The Lost Notebook » Work http://funinc.org Things that I tend to forget Fri, 20 Jan 2012 14:42:07 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Apache Reverse Proxy + SSH Reverse Tunnel http://funinc.org/20111229/apache-reverse-proxy-ssh-reverse-tunnel http://funinc.org/20111229/apache-reverse-proxy-ssh-reverse-tunnel#comments Thu, 29 Dec 2011 14:17:34 +0000 abdallah http://funinc.org/?p=328 Disclaimer: This setup is just a bit crazy, and I wouldn’t recommend it for a production site. Works for me.
I needed to allow some clients to test a web app I’m working on. But I didn’t want to deploy the code to a server for now for different reasons (mainly memory constraints). So the solution was to setup a reverse proxy using apache to my local machine. Check out the code after the break
Here’s the VirtualHost I created:

  1. <VirtualHost *:80>
  2.     ServerName proj312.grat.in
  3.     ProxyPass / http://home-ip:18000/
  4.     ProxyPassReverse / http://home-ip:18000/
  5. </VirtualHost>

The problem is that my home-ip is not fixed. A Dynamic DNS setup is the fix that comes to mind first. But, I thought I would try something else: Reverse SSH Tunnel
I used the recipe and explanations in this article. Mostly, all I needed to do was the following:

  1. ssh -fNR 18000:localhost:8000 myserver

Where the 18000 is the port on the server, and 8000 is the port on the home machine. No harm in using the same port numbers, btw.

I then changed the VirtualHost configuration in apache on the server to read:

  1. <VirtualHost *:80>
  2.     ServerName proj312.grat.in
  3.     ProxyPass / http://127.0.0.1:18000/
  4.     ProxyPassReverse / http://127.0.0.1:18000/
  5. </VirtualHost>

Restart apache on the server and all falls in place perfectly.

]]> http://funinc.org/20111229/apache-reverse-proxy-ssh-reverse-tunnel/feed 0 Suspend Ubuntu Desktop http://funinc.org/20111227/suspend-ubuntu-desktop http://funinc.org/20111227/suspend-ubuntu-desktop#comments Tue, 27 Dec 2011 12:06:25 +0000 abdallah http://funinc.org/?p=323 Simple command line: pm-suspend
An interesting alternative would be: pm-suspend-hybrid

From the man page:

pm-suspend-hybrid
Hybrid-suspend is the process where the system does everything it needs to hibernate, but suspends instead of shutting down. This means that your computer can
wake up quicker than for normal hibernation if you do not run out of power, and you can resume even if you run out of power. s2both(8) is an hybrid-suspend
implementation.

Background story: Electricity problems in Lebanon, and old UPS, causing me plenty of headaches. So I needed a quick way to suspend/hibernate the desktop without loosing all my volatile settings and open files. I added a shortcut for a ConnectBot host configuration on my android phone that runs this command on the desktop (remotely): sudo pm-suspend-hybrid
This way if the backup generator starts in time or not, everything is back up and running in under 45s12s (just clocked it!).

]]> http://funinc.org/20111227/suspend-ubuntu-desktop/feed 0 Quick SSH Tunnel using Putty http://funinc.org/20111221/quick-ssh-tunnel-using-putty http://funinc.org/20111221/quick-ssh-tunnel-using-putty#comments Wed, 21 Dec 2011 13:27:56 +0000 abdallah http://funinc.org/?p=314 Two easy steps to create a tunnel from a remote server port to your localhost. It’s handy if you’re trying to connect to a mysql, jboss, etc. installation bound to localhost only (for better security. Check out the screenshots after the break

1- Add the remote server’s information (Session)

2- Add the tunnel information (Connection – SSH – Tunnels)

You need to edit the Source port and Destination then click the “Add” button.

This should be enough. Either go back to the “Session” screen and save the configuration for later. Or simply click “Open” to get started.

Creating an SSH tunnel or forwarding ports is pretty easy when you’re on a Linux machine. Simply type the following in the shell:

  1. ssh -fLN 8080:127.0.0.1:8080 myserver.tld

Where the first 8080 is the local port and the second 8080 is the port on the server.

Practically, let’s say you have a glassfish installation on your server at 10.0.10.15. You cannot access the admin port 8484 on that server as it’s by default bound to localhost only. So, you can create a tunnel using the following command and access the glassfish admin site as if it’s on the local machine at http://127.0.0.1:8484/:

  1. ssh -fLN 8484:127.0.0.1:8484 10.0.10.15
]]> http://funinc.org/20111221/quick-ssh-tunnel-using-putty/feed 0 Django Class-Based Generic Views http://funinc.org/20111220/django-class-based-generic-views http://funinc.org/20111220/django-class-based-generic-views#comments Tue, 20 Dec 2011 14:09:59 +0000 abdallah http://funinc.org/?p=306 After working with Paypouy on a quick project using the php-based, shared-hosting-friendly CodeIgniter, I’m back to the more familiar waters of Python/Django.

I was asked to create a small organizer/calendar type app for a client to be used mainly from a smart phone. The app seemed very straight forward, so I thought I’d rely on the generic views for most of the work.

Check out some of the code after the break
Here’s a bit of code:

  1. # urls.py
  2. from django.conf.urls import patterns, include, url
  3. from django.views.generic import ListView, DetailView
  4. from app.views import \
  5.     CalendarView, DeleteCalView, UpdateCalView, CreateCalView
  6.  
  7. urlpatterns = patterns(”,
  8.     url(r‘^calendar/create/$’, CreateCalView.as_view(), name="cal_create"),
  9.     url(r‘^calendar/(?P<slug>[0-9]+)/$’, DetailView.as_view(model=Presentation, slug_field=‘number’), name=‘presentation’),
  10.     url(r‘^calendar/$’, ListView.as_view(model=Presentation, context_object_name=‘presentation’), name=‘presentation_list’),
  11.     url(r‘^calendar/upcoming/$’, CalendarView.as_view(), {‘as’: ‘upcoming’}, name=‘upcoming’),
  12.     url(r‘^calendar/presented/$’, CalendarView.as_view(), {‘as’: ‘presented’}, name=‘presented’),
  13.     url(r‘^calendar/unconfirmed/$’, CalendarView.as_view(), {‘as’: ‘unconfirmed’}, name=‘unconfirmed’),
  14.     url(r‘^calendar/confirm/(?P<pk>[0-9]+)/$’, UpdateCalView.as_view(), {‘as’: ‘confirm’}, name="cal_confirm"),
  15.     url(r‘^calendar/delete/(?P<pk>[0-9]+)/$’, DeleteCalView.as_view(), name="cal_del"),
  16. )

and some code from the Views:

  1. # views.py
  2. class CalendarView(ListView):
  3.     template_name = "calendar/calendar.html"
  4.    
  5.     def get_queryset(self):
  6.         called_as = self.kwargs[‘as’]
  7.         if (called_as in ["home", "upcoming"]):
  8.             return Calendar.objects.order_by(‘scheduled_on’).filter(scheduled_on__gt=datetime.now())
  9.         if (called_as=="presented"):
  10.             return Calendar.objects.order_by(‘scheduled_on’).filter(scheduled_on__lt=datetime.now(), status="P")
  11.         if (called_as=="unconfirmed"):
  12.             return Calendar.objects.order_by(‘scheduled_on’).filter(scheduled_on__gt=datetime.now(), status="R")
  13.        
  14.     def get_context_data(self, **kwargs):
  15.         called_as = self.kwargs[‘as’]
  16.         context = super(CalendarView, self).get_context_data(**kwargs)
  17.         if (called_as in ["home", "upcoming"]):
  18.             context[‘title’] = "Upcoming Presentations"
  19.         if (called_as=="presented"):
  20.             context[‘title’] = "Done"
  21.         if (called_as=="unconfirmed"):
  22.             context[‘title’] = "Unconfirmed Presentations"
  23.             context[‘actions’] = [‘confirm’, ‘delete’]
  24.         return context
  25.        
  26. class DeleteCalView(DeleteView):
  27.     model = Calendar
  28.     template_name = "calendar/delete.html"
  29.     success_url = "/"
  30.    
  31. class UpdateCalView(UpdateView):
  32.     model = Calendar
  33.     template_name = "calendar/update.html"
  34.     success_url = "/"
  35.    
  36.     def get_context_data(self, **kwargs):
  37.         called_as = self.kwargs[‘as’]
  38.         context = super(UpdateCalView, self).get_context_data(**kwargs)
  39.         if (called_as=="confirm"):
  40.             context[‘confirm_form’] = True  
  41.         return context
  42.        
  43. class CreateCalView(CreateView):
  44.     model = Calendar
  45.     template_name = "calendar/update.html"
  46.     success_url = "/"
  47.    
  48.     def get_initial(self):
  49.         initial = super(CreateView, self).get_initial()
  50.         initial = initial.copy()
  51.         initial[‘status’] = ‘R’
  52.         return initial
  53.  

I should mention that most of the code in the views.py could simply be removed and the equivalent added in the urls.py file. For example:

  1. class DeleteCalView(DeleteView):
  2.     model = Calendar
  3.     template_name = "calendar/delete.html"
  4.     success_url = "/"

could be replaced by editing the line in urls.py:

  1. url(r‘^calendar/delete/(?P<pk>[0-9]+)/$’,
  2.         DeleteView.as_view(model=Calendar, template_name="calendar/delete.html", success_url="/"),
  3.         name="cal_del"),

Note also that you can simply use the default template_name instead of adding your own (less code!).

Since the app would mostly be used from smart phones, I used jQueryMobile for most of the template work (and its DateBox plugin. Here’s a bit of code from that:

  1. <!– base.html>
  2. <head>
  3.         <link rel="stylesheet" href="/s/css/jquery.mobile-1.0.min.css" />
  4.         <link rel="stylesheet" href="/s/css/jquery.mobile.datebox.min.css" />
  5.         <script src="/s/js/jquery-1.7.1.min.js" ></script>
  6.         <script src="/s/js/jquery.mobile-1.0.min.js" ></script>
  7.         <script src="/s/js/jquery.mobile.datebox.min.js" ></script>
  8. <meta name="viewport" content="width=device-width, initial-scale=1">
  9.     </head>
  10.     <body>
  11.         <div data-role="page">
  12.             <div data-role="header">
  13.             {% block header %}{% endblock %}
  14.                 <div data-role="navbar">
  15.                     <ul><li><a href="{% url home %}" data-icon="home">Calendar</a></li>
  16.                         <li><a href="{% url cal_create %}" data-icon="plus" data-rel="dialog">Add</a></li></ul>
  17.                 </div>
  18.             </div>
  19.             <div data-role="content">
  20.             {% block content %}{% endblock %}
  21.             </div>
  22.                    </div>
  23.     </body>
  24.  

and the listing:

  1. {% extends "base.html" %}
  2. {% block header %}<h2>{{ title|default:"Presentations" }}</h2>{% endblock %}
  3.  
  4. {% block content %}
  5.     <div data-role="controlgroup" data-type="horizontal">
  6.         <a href="{% url presented %}" data-role="button">Presented</a>
  7.         <a href="{% url upcoming %}" data-role="button">Upcoming</a>
  8.         <a href="{% url unconfirmed %}" data-role="button">Unconfirmed</a>
  9.     </div>
  10.     <ul data-role="listview" data-inset="true" data-filter="true">
  11.         {% regroup object_list by presented_on|date:"F" as objects_by_month %}
  12.         {% for o in objects_by_month %}
  13.             <li data-role="list-divider">{{ o.grouper }}</li>
  14.             {% for c in o.list %}
  15.             <li>
  16.                 <a href="{% url cal_confirm c.pk %}" data-rel="dialog">
  17.                     <p>{{ c.scheduled_on }}</p><h3>{{ c.title }}</h3>
  18.                     <p>{{ c.speaker }}</p>
  19.                 </a>
  20.             </li>
  21.             {% endfor %}
  22.         {% endfor %}
  23.     </ul>
  24. {% endblock %}

It’s good to be back. And the project was fun and apparently very useful. In the spirit of agile development, the first iteration took about 3 hours to complete. I am still waiting for feedback to get started on the next one (should be related to hooking Google Calendar to the app).

]]> http://funinc.org/20111220/django-class-based-generic-views/feed 0 Safely Rebooting RimuHosting VPS (via API) http://funinc.org/20111026/safely-rebooting-rimuhosting-vps-via-api http://funinc.org/20111026/safely-rebooting-rimuhosting-vps-via-api#comments Wed, 26 Oct 2011 10:18:07 +0000 abdallah http://funinc.org/?p=300 First, get the API keys from the control panel at https://rimuhosting.com/cp/apikeys.jsp
API Keys page

The documentation for the API can be found here

So to reboot, I use the following script:

  1. #!/bin/bash
  2. APIKEY=00000000000000000000000000
  3. VPSOID=0000000
  4. VPSNAME=whatever
  5. curl -H "Content-Type: application/json" -H "Accept: application/json" -H "Authorization: rimuhosting apikey=$APIKEY" -X PUT -d ‘{"reboot_request": {"running_state": "RESTARTING"}}’ https://rimuhosting.com/r/orders/order-$VPSOID-$VPSNAME/vps/running-state

That seems to be much safer than running: sudo reboot

]]> http://funinc.org/20111026/safely-rebooting-rimuhosting-vps-via-api/feed 0 Using ePubLib for Android http://funinc.org/20111012/using-epublib-for-android http://funinc.org/20111012/using-epublib-for-android#comments Wed, 12 Oct 2011 09:01:15 +0000 abdallah http://funinc.org/?p=299 I’m rewriting the Examine the Scriptures Daily android app. With the ESD files published as ePub files it’s easier to get the data now, and it will allow more languages to be supported without the hassle of converting from WTLib.

Here’s the code snippet I’m using to read the ePub book. The library I’m using is ePubLib, and I’m displaying the page in a standard WebView:

  1.    // Load the book and get a specific date
  2.     AssetManager assetManager = getAssets();
  3.     try {
  4.         // find InputStream for book
  5.         InputStream epubInputStream = assetManager.open("es12_E.epub");
  6.         // Load Book from inputStream
  7.         this.book = (new EpubReader()).readEpub(epubInputStream);
  8.         getSpecificdate("2012-12-1");
  9.     } catch (IOException e) {
  10.         Log.e("epublib", e.getMessage());
  11.     }
  12.  
  13.     private void getSpecificdate(String day) {
  14.         Date d;
  15.         int dayOfMonth;
  16.         int monthOfYear;
  17.         Calendar cal = Calendar.getInstance();
  18.         try {
  19.             d = dateFormat.parse(day);
  20.             cal.setTime(d);
  21.             String hrefDate = hrefFormat.format(d).toUpperCase();
  22.             dayOfMonth=cal.get(Calendar.DAY_OF_MONTH);
  23.             monthOfYear=cal.get(Calendar.MONTH);
  24.             hrefDate += (dayOfMonth==1) ? ".xhtml" : "-split"+dayOfMonth+".xhtml";
  25.             hrefDate = dblzero.format(monthOfYear+4)+hrefDate.substring(2);
  26.            
  27.             // Here’s the part you’re looking for
  28.             Resource r = this.book.getResources().getByHref(hrefDate);
  29.             WebView wv = (WebView) findViewById(R.id.webView1);
  30.             String data = new String( r.getData() );
  31.             wv.loadDataWithBaseURL("file:///android_asset/", data, "text/html", "utf-8", null);
  32.         } catch (ParseException e) {
  33.             e.printStackTrace();
  34.         }
  35.        
  36.     }
]]> http://funinc.org/20111012/using-epublib-for-android/feed 6 Android Plugin for Eclipse Hanging http://funinc.org/20111005/android-plugin-for-eclipse-hanging http://funinc.org/20111005/android-plugin-for-eclipse-hanging#comments Wed, 05 Oct 2011 08:59:36 +0000 abdallah http://funinc.org/?p=297 For a couple of weeks now I have been trying to get the Android Plugin for Eclipse to play nicely on my new 64bit Ubuntu 11.10.
It was always hanging without a good explanation. The only message I got was “Loading Data for Android 2.3.3″ and it reaches 100% but stays there.

I thought it was related to the fact that I’m using the latest Indigo (3.7) eclipse, but that wasn’t it (I tried with earlier versions). I also thought it was because of the 64bit java I installed separately (not using apt). That wasn’t it either (the apt installed version didn’t work either). Stupid solutions, I know, but I had to try!

The solution was to rename the SDK directory and remove the _x64 from the end of that. After that, I set it in Windows -> Preferences -> Android -> SDK location and applied the changes and voila! It works now.

I’ll be fixing the ESD app based on some kind feedback from friends. And maybe work on other pending projects as well. Stay tuned.

]]> http://funinc.org/20111005/android-plugin-for-eclipse-hanging/feed 0 Recovering from a failed RAID drive http://funinc.org/20110928/recovering-from-a-failed-raid-drive http://funinc.org/20110928/recovering-from-a-failed-raid-drive#comments Wed, 28 Sep 2011 08:31:44 +0000 abdallah http://funinc.org/?p=296 I was trying to mount one of the disks from a failed RAID array. The disk was put in a USB enclosure and hooked to the machine. Here’s what I saw:

  1. srv0:~# mount /dev/sdc3 /mnt/usb/
  2. mount: unknown filesystem type ‘mdraid’
  3. srv0:~# mdadm –examine /dev/sdc
  4. mdadm: No md superblock detected on /dev/sdc.

I panicked a little, then tried the following that worked:

  1. srv0:~# mount /dev/sdc3 /mnt/usb/ -o ro -t ext3
  2. srv0:~# ls /mnt/usb
  3. bin   dev   etc   initrd.img  lib64   media  opt   root  selinux  sys  usr  vmlinuz
  4. boot  home  lib       lost+found  mnt    proc  sbin  srv      tmp  var
]]> http://funinc.org/20110928/recovering-from-a-failed-raid-drive/feed 0 Django uWSGI and Nginx on Ubuntu 11.10 http://funinc.org/20110923/django-uwsgi-and-nginx-on-ubuntu-11-10 http://funinc.org/20110923/django-uwsgi-and-nginx-on-ubuntu-11-10#comments Fri, 23 Sep 2011 17:12:45 +0000 abdallah http://funinc.org/?p=294 I’m working my way through installing my simple django app on a new Ubuntu machine using the components mentioned above.

So far, here’s what I’ve done:

  • apt-get install nginx-full
  • apt-get install uwsgi uwsgi-plugin-python
  • installed django from svn described in the docs

The nginx configuration can be found in /etc/nginx/sites-available/default. Of course, it’s best to make a copy of that file and edit it for the site/app I’m working on. Here’s what I put in it:

  1. server {
  2.     listen   80;
  3.     server_name sss.grat.in;
  4.     access_log /var/log/nginx/sss.grat.in-access.log;
  5.     location /media {
  6.         alias /home/sss/app/media/;
  7.     }
  8.     location /static {
  9.         alias /home/sss/app/static/;
  10.     }
  11.     location / {
  12.         uwsgi_pass unix:///var/run/sss.grat.in.sock;
  13.         include uwsgi_params;
  14.     }
  15. }

Now for the uWSGI configuration file. I created the file /etc/uwsgi/apps-available/sss.ini and added the following lines:

  1. [uwsgi]
  2. chdir = /home/sss/app
  3. pythonpath = /home/sss
  4. env = DJANGO_SETTINGS_MODULE=app.settings
  5. # load django
  6. module = django.core.handlers.wsgi:WSGIHandler()

it’s really just that. What took me so long was to figure out that in Debian/Ubuntu you have to install uwsgi-plugin-python, otherwise you’ll keep on getting weird error messages. Also, the default ini file has most of the settings (in /etc/default/uwsgi) so you should either read or edit that to make sure you’re getting all the right values.

]]> http://funinc.org/20110923/django-uwsgi-and-nginx-on-ubuntu-11-10/feed 1 Site ScreenShot Part 2 – Planning http://funinc.org/20110923/site-screenshot-part-2-planning http://funinc.org/20110923/site-screenshot-part-2-planning#comments Fri, 23 Sep 2011 12:16:51 +0000 abdallah http://funinc.org/?p=290 I was having a little conversation with my friend Ghassan from LebanonDesign and he mentioned his company was actually using something similar to SiteScreenShot to generate thumbnails for their different websites. So I thought I could scale my code to do the same. Of course, plenty of changes should be considered:

  • Snapshot generation currently takes 3-5 seconds to complete. So I need to do 2 things:
    • Tell the user that the app is actually working on generating the snapshot
    • Provide a way to retrieve the pic once the snapshot is generated
    • Make things go faster if possible
  • Getting more users means more load on the server, what should we use?
    • Replace Apache with Nginx for faster static file delivery
    • Use a queue manager like Celery/RabbitQM to distribute the load

I’m currently testing some code with django-celery and I’ll try to post more information here (so I can remember what I’m doing)

Also on my list is making the site accessible via a simple API.

I also need to research a better way to take the screenshots on a headless server.

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]]> http://funinc.org/20110923/site-screenshot-part-2-planning/feed 0