OpenTracing

Learn how to use OpenTracing with NGINX Ingress Controller.

NGINX Ingress Controller supports OpenTracing with the third-party module opentracing-contrib/nginx-opentracing.

Prerequisites

Use an Ingress Controller image that contains OpenTracing.
- You can find the images that include OpenTracing listed in the technical specs doc.
- Alternatively, you can build your own image using debian-image (or alpine-image) for NGINX or debian-image-plus (or alpine-image-plus) for NGINX Plus.
- Jaeger, Zipkin and Datadog tracers are installed by default.
Enable snippets annotations by setting the enable-snippets command-line argument to true.

Load the OpenTracing module.

You need to load the module with the configuration for the chosen tracer using the following ConfigMap keys:

opentracing-tracer: sets the path to the vendor tracer binary plugin. This is the path you used in the COPY line of step ii above.
opentracing-tracer-config: sets the tracer configuration in JSON format.

The following example shows how to use these two keys to load the module with Jaeger tracer:

opentracing-tracer: "/usr/local/lib/libjaegertracing_plugin.so"
opentracing-tracer-config: |
        {
            "service_name": "nginx-ingress",
            "propagation_format": "w3c",
            "sampler": {
                "type": "const",
                "param": 1
            },
            "reporter": {
                "localAgentHostPort": "jaeger-agent.default.svc.cluster.local:6831"
            }
        }

Enable OpenTracing globally

To enable OpenTracing globally (for all Ingress, VirtualServer and VirtualServerRoute resources), set the opentracing ConfigMap key to True:

opentracing: True

Enable or disable OpenTracing per Ingress resource

You can use annotations to enable or disable OpenTracing for a specific Ingress resource. As mentioned in the prerequisites section, both opentracing-tracer and opentracing-tracer-config must be configured.

Consider the following two cases:

OpenTracing is globally disabled

To enable OpenTracing for a specific Ingress resource, use the server snippet annotation:
```
nginx.org/server-snippets: |
    opentracing on;    
```
To enable OpenTracing for specific paths:
- You need to use Mergeable Ingress resources
- You need to use the location snippets annotation to enable OpenTracing for the paths of a specific Minion Ingress resource:
```
nginx.org/location-snippets: |
    opentracing on;    
```

OpenTracing is globally enabled

To disable OpenTracing for a specific Ingress resource, use the server snippet annotation:
```
nginx.org/server-snippets: |
    opentracing off;    
```
To disable OpenTracing for specific paths:
- You need to use Mergeable Ingress resources
- You need to use the location snippets annotation to disable OpenTracing for the paths of a specific Minion Ingress resource:
```
nginx.org/location-snippets: |
    opentracing off;    
```

Customize OpenTracing

You can customize OpenTracing through the supported OpenTracing module directives. Use the location-snippets ConfigMap keys or annotations to insert those directives into the generated NGINX configuration.

For example, to propagate the active span context for upstream requests, you need to set the opentracing_propagate_context directive, which you can add to an Ingress resource using the location snippets annotation:

nginx.org/location-snippets: |
   opentracing_propagate_context;

Note:
The opentracing_propagate_context and opentracing_grpc_propagate_context directives can be used in http, server or location contexts according to the module documentation. However, because of the way the module works and how NGINX Ingress Controller generates the NGINX configuration, it is only possible to use the directive in the location context.