What causes "Proxy doesn't have logging level 2" in apache/pulsar?

Raise the proxy log level first: POST /admin/v2/proxy-stats/logging/2 (requires superuser role)

apache/pulsar · warning · RestException

Proxy doesn't have logging level 2

Error message

Proxy doesn't have logging level 2

What it means

The proxy REST /topics stats endpoint only captures topic-level stats when the proxy's dynamic log level is >= 2, because topic stats collection piggybacks on verbose logging machinery. ProxyStats.topics enforces this precondition with HTTP 412 when proxyLogLevel is absent or below 2.

Source

Thrown at pulsar-proxy/src/main/java/org/apache/pulsar/proxy/stats/ProxyStats.java:105

            stats.add(new ConnectionStats(requestRate, byteRate, inboundChannel, outboundChannel));
        });
        return stats;
    }

    @GET
    @Path("/topics")
    @Operation(summary = "Proxy topic stats api")
    @ApiResponses(value = {
            @ApiResponse(responseCode = "200", description = "Proxy topic stats api",
                    content = @Content(schema = @Schema(type = "object"),
                            additionalPropertiesSchema = @Schema(implementation = Map.class))),
            @ApiResponse(responseCode = "412", description = "Proxy logging should be > 2 to capture topic stats"),
            @ApiResponse(responseCode = "503", description = "Proxy service is not initialized") })
    public Map<String, TopicStats> topics() {
        throwIfNotSuperUser("topics");
        Optional<Integer> logLevel = proxyService().getConfiguration().getProxyLogLevel();
        if (!logLevel.isPresent() || logLevel.get() < 2) {
            throw new RestException(Status.PRECONDITION_FAILED, "Proxy doesn't have logging level 2");
        }
        return proxyService().getTopicStats();
    }

    @POST
    @Path("/logging/{logLevel}")
    @Operation(hidden = true, summary = "Change proxy logging level dynamically",
            description = "It only changes the log level in memory; change it in the config file to persist the change")
    @ApiResponses(value = { @ApiResponse(responseCode = "412", description = "Proxy log level can be [0-2]"), })
    public void updateProxyLogLevel(@PathParam("logLevel") int logLevel) {
        throwIfNotSuperUser("updateProxyLogLevel");
        if (logLevel < 0 || logLevel > 2) {
            throw new RestException(Status.PRECONDITION_FAILED, "Proxy log level can be only [0-2]");
        }
        proxyService().setProxyLogLevel(logLevel);
    }

    @GET

View on GitHub (pinned to 820761864e)

Solutions

Raise the proxy log level first: POST /admin/v2/proxy-stats/logging/2 (requires superuser role)
Set proxyLogLevel=2 in the proxy configuration file so it survives restarts
If only aggregate metrics are needed, use the /metrics endpoint instead of topic-level stats
Ensure the client authenticating to the REST endpoint has superuser permissions so the request reaches the log-level check

Example fix

// before
proxyLogLevel=1

// after
proxyLogLevel=2

Defensive patterns

Strategy: validation

Validate before calling

Integer logLevel = proxyConfig.getProxyLogLevel().orElse(0);
if (logLevel < 2) {
    // raise first, then query
    admin.postProxyLogLevel(2);
}
Map<String, TopicStats> stats = admin.getTopics();

Type guard

boolean topicStatsEnabled(ProxyConfiguration cfg) {
    return cfg.getProxyLogLevel().map(l -> l >= 2).orElse(false);
}

Try / catch

try {
    return proxyStats.topics();
} catch (RestException e) {
    if (e.getResponseStatus() == 412) {
        proxyStats.updateProxyLogLevel(2);
        return proxyStats.topics();
    }
    throw e;
}

Prevention

Set proxyLogLevel=2 in the proxy config when topic-level stats are needed
Raise the level via POST /logging/2 after every proxy restart (in-memory change)
Have monitoring scrapers handle 412 by enabling level 2 first instead of failing the scrape
Use /metrics endpoint when topic-level granularity is not required

When it happens

Trigger: GET /admin/v2/proxy-stats/topics (via ProxyStats.topics) while getConfiguration().getProxyLogLevel() is unset or < 2 — e.g. before anyone called POST /logging/{logLevel} or the config file has no proxyLogLevel entry.

Common situations: Monitoring/scraping tools querying topic stats on a fresh proxy whose proxyLogLevel defaults below 2; operators forgetting to raise the log level after restart; automated dashboards hitting the endpoint on a proxy configured with proxyLogLevel=1.

Related errors

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/dbafee51d8222c49. Report an issue: GitHub.