Kotlin SDK - Configuration

NexusConfig is the single configuration object passed to NexusClient.create(). All fields are immutable after construction.

NexusConfig

data class NexusConfig(
    val baseUrl:  String,
    val apiKey:   String?       = null,
    val ttl:      Duration      = 60.seconds,
    val wif:      WifConfig?    = null,
    val observer: NexusObserver = NoopNexusObserver,
)

Field reference

Field	Type	Default	Description
`baseUrl`	`String`	-	Base URL of your Westyx Nexus service, for example `https://my-service.westyx.dev`. Trailing slash is stripped automatically.
`apiKey`	`String?`	`null`	Service API key. Use a `wxs_...` key for backend services. Use `wxp_...` only for frontend/browser contexts where secrets must not be accessible. Mutually exclusive with WIF in practice - if WIF is enabled, the session token takes precedence over `apiKey` for authentication.
`ttl`	`Duration`	`60.seconds`	How long a synced snapshot is considered fresh. After this duration, `ensureFresh()` triggers a background sync on the next getter call.
`wif`	`WifConfig?`	`null`	Workload identity federation settings. When `wif.enabled = true`, the SDK exchanges a cloud-provider OIDC token for a short-lived Nexus session token at startup. See Workload identity.
`observer`	`NexusObserver`	`NoopNexusObserver`	Callbacks for stream lifecycle and error events. The default no-op observer discards all events. See Stream observer.
`sseReconnectCooldown`	`IntArray?`	`null`	Schedule for reconnecting SSE after falling back to TTL polling due to max consecutive transport errors. Unit: minutes. `null` = default `[5, 10, 20, 40, 60]` min. Single-element = fixed interval. Multi-element = custom schedule (stays at last value).

TTL explanation

The ttl controls how stale the local in-memory snapshot can get before the SDK triggers a background refresh.

On every getter call (getString, getBoolean, etc.), ensureFresh() checks whether now - syncedAt < ttl.
If the snapshot is stale, a background coroutine calls sync(). The current call returns the stale value immediately - there is no blocking.
The stream push path (connectStream) bypasses this completely: when a push event arrives, sync() runs regardless of TTL.

Recommended values:

Scenario	TTL
Production service with SSE stream active	`60.seconds` or higher - stream covers freshness
Batch job or short-lived worker	`10.seconds` - aggressive polling, no stream needed
High-frequency read path, config rarely changes	`300.seconds` - reduce API call rate

WifConfig

data class WifConfig(
    val enabled:     Boolean                    = false,
    val provider:    String                     = "auto",
    val audience:    String                     = "westyx-nexus",
    val tokenSource: (suspend () -> String?)?   = null,
)

Field	Type	Default	Description
`enabled`	`Boolean`	`false`	Must be `true` to activate WIF. When `false`, WIF is completely bypassed even if other fields are set.
`provider`	`String`	`"auto"`	Cloud provider to fetch the OIDC token from. One of: `kubernetes`, `aws`, `gcp`, `azure`, `developer`, `auto`. `auto` tries each in order.
`audience`	`String`	`"westyx-nexus"`	OIDC audience claim sent to the cloud metadata endpoint (GCP only). Must match the trust policy configured in your Nexus project.
`tokenSource`	`(suspend () -> String?)?`	`null`	Custom async token supplier. When set, overrides `provider` entirely. Return `null` to signal that no token is available.

Minimal configs

val config = NexusConfig(
    baseUrl = "https://my-service.westyx.dev",
    apiKey  = System.getenv("NEXUS_API_KEY"),
)

val config = NexusConfig(
    baseUrl = "https://my-service.westyx.dev",
    wif = WifConfig(enabled = true),
)

val config = NexusConfig(
    baseUrl  = "https://my-service.westyx.dev",
    apiKey   = System.getenv("NEXUS_API_KEY"),
    ttl      = 30.seconds,
    observer = MyNexusObserver(),
)

Overview

Backend SDKs

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Kotlin SDK - Configuration

NexusConfig

Field reference

TTL explanation

WifConfig

Minimal configs

​NexusConfig

​Field reference

​TTL explanation

​WifConfig

​Minimal configs

NexusConfig

Field reference

TTL explanation

WifConfig

Minimal configs