1 files changed, 133 insertions, 0 deletions
diff --git a/config-provisioning/src/main/java/com/yahoo/config/provision/EndpointsChecker.java b/config-provisioning/src/main/java/com/yahoo/config/provision/EndpointsChecker.java
new file mode 100644
index 00000000000..d9ced0177e5
--- /dev/null
+++ b/config-provisioning/src/main/java/com/yahoo/config/provision/EndpointsChecker.java
@@ -0,0 +1,133 @@
+package com.yahoo.config.provision;
+
+import ai.vespa.http.DomainName;
+import ai.vespa.http.HttpURL;
+
+import javax.naming.NamingException;
+import javax.naming.directory.Attribute;
+import javax.naming.directory.Attributes;
+import javax.naming.directory.InitialDirContext;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * @author jonmv
+ */
+public interface EndpointsChecker {
+
+    record Endpoint(ClusterSpec.Id clusterName,
+                    HttpURL url,
+                    Optional<InetAddress> ipAddress,
+                    Optional<DomainName> canonicalName,
+                    boolean isPublic) { }
+
+    /** Status sorted by increasing readiness. */
+    enum Status { endpointsUnavailable, containersUnhealthy, available }
+
+    record Availability(Status status, String message) { }
+
+    interface HostNameResolver { Optional<InetAddress> resolve(DomainName hostName); }
+
+    interface CNameResolver { Optional<DomainName> resolve(DomainName hostName); }
+
+    interface ContainerHealthChecker { boolean healthy(Endpoint endpoint); }
+
+    static EndpointsChecker of(ContainerHealthChecker containerHealthChecker) {
+        return zoneEndpoints -> endpointsAvailable(zoneEndpoints, EndpointsChecker::resolveHostName, EndpointsChecker::resolveCname, containerHealthChecker);
+    }
+
+    static EndpointsChecker mock(HostNameResolver hostNameResolver, CNameResolver cNameResolver, ContainerHealthChecker containerHealthChecker) {
+        return zoneEndpoints -> endpointsAvailable(zoneEndpoints, hostNameResolver, cNameResolver, containerHealthChecker);
+    }
+
+    Availability endpointsAvailable(List<Endpoint> zoneEndpoints);
+
+    private static Availability endpointsAvailable(List<Endpoint> zoneEndpoints,
+                                                   HostNameResolver hostNameResolver,
+                                                   CNameResolver cNameResolver,
+                                                   ContainerHealthChecker containerHealthChecker) {
+        if (zoneEndpoints.isEmpty())
+            return new Availability(Status.endpointsUnavailable, "Endpoints not yet ready.");
+
+        for (Endpoint endpoint : zoneEndpoints) {
+            Optional<InetAddress> resolvedIpAddress = hostNameResolver.resolve(endpoint.url().domain());
+            if (resolvedIpAddress.isEmpty())
+                return new Availability(Status.endpointsUnavailable, "DNS lookup yielded no IP address for '" + endpoint.url().domain() + "'.");
+
+            if (resolvedIpAddress.equals(endpoint.ipAddress())) // We expect a certain IP address, and that's what we got, so we're good.
+                continue;
+
+            if (endpoint.ipAddress().isPresent()) // We expect a certain IP address, but that's not what we got.
+                return new Availability(Status.endpointsUnavailable,
+                                        "IP address of '" + endpoint.url().domain() + "' (" +
+                                        resolvedIpAddress.get().getHostAddress() + ") and load balancer " +
+                                        "' (" + endpoint.ipAddress().get().getHostAddress() + ") are not equal");
+
+            if (endpoint.canonicalName().isEmpty()) // We have no expected IP address, and no canonical name, so there's nothing more to check.
+                continue;
+
+            Optional<DomainName> cNameValue = cNameResolver.resolve(endpoint.url().domain());
+            if (cNameValue.filter(endpoint.canonicalName().get()::equals).isEmpty()) {
+                return new Availability(Status.endpointsUnavailable,
+                                        "CNAME '" + endpoint.url().domain() + "' points at " +
+                                        cNameValue.map(name -> "'" + name + "'").orElse("nothing") +
+                                        " but should point at load balancer " +
+                                        endpoint.canonicalName().map(name -> "'" + name + "'").orElse("nothing"));
+            }
+
+            Optional<InetAddress> loadBalancerAddress = hostNameResolver.resolve(endpoint.canonicalName().get());
+            if ( ! loadBalancerAddress.equals(resolvedIpAddress)) {
+                return new Availability(Status.endpointsUnavailable,
+                                        "IP address of CNAME '" + endpoint.url().domain() + "' (" +
+                                        resolvedIpAddress.get().getHostAddress() + ") and load balancer '" +
+                                        endpoint.canonicalName().get() + "' (" +
+                                        loadBalancerAddress.map(InetAddress::getHostAddress).orElse("empty") + ") are not equal");
+            }
+        }
+
+        for (Endpoint endpoint : zoneEndpoints)
+            if ( ! containerHealthChecker.healthy(endpoint))
+                return new Availability(Status.containersUnhealthy, "Failed to get enough healthy responses from " + endpoint.url());
+
+        return new Availability(Status.available, "Endpoints are ready");
+    }
+
+    /** Returns the IP address of the given host name, if any. */
+    private static Optional<InetAddress> resolveHostName(DomainName hostname) {
+        try {
+            return Optional.of(InetAddress.getByName(hostname.value()));
+        }
+        catch (UnknownHostException ignored) {
+            return Optional.empty();
+        }
+    }
+
+    /** Returns the host name of the given CNAME, if any. */
+    private static Optional<DomainName> resolveCname(DomainName endpoint) {
+        try {
+            InitialDirContext ctx = new InitialDirContext();
+            try {
+                Attributes attrs = ctx.getAttributes("dns:/" + endpoint.value(), new String[]{ "CNAME" });
+                for (Attribute attribute : Collections.list(attrs.getAll())) {
+                    Enumeration<?> vals = attribute.getAll();
+                    if (vals.hasMoreElements()) {
+                        String hostname = vals.nextElement().toString();
+                        return Optional.of(hostname.substring(0, hostname.length() - 1)).map(DomainName::of);
+                    }
+                }
+            }
+            finally {
+                ctx.close();
+            }
+        }
+        catch (NamingException e) {
+            throw new RuntimeException(e);
+        }
+        return Optional.empty();
+    }
+
+}