Headless RaspberryPI Setup – No Monitor, Keyboard or Ethernet

window-1-197

And the day to revive my good old RaspberryPi Version 1 Model B has come.

As it always happens, I end up finding myself chasing tails trying to set it up without having to plug and keyboard, display or ethernet to it. I just expect that it can magically plug into my local WiFi and start the ssh server so I can remotely login.

So this time around, and as a future note to self, here’s how I got it to work with all the little quirks and weirdnesses that ended up wasting about 1hour of my life until it was up and running:

1. Download the Raspbian OS image.

This can easily be downloaded from the Raspbian website here.

At the time of this post, I ended up downloading Raspbian Stretch. Initially I went for the Lite version and in the end I used the Desktop version in the hope I wouldn’t have to ‘apt-get install‘ as much stuff.

Not a very scientific measurement, but the Desktop version seemed to boot up and connect to the WiFi a lot quicker than the Lite version. I didn’t have a monitor plugged so I honestly have no idea what was going on.

2. Flash the image onto your SD/MicroSD card.

For this you can use the Etcher.io app. It’s a very clean cross-platform application to flash images onto SD card. I was honestly very very happy to see someone finally took the time to implement a cross platform flasher. The days of ‘dd‘ seem to be over. ūüôā

3. Configure the /boot partition.

Whether you are on a Windows or on a Mac, once you’ve flashed the SD card your computer should be able to mount a partition called ‘boot‘.

3.1. To tell Raspbian to start the ssh server once it boots, you will need to create an empty file called ‘ssh’ inside the ‘boot’ partition.

3.2 In order to give Raspbian the WiFi credentials and SSID you want it to connect to you will need to create a file called ‘wpa_supplicant.conf’ in the same ‘boot’ partition. Here’s what you should write inside this file. Please make sure to update $SSID and $PASSWORD with the name and password of your WiFi:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
  ssid="$SSID"
  psk="$PASSWORD"
  key_mgmt=WPA-PSK
}

4. Boot your RaspberryPi.

Unmount the SD card from your computer and insert it into your RaspberryPi.

The  RaspberryPi Version 1 Model B I own does not have onboard WiFi so I purchased a WiFi USB dongle. Make sure that is connected as well before you turn on the RaspberryPi.

And finally, power on your RaspberryPi. This is the step where you will need to be very patient. When I booted the Lite image, it took minutes (>10min) until it finally connected to the WiFi and was available to be ssh’ed into.

5. When is it ready to be used?

I usually just leave a ping command running in a tight loop in my terminal and wait until the RaspberryPi starts returning valid pings. Here’s the bash command I use:

$ ping raspberrypi | while read pong; do echo "$(date): $pong"; done

And voil√°, you should be good to go. Now you just need to run the following command type ‘raspberry’ as the password:

$ ssh pi@raspberrypi

6. So how did I waste 1h trying to set this up?

Well, the RaspberryPi can be quite unforgiving and gives you basically no feedback.

Once you turn it on, the red LED for Power stays fixed and the SD card led flickers around a bit but then switches off… and that’s it… No feedback whether an error happened, whether it’s stuck waiting for input, whether it’s absolutely fine, just nothing…

In my first few attempts to boot it and connect it to WiFi I waited about 5min on each attempt to see it connect and when no new MAC address was registering with the router I just assumed something went wrong, read a little more on the Internet about potentially problems and retry again with a different tweak.

Eventually, I saw that it worked because I mostly gave up and went to bed. And after 10min+ the damn thing finally lit up the WiFi LED in the USB dongle and it managed to connect. So basically, coincidence. I was already planning to plug it via ethernet the next day, or, if all failed, just plug the damn HDMI+Keyboard and connect to it directly.

For some reason the Raspbian Desktop image boots up and turns WiFi a lot more quickly (a couple of minutes), so I will now on stick to that.

7. Useful links and documentation.

Here are a couple of links that helped me out understanding a little more what was going on. I also went through a couple of reddit threads but at this point I stand no chance in getting those links back.

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Upgrading Jawbone Mini Jambox

91tRcTlun7L._SL1500_This is a post for the unlikely event that you find yourself owning an old ‘Jawbone Jambox Mini‘ **and** you want to change the voice pack back to original/default, after you spent a couple of years using the Japanese one – a voice pack you don’t really understand but thought it would be entertaining to listen to a new voice when you turn on the speaker.

So Jawbone went under in 2017 (https://en.wikipedia.org/wiki/Jawbone_(company)) so not an awful lot of hopes they will provide any new software or update the old one.

To make it a little gloomier, their website was completely taken down and they never really open sourced the code for their hardware nor did they post to some third-party website the last state of all the software for their products.

Luckily, before Jawbone’s website was completely taken down, Robert decided to capture all the latest software and posted it elsewhere with instructions on how to update. You can find all the goodies here:

NOW A WORD OF ADVICE!!

I use a macbook and I can confirm that if you try to use the Mac Jawbone Updater 2.2.5 to update/change the language pack of your Jawbone Mini Jambox, the upgrade will fail and you will end up with a bricked speaker. ūüė¶

The good news is that this is recoverable. Here’s how to do it:

  1. Unplug the Mini Jambox.
  2. Power down the Mini Jambox.
  3. Press and hold the Play/Pause button (circular button on top).
  4. While still holding the button, plug the Mini Jambox to a power source.
  5. Voil√°, your Jambox should now be in recovery mode and you can flash it/upgrade it with a new language package.

In order to properly upgrade the language pack of your Jawbone Mini Jambox you should be running on Windows and use the Windows “Jawbone Updater.exe”. I did try initially doing this via VMWare Fusion, running a Windows 8.1 VM inside my Mac OS X. That does not work.

You need to run the Jawbone Updater software from a native Windows operating system (no VMs involved).

And that’s it, your Jawbone Mini Jambox is good to go for a little longer.

Hadoop/Hive – Writing a Custom SerDe (Part 1)

(Special thanks to Denny Lee for reviewing this)

Apache Hadoop is an open source project composed of several software solutions for distributed computing. One interesting component is Apache Hive that lets one leverage the MapReducing powers of Hadoop through the simple interface of HiveQL language. This language is basically a SQL lookalike that triggers MapReduces for operations that are highly distributable over huge datasets.

A common hurdle once a company decides to use Hadoop and Hive is: “How do we make Hadoop understand our data formats.”. This is where the Hadoop SerDe terminology kicks in. SerDe is nothing but a short form for Serialization/Deserialization. Hadoop makes available quite a few Java interfaces in its API to allow users to write their very own data format readers and writers.

Step by step, one can make Hadoop and Hive understand new data formats by:
1) Writing format readers and writers in Java that call Hadoop APIs.
2) Packaging all code in a java library – eg., MySerDe.jar.
3) Adding the jar to the Hadoop installation and configuration files.
4) Creating Hive tables and explicitly set the input format, the output format and the row format.

Before diving into the Hadoop API and Java code it’s important to explain what really needs to be implemented. For concisiveness of terms I shall refer to row as the individual unit of information that will be processed. In the case of good old days SQL databases this indeed maps to a table row. However our datasource can be something as simple as Apache logs. In that case, a row would be a single log line. Other storage types might take complex message formats like Protobuf Messages, Thrift Structs, etc… For any of these, think of the top-level struct as our row. What’s common between them all is that inside each row there will be sub-fields (columns), and those will have specific types like integer, string, double, map, …

So going back to our SerDe implemention, the first thing that will be required is the row deserializer/serializer (RowSerDe). This java class will be in charge of mapping our row structure into Hive’s row structure. Let’s say each of our rows corresponds to a java class (ExampleCustomRow) with the three fields:

  1. int id;
  2. string description;
  3. byte[] payload;

The RowSerDe should be able to mirror this row class and their properties into Hive’s ObjectInspector interface. For each of our types it’ll find and return the equivalent type in the Hive API. Here’s the output of our RowSerDe for this example:

  1. int id -> JavaIntObjectInspector
  2. string description -> JavaStringObjectInspector
  3. byte[] payload -> JavaBinaryObjectInspector
  4. class ExampleCustomRow -> StructObjectInspector

In the example above, the row structure is very flat but for examples where our class contains others classes and so forth, the RowSerDe needs to be able to recursively reflect the whole structure into Hive API objects.

Once we have a way of mapping our rows into hadoop rows, we need to provide a way for hadoop to read our files or databases that contain multiple rows and extract them one by one. This is done via de Input and Output format APIs. A simple format for storing multiple rows in a file would be separating them by newline characters (like comma separated files do). An Input reader in this case would need to know how to read a byte stream and single out byte arrays of individual lines that would later be fed into to our custom SerDe class.

As you can probably imagine by now, the Output writer needs to do exactly the opposite: it receives the bytes that corresponds to each line and it knows how to append them and separate them (by newline characters) in the output byte stream.

How an Hadoop MapReduce interacts with a custom SerDe for Hive.
How an Hadoop MapReduce interacts with a custom SerDe for Hive.

Summarizing, in order to implement a complete SerDe one needs to implement:
1) The Hive Serde interface (contains both the Serializer and Deserializer interfaces).
2) Implement the InputFormat interface and the OutputFormat interface.

In the next post I’ll take a deep dive into the actual Hadoop/Hive APIs and Java code.
(Two years have gone by and I unfortunately never got round to writing anything else. Probably, anything I would write now would be outdated so I would encourage anyone who has questions to try to ping me directly or just ask directly the the hive community)

Como reparar o seu computador

Há uns tempos atrás o venerável jovem do xkcd teve um rasgo de brilhantismo ao descrever no post abaixo a típica situação pela qual o comum informático passa vezes sem conta.

Como achei que era uma perda enorme t√£o bom diagrama n√£o chegar √† comunidade n√£o inform√°tica portuguesa, onde o diagrama seria claramente mais¬†√ļtil resolvi traduzi-lo para Portugu√™s. Aqui¬†¬†vai o link para uma imagem com resolu√ß√£o aceit√°vel para imprimirem e colocarem na parede do vosso escrit√≥rio.

apoio_tecnico

SimplePhoto version 1.0.0

simplephoto-150x150Finally, after almost a year battling away with wxWidgets, GraphicsMagick, gcc, Visual Studio, CppUnitLite, … I finally get to release version 1.0.0 of SimplePhoto.

SimplePhoto is a batch processing application for images. For the time being it allows image format, image dimensions and groupings.

My main focus for this application was to make it’s memory footprint as little as possible. It’s been implemented in C++ and on Windows it takes around 5MB of memory when running. There are still loads of features to implement but I really wanted to get this out there ASAP. Next step is to open source it (probably hosting it at code.google.com).

Have fun!

Finding magic.mgk in a deployed Mac app

After a lot of frustration I decided that the best way to have GraphicsMagick/ImageMagick finding the required magic.mgk file inside YourApp.app/Contents/Resources is to patch the image library code.

The change is quite trivial and I’ve pasted the diff below. This patch was applied to GraphicsMagick version 1.3.7. Basically it uses the path provided via magick::InitializeMagick(“executable/path”) to find Contents/Resources. Have fun!!!

diff -r 152043af6bf4 magick/blob.c
--- a/magick/blob.c	Wed Nov 18 00:05:49 2009 +0000
+++ b/magick/blob.c	Wed Nov 18 00:29:25 2009 +0000
@@ -1741,6 +1741,18 @@
 #endif /* !defined(UseInstalledMagick) */
 
 
+
+  {
+		// ruibm added
+		
+		char buffer[2048];
+		sprintf(buffer, "%s/../Resources/", GetClientPath());
+		// printf("Adding [%s] to the search path.n", buffer);
+		AddConfigurePath(path_map,&path_index,buffer,exception);
+  }
+
+
+
   path_map_iterator=MagickMapAllocateIterator(path_map);
 
   if (logging)

Mac Application Deployment – dylib

Lately I’ve been battling away with the Mach-O binary file format. I am trying to create a Mac version of an application that depends on dylibs provided by wxWidgets and GraphicsMagick. I started this quest by finding out the hard way that mac binaries (libs and applications) store the path to their dylib dependencies in the binary itself. As you can imagine this is a big hassle for app deployment as you force every user wanting to install the app to have the same exact /usr/lib and /opt/local/lib as your machines does.

After a bit of scavenging in forums I found out that otool allows you to print the list of dependencies of a binary and that install_name_tool allows you to change them. Bearing this in mind I now wanted the simplest way I could get to change the list of dependencies both in my binary and inside all of its dependency dylibs. I ended up writing the python script below for this.

#!/usr/bin/python
# 
# Uses otool and install_name_tool to change a given path in the list of 
# dylib dependencies to another (hopefully relative) path to ease deployment.
# If this is applied to dylib files it will also change their ID.
#
# Author: Rui Barbosa Martins (ruibm@ruibm.com)

import os.path
import re
import subprocess
import sys

def RunCmd(cmd):
	obj = subprocess.Popen(cmd, shell=True, bufsize=42000, stdout=subprocess.PIPE)
	out = ""
	while (True) :
		content = obj.stdout.read()
		if content:
			out += content
		else:
			break
	ret_code = obj.wait()
	if ret_code == 0:
		return out
	else:
		return None
	
	
def GetDependencies(file):
	cmd = "otool -L " + file
	output = RunCmd(cmd)
	if not output:
		raise Exception("Problem running otool. [%s]" % (cmd))
	output = output.split("n")
	deps = list()
	for line in output:
		m = re.match("(.*)\(compatibility version.*", line);		
		if not m:
			continue
		dylib = m.group(1).strip()
		deps.append(dylib)
	return deps

	
def ChangeDependecies(file, dependencies, replaceFrom, replaceTo):
	print "Changing dependencies in %s" % (file)
	fname = os.path.basename(file)
	for d in dependencies:
		if not replaceFrom in d:
			continue
		
		new = d.replace(replaceFrom, replaceTo)
		if fname == os.path.basename(d):
			cmd = "install_name_tool -id %s %s" % (new, file)
			print "ID: %s -> %s" % (d, new)
		else:			
			cmd = "install_name_tool -change %s %s %s" % (d, new, file)
			print "Change: %s -> %s" % (d, new)
		RunCmd(cmd)
		

def main(argv) :
	if len(argv) != 4:
		print "Usage: %s [file] [replaceFrom] [replaceTo]" % (argv[0])
	file = argv[1]
	replaceFrom = argv[2]
	replaceTo = argv[3]
	deps = GetDependencies(file)
	ChangeDependecies(file, deps, replaceFrom, replaceTo)

if __name__ == "__main__":
	main(sys.argv)