Merge pull request #16 from datalust/dev

1.2.0 Release

seq-input-healthcheck.sln.DotSettings

@@ -0,0 +1,3 @@
+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Datalust/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=lepv/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

src/Seq.Input.HealthCheck/HealthCheckInput.cs

@@ -1,4 +1,18 @@
-using System;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Net.Http;
@@ -35,6 +49,14 @@ public class HealthCheckInput : SeqApp, IPublishJson, IDisposable
                        "response. The response must be UTF-8 `application/json` for this to be applied.")]
         public string DataExtractionExpression { get; set; }
 
+        [SeqAppSetting(
+            DisplayName = "Bypass HTTP caching",
+            IsOptional = true,
+            HelpText = "If selected, the unique probe id will be appended to the target URL query string as " +
+                       "`" + HttpHealthCheck.ProbeIdParameterName  + "`, in order to disable any " +
+                       "intermediary HTTP caching. The `Cache-Control: no-store` header will also be sent.")]
+        public bool BypassHttpCaching { get; set; }
+
         public void Start(TextWriter inputWriter)
         {
             _httpClient = HttpHealthCheckClient.Create();
@@ -51,7 +73,8 @@ public void Start(TextWriter inputWriter)
                     _httpClient,
                     App.Title,
                     targetUrl,
-                    extractor);
+                    extractor,
+                    BypassHttpCaching);
 
                 _healthCheckTasks.Add(new HealthCheckTask(
                     healthCheck,

src/Seq.Input.HealthCheck/HealthCheckReporter.cs

@@ -1,4 +1,18 @@
-using System;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.IO;
 using Newtonsoft.Json;
 

src/Seq.Input.HealthCheck/HealthCheckResult.cs

@@ -1,4 +1,18 @@
-using System;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.Globalization;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
@@ -31,27 +45,33 @@ class HealthCheckResult
         public int? StatusCode { get; }
         public string ContentType { get; }
         public long? ContentLength { get; }
+        public string ProbeId { get; }
 
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Ignore)]
         public string InitialContent { get; }
 
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Ignore)]
         public JToken Data { get; }
 
+        [JsonProperty(DefaultValueHandling = DefaultValueHandling.Ignore)]
+        public string ProbedUrl { get; }
+
         public HealthCheckResult(
             DateTime utcTimestamp,
             string healthCheckTitle,
             string method,
             string targetUrl,            
             string outcome,
+            string probeId,
             string level,
             double elapsed,
             int? statusCode,
             string contentType,
             long? contentLength,
             string initialContent,
             Exception exception,
-            JToken data)
+            JToken data,
+            string probedUrl)
         {
             if (utcTimestamp.Kind != DateTimeKind.Utc)
                 throw new ArgumentException("The timestamp must be UTC.", nameof(utcTimestamp));
@@ -62,6 +82,7 @@ public HealthCheckResult(
             Method = method ?? throw new ArgumentNullException(nameof(method));
             TargetUrl = targetUrl ?? throw new ArgumentNullException(nameof(targetUrl));
             Outcome = outcome ?? throw new ArgumentNullException(nameof(outcome));
+            ProbeId = probeId ?? throw new ArgumentNullException(nameof(probeId));
 
             Level = level;
             Elapsed = elapsed;
@@ -71,6 +92,7 @@ public HealthCheckResult(
             InitialContent = initialContent;
             Exception = exception?.ToString();
             Data = data;
+            ProbedUrl = probedUrl;
         }
     }
 }

src/Seq.Input.HealthCheck/HealthCheckTask.cs

@@ -1,4 +1,18 @@
-using System;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.Threading;
 using System.Threading.Tasks;
 using Serilog;

src/Seq.Input.HealthCheck/HttpHealthCheck.cs

@@ -1,11 +1,27 @@
-using System;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.Diagnostics;
 using System.IO;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Newtonsoft.Json.Linq;
+using Seq.Input.HealthCheck.Util;
 
 namespace Seq.Input.HealthCheck
 {
@@ -14,19 +30,23 @@ class HttpHealthCheck
         readonly string _title;
         readonly string _targetUrl;
         readonly JsonDataExtractor _extractor;
+        readonly bool _bypassHttpCaching;
         readonly HttpClient _httpClient;
         readonly byte[] _buffer = new byte[2048];
 
+        public const string ProbeIdParameterName = "__probe";
+
         static readonly UTF8Encoding ForgivingEncoding = new UTF8Encoding(false, false);
         const int InitialContentChars = 16;
         const string OutcomeSucceeded = "succeeded", OutcomeFailed = "failed";
 
-        public HttpHealthCheck(HttpClient httpClient, string title, string targetUrl, JsonDataExtractor extractor)
+        public HttpHealthCheck(HttpClient httpClient, string title, string targetUrl, JsonDataExtractor extractor, bool bypassHttpCaching)
         {
             _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
             _title = title ?? throw new ArgumentNullException(nameof(title));
             _targetUrl = targetUrl ?? throw new ArgumentNullException(nameof(targetUrl));
             _extractor = extractor;
+            _bypassHttpCaching = bypassHttpCaching;
         }
 
         public async Task<HealthCheckResult> CheckNow(CancellationToken cancel)
@@ -40,12 +60,24 @@ public async Task<HealthCheckResult> CheckNow(CancellationToken cancel)
             string initialContent = null;
             JToken data = null;
 
+            var probeId = Nonce.Generate(12);
+            var probedUrl = _bypassHttpCaching ?
+                UrlHelper.AppendParameter(_targetUrl, ProbeIdParameterName, probeId) :
+                _targetUrl;
+
             var utcTimestamp = DateTime.UtcNow;
             var sw = Stopwatch.StartNew();
 
             try
             {
-                var response = await _httpClient.GetAsync(_targetUrl, cancel);
+                var request = new HttpRequestMessage(HttpMethod.Get, probedUrl);
+                request.Headers.Add("X-Correlation-ID", probeId);
+
+                if (_bypassHttpCaching)
+                    request.Headers.CacheControl = new CacheControlHeaderValue { NoStore = true };
+
+                var response = await _httpClient.SendAsync(request, cancel);
+
                 statusCode = (int)response.StatusCode;
                 contentType = response.Content.Headers.ContentType?.ToString();
                 contentLength = response.Content.Headers.ContentLength;
@@ -73,14 +105,16 @@ public async Task<HealthCheckResult> CheckNow(CancellationToken cancel)
                 "GET",
                 _targetUrl,
                 outcome,
+                probeId,
                 level,
                 sw.Elapsed.TotalMilliseconds,
                 statusCode,
                 contentType,
                 contentLength,
                 initialContent,
                 exception,
-                data);
+                data,
+                _targetUrl == probedUrl ? null : probedUrl);
         }
 
         // Either initial content, or extracted data

src/Seq.Input.HealthCheck/HttpHealthCheckClient.cs

@@ -1,4 +1,18 @@
-using System.Net.Http;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System.Net.Http;
 
 namespace Seq.Input.HealthCheck
 {

src/Seq.Input.HealthCheck/JsonDataExtractor.cs

@@ -1,4 +1,18 @@
-using System;
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.IO;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
@@ -11,7 +25,7 @@ namespace Seq.Input.HealthCheck
 {
     public class JsonDataExtractor
     {
-        static JsonValueFormatter ValueFormatter = new JsonValueFormatter("$type");
+        static readonly JsonValueFormatter ValueFormatter = new JsonValueFormatter("$type");
         static readonly JsonSerializer Serializer = JsonSerializer.Create(new JsonSerializerSettings
         {
             DateParseHandling = DateParseHandling.None

src/Seq.Input.HealthCheck/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Seq.Input.HealthCheck.Tests")]

src/Seq.Input.HealthCheck/Seq.Input.HealthCheck.csproj

@@ -1,8 +1,8 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <VersionPrefix>1.1.0</VersionPrefix>
+    <VersionPrefix>1.2.0</VersionPrefix>
     <Description>Seq Health Check: periodically GET an HTTP resource and publish response metrics to Seq.</Description>
     <Authors>Datalust and Contributors</Authors>
     <PackageTags>seq-app</PackageTags>
@@ -16,10 +16,11 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.WebUtilities" Version="2.2.0" />
     <PackageReference Include="newtonsoft.json" Version="12.0.1" />
     <PackageReference Include="Seq.Apps" Version="5.1.0" />
-    <PackageReference Include="Serilog" Version="2.8.0" />
-    <PackageReference Include="Serilog.Filters.Expressions" Version="2.0.1-dev-00046" />
+    <PackageReference Include="Serilog" Version="2.9.0" />
+    <PackageReference Include="Serilog.Filters.Expressions" Version="2.1.0" />
     <PackageReference Include="Serilog.Formatting.Compact.Reader" Version="1.0.3" />
   </ItemGroup>
 

src/Seq.Input.HealthCheck/Util/Nonce.cs

@@ -0,0 +1,53 @@
+// Copyright 2019 Datalust and contributors. 
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+
+namespace Seq.Input.HealthCheck.Util
+{
+    static class Nonce
+    {
+        public static string Generate(int chars)
+        {
+            if (chars < 0) throw new ArgumentOutOfRangeException(nameof(chars));
+            return new string(GenerateChars(chars).ToArray());
+        }
+
+        static IEnumerable<char> GenerateChars(int count)
+        {
+            var rem = count;
+            var buf = new byte[128];
+            using (var rng = RandomNumberGenerator.Create())
+            {
+                while (rem > 0)
+                {
+                    rng.GetBytes(buf);
+                    var b64 = Convert.ToBase64String(buf);
+                    for (var i = 0; i < b64.Length && rem > 0; ++i)
+                    {
+                        var c = b64[i];
+                        if (char.IsLetterOrDigit(c))
+                        {
+                            yield return c;
+                            rem--;
+                        }
+                    }
+                }
+            }
+        }
+    }
+}