for failures if (analysis.HealthStatus == HealthStatus.Critical) { decision.Action = RolloutAction.Rollback; decision.Reason = "Critical health degradation detected"; decision.TriggeringMetrics = analysis.CriticalMetrics; return decision; } // Check if current stage requirements met if (!IsStageRequirementsMet(session.CurrentStage, analysis)) { if (analysis.StageDuration > session.CurrentStage.MaxDuration) { decision.Action = RolloutAction.Rollback; decision.Reason = $"Stage {session.CurrentStage.Name} exceeded max duration"; } else { decision.Action = RolloutAction.Wait; decision.Reason = "Waiting for stage requirements"; } return decision; } // Check if we're at final stage if (session.IsAtFinalStage) { decision.Action = RolloutAction.Complete; decision.Reason = "All stages completed successfully"; return decision; } // Ready to advance decision.Action = RolloutAction.Advance; decision.NextStage = session.GetNextStage(); decision.Reason = $"Stage {session.CurrentStage.Name} requirements met, advancing"; return decision; } } public sealed record RolloutSession { public Guid Id { get; init; } public Guid ReleaseId { get; init; } public Guid EnvironmentId { get; init; } public RolloutStrategy Strategy { get; init; } public RolloutStatus Status { get; init; } // Progress public int CurrentStageIndex { get; init; } public RolloutStage CurrentStage => Strategy.Stages[CurrentStageIndex]; public bool IsAtFinalStage => CurrentStageIndex >= Strategy.Stages.Length - 1; public double CurrentTrafficPercent { get; init; } // Timing public DateTimeOffset StartedAt { get; init; } public DateTimeOffset? CompletedAt { get; init; } public DateTimeOffset StageStartedAt { get; init; } // History public ImmutableArray DecisionHistory { get; init; } // Terminal check public bool IsTerminal => Status is RolloutStatus.Completed or RolloutStatus.RolledBack or RolloutStatus.Failed; } ``` #### 2. MetricsAnalyzer Analyzes metrics for rollout decisions: ```csharp public sealed class MetricsAnalyzer { private readonly ImmutableArray _providers; public async Task AnalyzeAsync( RolloutSession session, CancellationToken ct) { var analysis = new MetricsAnalysis { SessionId = session.Id, AnalyzedAt = _timeProvider.GetUtcNow(), StageDuration = _timeProvider.GetUtcNow() - session.StageStartedAt }; // Collect metrics from all providers var metrics = new Dictionary(); foreach (var provider in _providers) { var providerMetrics = await provider.CollectAsync(session, ct); foreach (var (name, value) in providerMetrics) { metrics[$"{provider.Name}:{name}"] = value; } } // Get baseline for comparison var baseline = await _baselineStore.GetAsync(session.EnvironmentId, ct); // Analyze each metric against thresholds foreach (var threshold in session.Strategy.SuccessThresholds) { var metricValue = metrics.GetValueOrDefault(threshold.MetricName); if (metricValue == null) { analysis.MissingMetrics.Add(threshold.MetricName); continue; } var evaluation = EvaluateMetric(metricValue, threshold, baseline); analysis.MetricEvaluations.Add(evaluation); if (evaluation.Status == MetricStatus.Critical) { analysis.CriticalMetrics.Add(evaluation); } } // Calculate overall health analysis.HealthStatus = CalculateOverallHealth(analysis.MetricEvaluations); // Calculate recommended traffic percentage analysis.RecommendedTrafficPercent = CalculateRecommendedTraffic( session, analysis.MetricEvaluations); return analysis; } private MetricEvaluation EvaluateMetric( MetricValue value, MetricThreshold threshold, Baseline? baseline) { var evaluation = new MetricEvaluation { MetricName = threshold.MetricName, CurrentValue = value.Value, Threshold = threshold, BaselineValue = baseline?.GetMetric(threshold.MetricName) }; // Compare against threshold var meetsThreshold = threshold.Comparison switch { ComparisonOperator.LessThan => value.Value < threshold.Value, ComparisonOperator.LessThanOrEqual => value.Value <= threshold.Value, ComparisonOperator.GreaterThan => value.Value > threshold.Value, ComparisonOperator.GreaterThanOrEqual => value.Value >= threshold.Value, ComparisonOperator.Equal => Math.Abs(value.Value - threshold.Value) < 0.001, _ => false }; // Compare against baseline if available double? baselineDeviation = null; if (evaluation.BaselineValue.HasValue) { baselineDeviation = (value.Value - evaluation.BaselineValue.Value) / Math.Max(evaluation.BaselineValue.Value, 0.001); } evaluation.MeetsThreshold = meetsThreshold; evaluation.BaselineDeviation = baselineDeviation; evaluation.Status = DetermineStatus(meetsThreshold, baselineDeviation, threshold); return evaluation; } private double CalculateRecommendedTraffic( RolloutSession session, IReadOnlyList evaluations) { // All metrics healthy -> advance to next stage's target if (evaluations.All(e => e.Status == MetricStatus.Healthy)) { return session.IsAtFinalStage ? 100.0 : session.GetNextStage().TrafficPercent; } // Some degradation -> hold current or reduce var worstStatus = evaluations.Max(e => e.Status); return worstStatus switch { MetricStatus.Warning => session.CurrentTrafficPercent, // Hold MetricStatus.Degraded => Math.Max(session.CurrentTrafficPercent * 0.5, 5), // Reduce 50% MetricStatus.Critical => 0, // Rollback _ => session.CurrentTrafficPercent }; } } public sealed record MetricsAnalysis { public Guid SessionId { get; init; } public DateTimeOffset AnalyzedAt { get; init; } public TimeSpan StageDuration { get; init; } public HealthStatus HealthStatus { get; init; } public double RecommendedTrafficPercent { get; init; } public List MetricEvaluations { get; init; } = new(); public List CriticalMetrics { get; init; } = new(); public List MissingMetrics { get; init; } = new(); } ``` #### 3. CanaryController Manages canary deployments with automated progression: ```csharp public sealed class CanaryController { public async Task CreateCanaryAsync( CanaryConfig config, CancellationToken ct) { var canary = new CanaryDeployment { Id = Guid.NewGuid(), ReleaseId = config.ReleaseId, EnvironmentId = config.EnvironmentId, BaselineReleaseId = config.BaselineReleaseId, Stages = config.Stages, SuccessThresholds = config.SuccessThresholds, CreatedAt = _timeProvider.GetUtcNow(), Status = CanaryStatus.Initializing }; // Deploy canary version await DeployCanaryVersionAsync(canary, ct); // Initialize traffic at first stage canary.CurrentStageIndex = 0; canary.CurrentTrafficPercent = canary.Stages[0].TrafficPercent; await _trafficManager.SetCanaryTrafficAsync(canary, ct); canary.Status = CanaryStatus.Running; canary.StageStartedAt = _timeProvider.GetUtcNow(); await _canaryStore.SaveAsync(canary, ct); return canary; } public async Task AnalyzeCanaryAsync( Guid canaryId, CancellationToken ct) { var canary = await _canaryStore.GetAsync(canaryId, ct); // Collect metrics for both versions var canaryMetrics = await CollectVersionMetricsAsync( canary.ReleaseId, canary.EnvironmentId, ct); var baselineMetrics = await CollectVersionMetricsAsync( canary.BaselineReleaseId, canary.EnvironmentId, ct); var analysis = new CanaryAnalysis { CanaryId = canaryId, AnalyzedAt = _timeProvider.GetUtcNow(), CanaryMetrics = canaryMetrics, BaselineMetrics = baselineMetrics }; // Compare each threshold foreach (var threshold in canary.SuccessThresholds) { var canaryValue = canaryMetrics.GetValueOrDefault(threshold.MetricName); var baselineValue = baselineMetrics.GetValueOrDefault(threshold.MetricName); if (canaryValue == null || baselineValue == null) { analysis.InsufficientData = true; continue; } var comparison = new MetricComparison { MetricName = threshold.MetricName, CanaryValue = canaryValue.Value, BaselineValue = baselineValue.Value, Threshold = threshold }; // Calculate statistical significance comparison.Difference = canaryValue.Value - baselineValue.Value; comparison.DifferencePercent = comparison.Difference / Math.Max(baselineValue.Value, 0.001); comparison.IsStatisticallySignificant = CalculateSignificance( canaryValue, baselineValue, threshold.MinSampleSize); // Determine if canary is better/worse/same comparison.Verdict = DetermineVerdict(comparison, threshold); analysis.Comparisons.Add(comparison); } // Overall verdict analysis.OverallVerdict = DetermineOverallVerdict(analysis.Comparisons); return analysis; } private CanaryVerdict DetermineVerdict( MetricComparison comparison, MetricThreshold threshold) { if (!comparison.IsStatisticallySignificant) return CanaryVerdict.Inconclusive; var isBetter = threshold.DesiredDirection switch { MetricDirection.Lower => comparison.Difference < 0, MetricDirection.Higher => comparison.Difference > 0, _ => false }; if (isBetter) return CanaryVerdict.Better; // Check if within acceptable margin var margin = Math.Abs(comparison.DifferencePercent); if (margin <= threshold.AcceptableMargin) return CanaryVerdict.Same; return CanaryVerdict.Worse; } } public sealed record CanaryDeployment { public Guid Id { get; init; } public Guid ReleaseId { get; init; } public Guid BaselineReleaseId { get; init; } public Guid EnvironmentId { get; init; } public CanaryStatus Status { get; init; } // Configuration public ImmutableArray Stages { get; init; } public ImmutableArray SuccessThresholds { get; init; } // Progress public int CurrentStageIndex { get; init; } public double CurrentTrafficPercent { get; init; } public DateTimeOffset StageStartedAt { get; init; } // Analysis history public ImmutableArray AnalysisHistory { get; init; } // Timing public DateTimeOffset CreatedAt { get; init; } public DateTimeOffset? CompletedAt { get; init; } } ``` #### 4. FeatureFlagBridge Coordinates deployments with feature flags: ```csharp public sealed class FeatureFlagBridge { private readonly ImmutableArray _providers; public async Task SyncFlagsForReleaseAsync( Guid releaseId, FeatureFlagSyncConfig config, CancellationToken ct) { var release = await _releaseStore.GetAsync(releaseId, ct); var flags = await GetAssociatedFlagsAsync(releaseId, ct); var sync = new FeatureFlagSync { Id = Guid.NewGuid(), ReleaseId = releaseId, SyncedAt = _timeProvider.GetUtcNow() }; foreach (var flag in flags) { var provider = _providers.First(p => p.Name == flag.Provider); switch (config.Action) { case FlagSyncAction.EnableForTraffic: // Enable flag for canary traffic percentage await provider.SetRolloutPercentageAsync( flag.Key, config.TrafficPercent, ct); break; case FlagSyncAction.EnableForUsers: // Enable for specific user segment await provider.EnableForSegmentAsync( flag.Key, config.UserSegment, ct); break; case FlagSyncAction.EnableFully: // Enable 100% await provider.EnableAsync(flag.Key, ct); break; case FlagSyncAction.Disable: // Disable flag (rollback scenario) await provider.DisableAsync(flag.Key, ct); break; } sync.FlagsUpdated.Add(new FlagUpdate { FlagKey = flag.Key, Provider = flag.Provider, Action = config.Action, NewState = await provider.GetStateAsync(flag.Key, ct) }); } return sync; } public async Task> GetAssociatedFlagsAsync( Guid releaseId, CancellationToken ct) { var release = await _releaseStore.GetAsync(releaseId, ct); // Get flags from release metadata var flagKeys = release.Metadata.GetValueOrDefault("feature_flags", "") .Split(',', StringSplitOptions.RemoveEmptyEntries); var flags = new List(); foreach (var key in flagKeys) { foreach (var provider in _providers) { var flag = await provider.GetFlagAsync(key, ct); if (flag != null) { flags.Add(flag); break; } } } return flags; } public async Task CoordinateRolloutWithFlagsAsync( RolloutSession session, CancellationToken ct) { var flags = await GetAssociatedFlagsAsync(session.ReleaseId, ct); if (!flags.Any()) return; // Sync flag rollout percentage with traffic percentage await SyncFlagsForReleaseAsync(session.ReleaseId, new FeatureFlagSyncConfig { Action = FlagSyncAction.EnableForTraffic, TrafficPercent = session.CurrentTrafficPercent }, ct); _logger.LogInformation( "Synced {FlagCount} feature flags to {TrafficPercent}%", flags.Count, session.CurrentTrafficPercent); } } public interface IFeatureFlagProvider { string Name { get; } Task GetFlagAsync(string key, CancellationToken ct); Task EnableAsync(string key, CancellationToken ct); Task DisableAsync(string key, CancellationToken ct); Task SetRolloutPercentageAsync(string key, double percent, CancellationToken ct); Task EnableForSegmentAsync(string key, string segment, CancellationToken ct); Task GetStateAsync(string key, CancellationToken ct); } // Implementations for popular providers public sealed class LaunchDarklyProvider : IFeatureFlagProvider { } public sealed class SplitProvider : IFeatureFlagProvider { } public sealed class UnleashProvider : IFeatureFlagProvider { } public sealed class FlagsmithProvider : IFeatureFlagProvider { } public sealed class ConfigCatProvider : IFeatureFlagProvider { } ``` #### 5. TrafficManager Manages traffic routing across load balancers: ```csharp public sealed class TrafficManager { private readonly ImmutableArray _adapters; public async Task SetTrafficSplitAsync( TrafficSplitRequest request, CancellationToken ct) { var targets = await _targetStore.GetByEnvironmentAsync(request.EnvironmentId, ct); // Group targets by load balancer type var targetsByLB = targets.GroupBy(t => t.LoadBalancerType); var config = new TrafficConfiguration { Id = Guid.NewGuid(), EnvironmentId = request.EnvironmentId, AppliedAt = _timeProvider.GetUtcNow() }; foreach (var group in targetsByLB) { var adapter = _adapters.FirstOrDefault(a => a.Type == group.Key); if (adapter == null) { _logger.LogWarning("No adapter for load balancer type {Type}", group.Key); continue; } foreach (var target in group) { await adapter.SetWeightsAsync(target, request.Weights, ct); config.AppliedTargets.Add(target.Id); } } await _configStore.SaveAsync(config, ct); return config; } public async Task SetCanaryTrafficAsync( CanaryDeployment canary, CancellationToken ct) { var weights = new TrafficWeights { Weights = new Dictionary { [canary.BaselineReleaseId.ToString()] = 100 - canary.CurrentTrafficPercent, [canary.ReleaseId.ToString()] = canary.CurrentTrafficPercent }.ToImmutableDictionary() }; await SetTrafficSplitAsync(new TrafficSplitRequest { EnvironmentId = canary.EnvironmentId, Weights = weights }, ct); } public async Task GetTrafficMetricsAsync( Guid environmentId, CancellationToken ct) { var targets = await _targetStore.GetByEnvironmentAsync(environmentId, ct); var metrics = new TrafficMetrics { EnvironmentId = environmentId, CollectedAt = _timeProvider.GetUtcNow() }; foreach (var target in targets) { var adapter = _adapters.FirstOrDefault(a => a.Type == target.LoadBalancerType); if (adapter == null) continue; var targetMetrics = await adapter.GetMetricsAsync(target, ct); metrics.TargetMetrics[target.Id] = targetMetrics; } return metrics; } } public interface ILoadBalancerAdapter { LoadBalancerType Type { get; } Task SetWeightsAsync(Target target, TrafficWeights weights, CancellationToken ct); Task GetMetricsAsync(Target target, CancellationToken ct); Task HealthCheckAsync(Target target, CancellationToken ct); } // Adapters for various load balancers public sealed class NginxAdapter : ILoadBalancerAdapter { public LoadBalancerType Type => LoadBalancerType.Nginx; public async Task SetWeightsAsync(Target target, TrafficWeights weights, CancellationToken ct) { // Generate nginx upstream config with weights var config = GenerateUpstreamConfig(target, weights); // Write config and reload await WriteConfigAsync(target, config, ct); await ReloadNginxAsync(target, ct); } private string GenerateUpstreamConfig(Target target, TrafficWeights weights) { var sb = new StringBuilder(); sb.AppendLine($"upstream {target.Name} {{"); foreach (var (version, weight) in weights.Weights) { var servers = GetServersForVersion(target, version); foreach (var server in servers) { sb.AppendLine($" server {server} weight={weight};"); } } sb.AppendLine("}"); return sb.ToString(); } } public sealed class HAProxyAdapter : ILoadBalancerAdapter { } public sealed class TraefikAdapter : ILoadBalancerAdapter { } public sealed class AWSALBAdapter : ILoadBalancerAdapter { } public sealed class EnvoyAdapter : ILoadBalancerAdapter { } ``` #### 6. ExperimentEngine Manages A/B experiments: ```csharp public sealed class ExperimentEngine { public async Task CreateExperimentAsync( ExperimentConfig config, CancellationToken ct) { var experiment = new Experiment { Id = Guid.NewGuid(), Name = config.Name, EnvironmentId = config.EnvironmentId, Hypothesis = config.Hypothesis, Variants = config.Variants, TrafficAllocation = config.TrafficAllocation, SuccessMetrics = config.SuccessMetrics, GuardrailMetrics = config.GuardrailMetrics, MinSampleSize = config.MinSampleSize, MaxDuration = config.MaxDuration, CreatedAt = _timeProvider.GetUtcNow(), Status = ExperimentStatus.Draft }; await _experimentStore.SaveAsync(experiment, ct); return experiment; } public async Task StartExperimentAsync( Guid experimentId, CancellationToken ct) { var experiment = await _experimentStore.GetAsync(experimentId, ct); // Validate prerequisites await ValidateExperimentAsync(experiment, ct); // Deploy all variants foreach (var variant in experiment.Variants) { await DeployVariantAsync(experiment, variant, ct); } // Set up traffic split var weights = new TrafficWeights { Weights = experiment.Variants .ToImmutableDictionary( v => v.Id.ToString(), v => experiment.TrafficAllocation.GetValueOrDefault(v.Id, 0)) }; await _trafficManager.SetTrafficSplitAsync(new TrafficSplitRequest { EnvironmentId = experiment.EnvironmentId, Weights = weights }, ct); experiment = experiment with { Status = ExperimentStatus.Running, StartedAt = _timeProvider.GetUtcNow() }; await _experimentStore.SaveAsync(experiment, ct); return experiment; } public async Task AnalyzeExperimentAsync( Guid experimentId, CancellationToken ct) { var experiment = await _experimentStore.GetAsync(experimentId, ct); var results = new ExperimentResults { ExperimentId = experimentId, AnalyzedAt = _timeProvider.GetUtcNow() }; // Collect metrics for each variant foreach (var variant in experiment.Variants) { var variantMetrics = await CollectVariantMetricsAsync(experiment, variant, ct); results.VariantMetrics[variant.Id] = variantMetrics; } // Statistical analysis var control = experiment.Variants.First(v => v.IsControl); foreach (var variant in experiment.Variants.Where(v => !v.IsControl)) { var analysis = PerformStatisticalAnalysis( results.VariantMetrics[control.Id], results.VariantMetrics[variant.Id], experiment.SuccessMetrics); results.VariantAnalyses[variant.Id] = analysis; } // Check guardrail metrics results.GuardrailViolations = await CheckGuardrailsAsync(experiment, results, ct); // Determine winner results.Winner = DetermineWinner(experiment, results); results.Confidence = CalculateOverallConfidence(results); results.Recommendation = GenerateRecommendation(experiment, results); return results; } private VariantAnalysis PerformStatisticalAnalysis( VariantMetrics control, VariantMetrics treatment, ImmutableArray successMetrics) { var analysis = new VariantAnalysis(); foreach (var metric in successMetrics) { var controlValues = control.GetMetricValues(metric.Name); var treatmentValues = treatment.GetMetricValues(metric.Name); // Calculate effect size var effectSize = (treatmentValues.Mean - controlValues.Mean) / controlValues.Mean; // Perform t-test var tTest = PerformTTest(controlValues, treatmentValues); // Calculate confidence interval var ci = CalculateConfidenceInterval(controlValues, treatmentValues, 0.95); analysis.MetricResults[metric.Name] = new MetricAnalysisResult { ControlMean = controlValues.Mean, TreatmentMean = treatmentValues.Mean, EffectSize = effectSize, PValue = tTest.PValue, IsSignificant = tTest.PValue < 0.05, ConfidenceInterval = ci, SampleSize = controlValues.Count + treatmentValues.Count }; } return analysis; } } public sealed record Experiment { public Guid Id { get; init; } public string Name { get; init; } public Guid EnvironmentId { get; init; } public string Hypothesis { get; init; } public ExperimentStatus Status { get; init; } // Variants public ImmutableArray Variants { get; init; } public ImmutableDictionary TrafficAllocation { get; init; } // Metrics public ImmutableArray SuccessMetrics { get; init; } public ImmutableArray GuardrailMetrics { get; init; } // Configuration public int MinSampleSize { get; init; } public TimeSpan MaxDuration { get; init; } // Timing public DateTimeOffset CreatedAt { get; init; } public DateTimeOffset? StartedAt { get; init; } public DateTimeOffset? EndedAt { get; init; } } ``` --- ## Rollout Strategies ### Canary Strategy ```yaml strategy: type: canary stages: - name: "canary-5" traffic_percent: 5 duration: "00:15:00" observation_period: "00:05:00" - name: "canary-25" traffic_percent: 25 duration: "00:30:00" observation_period: "00:10:00" - name: "canary-50" traffic_percent: 50 duration: "01:00:00" observation_period: "00:15:00" - name: "full-rollout" traffic_percent: 100 duration: "00:00:00" success_thresholds: - metric: error_rate comparison: less_than value: 0.01 desired_direction: lower - metric: latency_p99 comparison: less_than value: 1000 desired_direction: lower auto_rollback: enabled: true on_metric_failure: true on_analysis_failure: true ``` ### Linear Strategy ```yaml strategy: type: linear increment_percent: 10 increment_interval: "00:10:00" max_traffic_percent: 100 success_thresholds: - metric: success_rate comparison: greater_than value: 0.99 ``` ### Exponential Strategy ```yaml strategy: type: exponential initial_percent: 1 multiplier: 2.0 max_traffic_percent: 100 stage_duration: "00:10:00" # Results in: 1% → 2% → 4% → 8% → 16% → 32% → 64% → 100% ``` ### Blue-Green Strategy ```yaml strategy: type: blue_green stages: - name: "deploy-green" action: deploy_standby - name: "smoke-test" action: run_tests test_suite: smoke - name: "switch-traffic" action: switch_traffic switch_mode: instant # or 'gradual' - name: "verify" action: verify duration: "00:30:00" - name: "cleanup" action: terminate_blue ``` --- ## API Design ### REST Endpoints ``` # Rollouts POST /api/v1/rollouts # Start rollout GET /api/v1/rollouts # List rollouts GET /api/v1/rollouts/{id} # Get rollout POST /api/v1/rollouts/{id}/pause # Pause rollout POST /api/v1/rollouts/{id}/resume # Resume rollout POST /api/v1/rollouts/{id}/advance # Manual advance POST /api/v1/rollouts/{id}/rollback # Manual rollback POST /api/v1/rollouts/{id}/complete # Force complete # Canary POST /api/v1/canary # Start canary GET /api/v1/canary/{id} # Get canary GET /api/v1/canary/{id}/analysis # Get analysis # Experiments POST /api/v1/experiments # Create experiment GET /api/v1/experiments # List experiments GET /api/v1/experiments/{id} # Get experiment POST /api/v1/experiments/{id}/start # Start experiment POST /api/v1/experiments/{id}/stop # Stop experiment GET /api/v1/experiments/{id}/results # Get results # Traffic GET /api/v1/traffic/{environmentId} # Get traffic config POST /api/v1/traffic/{environmentId} # Set traffic split GET /api/v1/traffic/{environmentId}/metrics # Get traffic metrics # Feature Flags GET /api/v1/releases/{id}/flags # Get release flags POST /api/v1/releases/{id}/flags/sync # Sync flags ``` --- ## Metrics & Observability ### Prometheus Metrics ``` # Rollout Progress stella_rollout_traffic_percent{session_id, stage} stella_rollout_stage_duration_seconds{session_id, stage} stella_rollout_decisions_total{session_id, action} # Canary Analysis stella_canary_health_score{canary_id} stella_canary_metric_comparison{canary_id, metric, verdict} stella_canary_sample_size{canary_id, variant} # Experiments stella_experiment_variant_traffic{experiment_id, variant_id} stella_experiment_metric_value{experiment_id, variant_id, metric} stella_experiment_statistical_significance{experiment_id, variant_id} # Traffic stella_traffic_split_percent{environment_id, version} stella_traffic_requests_total{environment_id, version} stella_traffic_errors_total{environment_id, version} ``` --- ## Test Strategy ### Unit Tests - Metric threshold evaluation - Statistical significance calculation - Traffic weight calculation - Strategy stage progression ### Integration Tests - Full canary lifecycle - Experiment creation and analysis - Traffic manager with mock LB - Feature flag synchronization ### Chaos Tests - Metrics provider failures - Load balancer unavailability - Rapid traffic shifts ### Golden Tests - Deterministic analysis results - Consistent winner selection - Reproducible rollout decisions --- ## Migration Path ### Phase 1: Metrics Integration (Week 1-2) - Metrics analyzer - Baseline management - Provider adapters ### Phase 2: Rollout Controller (Week 3-4) - Session management - Stage progression - Decision engine ### Phase 3: Canary (Week 5-6) - Canary controller - Statistical analysis - Auto-progression ### Phase 4: Traffic Management (Week 7-8) - Load balancer adapters - Weight synchronization - Health monitoring ### Phase 5: Feature Flags (Week 9-10) - Provider integrations - Rollout coordination - Flag lifecycle ### Phase 6: Experiments (Week 11-12) - Experiment engine - Statistical analysis - Results visualization