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Update ReplicaSet using Java Kubernetes Client

I am writing a client that manages Kubernetes objects. Is it possible to update ReplicaSets using a Java client?

Yes, you can update ReplicaSet using Java Kubernetes Client. Depending on which Kubernetes client you use here are the code snippets.
Kubernetes Java Client
AppsV1Api api = new AppsV1Api();
api.patchNamespacedReplicaSet(...);
Fabric8 Kubernetes & OpenShift Java Client
KubernetesClient client = new DefaultKubernetesClient();
client.apps().replicaSets().createOrReplace(...);

I was just doing this this morning!
Yes you can do that. Checkout Fabric8 Kubernetes client for Java (https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-tests/src/test/java/io/fabric8/kubernetes/client/mock/ReplicaSetTest.java)
An example of the change would be:
try (KubernetesClient k8sClient = new DefaultKubernetesClient()) {
ReplicaSetList list = k8sClient.apps().replicaSets().inNamespace("default").list();
for (ReplicaSet next : list.getItems()) {
next.getSpec().setReplicas(10);
k8sClient.apps().replicaSets().create(next);
}
} catch (Exception e) {
//TODO: logging
}
Just be sure to use the correct one. In this example I am changing all of them in the default namespace.

Restlet framework: how to bind to localhost only?

I need to build a (standalone Java) restlet-based service that only listens on localhost, i.e. no requests from network are allowed.
I was trying to do the obvious:
Server srv = new Server(Protocol.HTTPS, "localhost", httpsPort);
component.getServers().add(srv);
But the service still listens on 0.0.0.0. :-(
I went into the code and found that HttpsServerHelper ignores the hostname when creating the service:
this.server = HttpsServer.create(new InetSocketAddress(getHelped().getPort()), 0);
Similar code exists in plain HTTP's HttpServerHelper, where it is even more clear.
My question then is this:
How can I configure Restlet component/service to only listen on localhost?

I don't know which server you use under the hood within your standalone Restlet application. You should use a server connector other than the default one and I recommend you to use the Jetty one.
To do that, simply put the jar of the extension org.restlet.ext.jetty in your classpath.
In this case, using the following code should correspond to your needs:
component.getServers().add(Protocol.HTTP, "localhost", 8182);
Here is the corresponding trace at application startup:
2015-09-03 09:47:22.180:INFO::jetty-7.1.6.v20100715
2015-09-03 09:47:22.211:INFO::Started SelectChannelConnector#localhost:8182
In addition, here is the link in the Restlet documentation regarding Restlet connectors: http://restlet.com/technical-resources/restlet-framework/guide/2.3/core/base/connectors.
Hope it helps you,
Thierry

The easier way to achieve that is to use virtual hosts.
Virtual hosts are the first routing barrier when handling a request, especially it helps routing on a domain.
Here is a sample code that illustrates this:
Component c = new Component();
c.getServers().add(Protocol.HTTP, 8182);
VirtualHost host = new VirtualHost();
host.setHostDomain("localhost");
c.getHosts().add(host);
host.attach(new Restlet() {
#Override
public void handle(Request request, Response response) {
response.setEntity("hello, world", MediaType.TEXT_PLAIN);
}
});
c.start();
Usually, applications are attached on the default host of a component. This default host does nothing, except routing requests based on the context path of the attached application:
c.getDefaultHost().attach("/contextPath1", new Test1Application());
c.getDefaultHost().attach("/contextPath2", new Test2Application());
When you would like to filter calls based on other data than the request's path, virtual host may be the solution.
Here is a diagram that may help you:
http://restlet.com/technical-resources/restlet-framework/tutorials/2.3#part05

java ignores proxy settings

I have set up a local proxy server for request logging but my java code ignores it and connects directly (Windows XP, JDK 1.7). Web browsers work with it. So I wrote test code for discussion that seems to connect directly even if a (bogus) proxy is specified. With the bogus proxy, I would expect connection failure but the code succeeds, connecting directly:
System.setProperty("http.proxyHost", "localhost");
System.setProperty("http.proxyPort", "12345");
System.setProperty("http.nonProxyHosts", "noNonProxyHost.com");
URL url = new URL("http://docs.oracle.com/javase/7/docs/technotes/guides/net/proxies.html");
InputStream in = url.openStream();
System.out.println("Connection via bogus proxy succeeded");
The code is run as standalone Java, no Maven, no applet, no container. I have a direct internet connection.

In your case using java.net.URL(), if the proxy server cannot be reached at http.proxyHost and http.proxyPort then it simply falls back and tries to do a direct connect. If that succeeds, you'll see no exception thrown which is why your code works without error. You should see a pause while it tries to find the proxy though.
This sample code below happily fetches the URL and displays it, without error, even when run with bogus proxy settings. -Dhttp.proxyHost=bogus -Dhttp.proxyPort=2345 but will talk to my local proxy localhost port 8888 if set correctly
import java.io.*;
import java.net.URL;
import java.util.*;
public class URLClient {
private static String sUrl = "http://www.apache.org/";
public static void main(String[] args) {
try {
URL url = new URL(sUrl);
InputStream is = url.openStream();
java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
String output = s.hasNext() ? s.next() : "";
System.out.println(output);
} catch(Throwable e) {
System.err.println("exception");
}
}
}
The problem I was originally having with http.proxyHost and http.proxyPort being ignored (Google led me to your question) was that those settings are completely ignored by apache.commons.httpClient because it uses its own sockets, as described here.
http://cephas.net/blog/2007/11/14/java-commons-http-client-and-http-proxies/

I have faced a similar problem recently. First of all, one part of the above answer from Daemon42 explains pretty well, why the bogus proxy server didn't lead to a failure of the program:
if the proxy server cannot be reached at http.proxyHost and http.proxyPort then it simply falls back and tries to do a direct connect. If that succeeds, you'll see no exception thrown which is why your code works without error. You should see a pause while it tries to find the proxy though.
Still, your actual question was, why the proxy server configured via the operating system is not used by the Java application. As stated in the Oracle documentation (https://docs.oracle.com/javase/8/docs/technotes/guides/net/proxies.html), the system proxy settings are not evaluated by Java by default. To do so, you have to set the value of the system property "java.net.useSystemProxies" to the value "true".
You can set that system property on the command line, or you can edit the JRE installation file jre/lib/net.properties, that way you have to change it only once on a given system.

connecting to a URL in Java through a proxy

I'm trying to write a small java program that connects to a twitter search URL (which returns a JSON list of tweets) using the URL connection libary.
My code which is taken from the java tutorials looks like :
public static void main(String[] args) throws Exception {
URL oracle = new URL("http://search.twitter.com/search.json?q=hi");
URLConnection yc = oracle.openConnection();
BufferedReader in = new BufferedReader(
new InputStreamReader(
yc.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
}
but for some reason I keep getting the following Exception:
in thread "main" java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
I don't know if this is something due to the way I've written the code, and eclipse setting or something to do with my network. I do have a proxy server configured for internet access. As far as I know this is properly configured because I am getting updates and can install new software through eclipse. Do I need to put the proxy information in the URL method somehow or is something else the problem.

URL rely on System properties for proxy, try setting proxy like this:
System.setProperty("http.proxyHost", "yourproxyserver");
System.setProperty("http.proxyPort", "portnumber");

Unfortunately, a correct proxy setup in Eclipse seems not to help with proxying Java programs started in Eclipse. Similarly, setting the Java system settings to use the systemwide proxy settings doesn't either. Not when you have a proxy that requires authentication, anyway.
As Thomas Johan Eggum said, if you have a "normal," non-authenticating proxy then setting the two JVM variables http.proxyHost and http.proxyPort either in the command line via -D or programmatically (see below) will take care of things.
For an authenticating proxy server, i.e. one that wants to see a user ID and password, many people recommend setting http.proxyUser and http.proxyPassword. That's bad advice, because these don't work. Apparently they are not defined in the Java docs.
Unfortunately, it looks like the way to "do" authentication is to use an Authenticator, programmatically. If you're going to do that, you might as well do the whole thing programmatically, i.e. including host and port. Here's how I got that to work:
public static void main(String[] args) {
try {
System.setProperty("http.proxyHost", "my.proxy.host");
System.setProperty("http.proxyPort", "8080-or-whatever-proxy-port");
Authenticator.setDefault(new DummyAuthenticator());
/* do your main program stuff */
} catch (Exception e) {
e.printStackTrace();
}
}
private static class DummyAuthenticator extends Authenticator {
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(
"my-user-id", "my-password".toCharArray()
);
}
}

Java HttpURLConnection uses SOCKS proxy instead of HTTP

I have a very simple code that uses HttpURLConnection to access some web site via proxy
System.setProperty("java.net.useSystemProxies", "true");
System.out.println("Proxy: " + ProxySelector.getDefault().select(new URI(urlS)));
URL url = new URL(urlS);
HttpURLConnection ic = (HttpURLConnection)url.openConnection();
ic.connect();
For some reason, Java thinks that I need SOCKS proxy, not http, throwing the following exception:
ERROR: Can't connect to SOCKS proxy:Connection timed out: connect

If you are having this issues on Windows, you may run into a Java bug.
Java treats any system proxy setting as SOCKS. You have to either disable useSystemProxies or don't use proxy in Windows.
If proxy is needed, try to uncheck "Use the same proxy server for all protocols", making sure the field for the SOCKS proxy is blank. That fixed our problem.

The real problem is that Java assumes that the "Use the same proxy server for all protocols" check affects SOCKS proxy too (I don't know the logic behind this dialog in Windows, but it is, at least, confusing)
If the check is set, you get proxies enabled for both HTTP and SOCKS, wich is very unlikely to be the desired configuration.
One way to solve it is unchecking the check and leaving blank the SOCKS field.
I finally solved it creating a ProxySelector wich first calls the default selector and if it finds the same configuration for HTTP and SOCKS connections, it omits the SOCKS proxy.
public class SocksFixerProxySelector extends ProxySelector {
ProxySelector base;
public SocksFixerProxySelector() {
base = ProxySelector.getDefault();
}
#Override
public List<Proxy> select(URI uri) {
List<Proxy> baseList = base.select(uri);
try {
if (uri.getScheme().equals("socket")) {
Proxy socksProxy = findByType(baseList, Type.SOCKS);
if (socksProxy != null) {
URI httpTestUri = new URI("http", uri.getHost(), uri.getPath(), uri.getFragment());
Proxy httpProxy = findByType(base.select(httpTestUri), Type.HTTP);
if (httpProxy != null && socksProxy.address().equals(httpProxy.address())) {
// Quitamos SOCKS
List<Proxy> filteredList = new ArrayList<>(baseList);
filteredList.remove(socksProxy);
return filteredList;
}
}
}
} catch (Exception e) {
}
return baseList;
}
#Override
public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {
base.connectFailed(uri, sa, ioe);
}
private Proxy findByType(List<Proxy> proxies, Proxy.Type type) {
for (Proxy proxy : proxies) {
if (proxy.type() == type)
return proxy;
}
return null;
}
Maybe a better solution would be to inspect the registry and detect the right settings, but I didn't want to mess with Windows specific code (and all those script settings looked bad, too )

You need to use the http.proxyHost system property instead. See http://java.sun.com/javase/6/docs/technotes/guides/net/proxies.html for details.
java -Dhttp.proxyHost=webcache.mydomain.com GetURL

Check that something has not set the "socksProxyHost" property in the Systems properties.
EDIT
The "useSystemProxies" property is described thus:
"On recent Windows systems and on Gnome 2.x platforms it is possible to tell the default ProxySelector to use the system proxy settings (both recent versions of Windows and Gnome 2.x let you set proxies globally through their user interface). If the system property java.net.useSystemProxies is set to true (by default it is set to false for compatibility sake), then the default ProxySelector will try to use these settings."
So, assuming that you have not supplied your own ProxySelector class, you should also check the system proxy settings to ensure that they don't say to use SOCKS.