Moved dependency ready check here from dd-dataverse-ingest. (#29)

* Moved dependency ready check here from dd-datavers-ingest.

* Update src/main/java/nl/knaw/dans/lib/util/healthcheck/HealthChecksDependenciesReadyCheck.java

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update src/main/java/nl/knaw/dans/lib/util/healthcheck/HealthChecksDependenciesReadyCheck.java

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: janvanmansum

src/main/java/nl/knaw/dans/lib/util/healthcheck/DependenciesReadyCheck.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2021 DANS - Data Archiving and Networked Services (info@dans.knaw.nl)
+ *
+ * Licensed 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
+ *
+ * http://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 nl.knaw.dans.lib.util.healthcheck;
+
+/**
+ * Interface for checking if all dependencies are ready.
+ */
+public interface DependenciesReadyCheck {
+    /**
+     * Wait until all dependencies are ready. This method should block until all dependencies are ready.
+     *
+     * @param checks the names of the checks to wait for; if empty, all checks are waited for
+     */
+    void waitUntilReady(String... checks);
+}

src/main/java/nl/knaw/dans/lib/util/healthcheck/DependenciesReadyCheckConfig.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2021 DANS - Data Archiving and Networked Services (info@dans.knaw.nl)
+ *
+ * Licensed 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
+ *
+ * http://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 nl.knaw.dans.lib.util.healthcheck;
+
+import io.dropwizard.util.Duration;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.util.List;
+
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class DependenciesReadyCheckConfig {
+    private List<String> healthChecks;
+    private Duration pollInterval;
+}

src/main/java/nl/knaw/dans/lib/util/healthcheck/HealthChecksDependenciesReadyCheck.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2021 DANS - Data Archiving and Networked Services (info@dans.knaw.nl)
+ *
+ * Licensed 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
+ *
+ * http://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 nl.knaw.dans.lib.util.healthcheck;
+
+import com.codahale.metrics.health.HealthCheck;
+import io.dropwizard.core.setup.Environment;
+import io.dropwizard.lifecycle.Managed;
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static java.lang.Thread.sleep;
+
+/**
+ * Implementation of {@link DependenciesReadyCheck} that waits until all health checks are healthy.
+ */
+@Slf4j
+public class HealthChecksDependenciesReadyCheck implements DependenciesReadyCheck, Managed {
+    private final List<HealthCheck> healthChecks = new ArrayList<>();
+    private final Environment environment;
+    private final DependenciesReadyCheckConfig config;
+
+    private long pollInterval;
+    private boolean running = false;
+
+    public HealthChecksDependenciesReadyCheck(Environment environment, DependenciesReadyCheckConfig config) {
+        this.environment = environment;
+        this.config = config;
+    }
+
+    @Override
+    public void start() throws Exception {
+        for (var name : config.getHealthChecks()) {
+            var healthCheck = environment.healthChecks().getHealthCheck(name);
+            if (healthCheck == null) {
+                throw new IllegalArgumentException("Health check with name " + name + " not found");
+            }
+            healthChecks.add(healthCheck);
+        }
+        pollInterval = config.getPollInterval().toMilliseconds();
+        running = true;
+    }
+
+    @Override
+    public void stop() {
+        running = false;
+    }
+
+    @Override
+    public void waitUntilReady(String... checks) {
+        List<HealthCheck> checksToWaitFor = getChecksToWaitFor(checks);
+        while (running && !allHealthy(checksToWaitFor)) {
+            log.warn("Not all health checks are healthy yet, waiting for {} ms", pollInterval);
+            try {
+                sleep(pollInterval);
+            }
+            catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                log.warn("Interrupted while waiting for health checks to become healthy, stopping wait");
+                break;
+            }
+        }
+    }
+
+    private List<HealthCheck> getChecksToWaitFor(String... checks) {
+        if (checks.length == 0) {
+            return healthChecks;
+        }
+        var checkNames = Arrays.asList(checks);
+        var registeredChecks = environment.healthChecks();
+        return checkNames.stream()
+            .map(name -> {
+                var healthCheck = registeredChecks.getHealthCheck(name);
+                if (healthCheck == null) {
+                    throw new IllegalArgumentException("Health check with name " + name + " not found");
+                }
+                return healthCheck;
+            })
+            .collect(Collectors.toList());
+    }
+
+    private boolean allHealthy(List<HealthCheck> checksToWaitFor) {
+        for (var healthCheck : checksToWaitFor) {
+            if (!healthCheck.execute().isHealthy()) {
+                return false;
+            }
+        }
+        return true;
+    }
+}