Provide a performance bar link to the Jaeger UI

Jaeger is a distributed tracing tool. This change adds a "Tracing" link
to the performance bar to directly link to a current request in Jaeger.

This is useful for two reasons: 1 - it provides affordance to developers
that the distributed tracing tool is available, so that it can quickly
be discovered. 2 - it allows developers to quickly find a specific trace
without having to manually navigate to a second user-interface.

1 files changed, 66 insertions, 0 deletions

diff --git a/spec/lib/gitlab/tracing_spec.rb b/spec/lib/gitlab/tracing_spec.rb
new file mode 100644
index 00000000000..2cddc895026
--- /dev/null
+++ b/spec/lib/gitlab/tracing_spec.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'rspec-parameterized'
+
+describe Gitlab::Tracing do
+  using RSpec::Parameterized::TableSyntax
+
+  describe '.enabled?' do
+    where(:connection_string, :enabled_state) do
+      nil                     | false
+      ""                      | false
+      "opentracing://jaeger"  | true
+    end
+
+    with_them do
+      it 'should return the correct state for .enabled?' do
+        expect(described_class).to receive(:connection_string).and_return(connection_string)
+
+        expect(described_class.enabled?).to eq(enabled_state)
+      end
+    end
+  end
+
+  describe '.tracing_url_enabled?' do
+    where(:enabled?, :tracing_url_template, :tracing_url_enabled_state) do
+      false | nil                | false
+      false | ""                 | false
+      false | "http://localhost" | false
+      true  | nil                | false
+      true  | ""                 | false
+      true  | "http://localhost" | true
+    end
+
+    with_them do
+      it 'should return the correct state for .tracing_url_enabled?' do
+        expect(described_class).to receive(:enabled?).and_return(enabled?)
+        allow(described_class).to receive(:tracing_url_template).and_return(tracing_url_template)
+
+        expect(described_class.tracing_url_enabled?).to eq(tracing_url_enabled_state)
+      end
+    end
+  end
+
+  describe '.tracing_url' do
+    where(:tracing_url_enabled?, :tracing_url_template, :correlation_id, :process_name, :tracing_url) do
+      false | "https://localhost"                                  | "123" | "web" | nil
+      true  | "https://localhost"                                  | "123" | "web" | "https://localhost"
+      true  | "https://localhost?service=%{service}"               | "123" | "web" | "https://localhost?service=web"
+      true  | "https://localhost?c=%{correlation_id}"              | "123" | "web" | "https://localhost?c=123"
+      true  | "https://localhost?c=%{correlation_id}&s=%{service}" | "123" | "web" | "https://localhost?c=123&s=web"
+      true  | "https://localhost?c=%{correlation_id}"              | nil   | "web" | "https://localhost?c="
+    end
+
+    with_them do
+      it 'should return the correct state for .tracing_url' do
+        expect(described_class).to receive(:tracing_url_enabled?).and_return(tracing_url_enabled?)
+        allow(described_class).to receive(:tracing_url_template).and_return(tracing_url_template)
+        allow(Gitlab::CorrelationId).to receive(:current_id).and_return(correlation_id)
+        allow(Gitlab).to receive(:process_name).and_return(process_name)
+
+        expect(described_class.tracing_url).to eq(tracing_url)
+      end
+    end
+  end
+end