Adds a very mad-katz metrics dashboard

src/Microsoft.Tye.Hosting/Dashboard/Pages/Index.razor

@@ -88,8 +88,6 @@
         {
             _subscriptions.Add(a.ReplicaEvents.Subscribe(OnReplicaChanged));
         }
-
-        base.OnInitialized();
     }
 
     private void OnReplicaChanged(ReplicaEvent replicaEvent)

src/Microsoft.Tye.Hosting/Dashboard/Pages/ServiceDetails.razor

@@ -18,6 +18,10 @@ else
         case ServiceType.Project:
             break;
     }
+
+    <hr />
+
+    <MetricsDisplay Service="_service" />
 }
 
 @code {

src/Microsoft.Tye.Hosting/Dashboard/Shared/MetricsDisplay.razor

@@ -0,0 +1,74 @@
+@implements IDisposable
+@using System.Threading;
+
+<h4>Metrics</h4>
+<ReplicaSelector Service="@Service" ReplicaChanged="OnReplicaChanged" />
+
+<div class="px-4 py-2">
+<table class="table table-striped table-bordered">
+    <colgroup>
+       <col span="1" style="width: 75%;">
+       <col span="1" style="width: 25%;">
+    </colgroup>
+    <thead class="thead-light">
+        <tr>
+            <th scope="col">Metric</th>
+            <th scope="col">Value</th>
+        </tr>
+    </thead>
+    @if (replica is object)
+    {
+        <tbody>
+            @foreach (var metric in replica.Metrics.OrderBy(kvp => kvp.Key))
+            {
+                <tr>
+                    <td>@metric.Key</td>
+                    <td>@metric.Value</td>
+                </tr>
+            }
+        </tbody>
+    }
+    else
+    {
+        <tbody></tbody>
+    }
+</table>
+</div>
+
+@code {
+    ReplicaStatus? replica;
+    Timer? timer;
+
+    [Parameter] public Service Service { get; set; } = default!;
+
+    protected override void OnParametersSet()
+    {
+        replica = Service?.Replicas.FirstOrDefault().Value;
+        OnReplicaChanged(replica);
+    }
+
+    void OnReplicaChanged(ReplicaStatus? replica)
+    {
+        this.replica = replica;
+        if (this.replica == null && timer is object)
+        {
+            timer.Dispose();
+            timer = null;
+        }
+
+        if (this.replica != null)
+        {
+            timer ??= new Timer(Timer_Tick, state: null, 1000, 1000);
+        }
+    }
+
+    void Timer_Tick(object? _)
+    {
+        _ = InvokeAsync(() => StateHasChanged());
+    }
+
+    void IDisposable.Dispose()
+    {
+        timer?.Dispose();
+    }
+}

src/Microsoft.Tye.Hosting/Dashboard/Shared/ReplicaSelector.razor

@@ -0,0 +1,55 @@
+@implements IDisposable
+
+<label>Replica:</label>
+<select value="@selected" @onchange="ReplicaSelected">
+    @foreach (var replica in Service.Replicas)
+    {
+        <option value="@replica.Key">@replica.Key</option>
+    }
+</select>
+
+@code {
+    IDisposable? subscription;
+    string? selected;
+
+    [Parameter] public Service Service { get; set; } = default!;
+
+    [Parameter] public EventCallback<ReplicaStatus?> ReplicaChanged { get; set; }
+
+    protected override void OnParametersSet()
+    {
+        subscription?.Dispose();
+        subscription = Service.ReplicaEvents.Subscribe(OnReplicasChanged);
+    }
+
+    void OnReplicasChanged(ReplicaEvent @event)
+    {
+        _ = InvokeAsync(() =>
+        {
+            if (@event.State == ReplicaState.Stopped && @event.Replica.Name == selected)
+            {
+                selected = null;
+            }
+
+            StateHasChanged();
+        });
+    }
+
+    async Task ReplicaSelected(ChangeEventArgs e)
+    {
+        selected = (string?)e.Value;
+        ReplicaStatus? replica = null;
+        if (selected is string)
+        {
+            Service.Replicas.TryGetValue(selected, out replica);
+        }
+
+        await ReplicaChanged.InvokeAsync(replica);
+    }
+
+    void IDisposable.Dispose()
+    {
+        subscription?.Dispose();
+    }
+}
+

src/Microsoft.Tye.Hosting/Model/ReplicaStatus.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 
 namespace Microsoft.Tye.Hosting.Model
@@ -22,7 +23,7 @@ namespace Microsoft.Tye.Hosting.Model
 
         public Dictionary<object, object> Items { get; } = new Dictionary<object, object>();
 
-        public Dictionary<string, string> Metrics { get; set; } = new Dictionary<string, string>();
+        public ConcurrentDictionary<string, string> Metrics { get; set; } = new ConcurrentDictionary<string, string>();
 
         public IDictionary<string, string>? Environment { get; set; }
     }