feat: add instana as possible tracing provider

docs/docs/guides/tracing.mdx

@@ -0,0 +1,43 @@
+---
+id: tracing
+title: Distributed Tracing
+---
+
+Configuring Distributed Tracing (DT) will enable you to obtain a visualization
+of the call paths that take place in order to process a request made to Kratos.
+It's yet another tool that you can use to aid you in profiling, debugging and
+ultimately understanding your deployment of Kratos better. Kratos currently
+supports the following tracing options:
+
+- Tracing backend(s): Jaeger, Elastic APM, Datadog, Zipkin and Instana - _Note:
+  adding support for other
+  [opentracing compliant backends](https://opentracing.io/docs/supported-tracers)
+  is planned. To aid in priority, please
+  [create an issue](https://github.com/ory/kratos/issues) with your feature
+  request._
+- Following existing traces: If you have deployed Kratos behind a proxy that has
+  initiated a trace, Kratos will attempt to join that trace by examining the
+  request headers for tracing context.
+
+### What a Kratos trace includes
+
+In DT speak, a trace is comprised of one or more spans which are logical units
+of work. Each Kratos span is encapsulated with the following state:
+
+- A name
+- A start time
+- A finish time
+- A set of zero or more tags
+
+Kratos currently creates the following spans:
+
+- Top level span (_named after the request path_) for the requested endpoint.
+  Span tags: - http method - http status code - error IFF status code >= 400
+- Child span will be created if bcrypt is called. Span tags: - bcrypt work
+  factor
+- All SQL database interactions. Spans/tags will vary depending on the database
+  driver used.
+
+This is still evolving and subject to change as tracing support continues to
+expand in Kratos. If you see something that is missing/wrong, please create an
+issue.

docs/sidebar.json

@@ -62,7 +62,9 @@
       "guides/secret-key-rotation",
       "guides/high-availability-ha",
       "guides/docker",
-      "guides/setting-up-password-hashing-parameters"
+      "guides/setting-up-password-hashing-parameters",
+      "guides/integration-with-other-systems-using-web-hooks",
+      "guides/tracing"
     ]
   },
   {

driver/config/.schema/config.schema.json

@@ -1199,12 +1199,13 @@
       "properties": {
         "provider": {
           "type": "string",
-          "description": "Set this to the tracing backend you wish to use. Supports Jaeger, Zipkin and DataDog. If omitted or empty, tracing will be disabled. Use environment variables to configure DataDog (see https://docs.datadoghq.com/tracing/setup/go/#configuration).",
+          "description": "Set this to the tracing backend you wish to use. Supports Jaeger, Zipkin, DataDog, elastic-apm and instana. If omitted or empty, tracing will be disabled. Use environment variables to configure DataDog (see https://docs.datadoghq.com/tracing/setup/go/#configuration).",
           "enum": [
             "jaeger",
             "zipkin",
             "datadog",
-            "elastic-apm"
+            "elastic-apm",
+            "instana"
           ],
           "examples": [
             "jaeger"