feat: support classic ingest keys (#371)

## Which problem is this PR solving?

We've released Ingest Keys, but need to update the key detection logic
to allow Ingest Keys to be used to send data to Classic environments.

## Short description of the changes
- updates the Classic API Key detection logic to understand the shape of
a Classic Ingest Key
- updates tests with a more comprehensive list of cases
- bonus: updated the circleCI image for smoke tests to
`ubuntu-2204:2024.01.1` since the one we were using [is
deprecated](https://discuss.circleci.com/t/linux-image-deprecations-and-eol-for-2024/50177)

## How to verify that this has the expected result

It should be possible to use [an ingest
key](https://docs.honeycomb.io/working-with-your-data/settings/api-keys/#ingest-keys-1)
pointed to a classic environment after this change. Please note that the
ability to create ingest keys in classic environments isn't yet publicly
available (since we need to update this library and others to understand
classic ingest keys).

---------

Co-authored-by: Mike Goldsmith <goldsmith.mike@gmail.com>
Co-authored-by: Phillip Carter <pcarter@fastmail.com>

.circleci/config.yml

@@ -64,7 +64,7 @@ jobs:
 
   smoke_test:
     machine:
-      image: ubuntu-2004:202107-02
+      image: ubuntu-2204:2024.01.1
     steps:
       - checkout
       - attach_workspace:

src/Honeycomb.OpenTelemetry/HoneycombOptions.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.Metrics;
+using System.Text.RegularExpressions;
 
 namespace Honeycomb.OpenTelemetry
 {
@@ -18,6 +19,8 @@ public class HoneycombOptions
         private const string OtelExporterOtlpProtocolGrpc = "grpc";
         private const string OtelExporterHttpTracesPath = "/v1/traces";
         private const string OtelExporterHttpMetricsPath = "/v1/metrics";
+        private const string ClassicKeyRegex = "^[a-f0-9]*$";
+        private const string IngestClassicKeyRegex = "^hc[a-z]ic_[a-z0-9]*$";
         private bool isHttp = false;
 
         /// <summary>
@@ -48,12 +51,27 @@ public class HoneycombOptions
         public string ApiKey { get; set; }
 
         /// <summary>
-        /// Returns whether the provided API key is a legacy key.
+        /// Returns whether the provided API key is a classic key.
         /// </summary>
         /// <remarks>
-        /// Legacy keys have 32 characters.
+        /// Classic configuration keys have 32 characters and classic ingest keys have 64 characters.
         /// </remarks>
-        internal static bool IsClassicKey(string apikey) => apikey?.Length == 32;
+        internal static bool IsClassicKey(string apikey)
+        {
+            if (String.IsNullOrEmpty(apikey))
+            {
+                return false;
+            }
+            else if (apikey.Length == 32)
+            {
+                return Regex.Match(apikey, ClassicKeyRegex).Success;
+            }
+            else if (apikey.Length == 64)
+            {
+                return Regex.Match(apikey, IngestClassicKeyRegex).Success;
+            }
+            return false;
+        }
 
         /// <summary>
         /// Write links to honeycomb traces as they come in

test/Honeycomb.OpenTelemetry.Tests/HoneycombOptionsTests.cs

@@ -523,17 +523,17 @@ public void DoesNotAppendMetricsPathToGenericEndpointIfPathSpecified(string prot
             Assert.DoesNotContain("/v1/metrics", options.GetMetricsEndpoint());
         }
 
-        [Fact]
-        public void Legacy_key_length()
-        {
-            var options = new HoneycombOptions { ApiKey = "1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a" };
-            Assert.True(HoneycombOptions.IsClassicKey(options.ApiKey));
-        }
-        [Fact]
-        public void Not_legacy_key_length()
+        [Theory]
+        [InlineData("", false)]
+        [InlineData("12345678901234567890123456789012", true)]
+        [InlineData("hcaic_1234567890123456789012345678901234567890123456789012345678", true)]
+        [InlineData("kgvSpPwegJshQkuowXReLD", false)]
+        [InlineData("hcaic_12345678901234567890123456", false)]
+        [InlineData("hcxik_01hqk4k20cjeh63wca8vva5stw70nft6m5n8wr8f5mjx3762s8269j50wc", false)]
+        public void IsClassicKey(string key, bool expected)
         {
-            var options = new HoneycombOptions { ApiKey = "specialenvkey" };
-            Assert.False(HoneycombOptions.IsClassicKey(options.ApiKey));
+            var options = new HoneycombOptions { ApiKey = key };
+            Assert.Equal(HoneycombOptions.IsClassicKey(key), expected);
         }
     }
-}
+}