Generalize remote license checker (#32971)

Machine learning has baked a remote license checker for use in checking
license compatibility of a remote license. This remote license checker
has general usage for any feature that relies on a remote cluster. For
example, cross-cluster replication will pull changes from a remote
cluster and require that the local and remote clusters have platinum
licenses. This commit generalizes the remote cluster license check for
use in cross-cluster replication.

x-pack/plugin/core/src/main/java/org/elasticsearch/license/RemoteClusterLicenseChecker.java

@@ -0,0 +1,281 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+package org.elasticsearch.license;
+
+import org.elasticsearch.ElasticsearchException;
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.support.ContextPreservingActionListener;
+import org.elasticsearch.client.Client;
+import org.elasticsearch.common.util.concurrent.ThreadContext;
+import org.elasticsearch.protocol.xpack.XPackInfoRequest;
+import org.elasticsearch.protocol.xpack.XPackInfoResponse;
+import org.elasticsearch.protocol.xpack.license.LicenseStatus;
+import org.elasticsearch.transport.RemoteClusterAware;
+import org.elasticsearch.xpack.core.action.XPackInfoAction;
+
+import java.util.EnumSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Locale;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+/**
+ * Checks remote clusters for license compatibility with a specified license predicate.
+ */
+public final class RemoteClusterLicenseChecker {
+
+ /**
+ * Encapsulates the license info of a remote cluster.
+ */
+ public static final class RemoteClusterLicenseInfo {
+
+ private final String clusterAlias;
+
+ /**
+ * The alias of the remote cluster.
+ *
+ * @return the cluster alias
+ */
+ public String clusterAlias() {
+ return clusterAlias;
+ }
+
+ private final XPackInfoResponse.LicenseInfo licenseInfo;
+
+ /**
+ * The license info of the remote cluster.
+ *
+ * @return the license info
+ */
+ public XPackInfoResponse.LicenseInfo licenseInfo() {
+ return licenseInfo;
+ }
+
+ RemoteClusterLicenseInfo(final String clusterAlias, final XPackInfoResponse.LicenseInfo licenseInfo) {
+ this.clusterAlias = clusterAlias;
+ this.licenseInfo = licenseInfo;
+ }
+
+ }
+
+ /**
+ * Encapsulates a remote cluster license check. The check is either successful if the license of the remote cluster is compatible with
+ * the predicate used to check license compatibility, or the check is a failure.
+ */
+ public static final class LicenseCheck {
+
+ private final RemoteClusterLicenseInfo remoteClusterLicenseInfo;
+
+ /**
+ * The remote cluster license info. This method should only be invoked if this instance represents a failing license check.
+ *
+ * @return the remote cluster license info
+ */
+ public RemoteClusterLicenseInfo remoteClusterLicenseInfo() {
+ assert isSuccess() == false;
+ return remoteClusterLicenseInfo;
+ }
+
+ private static final LicenseCheck SUCCESS = new LicenseCheck(null);
+
+ /**
+ * A successful license check.
+ *
+ * @return a successful license check instance
+ */
+ public static LicenseCheck success() {
+ return SUCCESS;
+ }
+
+ /**
+ * Test if this instance represents a successful license check.
+ *
+ * @return true if this instance represents a successful license check, otherwise false
+ */
+ public boolean isSuccess() {
+ return this == SUCCESS;
+ }
+
+ /**
+ * Creates a failing license check encapsulating the specified remote cluster license info.
+ *
+ * @param remoteClusterLicenseInfo the remote cluster license info
+ * @return a failing license check
+ */
+ public static LicenseCheck failure(final RemoteClusterLicenseInfo remoteClusterLicenseInfo) {
+ return new LicenseCheck(remoteClusterLicenseInfo);
+ }
+
+ private LicenseCheck(final RemoteClusterLicenseInfo remoteClusterLicenseInfo) {
+ this.remoteClusterLicenseInfo = remoteClusterLicenseInfo;
+ }
+
+ }
+
+ private final Client client;
+ private final Predicate<XPackInfoResponse.LicenseInfo> predicate;
+
+ /**
+ * Constructs a remote cluster license checker with the specified license predicate for checking license compatibility. The predicate
+ * does not need to check for the active license state as this is handled by the remote cluster license checker.
+ *
+ * @param client the client
+ * @param predicate the license predicate
+ */
+ public RemoteClusterLicenseChecker(final Client client, final Predicate<XPackInfoResponse.LicenseInfo> predicate) {
+ this.client = client;
+ this.predicate = predicate;
+ }
+
+ public static boolean isLicensePlatinumOrTrial(final XPackInfoResponse.LicenseInfo licenseInfo) {
+ final License.OperationMode mode = License.OperationMode.resolve(licenseInfo.getMode());
+ return mode == License.OperationMode.PLATINUM || mode == License.OperationMode.TRIAL;
+ }
+
+ /**
+ * Checks the specified clusters for license compatibility. The specified callback will be invoked once if all clusters are
+ * license-compatible, otherwise the specified callback will be invoked once on the first cluster that is not license-compatible.
+ *
+ * @param clusterAliases the cluster aliases to check
+ * @param listener a callback
+ */
+ public void checkRemoteClusterLicenses(final List<String> clusterAliases, final ActionListener<LicenseCheck> listener) {
+ final Iterator<String> clusterAliasesIterator = clusterAliases.iterator();
+ if (clusterAliasesIterator.hasNext() == false) {
+ listener.onResponse(LicenseCheck.success());
+ return;
+ }
+
+ final AtomicReference<String> clusterAlias = new AtomicReference<>();
+
+ final ActionListener<XPackInfoResponse> infoListener = new ActionListener<XPackInfoResponse>() {
+
+ @Override
+ public void onResponse(final XPackInfoResponse xPackInfoResponse) {
+ final XPackInfoResponse.LicenseInfo licenseInfo = xPackInfoResponse.getLicenseInfo();
+ if ((licenseInfo.getStatus() == LicenseStatus.ACTIVE) == false || predicate.test(licenseInfo) == false) {
+ listener.onResponse(LicenseCheck.failure(new RemoteClusterLicenseInfo(clusterAlias.get(), licenseInfo)));
+ return;
+ }
+
+ if (clusterAliasesIterator.hasNext()) {
+ clusterAlias.set(clusterAliasesIterator.next());
+ // recurse to the next cluster
+ remoteClusterLicense(clusterAlias.get(), this);
+ } else {
+ listener.onResponse(LicenseCheck.success());
+ }
+ }
+
+ @Override
+ public void onFailure(final Exception e) {
+ final String message = "could not determine the license type for cluster [" + clusterAlias.get() + "]";
+ listener.onFailure(new ElasticsearchException(message, e));
+ }
+
+ };
+
+ // check the license on the first cluster, and then we recursively check licenses on the remaining clusters
+ clusterAlias.set(clusterAliasesIterator.next());
+ remoteClusterLicense(clusterAlias.get(), infoListener);
+ }
+
+ private void remoteClusterLicense(final String clusterAlias, final ActionListener<XPackInfoResponse> listener) {
+ final ThreadContext threadContext = client.threadPool().getThreadContext();
+ final ContextPreservingActionListener<XPackInfoResponse> contextPreservingActionListener =
+ new ContextPreservingActionListener<>(threadContext.newRestorableContext(false), listener);
+ try (ThreadContext.StoredContext ignore = threadContext.stashContext()) {
+ // we stash any context here since this is an internal execution and should not leak any existing context information
+ threadContext.markAsSystemContext();
+
+ final XPackInfoRequest request = new XPackInfoRequest();
+ request.setCategories(EnumSet.of(XPackInfoRequest.Category.LICENSE));
+ try {
+ client.getRemoteClusterClient(clusterAlias).execute(XPackInfoAction.INSTANCE, request, contextPreservingActionListener);
+ } catch (final Exception e) {
+ contextPreservingActionListener.onFailure(e);
+ }
+ }
+ }
+
+ /**
+ * Predicate to test if the index name represents the name of a remote index.
+ *
+ * @param index the index name
+ * @return true if the collection of indices contains a remote index, otherwise false
+ */
+ public static boolean isRemoteIndex(final String index) {
+ return index.indexOf(RemoteClusterAware.REMOTE_CLUSTER_INDEX_SEPARATOR) != -1;
+ }
+
+ /**
+ * Predicate to test if the collection of index names contains any that represent the name of a remote index.
+ *
+ * @param indices the collection of index names
+ * @return true if the collection of index names contains a name that represents a remote index, otherwise false
+ */
+ public static boolean containsRemoteIndex(final List<String> indices) {
+ return indices.stream().anyMatch(RemoteClusterLicenseChecker::isRemoteIndex);
+ }
+
+ /**
+ * Filters the collection of index names for names that represent a remote index. Remote index names are of the form
+ * {@code cluster_name:index_name}.
+ *
+ * @param indices the collection of index names
+ * @return list of index names that represent remote index names
+ */
+ public static List<String> remoteIndices(final List<String> indices) {
+ return indices.stream().filter(RemoteClusterLicenseChecker::isRemoteIndex).collect(Collectors.toList());
+ }
+
+ /**
+ * Extract the list of remote cluster aliases from the list of index names. Remote index names are of the form
+ * {@code cluster_alias:index_name} and the cluster_alias is extracted for each index name that represents a remote index.
+ *
+ * @param indices the collection of index names
+ * @return the remote cluster names
+ */
+ public static List<String> remoteClusterAliases(final List<String> indices) {
+ return indices.stream()
+ .filter(RemoteClusterLicenseChecker::isRemoteIndex)
+ .map(index -> index.substring(0, index.indexOf(RemoteClusterAware.REMOTE_CLUSTER_INDEX_SEPARATOR)))
+ .distinct()
+ .collect(Collectors.toList());
+ }
+
+ /**
+ * Constructs an error message for license incompatibility.
+ *
+ * @param feature the name of the feature that initiated the remote cluster license check.
+ * @param remoteClusterLicenseInfo the remote cluster license info of the cluster that failed the license check
+ * @return an error message representing license incompatibility
+ */
+ public static String buildErrorMessage(
+ final String feature,
+ final RemoteClusterLicenseInfo remoteClusterLicenseInfo,
+ final Predicate<XPackInfoResponse.LicenseInfo> predicate) {
+ final StringBuilder error = new StringBuilder();
+ if (remoteClusterLicenseInfo.licenseInfo().getStatus() != LicenseStatus.ACTIVE) {
+ error.append(String.format(Locale.ROOT, "the license on cluster [%s] is not active", remoteClusterLicenseInfo.clusterAlias()));
+ } else {
+ assert predicate.test(remoteClusterLicenseInfo.licenseInfo()) == false : "license must be incompatible to build error message";
+ final String message = String.format(
+ Locale.ROOT,
+ "the license mode [%s] on cluster [%s] does not enable [%s]",
+ License.OperationMode.resolve(remoteClusterLicenseInfo.licenseInfo().getMode()),
+ remoteClusterLicenseInfo.clusterAlias(),
+ feature);
+ error.append(message);
+ }
+
+ return error.toString();
+ }
+
+}