Rename back to HostName, and merge the value class and utilities

1 files changed, 58 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/net/HostName.java b/vespajlib/src/main/java/com/yahoo/net/HostName.java
new file mode 100644
index 00000000000..47bd8246bb3
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/net/HostName.java
@@ -0,0 +1,58 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.net;
+
+import ai.vespa.validation.PatternedStringWrapper;
+
+import java.util.Optional;
+
+import static ai.vespa.validation.Validation.requireLength;
+
+/**
+ * Hostnames match {@link DomainName#domainNamePattern}, but are restricted to 64 characters in length.
+ *
+ * This class also has utilities for getting the hostname of the system running the JVM.
+ * Detection of the hostname is now done before starting any Vespa
+ * programs and provided in the environment variable VESPA_HOSTNAME;
+ * if that variable isn't set a default of "localhost" is always returned.
+ *
+ * @author arnej
+ * @author jonmv
+ */
+public class HostName extends PatternedStringWrapper<HostName> {
+
+    private static HostName preferredHostName = null;
+
+    private HostName(String value) {
+        super(requireLength(value, "hostname length", 1, 64), DomainName.domainNamePattern, "hostname");
+    }
+
+    public static HostName of(String value) {
+        return new HostName(value);
+    }
+
+    /**
+     * Return a public and fully qualified hostname for localhost that
+     * resolves to an IP address on a network interface.
+     *
+     * @return the preferred name of localhost
+     */
+    public static synchronized String getLocalhost() {
+        if (preferredHostName == null) {
+            preferredHostName = getPreferredHostName();
+        }
+        return preferredHostName.value();
+    }
+
+    static private HostName getPreferredHostName() {
+        Optional<String> vespaHostEnv = Optional.ofNullable(System.getenv("VESPA_HOSTNAME"));
+        if (vespaHostEnv.isPresent() && ! vespaHostEnv.get().trim().isEmpty()) {
+            return of(vespaHostEnv.get().trim());
+        }
+        return of("localhost");
+    }
+
+    public static void setHostNameForTestingOnly(String hostName) {
+        preferredHostName = HostName.of(hostName);
+    }
+
+}