Create disk memory health checker

core/src/main/java/com/linecorp/armeria/server/healthcheck/DiskMemoryHealthChecker.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2024 LY Corporation
+ *
+ * LY Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package com.linecorp.armeria.server.healthcheck;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.requireNonNull;
+
+import java.io.File;
+
+/**
+ * A {@link HealthChecker} that reports as unhealthy
+ * when the target free disk space or total disk space exceed a file disk usable or total memory space.
+ * For example:
+ * <pre>{@code
+ * final DiskMemoryHealthChecker diskMemoryHealthChecker = HealthChecker.ofDisk(100, 100, "/tmp");
+ *
+ * // Returns false if a file disk usable/total memory space is less than 100 bytes,
+ * // or true if a file disk usable/total memory space is greater than or equal to 100 bytes.
+ * final boolean healthy = diskMemoryHealthChecker.isHealthy();
+ * }</pre>
+ */
+// Forked from <a href="https://github.com/micrometer-metrics/micrometer/blob/8339d57bef8689beb8d7a18b429a166f6595f2af/micrometer-core/src/main/java/io/micrometer/core/instrument/binder/system/DiskSpaceMetrics.java">DiskSpaceMetrics.java</a> in the micrometer core.
+final class DiskMemoryHealthChecker implements HealthChecker {
+
+    private final File file;
+
+    private final long targetFreeDiskSpace;
+
+    private final long targetTotalDiskSpace;
+
+    DiskMemoryHealthChecker(long targetFreeDiskSpace, long targetTotalDiskSpace, String path) {
+        this(targetFreeDiskSpace, targetTotalDiskSpace, new File(requireNonNull(path, "path")));
+    }
+
+    private DiskMemoryHealthChecker(long targetFreeDiskSpace, long targetTotalDiskSpace, File file) {
+        checkArgument(targetFreeDiskSpace >= 0, "freeDiskSpace: %s (expected: >= 0)", targetFreeDiskSpace);
+        checkArgument(targetTotalDiskSpace > 0, "totalDiskSpace: %s (expected: > 0)", targetTotalDiskSpace);
+        this.targetFreeDiskSpace = targetFreeDiskSpace;
+        this.targetTotalDiskSpace = targetTotalDiskSpace;
+        this.file = file;
+    }
+
+    /**
+     * Returns true if the file usable and total disk space are greater or equal than the target space.
+     * @return boolean
+     */
+    @Override
+    public boolean isHealthy() {
+        return file.getUsableSpace() >= targetFreeDiskSpace && file.getTotalSpace() >= targetTotalDiskSpace;
+    }
+}

core/src/main/java/com/linecorp/armeria/server/healthcheck/HealthChecker.java

@@ -105,6 +105,20 @@ static HealthChecker ofCpu(double targetSystemCpuUsage, double targetProcessCpuU
         return new CpuHealthChecker(targetSystemCpuUsage, targetProcessCpuUsage);
     }
 
+    /**
+     * Creates a new instance of {@link HealthChecker}
+     * which reports health based on disk space of specific file path.
+     * Both free disk space and total disk space must be (inclusive) lower than the specified threshold in order
+     * for the {@link HealthChecker} to report as healthy.
+     *
+     * @param targetFreeDiskSpace Target free disk space in bytes.
+     * @param targetTotalDiskSpace Target total disk space in bytes.
+     * @return an instance of {@link HealthChecker} configured with the provided disk memory space targets.
+     */
+    static HealthChecker ofDisk(long targetFreeDiskSpace, long targetTotalDiskSpace, String path) {
+        return new DiskMemoryHealthChecker(targetFreeDiskSpace, targetTotalDiskSpace, path);
+    }
+
     /**
      * Returns {@code true} if and only if the {@link Server} is healthy.
      */

core/src/test/java/com/linecorp/armeria/server/healthcheck/DiskMemoryCheckerTest.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2024 LY Corporation
+ *
+ * LY Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package com.linecorp.armeria.server.healthcheck;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.junit.jupiter.api.Test;
+
+class DiskMemoryCheckerTest {
+
+    @Test
+    void throwExceptionWhenTargetFreeDiskSpaceLowerThanZero() {
+        assertThatThrownBy(() -> {
+            final DiskMemoryHealthChecker healthChecker =
+                    (DiskMemoryHealthChecker) HealthChecker.ofDisk(-1, 1, "/tmp");
+        }).isInstanceOf(IllegalArgumentException.class)
+          .hasMessageContaining("freeDiskSpace: -1 (expected: >= 0)");
+    }
+
+    @Test
+    void throwExceptionWhenTargetTotalDiskSpaceLowerOrEqualThanZero() {
+        assertThatThrownBy(() -> {
+            final DiskMemoryHealthChecker healthChecker =
+                    (DiskMemoryHealthChecker) HealthChecker.ofDisk(1, 0, "/tmp");
+        }).isInstanceOf(IllegalArgumentException.class)
+          .hasMessageContaining("totalDiskSpace: 0 (expected: > 0)");
+    }
+
+    @Test
+    void shouldReturnTrueWhenDiskSpaceIsHealthy() {
+        final DiskMemoryHealthChecker diskMemoryHealthChecker =
+                (DiskMemoryHealthChecker) HealthChecker.ofDisk(
+                        1, 1, System.getProperty("user.dir")
+                );
+        assertThat(diskMemoryHealthChecker.isHealthy()).isTrue();
+    }
+}