com.yahoo.config.model.provision.Hosts Maven / Gradle / Ivy
// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.config.model.provision;
import com.google.common.collect.ImmutableMap;
import com.yahoo.config.model.builder.xml.XmlHelper;
import com.yahoo.net.HostName;
import com.yahoo.text.XML;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.logging.Logger;
/**
* A collection of hosts
*
* @author bratseth
*/
public class Hosts {
public static final Logger log = Logger.getLogger(Hosts.class.getPackage().toString());
private final ImmutableMap hosts;
public Hosts(Collection hosts) {
validateAliases(hosts);
ImmutableMap.Builder hostsBuilder = new ImmutableMap.Builder<>();
for (Host host : hosts)
hostsBuilder.put(host.hostname(), host);
this.hosts = hostsBuilder.build();
}
/** Throw IllegalArgumentException if host aliases breaks invariants */
private void validateAliases(Collection hosts) {
Set aliases = new HashSet<>();
for (Host host : hosts) {
if (!host.aliases().isEmpty()) {
if (host.aliases().isEmpty())
throw new IllegalArgumentException("Host '" + host.hostname() + "' must have at least one tag.");
for (String alias : host.aliases()) {
if (aliases.contains(alias))
throw new IllegalArgumentException("Alias '" + alias + "' is used by multiple hosts.");
aliases.add(alias);
}
}
}
}
/**
* Builds host system from a hosts.xml file
*
* @param hostsFile a reader for host from application package
* @return the HostSystem for this application package
*/
public static Hosts readFrom(Reader hostsFile) {
List hosts = new ArrayList<>();
Document doc = XmlHelper.getDocument(hostsFile);
for (Element hostE : XML.getChildren(doc.getDocumentElement(), "host")) {
String name = hostE.getAttribute("name");
if (name.isEmpty()) {
throw new IllegalArgumentException("Missing 'name' attribute for host.");
}
if ("localhost".equals(name)) {
name = HostName.getLocalhost();
}
List hostAliases = getHostAliases(hostE.getChildNodes());
if (hostAliases.isEmpty()) {
throw new IllegalArgumentException("No host aliases defined for host '" + name + "'");
}
hosts.add(new Host(name, hostAliases));
}
return new Hosts(hosts);
}
/** Returns an immutable collection of the hosts of this */
public Collection asCollection() { return hosts.values(); }
@Override
public String toString() {
return "Hosts: " + hosts.keySet();
}
/**
* Get all aliases for one host from a list of 'alias' xml nodes.
*
* @param hostAliases List of xml nodes, each representing one hostalias
* @return a list of alias strings.
*/
private static List getHostAliases(NodeList hostAliases) {
List aliases = new LinkedList<>();
for (int i = 0; i < hostAliases.getLength(); i++) {
Node n = hostAliases.item(i);
if (! (n instanceof Element e)) {
continue;
}
if (! e.getNodeName().equals("alias")) {
throw new IllegalArgumentException("Unexpected tag: '" + e.getNodeName() + "' at node " +
XML.getNodePath(e, " > ") + ", expected 'alias'.");
}
String alias = e.getFirstChild().getNodeValue();
if ((alias == null) || (alias.isEmpty())) {
throw new IllegalArgumentException("Missing value for the alias tag at node " +
XML.getNodePath(e, " > ") + "'.");
}
aliases.add(alias);
}
return aliases;
}
}