Add missing spans section (#1100)

* Add missing spans section
* Add navTitles to collector and protocol pages while I'm here
* decrease image size
* improve page navigation structure

* remove ordering, since it won't matter

* remove unneeded "your" in titles

* improve more headers 😅

* Apply suggestions from Susa's review

Co-authored-by: Susa Tünker <[email protected]>

* improve formatting in headers, and steps in each troubleshoot option

* fix indentation

---------

Co-authored-by: Susa Tünker <[email protected]>

Author: MariadeAnton

site/content/docs/traces-open-telemetry/importing-traces/http-vs-grpc-protocols.md

@@ -2,6 +2,7 @@
 title: HTTP vs. gRPC OpenTelemetry protocols
 head:
   title: "Choosing between HTTP and gRPC OpenTelemetry protocols"
+navTitle: HTTP vs gRPC OpenTelemetry protocols
 metatags:
   title: "Choosing between HTTP and gRPC OpenTelemetry protocols"
   description: "Learn about the trade-offs between using HTTP and gRPC for sending data to an OpenTelemetry backend."

site/content/docs/traces-open-telemetry/importing-traces/sending-traces-otel-collector.md

@@ -4,6 +4,7 @@ title: Setting up the OpenTelemetry collector
 metatags:
   title: "Setting up the OpenTelemetry collector"
   description: "Set up the OpenTelemetry collector and send traces to Checkly."
+navTitle: OpenTelemetry Collector configuration
 weight: 20
 menu:
   platform:

site/content/docs/traces-open-telemetry/importing-traces/troubleshooting-missing-spans.md

@@ -0,0 +1,116 @@
+---
+title: Troubleshooting missing or orphan spans
+weight: 20
+menu:
+  platform:
+    parent: "Send your traces to Checkly"
+    identifier: troubleshooting-missing-spans
+navTitle: Missing spans
+beta: true
+---
+
+This guide will walk you through the process of identifying missing spans, understanding their root causes, and implementing solutions to ensure your OpenTelemetry setup with Checkly provides complete and accurate tracing information. 
+
+## Missing spans
+
+Missing spans, also known as orphan spans, are segments of a trace that are disconnected from either their parent spans or from the root span.
+
+An instrumented distributed system will emit spans, creating a hierarchical chain that follows the flow of the request through the different components and services.
+
+When a span is missing, they create a hole in this chain, making it difficult to diagnose issues and understand the full picture. If this happens, you will notice a span missing from the visualization in Checkly.
+
+Checkly uses contextual span data—such as the trace it belongs to and its parent span—to display any missing pieces in the span chain. This helps you identify which application or service may be incorrectly instrumented.
+
+![Trace with missing spans](/docs/images/otel/traces-missing-spans.png)
+
+
+## Troubleshooting missing spans
+
+Missing spans can happen due to various reasons. Whether you're sending data to Checkly directly from your applications and services, or through the OpenTelemetry Collector, these are steps to confirm everything is properly set up.
+
+### Verify sampling strategy
+
+   Using Checkly Traces, we recommend sampling for the tracestate header `checkly=true`, which will reduce your Egress/Ingress costs and ensure that all the spans that were originated through a check are there.
+
+   #### Sampling in the OpenTelemetry Collector
+
+   * **Step 1**. Make sure that you're filtering out non-checkly spans:
+
+      ```yaml
+      processors:
+         batch:
+         filter/checkly:
+            error_mode: ignore
+            traces:
+               span:
+               # filter out spans in which tracestate is not "checkly=true"
+               - 'trace_state["checkly"] != "true"'
+      ``` 
+   * **Step 2**. Confirm that your Collector pipeline uses this processor:
+
+      ```yaml
+      service:
+         pipelines:
+            traces:
+               processors: [filter/checkly, batch]
+      ```
+
+   #### Sampling directly in your applications' code. 
+   Choose the specific [instrumentation language guide](docs/traces-open-telemetry/instrumenting-code/) and review your configuration against Step 2 in the guides.
+
+### Review OpenTelemetry Exporter configuration
+  
+Ensure the right Authorization keys and endpoints are in use.
+
+   #### Exporting through the OpenTelemetry Collector
+      
+   * **Step 1**. Make sure that your exporter uses the right endpoint authorization:
+
+      ```yaml
+      exporters:
+         otlp/checkly:
+            endpoint: "otel.eu-west-1.checklyhq.com:4317"
+            headers:
+               authorization: "${env:CHECKLY_OTEL_API_KEY}"
+      ``` 
+   * **Step 2**. Confirm that your Collector pipeline uses this exporter:
+
+      ```yaml
+      service:
+         pipelines:
+            traces:
+               exporters: [otlp/checkly]
+      ```
+
+#### Exporting directly from your Application's code
+   
+   Confirm your environment variables use the correct endpoint and authorization:
+
+   ```bash
+   OTEL_EXPORTER_OTLP_HEADERS="authorization=<your-api-key>"
+         
+   OTEL_EXPORTER_OTLP_ENDPOINT="https://otel.eu-west-1.checklyhq.com"
+   ```
+
+### Checkly Private Location setup
+   When setting up Traces with a [Checkly Private Location](docs/private-locations/#configuring-a-private-location):
+  * **Step 1**. Ensure your [Checkly Agent](https://hub.docker.com/r/checkly/agent) version is at least 3.3.5.
+  
+  * **Step 2**. Review your internal Firewall rules: 
+    * Identify the ports used by OpenTelemetry, commonly:
+      * Port 4317 for gRPC protocol
+      * Port 4318 for HTTP protocol
+  
+    * Access your firewall settings and add rules to allow outgoing traffic on the identified port.
+  
+      For example, to allow HTTP traces to be sent out:
+
+      ```bash
+      A OUTPUT -p tcp --dport 4318 -j ACCEPT
+      ```
+
+
+### Incomplete instrumentation
+   
+   To see the full picture, and identify the root cause of a problem faster, ensure your applications and services are [instrumented with the OpenTelemetry SDK](docs/traces-open-telemetry/instrumenting-code/).
+