feat: require TransactionRunner in okapi-spring-boot autoconfig (KOJAK-67)

CHANGELOG.md

@@ -25,6 +25,27 @@ Until `1.0.0`, breaking changes may appear in any release and are flagged with *
   history; the resulting schema is unchanged. Existing installations from an earlier
   release: the `outbox:001` changeset checksum changed — they must start on a fresh
   okapi schema, or clear okapi's rows from `okapi_databasechangelog`, before upgrading.
+- **`OutboxProcessorScheduler` / `OutboxPurgerScheduler` constructors now require a
+  non-null `TransactionRunner`** (previously a nullable `TransactionTemplate?`, with
+  `OutboxPurgerScheduler`'s parameter defaulted to `null`). Spring Boot autoconfig users
+  are unaffected — the autoconfig derives a `TransactionRunner` from any
+  `PlatformTransactionManager` on the classpath. Users constructing the schedulers
+  directly must supply a `TransactionRunner` (e.g. `SpringTransactionRunner(template)` or
+  a thin lambda wrapping their framework's native transaction primitive). The previous
+  null-default silently degraded `FOR UPDATE SKIP LOCKED` to JDBC auto-commit, permitting
+  duplicate delivery across processor instances. ([#49](https://github.com/softwaremill/okapi/pull/49))
+- **`okapi-spring-boot` autoconfig refuses to start when it cannot verify the
+  PlatformTransactionManager↔outbox-DataSource binding** in a multi-DataSource context.
+  Specifically: if `extractDataSource` cannot determine the PTM's DataSource (e.g. JTA,
+  Exposed's `SpringTransactionManager`, or any PTM that exposes neither a `DataSource`
+  resourceFactory nor a public `getDataSource()`), AND the context has ≥2 `DataSource`
+  beans, AND `okapi.transaction-manager-qualifier` is not set, the context refresh now
+  fails with an actionable message. `okapi.datasource-qualifier` alone is not
+  sufficient — it picks the outbox DataSource but does not constrain which PTM
+  brackets it. Single-DataSource contexts and setups that explicitly name the PTM
+  via `okapi.transaction-manager-qualifier` are unaffected. Escape hatch: supply an
+  explicit `@Bean TransactionRunner` to bypass validation.
+  ([#49](https://github.com/softwaremill/okapi/pull/49))
 
 ### Added
 

README.md

@@ -81,6 +81,29 @@ springOutboxPublisher.publish(
 > **Note:** Spring and Kafka versions are not forced by okapi — you control them.
 > Okapi uses plain JDBC internally — it works with any `PlatformTransactionManager` (JPA, JDBC, jOOQ, Exposed, etc.).
 
+`okapi-spring-boot` requires a `TransactionRunner` bean to bracket each scheduler tick in a transaction. The autoconfiguration derives one from any `PlatformTransactionManager` on the classpath (`spring-boot-starter-jdbc` or `spring-boot-starter-data-jpa` provide one out of the box) — no extra wiring needed in typical setups. If your application has no `PlatformTransactionManager` (single-instance, no transaction infrastructure) you must opt in explicitly:
+
+```kotlin
+@Bean
+fun outboxTransactionRunner(): TransactionRunner = object : TransactionRunner {
+    override fun <T> runInTransaction(block: () -> T): T = block()
+}
+```
+
+Without bracketing, `FOR UPDATE SKIP LOCKED` collapses to the single SELECT statement under JDBC auto-commit, which silently allows duplicate delivery across processor instances. This opt-in is intentionally manual to keep accidental misconfiguration out of multi-instance deployments.
+
+**Multi-DataSource contexts.** If your application has multiple `DataSource` beans and uses a `PlatformTransactionManager` from which okapi cannot extract a `DataSource` (JTA, Exposed's `SpringTransactionManager`, JPA without a JDBC `DataSource`), the autoconfiguration refuses to start until you set `okapi.transaction-manager-qualifier` to the bean name of the PTM that brackets the outbox `DataSource`. `okapi.datasource-qualifier` alone is not sufficient: it picks the outbox `DataSource` but does not constrain which PTM brackets it. Alternative escape hatch: supply your own `@Bean TransactionRunner`. Single-DataSource setups and PTMs whose `DataSource` can be introspected (`DataSourceTransactionManager`, `JpaTransactionManager`, `HibernateTransactionManager`) are unaffected.
+
+**Constructing schedulers directly (non-autoconfig usage).** When wiring `OutboxProcessorScheduler` / `OutboxPurgerScheduler` manually (Ktor, custom Spring contexts without autoconfig, etc.), supply a `TransactionRunner` explicitly — the parameter is required, with no default:
+
+```kotlin
+OutboxProcessorScheduler(
+    outboxProcessor = processor,
+    transactionRunner = SpringTransactionRunner(template), // or your framework's equivalent
+    config = OutboxSchedulerConfig(...),
+)
+```
+
 ## How It Works
 
 Okapi implements the [transactional outbox pattern](https://softwaremill.com/microservices-101/) (see also: [microservices.io description](https://microservices.io/patterns/data/transactional-outbox.html)):

gradle/libs.versions.toml

@@ -20,6 +20,12 @@ h2 = "2.4.240"
 micrometer = "1.16.5"
 jmh = "1.37"
 jmhGradlePlugin = "0.7.3"
+pitestGradlePlugin = "1.19.0"
+pitestTool = "1.17.0"
+pitestJunit5Plugin = "1.2.1"
+# Hibernate ORM 7.x (the line Spring Framework 7.x targets); integration-tests only, to exercise
+# JpaTransactionManager fail-fast extraction.
+hibernate = "7.1.4.Final"
 
 [libraries]
 kotlinGradlePlugin = { module = "org.jetbrains.kotlin:kotlin-gradle-plugin", version.ref = "kotlin" }
@@ -44,10 +50,14 @@ kafkaClients = { module = "org.apache.kafka:kafka-clients", version.ref = "kafka
 springContext = { module = "org.springframework:spring-context", version.ref = "spring" }
 springTx = { module = "org.springframework:spring-tx", version.ref = "spring" }
 springJdbc = { module = "org.springframework:spring-jdbc", version.ref = "spring" }
+springOrm = { module = "org.springframework:spring-orm", version.ref = "spring" }
+hibernateCore = { module = "org.hibernate.orm:hibernate-core", version.ref = "hibernate" }
 springBootAutoconfigure = { module = "org.springframework.boot:spring-boot-autoconfigure", version.ref = "springBoot" }
 springBootStarterValidation = { module = "org.springframework.boot:spring-boot-starter-validation", version.ref = "springBoot" }
 springBootTest = { module = "org.springframework.boot:spring-boot-test", version.ref = "springBoot" }
 springBootStarterActuator = { module = "org.springframework.boot:spring-boot-starter-actuator", version.ref = "springBoot" }
+# Spring Boot 4.0 split TransactionAutoConfiguration into a dedicated module (was in spring-boot-autoconfigure in 3.x).
+springBootTransaction = { module = "org.springframework.boot:spring-boot-transaction", version.ref = "springBoot" }
 assertjCore = { module = "org.assertj:assertj-core", version.ref = "assertj" }
 micrometerCore = { module = "io.micrometer:micrometer-core", version.ref = "micrometer" }
 micrometerTest = { module = "io.micrometer:micrometer-test", version.ref = "micrometer" }
@@ -62,3 +72,5 @@ jmhGeneratorAnnprocess = { module = "org.openjdk.jmh:jmh-generator-annprocess",
 [plugins]
 ktlint = { id = "org.jlleitschuh.gradle.ktlint", version.ref = "ktlint" }
 jmh = { id = "me.champeau.jmh", version.ref = "jmhGradlePlugin" }
+# Mutation-testing — opt-in only, declared in okapi-spring-boot but applied conditionally
+pitest = { id = "info.solidsoft.pitest", version.ref = "pitestGradlePlugin" }

okapi-integration-tests/build.gradle.kts

@@ -44,5 +44,18 @@ dependencies {
     testImplementation(libs.springContext)
     testImplementation(libs.springTx)
     testImplementation(libs.springBootAutoconfigure)
+    testImplementation(libs.springBootTest)
     testImplementation(libs.springJdbc)
+    // Spring Boot 4.x doesn't pull AssertJ transitively but ApplicationContextRunner needs it
+    testImplementation(libs.assertjCore)
+
+    // Exposed-Spring bridge (proves autoconfig works with non-DataSourceTransactionManager PTMs)
+    testImplementation(libs.exposedCore)
+    testImplementation(libs.exposedJdbc)
+    testImplementation(libs.exposedSpringTransaction)
+
+    // JPA + Hibernate — proves extractDataSource() pulls JpaTransactionManager.getDataSource()
+    // and validatePtmDataSourceMatch fails fast on PTM↔DataSource mismatch under JPA.
+    testImplementation(libs.springOrm)
+    testImplementation(libs.hibernateCore)
 }

okapi-integration-tests/src/test/kotlin/com/softwaremill/okapi/test/support/PostgresTestSupport.kt

@@ -37,10 +37,26 @@ class PostgresTestSupport {
         }
     }
 
-    private fun runLiquibase() {
-        val connection = DriverManager.getConnection(container.jdbcUrl, container.username, container.password)
-        val db = DatabaseFactory.getInstance().findCorrectDatabaseImplementation(JdbcConnection(connection))
-        Liquibase("com/softwaremill/okapi/db/postgres/changelog.xml", ClassLoaderResourceAccessor(), db).use { it.update("") }
-        connection.close()
+    private fun runLiquibase() = runOkapiLiquibaseOn(container)
+}
+
+/**
+ * Applies okapi's PostgreSQL Liquibase changelog to the given container. For tests that manage
+ * their own PostgreSQL containers (e.g. 2-DataSource setups) and can't use the single-container
+ * `PostgresTestSupport` class.
+ */
+fun runOkapiLiquibaseOn(container: PostgreSQLContainer<Nothing>) {
+    DriverManager.getConnection(container.jdbcUrl, container.username, container.password).use { conn ->
+        val db = DatabaseFactory.getInstance().findCorrectDatabaseImplementation(JdbcConnection(conn))
+        Liquibase("com/softwaremill/okapi/db/postgres/changelog.xml", ClassLoaderResourceAccessor(), db).use {
+            it.update("")
+        }
     }
 }
+
+/** Builds a plain `PGSimpleDataSource` pointing at the given container. */
+fun pgDataSourceOf(container: PostgreSQLContainer<Nothing>): DataSource = PGSimpleDataSource().apply {
+    setURL(container.jdbcUrl)
+    user = container.username
+    password = container.password
+}