Made the auto-update-checker suggest channels to server administrators if they're upgrading past their preferred channel.

src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -175,6 +175,7 @@ public final class CraftServer implements Server {
 
         updater = new AutoUpdater(new BukkitDLUpdaterService(configuration.getString("auto-updater.host")), getLogger(), configuration.getString("auto-updater.preferred-channel"));
         updater.setEnabled(configuration.getBoolean("auto-updater.enabled"));
+        updater.setSuggestChannels(configuration.getBoolean("auto-updater.suggest-channels"));
         updater.getOnBroken().addAll(configuration.getStringList("auto-updater.on-broken"));
         updater.getOnUpdate().addAll(configuration.getStringList("auto-updater.on-update"));
         updater.check(serverVersion);

src/main/java/org/bukkit/craftbukkit/updater/ArtifactDetails.java

@@ -10,6 +10,23 @@ public class ArtifactDetails {
     private String version;
     private Date created;
     private FileDetails file;
+    private ChannelDetails channel;
+
+    public ChannelDetails getChannel() {
+        return channel;
+    }
+
+    public void setChannel(ChannelDetails channel) {
+        this.channel = channel;
+    }
+
+    public boolean isIsBroken() {
+        return isBroken;
+    }
+
+    public void setIsBroken(boolean isBroken) {
+        this.isBroken = isBroken;
+    }
 
     public FileDetails getFile() {
         return file;
@@ -78,4 +95,34 @@ public class ArtifactDetails {
             this.url = url;
         }
     }
+
+    public static class ChannelDetails {
+        private String name;
+        private String slug;
+        private int priority;
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public int getPriority() {
+            return priority;
+        }
+
+        public void setPriority(int priority) {
+            this.priority = priority;
+        }
+
+        public String getSlug() {
+            return slug;
+        }
+
+        public void setSlug(String slug) {
+            this.slug = slug;
+        }
+    }
 }

src/main/java/org/bukkit/craftbukkit/updater/AutoUpdater.java

@@ -16,6 +16,7 @@ public class AutoUpdater {
     private boolean enabled;
     private ArtifactDetails current = null;
     private ArtifactDetails latest = null;
+    private boolean suggestChannels = true;
 
     public AutoUpdater(BukkitDLUpdaterService service, Logger log, String channel) {
         this.service = service;
@@ -35,6 +36,14 @@ public class AutoUpdater {
         this.enabled = isEnabled;
     }
 
+    public boolean shouldSuggestChannels() {
+        return suggestChannels;
+    }
+
+    public void setSuggestChannels(boolean suggestChannels) {
+        this.suggestChannels = suggestChannels;
+    }
+
     public List<String> getOnBroken() {
         return onBroken;
     }
@@ -100,6 +109,17 @@ public class AutoUpdater {
 
                     log.severe("Unfortunately, there is not yet a newer version suitable for your server. We would advise you wait an hour or two, or try out a dev build.");
                     log.severe("----- ------------------- -----");
+                } else if ((current != null) && (shouldSuggestChannels())) {
+                    ArtifactDetails.ChannelDetails prefChan = service.getChannel(channel, "preferred channel details");
+
+                    if ((prefChan != null) && (current.getChannel().getPriority() < prefChan.getPriority())) {
+                        log.info("----- Bukkit Auto Updater -----");
+                        log.info("It appears that you're running a " + current.getChannel().getName() + ", when you've specified in bukkit.yml that you prefer to run " + prefChan.getName() + "s.");
+                        log.info("If you would like to be kept informed about new " + current.getChannel().getName() + " releases, it is recommended that you change 'preferred-channel' in your bukkit.yml to '" + current.getChannel().getSlug() + "'.");
+                        log.info("With that set, you will be told whenever a new version is available for download, so that you can always keep up to date and secure with the latest fixes.");
+                        log.info("If you would like to disable this warning, simply set 'suggest-channels' to false in bukkit.yml.");
+                        log.info("----- ------------------- -----");
+                    }
                 }
             }
         }.start();

src/main/java/org/bukkit/craftbukkit/updater/BukkitDLUpdaterService.java

@@ -13,7 +13,8 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 
 public class BukkitDLUpdaterService {
-    private static final String API_PREFIX = "/api/1.0/downloads/projects/craftbukkit/view/";
+    private static final String API_PREFIX_ARTIFACT = "/api/1.0/downloads/projects/craftbukkit/view/";
+    private static final String API_PREFIX_CHANNEL = "/api/1.0/downloads/channels/";
     private static final DateDeserializer dateDeserializer = new DateDeserializer();
     private final String host;
 
@@ -34,7 +35,7 @@ public class BukkitDLUpdaterService {
     }
 
     public ArtifactDetails fetchArtifact(String slug) throws UnsupportedEncodingException, IOException {
-        URL url = new URL("http", host, API_PREFIX + slug);
+        URL url = new URL("http", host, API_PREFIX_ARTIFACT + slug);
         InputStreamReader reader = null;
 
         try {
@@ -50,6 +51,35 @@ public class BukkitDLUpdaterService {
         }
     }
 
+    public ArtifactDetails.ChannelDetails getChannel(String slug, String name) {
+        try {
+            return fetchChannel(slug);
+        } catch (UnsupportedEncodingException ex) {
+            Logger.getLogger(BukkitDLUpdaterService.class.getName()).log(Level.WARNING, "Could not get " + name + ": " + ex.getClass().getSimpleName());
+        } catch (IOException ex) {
+            Logger.getLogger(BukkitDLUpdaterService.class.getName()).log(Level.WARNING, "Could not get " + name + ": " + ex.getClass().getSimpleName());
+        }
+
+        return null;
+    }
+
+    public ArtifactDetails.ChannelDetails fetchChannel(String slug) throws UnsupportedEncodingException, IOException {
+        URL url = new URL("http", host, API_PREFIX_CHANNEL + slug);
+        InputStreamReader reader = null;
+
+        try {
+            reader = new InputStreamReader(url.openStream());
+            Gson gson = new GsonBuilder().registerTypeAdapter(Date.class, dateDeserializer).setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).create();
+            ArtifactDetails.ChannelDetails fromJson = gson.fromJson(reader, ArtifactDetails.ChannelDetails.class);
+
+            return fromJson;
+        } finally {
+            if (reader != null) {
+                reader.close();
+            }
+        }
+    }
+
     static class DateDeserializer implements JsonDeserializer<Date> {
         private static final SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 

src/main/resources/configurations/bukkit.yml

@@ -31,6 +31,7 @@ auto-updater:
     on-update: [warn-console, warn-ops]
     preferred-channel: rb
     host: dl.bukkit.org
+    suggest-channels: true
 aliases:
 #    icanhasbukkit:
 #    - version