Merge pull request #17 from Kilemonn/correlation-id

Correlation

src/main/kotlin/au/kilemon/messagequeue/filter/CorrelationIdFilter.kt

@@ -0,0 +1,71 @@
+package au.kilemon.messagequeue.filter
+
+import au.kilemon.messagequeue.logging.HasLogger
+import org.slf4j.Logger
+import org.slf4j.MDC
+import org.springframework.core.annotation.Order
+import org.springframework.stereotype.Component
+import org.springframework.web.filter.OncePerRequestFilter
+import java.util.*
+import javax.servlet.FilterChain
+import javax.servlet.http.HttpServletRequest
+import javax.servlet.http.HttpServletResponse
+
+/**
+ * A request filter that either takes the incoming provided [CORRELATION_ID_HEADER] and sets it into the [MDC] OR
+ * generates a new [UUID] that is used as the [CORRELATION_ID] for this request.
+ * This [CORRELATION_ID] is removed from the [MDC] when the request is returned to the caller.
+ *
+ * @author github.com/Kilemonn
+ */
+@Component
+@Order(1)
+class CorrelationIdFilter: OncePerRequestFilter(), HasLogger
+{
+    companion object
+    {
+        const val CORRELATION_ID_HEADER = "X-Correlation-Id"
+
+        // This is also used in the logback.xml as a parameter
+        const val CORRELATION_ID = "correlationId"
+    }
+
+    override val LOG: Logger = initialiseLogger()
+
+    override fun doFilterInternal(request: HttpServletRequest, response: HttpServletResponse, filterChain: FilterChain)
+    {
+        try
+        {
+            setCorrelationId(request.getHeader(CORRELATION_ID_HEADER))
+
+            filterChain.doFilter(request, response)
+        }
+        finally
+        {
+            MDC.clear()
+        }
+    }
+
+    /**
+     * Handle the setting of the [CORRELATION_ID] based on the [providedId] if it is not null it will be used, otherwise
+     * a new [UUID] will be generated and set into the [MDC].
+     *
+     * @param providedId the correlation ID provided by the user, if it is null a new one will be generated
+     */
+    fun setCorrelationId(providedId: String?)
+    {
+        val correlationId: String
+        if (providedId != null)
+        {
+            correlationId = providedId
+            LOG.trace("Using provided ID [{}] as correlation id.", correlationId)
+        }
+        else
+        {
+            correlationId = UUID.randomUUID().toString()
+            LOG.trace("Using generated UUID [{}] as correlation id.", correlationId)
+        }
+
+        MDC.put(CORRELATION_ID, correlationId)
+    }
+}

src/main/kotlin/au/kilemon/messagequeue/rest/controller/RestParameters.kt

@@ -0,0 +1,19 @@
+package au.kilemon.messagequeue.rest.controller
+
+/**
+ * A collection of constants used as REST parameters.
+ *
+ * @author github.com/Kilemonn
+ */
+object RestParameters
+{
+    const val ASSIGNED_TO = "assignedTo"
+
+    const val QUEUE_TYPE = "queueType"
+
+    const val DETAILED = "detailed"
+
+    const val UUID = "uuid"
+
+    const val INCLUDE_EMPTY = "includeEmpty"
+}

src/main/kotlin/au/kilemon/messagequeue/rest/response/ErrorResponse.kt

@@ -0,0 +1,13 @@
+package au.kilemon.messagequeue.rest.response
+
+import au.kilemon.messagequeue.filter.CorrelationIdFilter
+import com.fasterxml.jackson.annotation.JsonPropertyOrder
+import org.slf4j.MDC
+
+/**
+ * An error response object returned when errors occur.
+ *
+ * @author github.com/Kilemonn
+ */
+@JsonPropertyOrder("correlationId", "message")
+data class ErrorResponse(val message: String?, val correlationId: String? = MDC.get(CorrelationIdFilter.CORRELATION_ID))

src/main/kotlin/au/kilemon/messagequeue/rest/response/MessageResponse.kt

@@ -1,12 +1,14 @@
 package au.kilemon.messagequeue.rest.response
 
+import au.kilemon.messagequeue.filter.CorrelationIdFilter
 import au.kilemon.messagequeue.message.QueueMessage
 import com.fasterxml.jackson.annotation.JsonPropertyOrder
+import org.slf4j.MDC
 
 /**
  * A response object which wraps the [QueueMessage], and exposes the `type` [String].
  *
  * @author github.com/Kilemonn
  */
-@JsonPropertyOrder("queueType", "message")
-data class MessageResponse(val message: QueueMessage, val queueType: String = message.type)
+@JsonPropertyOrder("correlationId", "queueType", "message")
+data class MessageResponse(val message: QueueMessage, val queueType: String = message.type, val correlationId: String? = MDC.get(CorrelationIdFilter.CORRELATION_ID))

src/main/kotlin/au/kilemon/messagequeue/rest/response/RestResponseExceptionHandler.kt

@@ -0,0 +1,22 @@
+package au.kilemon.messagequeue.rest.response
+
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.ControllerAdvice
+import org.springframework.web.bind.annotation.ExceptionHandler
+import org.springframework.web.server.ResponseStatusException
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler
+
+/**
+ * A response handler which maps the thrown [ResponseStatusException] into the [ErrorResponse].
+ *
+ * @author github.com/Kilemonn
+ */
+@ControllerAdvice
+class RestResponseExceptionHandler: ResponseEntityExceptionHandler()
+{
+    @ExceptionHandler(ResponseStatusException::class)
+    fun handleResponseStatusException(ex: ResponseStatusException): ResponseEntity<ErrorResponse>
+    {
+        return ResponseEntity<ErrorResponse>(ErrorResponse(ex.reason), ex.status)
+    }
+}

src/main/resources/logback.xml

@@ -2,7 +2,7 @@
 <configuration>
     <!-- Properties list for use below -->
     <property name="LOGS" value="./logs"/>
-    <property name="PATTERN" value="%d %p %C{1.} [%t] %m%n"/>
+    <property name="PATTERN" value="%d %p [%X{correlationId}] %C{1.} [%t] %m%n"/>
     <property name="ARCHIVED_FILE_SUFFIX" value="-%d{yyyy-MM-dd}.%i"/>
 
     <!-- Console appender formatting -->

src/test/kotlin/au/kilemon/messagequeue/filter/TestCorrelationIdFilter.kt

@@ -0,0 +1,50 @@
+package au.kilemon.messagequeue.filter
+
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.slf4j.MDC
+import java.util.*
+
+/**
+ * Test [CorrelationIdFilter] to make sure the [CorrelationIdFilter.CORRELATION_ID] is set correctly.
+ *
+ * @author github.com/Kilemonn
+ */
+class TestCorrelationIdFilter
+{
+    private val correlationIdFilter = CorrelationIdFilter()
+
+    @BeforeEach
+    fun setUp()
+    {
+        MDC.clear()
+    }
+
+    /**
+     * Ensure the provided `correlationId` is used when [CorrelationIdFilter.setCorrelationId] is called with a non-null
+     * argument.
+     */
+    @Test
+    fun testSetCorrelationId_providedId()
+    {
+        val correlationId = "a-correlation-id-123456"
+        Assertions.assertNull(MDC.get(CorrelationIdFilter.CORRELATION_ID))
+
+        correlationIdFilter.setCorrelationId(correlationId)
+        Assertions.assertEquals(correlationId, MDC.get(CorrelationIdFilter.CORRELATION_ID))
+    }
+
+    /**
+     * Ensure that a [UUID] `correlationId` will be generated when [CorrelationIdFilter.setCorrelationId] is called
+     * with a `null` argument.
+     */
+    @Test
+    fun testSetCorrelationId_generatedId()
+    {
+        Assertions.assertNull(MDC.get(CorrelationIdFilter.CORRELATION_ID))
+        correlationIdFilter.setCorrelationId(null)
+        val generatedCorrelationId = MDC.get(CorrelationIdFilter.CORRELATION_ID)
+        Assertions.assertEquals(UUID.fromString(generatedCorrelationId).toString(), generatedCorrelationId)
+    }
+}