EDG-912: honour HIVEMQ_CONFIG_SECONDARY, gate base-dn, allow several LDAP servers

[marregui]

Found during a local QA run of the Helm chart against current Edge master. Details and evidence in EDG-912.

Not required for 2026.13. All three are pre-existing — identical code on 2026.12 — and none affects a non-k8s deployment.

1. HIVEMQ_CONFIG_SECONDARY was ignored

SystemInformationImpl.setFolders():

secondaryConfigFolder = Objects.requireNonNullElseGet(
        configFolder,                       // never null — assigned three statements earlier
        () -> setUpHiveMQFolder(CONFIG_FOLDER_SECONDARY, ...));   // so this never runs

The else-branch was a no-op: the secondary folder always equalled the primary one. Consequence in k8s — Edge read topic filters from conf-k8s instead of the chart's conf-secondary ConfigMap, found none, and wrote an empty topic-filters.xml into the primary folder. Anything declared in topicFilters: was invisible.

Now calls setUpHiveMQFolder directly.

Blast radius is small and I checked it deliberately: getSecondaryHiveMQHomeFolder() has exactly one production consumer, TopicFilterPersistenceReaderWriter. Deployments that do not set the variable are bit-for-bit unaffected. The persistence file now lands on a read-only ConfigMap mount, so I went looking for a write path that would start failing — there isn't one, all four write endpoints in TopicFilterResourceImpl are guarded by isConfigWriteable() and the chart hardcodes HIVEMQ_CONFIG_WRITEABLE=false.

2. <base-dn> crash-looped when unset

docker/config-k8s.xml referenced ${ENV:HIVEMQ_LDAP_BASE_DN} unconditionally while the chart only sets it when configured, so EnvVarUtil aborted the boot. base-dn is genuinely optional — minOccurs="0", and its absence selects the documented legacy mode where rdns is treated as an absolute DN.

Wrapped in ${IF:HIVEMQ_LDAP_BASE_DN_ENABLED} and registered in IfUtil.SUPPORTED_ENVS, the same idiom already used for required-object-class.

Rejected: having the chart emit an empty element. base-dn is typed nonEmptyString, so that trades a boot abort for a schema violation. Also rejected: making baseDn mandatory in the chart, which removes a supported Edge mode.

3. More than one <ldap-server> was schema-invalid

maxOccurs defaulted to 1, so a second entry failed with cvc-complex-type.2.4.d. Edge's own model is a List<LdapServerEntity> and LdapClient builds a RoundRobinServerSet over it, so the schema was the defect, not the model. Now maxOccurs="unbounded".

Merge order

Companion chart PR: hivemq/helm-charts#1039

• Do not merge the base-dn gate ahead of the chart PR. Today the chart sets HIVEMQ_LDAP_BASE_DN and the template renders the element unconditionally. Add the gate on this side alone and every user who has configured a base DN silently loses it and falls back to legacy resolution. Either both, or neither.
• The config.xsd change is safe to merge first and de-risks the chart PR — nobody can currently have a second <ldap-server>, so it cannot regress an existing config.
• The SystemInformationImpl fix is fully independent.

Tests

ConfigK8sTemplateTest is new: it drives the real docker/config-k8s.xml through the actual render-and-validate pipeline with the environment the chart sets. This is the class of bug behind all three findings — a missing ${IF:} gate deletes an element rather than failing — so it now has coverage.

Each new test was confirmed to fail against the unfixed code:

Test	Fails without
SystemInformationImplTest — 3 of the 4 new cases	fix 1
ConfigK8sTemplateTest.ldapWithoutABaseDn_isStillAValidConfiguration	fix 2
ApiConfiguratorTest.ldapWithSeveralServers_isAccepted, ConfigK8sTemplateTest.ldapWithThreeServersAndATruststore_survivesTheTemplate	fix 3

Full local run of what check-backend.yml runs — :test :hivemq-edge:forbiddenApis :hivemqEdgeZip — 6389 tests, 0 failures, 3 skipped. Spotless clean via the composite. Verified end to end in kind against an image built from this branch.

[github-actions]

Test Results

  667 files  + 1    667 suites  +1   8m 58s ⏱️ +15s
6 360 tests +11  6 357 ✅ +11  3 💤 ±0  0 ❌ ±0 
6 389 runs  +11  6 386 ✅ +11  3 💤 ±0  0 ❌ ±0 

Results for commit d7b8a17. ± Comparison against base commit 4c526da.

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Coverage Report

Overall Project	70.84%	✅
Files changed	100%	✅

File	Coverage
IfUtil.java	94.13%	✅
SystemInformationImpl.java	94.04%	✅