apache/skywalking · critical · ModuleStartException

Layer has already set rule.

Error message

Layer {} has already set {} rule.

What it means

Thrown during static rule load when two rules targeting the SAME Layer share the same name: per-layer DSL maps (initDsls keyed by Layer) reject the second registration of an identical name. This is the layer-scoped twin of the auto-layer duplicate-name error — the same name in two different layers is fine, but not twice within one layer.

Solutions

1. Rename the duplicate rule within that layer
2. If the rules genuinely target different layers, verify both layer: declarations resolve to distinct Layer values
3. Delete the stale copy if the file was duplicated wholesale

Example fix

# before: two entries with layer: MESH named 'envoy-als'
# after: rename the second
ruleName: envoy-als-custom

# Detect duplicate names within a layer:
#   awk '/^layer:/{L=$2} /^ruleName:/{print L, $2}' lal/*.yaml | sort | uniq -d

When it happens

Trigger: Two rules both declaring layer: MESH (or resolved to the same layer) with identical ruleName; copy-pasting an envoy-als style rule and keeping the name; a layerDefinitions inline entry plus an explicit layer: that resolve to the same Layer object.

Common situations: Extending a shipped per-layer rule file (envoy-als.yaml etc.) by duplicating an entry and editing only the body; merging contributed rule files for the same layer.

Related errors

• Auto-layer rules have duplicate name
• Failed to load static LAL rules.
• LAL rule layerDefinitions entry rejected
• Failed to compile LAL expression
• Failed to create LAL listener factory.

AI-assisted analysis of apache/skywalking@102af09b4a (2026-08-14). Data as JSON: /api/errors/cad2f9a9873e8b25. Report an issue: GitHub.

Appendix: source

Thrown at oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/provider/log/listener/LogFilterListener.java:258

         */
        public void loadStaticRules() throws Exception {
            final Map<Layer, Map<String, DSL>> initDsls = new HashMap<>();
            final Map<String, DSL> initAutoDsls = new HashMap<>();
            final List<LALConfig> configList = LALConfigs.load(analyzerConfig.getLalPath(), analyzerConfig.lalFiles())
                                                         .stream()
                                                         .flatMap(it -> it.getRules().stream())
                                                         .collect(Collectors.toList());
            for (final LALConfig c : configList) {
                final CompiledLAL compiled = compile(c);
                if (compiled.layer == null) {
                    if (initAutoDsls.put(c.getName(), compiled.dsl) != null) {
                        throw new ModuleStartException(
                            "Auto-layer rules have duplicate name: " + c.getName());
                    }
                } else {
                    final Map<String, DSL> layerDsls = initDsls.computeIfAbsent(compiled.layer, k -> new HashMap<>());
                    if (layerDsls.put(c.getName(), compiled.dsl) != null) {
                        throw new ModuleStartException(
                            "Layer " + compiled.layer.name() + " has already set " + c.getName() + " rule.");
                    }
                }
                // Publish per-rule debug holder into the dsl-debugging registry. sourceName, not
                // sourcePath: both routes derive it through LALConfigs.stampSource, so a
                // runtime-rule replace puts over the static binding without orphaning it.
                LalStaticBindingHook.publish(c.getSourceName(), c.getName(), compiled.dsl.getExpression());
            }
            // Publish: readers from now on see the startup-complete registry.
            this.dsls = initDsls;
            this.autoDsls = initAutoDsls;
        }

        /**
         * Compile a single LALConfig into a runnable {@link DSL}. Used by both the startup
         * constructor and the runtime-rule hot-update path (LalFileApplier).
         */
        public CompiledLAL compile(final LALConfig c) throws ModuleStartException {

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