VaultHealthImpl cannot deserialize sys/health when performance_standby is absent

Summary

VaultSysTemplate.VaultHealthImpl takes performance_standby as a primitive boolean creator parameter. If the server response omits that field, deserialization fails instead of defaulting to false.

OpenBao removed performance_standby from GET /sys/health in 2.6.0, so every health check against OpenBao 2.6.0 or later throws.

Stack trace

o.s.c.v.c.VaultReactiveHealthIndicator : Health check failed

org.springframework.core.codec.DecodingException: JSON decoding error: Cannot map `null` into type `boolean`
(set `DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES` to 'false' to allow)
	at org.springframework.http.codec.AbstractJacksonDecoder.processException(AbstractJacksonDecoder.java:261)
	*__checkpoint ⇢ Body from GET https://openbao.example.com:8200/v1/sys/health [DefaultClientResponse]
Caused by: tools.jackson.databind.exc.MismatchedInputException: Cannot map `null` into type `boolean`
 (through reference chain: org.springframework.vault.core.VaultSysTemplate$VaultHealthImpl["performance_standby"])
	at tools.jackson.databind.DeserializationContext.handleNullForPrimitives(DeserializationContext.java:1467)
	at tools.jackson.databind.deser.bean.PropertyValueBuffer._findMissing(PropertyValueBuffer.java:298)

The path through PropertyValueBuffer._findMissing shows this is an absent property rather than an explicit JSON null.

Why it surfaces now

Two independent changes combine.

1. OpenBao 2.6.0 stopped returning performance_standby. The field described the Vault Enterprise performance standby concept, which OpenBao is retiring in favour of all standby nodes serving reads. Their own client struct in api/sys_health.go keeps the field with the comment // not present in OpenBao, but left here for compatibility.
2. Jackson 3 enables FAIL_ON_NULL_FOR_PRIMITIVES by default. Under Jackson 2 an absent primitive quietly became false, which is why this never showed up before Spring Boot 4.

@JsonIgnoreProperties(ignoreUnknown = true) on VaultHealthImpl covers unexpected extra fields, not missing ones, so it does not help here.

Of the creator parameters, performance_standby is the only one affected. initialized, sealed, standby and server_time_utc are still returned, and replication_dr_mode is a nullable String that is already handled.

Reproduce

docker run -d -p 8200:8200 -e BAO_DEV_ROOT_TOKEN_ID=root openbao/openbao:2.6.2 server -dev -dev-listen-address=0.0.0.0:8200
curl -s http://127.0.0.1:8200/v1/sys/health

Response, with no performance_standby key:

{"initialized":true,"sealed":false,"standby":false,"replication_performance_mode":"disabled","replication_dr_mode":"disabled","server_time_utc":1788552096,"version":"2.6.2","cluster_name":"vault-cluster-8e617dcd","cluster_id":"92429cc1-b8f7-1c2b-a304-abf12923a5a2"}

The same command against openbao/openbao:2.5.4 includes "performance_standby":false and works fine.

Impact

VaultReactiveHealthIndicator and VaultHealthIndicator report DOWN with a decoding error rather than a health state. Where a Kubernetes liveness probe points at the aggregate /actuator/health, this restarts pods in a loop even though the application is running normally and has already read all of its secrets.

Suggested fix

Make performanceStandby a boxed Boolean, or otherwise let an absent performance_standby map to false. The value only feeds isPerformanceStandby(), and a server that does not report the field has no performance standby state to report.

Not a duplicate of #397 or #501

Both of those concern Vault Enterprise nodes that are performance standbys and return HTTP 473, and #397 was resolved as a synchronous RestTemplate error handling bug fixed in Spring Framework 5.2.5. This is the opposite situation: the field is absent on a healthy active node returning HTTP 200, and it reproduces on the reactive indicator, which #397 records as unaffected.

Versions

Component	Version
Spring Boot	4.1.0
Spring Cloud	2025.1.2
spring-cloud-vault-config	5.0.2
spring-vault-core	4.0.3
jackson-databind	3.1.4
OpenBao	2.6.0, 2.6.1, 2.6.2
Java	25

Start with VaultSysTemplate.VaultHealthImpl and its performance_standby creator parameter. Reproduce against OpenBao 2.6.2 using the provided Docker and curl commands, then verify that the health response deserializes successfully and VaultReactiveHealthIndicator and VaultHealthIndicator no longer report a decoding error when the field is absent.