All you need is docker (and fig)

IntroductionSuppose you want to run scala repl or groovy shell or any other repl-like executable. You should download executable, unpack it, set PATH environmnt variable and now you could use it. Can it be simple? Yes, dockerize everything.Prepare cont…

Introduction

Suppose you want to run scala repl or groovy shell or any other repl-like executable. You should download executable, unpack it, set PATH environmnt variable and now you could use it. Can it be simple? Yes, dockerize everything.

Prepare containers

I expect that you have installed docker and fig on your machine.
Checkout this project from github and build containers:
$ cd docker-with-fig
$ fig build 
It could take several minutes, depends on your internet connection.
You could also build only some of available container, for example with scala and groovy:
$ fig build scala groovy
Available containers are:
  • haskell
  • scala
  • groovy
  • python27
  • python34
  • clojure

Run containers

Now you could start for example scala:
$ fig run scala
Welcome to Scala version 2.11.6 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_40).
Type in expressions to have them evaluated.
Type :help for more information.

scala>
Or groovy:
$ fig run groovy
Mar 29, 2015 7:48:22 AM java.util.prefs.FileSystemPreferences$1 run
INFO: Created user preferences directory.
Groovy Shell (2.4.2, JVM: 1.8.0_40)
Type ':help' or ':h' for help.
-------------------------------------------------------------------------------
groovy:000>
Or clojure with lein:
$ fig run clojure
nREPL server started on port 52730 on host 127.0.0.1 - nrepl://127.0.0.1:52730
REPL-y 0.3.5, nREPL 0.2.6
Clojure 1.6.0
Java HotSpot(TM) 64-Bit Server VM 1.8.0_40-b25
    Docs: (doc function-name-here)
          (find-doc "part-of-name-here")
  Source: (source function-name-here)
 Javadoc: (javadoc java-object-or-class-here)
    Exit: Control+D or (exit) or (quit)
 Results: Stored in vars *1, *2, *3, an exception in *e

user=>
Or python 3.4:
$ fig run python34
Python 3.4.2 (default, Oct  8 2014, 13:08:17) 
[GCC 4.9.1] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
Or ghci haskell:
$fig run haskell
GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude>
You could also run command on docker container with use of files from your current directory because it is mapped to /project directory on docker. Container starts with /project directory as current directory.
For example you have a simple file in your current dir:
$ cat simplePrint.scala 

println("Hello World")


You could run command with this file:

$ fig -f PATH_TO_DOCKER_WITH_FIG_PROJECT/fig.yml run scala scala simplePrint.scala

Hello World

First ‘scala’ in command means that you want to run scala container and ‘scala simplePrint.scala’ means that you want to execute this command on container.

Conclusion

It is simple, isn’t it? All you need is docker and fig and you could use repl or run command with scala, groovy, cojure and any other which are currently supported…
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Phonegap / Cordova and cross domain ssl request problem on android.

In one app I have participated, there was a use case:
  • User fill up a form.
  • User submit the form.
  • System send data via https to server and show a response.
During development there wasn’t any problem, but when we were going to release production version then some unsuspected situation occurred. I prepare the production version accordingly with standard flow for Android environment:
  • ant release
  • align
  • signing
During conduct tests on that version, every time I try to submit the form, a connection error appear. In that situation, at the first you should check whitelist in cordova settings. Every URL you want to connect to, must be explicit type in:
res/xml/cordova.xml
If whitelist looks fine, the error is most likely caused by inner implementation of Android System. The Android WebView does not allow by default self-signed SSL certs. When app is debug-signed the SSL error is ignored, but if app is release-signed connection to untrusted services is blocked.



Workaround


You have to remember that secure connection to service with self-signed certificate is risky and unrecommended. But if you know what you are doing there is some workaround of the security problem. Behavior of method
CordovaWebViewClient.onReceivedSslError
must be changed.


Thus add new class extended CordovaWebViewClient and override ‘onReceivedSslError’. I strongly suggest to implement custom onReceiveSslError as secure as possible. I know that the problem occours when app try connect to example.domain.com and in spite of self signed certificate the domain is trusted, so only for that case the SslError is ignored.

public class MyWebViewClient extends CordovaWebViewClient {

   private static final String TAG = MyWebViewClient.class.getName();
   private static final String AVAILABLE_SLL_CN
= "example.domain.com";

   public MyWebViewClient(DroidGap ctx) {
       super(ctx);
   }

   @Override
   public void onReceivedSslError(WebView view,
SslErrorHandler handler,
android.net.http.SslError error) {

String errorSourceCName = error.getCertificate().
getIssuedTo().getCName();

       if( AVAILABLE_SLL_CN.equals(errorSourceCName) ) {
           Log.i(TAG, "Detect ssl connection error: " +
error.toString() +
„ so the error is ignored”);

           handler.proceed();
           return;
       }

       super.onReceivedSslError(view, handler, error);
   }
}
Next step is forcing yours app to  use custom implementation of WebViewClient.

public class Start extends DroidGap
{
   private static final String TAG = Start.class.getName();

   @Override
   public void onCreate(Bundle savedInstanceState)
   {
       super.onCreate(savedInstanceState);
       super.setIntegerProperty("splashscreen", R.drawable.splash);
       super.init();

       MyWebViewClient myWebViewClient = new MyWebViewClient(this);
       myWebViewClient.setWebView(this.appView);

       this.appView.setWebViewClient(myWebViewClient);
       
// yours code

   }
}
That is all ypu have to do if minSdk of yours app is greater or equals 8. In older version of Android there is no class
android.net.http.SslError
So in class MyCordovaWebViewClient class there are errors because compliator doesn’t see SslError class. Fortunately Android is(was) open source, so it is easy to find source of the class. There is no inpediments to ‘upgrade’ app and just add the file to project. I suggest to keep original packages. Thus after all operations the source tree looks like:

Class SslError placed in source tree. 
 Now the app created in release mode can connect via https to services with self-signed SSl certificates.