Configure OBI routes decorator

YAML section: routes

You can configure the component under the routes section of your YAML configuration or with environment variables.

You must configure this section in the YAML file. If you don’t provide a routes section, OBI creates a default routes pipeline stage and uses the heuristic routes decorator.

For example:

routes:
  patterns:
    - /basic/:rnd
  unmatched: path
  ignored_patterns:
    - /metrics
  ignore_mode: traces

Patterns

OBI matches the provided URL path patterns and sets the http.route trace/metric property. Use the routes property whenever possible to reduce the cardinality of generated metrics.

Each route pattern is a URL path with tags that group path segments. You can use the :name or {name} format for the matcher tags.

For example, if you define the following patterns:

routes:
  patterns:
    - /user/{id}
    - /user/{id}/basket/{product}

Traces with these HTTP paths include the same http.route='/user/{id}' property:

/user/123
/user/456

Traces with these HTTP paths include the same http.route='/user/{id}'/basket/{product} property:

/user/123/basket/1
/user/456/basket/3

The route matcher also supports the wildcard character *, which matches path prefixes. For example, if you define this pattern:

routes:
  patterns:
    - /user/*

Any traces with HTTP paths starting with /user (including /user itself) match the route /user/*. All of the following paths match as /user/*:

/user
/user/123
/user/123/basket/1
/user/456/basket/3

Ignored patterns

OBI matches the provided URL path against the defined patterns and discards the trace and/or metric events if they match any of the ignored_patterns. The format for the ignored_patterns field is identical to the patterns field. You can define the ignored patterns with or without any of the wildcard options. For example, if you define these ignored patterns:

routes:
  ignored_patterns:
    - /health
    - /v1/*

Any event paths with a prefix of /v1 or equal to /health are ignored.

This option is useful if you want to prevent certain paths used for development or service health monitoring from being recorded as traces or metrics.

Ignore mode

Use this property with the ignored_patterns property to refine which type of events are ignored.

Possible values for the ignore_mode property are:

• all discards both metrics and traces that match the ignored_patterns
• traces discards only the traces that match the ignored_patterns, no metric events are ignored
• metrics discards only the metrics that match the ignored_patterns, no trace events are ignored

If you want to ignore certain types of events, for example, you may want to know the performance metrics of your health check API, but you don’t want the overhead of those trace records in your traces database. In this case, set the ignore_mode property to traces, so only traces matching the ignored_patterns are discarded, while metrics are still recorded.

Unmatched

This property specifies what to do when a trace HTTP path doesn’t match any of the patterns entries.

Possible values for the unmatched property are:

• unset leaves the http.route property unset
• path copies the http.route field property to the path value. This option can lead to cardinality explosion at the ingestion side
• wildcard sets the http.route field property to a generic asterisk-based /** value
• heuristic automatically derives the http.route field property from the path value, based on these rules:
  • Any path components with numbers or characters outside of the ASCII alphabet (or - and _) are replaced by wildcard_char
  • Any alphabetical components that don’t look like words are replaced by wildcard_char

Wildcard char

Use this property with unmatched: heuristic to choose what character the path components identified by the heuristic mode are replaced by. By default, OBI uses an asterisk '*'. The value should be quoted and must be a single character.

Heuristic route decorator mode

The heuristic decorator is a best effort route decorator, which may still lead to cardinality explosion in some scenarios. For example, the GitHub URL paths are a good example where the heuristic route decorator won’t work, since the URL paths are constructed like a directory tree. In this scenario, all paths remain unique and lead to cardinality explosion.

If your URL path patterns follow a certain structure, and the unique IDs are made up of numbers or random characters, then the heuristic decorator may be a low effort configuration option that works for your use case. For example, the following mock Google Docs URLs are correctly reduced to a low cardinality version:

Both URL paths below:

document/d/CfMkAGbE_aivhFydEpaRafPuGWbmHfG/edit (no numbers in the ID)
document/d/C2fMkAGb3E_aivhFyd5EpaRafP123uGWbmHfG/edit

are converted to a low cardinality route (using the default wildcard_char):

document/d/*/edit