feat(site): HTTP deployment-config fetcher + DI + options

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Deployment/HttpDeploymentConfigFetcher.cs

@@ -0,0 +1,57 @@
+using Microsoft.Extensions.Logging;
+
+namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Deployment;
+
+/// <summary>HTTP <see cref="IDeploymentConfigFetcher"/> — GETs the config from central's internal endpoint.</summary>
+public sealed class HttpDeploymentConfigFetcher : IDeploymentConfigFetcher
+{
+    private readonly HttpClient _http;
+    private readonly ILogger<HttpDeploymentConfigFetcher> _log;
+
+    public HttpDeploymentConfigFetcher(HttpClient http, ILogger<HttpDeploymentConfigFetcher> log)
+    {
+        _http = http;
+        _log = log;
+    }
+
+    public async Task<string> FetchAsync(string centralFetchBaseUrl, string deploymentId, string token, CancellationToken ct)
+    {
+        var url = $"{centralFetchBaseUrl.TrimEnd('/')}/api/internal/deployments/{Uri.EscapeDataString(deploymentId)}/config";
+        using var req = new HttpRequestMessage(HttpMethod.Get, url);
+        req.Headers.Add("X-Deployment-Token", token);
+
+        HttpResponseMessage resp;
+        try
+        {
+            resp = await _http.SendAsync(req, ct);
+        }
+        catch (OperationCanceledException) when (ct.IsCancellationRequested)
+        {
+            throw; // genuine caller cancellation — propagate
+        }
+        catch (Exception ex)
+        {
+            // Includes HttpClient.Timeout (surfaces as TaskCanceledException with ct NOT cancelled) — treat as transport.
+            _log.LogWarning(ex, "deployment-config fetch transport error for {DeploymentId}", deploymentId);
+            throw new DeploymentConfigFetchException($"deployment-config fetch transport error: {ex.Message}", isSuperseded: false, ex);
+        }
+
+        using (resp)
+        {
+            if (resp.StatusCode == System.Net.HttpStatusCode.NotFound)
+            {
+                _log.LogWarning("deployment-config not found (expired/superseded/unknown) for {DeploymentId} (HTTP 404)", deploymentId);
+                throw new DeploymentConfigFetchException($"deployment-config not found (expired/superseded/unknown): {deploymentId}", isSuperseded: true);
+            }
+            if (!resp.IsSuccessStatusCode)
+            {
+                _log.LogWarning("deployment-config fetch failed for {DeploymentId}: HTTP {StatusCode}", deploymentId, (int)resp.StatusCode);
+                throw new DeploymentConfigFetchException($"deployment-config fetch failed: HTTP {(int)resp.StatusCode}", isSuperseded: false);
+            }
+
+            var body = await resp.Content.ReadAsStringAsync(ct);
+            _log.LogDebug("deployment-config fetched for {DeploymentId} (HTTP {StatusCode})", deploymentId, (int)resp.StatusCode);
+            return body;
+        }
+    }
+}

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Deployment/IDeploymentConfigFetcher.cs

@@ -0,0 +1,24 @@
+namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Deployment;
+
+/// <summary>
+/// Fetches a deployment's flattened config JSON from central over HTTP
+/// (notify-and-fetch). The site calls this after receiving a small notify.
+/// </summary>
+public interface IDeploymentConfigFetcher
+{
+    /// <summary>
+    /// GETs the flattened config JSON for <paramref name="deploymentId"/> from
+    /// <paramref name="centralFetchBaseUrl"/>, presenting <paramref name="token"/>
+    /// in the X-Deployment-Token header. Throws <see cref="DeploymentConfigFetchException"/>
+    /// on any non-success; a 404 (expired/superseded/unknown) sets IsSuperseded.
+    /// </summary>
+    Task<string> FetchAsync(string centralFetchBaseUrl, string deploymentId, string token, CancellationToken ct);
+}
+
+/// <summary>Raised when a deployment-config fetch fails. <see cref="IsSuperseded"/> is true on HTTP 404.</summary>
+public sealed class DeploymentConfigFetchException : Exception
+{
+    public bool IsSuperseded { get; }
+    public DeploymentConfigFetchException(string message, bool isSuperseded, Exception? inner = null)
+        : base(message, inner) => IsSuperseded = isSuperseded;
+}