Adds rate limit service, basic configuration for bucket and quotas.

build.gradle

@@ -55,6 +55,7 @@ dependencies {
 	implementation("io.springfox:springfox-boot-starter:3.0.0")
 	implementation('io.springfox:springfox-swagger-ui:3.0.0')
 	implementation("org.eclipse.jgit:org.eclipse.jgit:6.3.0.202209071007-r")
+	implementation("com.github.vladimir-bukhtoyarov:bucket4j-core:7.6.0")
 	// Foundation
 	implementation('org.webjars:foundation:6.4.3')
 

src/main/kotlin/de/paulbrejla/holidays/application/api/RateLimitService.kt

@@ -0,0 +1,9 @@
+package de.paulbrejla.holidays.application.api
+
+import io.github.bucket4j.Bucket
+
+interface RateLimitService {
+    fun resolveBucket(bucketId: String): Bucket
+    fun fetchBucket(bucketId: String): Bucket?
+    fun isWithinQuota(maxRequests: Int, currentRequests: Int): Boolean
+}

src/main/kotlin/de/paulbrejla/holidays/application/impl/GlobalRateLimitServiceImpl.kt

@@ -0,0 +1,56 @@
+package de.paulbrejla.holidays.application.impl
+
+import de.paulbrejla.holidays.application.api.RateLimitService
+import io.github.bucket4j.Bandwidth
+import io.github.bucket4j.Bucket
+import io.github.bucket4j.Refill
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.stereotype.Component
+import java.time.Duration
+import java.util.concurrent.ConcurrentHashMap
+
+@Component("rateLimitService")
+class GlobalRateLimitServiceImpl : RateLimitService {
+    // For now we create one global bucket that all requests consume from.
+    @Value("\${rateLimit.globalBucket.id}")
+    var globalBucketId: String = ""
+
+    @Value("\${rateLimit.globalBucket.capacity}")
+    var globalBucketCapacity: Long = 0
+
+
+    private var buckets: MutableMap<String, Bucket> = ConcurrentHashMap<String, Bucket>()
+    override fun resolveBucket(bucketId: String): Bucket {
+        return if (buckets.containsKey(bucketId)) {
+            buckets[bucketId]!!
+        } else {
+            createBucket().let {
+                buckets[bucketId] = it
+                it
+            }
+        }
+    }
+
+    override fun fetchBucket(bucketId: String): Bucket? {
+        return buckets[bucketId]
+    }
+
+    override fun isWithinQuota(maxRequests: Int, currentRequests: Int): Boolean {
+        TODO("Not yet implemented")
+    }
+
+    /**
+     * We only allow 1000 requests per hour from now on. These 1000 requests are refilled when the new
+     * hour starts.
+     */
+    private fun createBucket(): Bucket {
+        return Bucket.builder()
+            .addLimit(
+                Bandwidth.classic(
+                    globalBucketCapacity,
+                    Refill.intervally(globalBucketCapacity, Duration.ofHours(1))
+                )
+            )
+            .build()
+    }
+}

src/main/resources/application.yml

@@ -9,10 +9,14 @@ spring:
       enabled: false
       path: /h2-console
 server:
-  port: ${APPLICATION_PORT:80}
+  port: ${SERVER_PORT:80}
 loader:
   source: ${LOADER_SOURCE}
   remoteURL: ${LOADER_REMOTE_URL}
   branch: ${LOADER_BRANCH}
   filePath: ${LOADER_FILE_PATH}
-  authToken: ${LOADER_AUTH_TOKEN}
+  authToken: ${LOADER_AUTH_TOKEN}
+rateLimit:
+  globalBucket:
+   id: ${RATE_LIMIT_GLOBAL_BUCKET_ID:global}
+   capacity: ${RATE_LIMIT_GLOBAL_BUCKET_CAPACITY:500}