The scope of the variables registered by this core.ctx.register_var()

[renshunhang]

What is the scope of the variables registered by the core.ctx.register_var() method? Does it take effect for each request, or does it apply to all requests?
For each request, I registered many variables using the register_var method in order to report these values to the log_format defined for loki-logger.

[dosubot[bot]]

Variables registered by core.ctx.register_var() are scoped per request—their values are computed based on the current request context and are not shared globally across requests. This makes them suitable for logging dynamic, request-specific data in plugins like loki-logger, especially when used in log_format fields reference.

However, there is a known bug in the loki-logger plugin: if log_labels are configured globally or the same config table is reused across requests, label values can leak between requests due to in-place mutation. To avoid this, configure loki-logger per route or service and avoid sharing mutable config tables. The log_format fields themselves are built per request and are less likely to leak values reference.

In summary: register_var variables are per-request, but be careful with loki-logger log_labels configuration to prevent cross-request data leakage.

To reply, just mention @dosu.

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