topamax once a day

MongoDB vs. Postgres; A specific use case

  

I’ve recently taken a job at Ansible working on the enterprise offering Tower. In case you don’t know, Tower is a front-end for your Ansible playbooks w/ enterprise permission management. I was tasked with evaluating our database needs for a new System Tracking feature that we released. Working remotely at the time forced me to create detailed presentations on my progress and evaluation. I ended up taking the internal presentations and created a blog post about the evaluation process.

http://www.ansible.com/blog/how-we-chose-mongodb-for-ansible-tower-system-tracking-feature

Devstack on EC2 via Ansible

  

So you want to get an instance of OpenStack running to poke around and see what all the fuss is about without going insane. Welcome to Devstack. Once Devstack is setup you will have access to a web-based control panel with prepopulated data and instances. You will also be able to explore the OpenStack API with v2.0 and v3 authentication (keystone).

devstack webpanel

devstack webpanel

Setup

git clone https://github.com/chrismeyersfsu/playbook-devstack
cd playbook-devstack/
sudo ansible-galaxy install -r requirements.yml

  • Create an ec2 elastic ip address and override the playbook variable ec2_elastic_ip.
  • Map a domain/subdomain in route53 (or other dns service) to your elasic ip address. (i.e. devstack.example.com)
  • Set your webportal login password by overriding the playbook variable nova_password

Execution

Be aware that the playbook may take > 20 minutes on an ec2 instance to complete.

ansible-playbook site.yml -i ‘devstack.example.com,’

When finished you should be able to visit http://devstack.example.com and login using demo / nova_password. You should then see the webpanel similar to the image above. The v2.0 and v3 APIs are accessabile via http://devstack.example.com:5000/v2.0/ and http://devstack.example.com:5000/v3/.

Debugging

So things maybe didn’t go according to plan. Here are some playbook invocation variations that you can be used to execute a subset of the tasks.

  • Do not provision a new ec2 instance. Only run the devstack install task.

ansible-playbook site.yml -i ‘devstack.testing.ansible.com,` -vvvv –tags “devstack_setup”

  • Do not provision a new ec2 instance nor run the devstack install task. Only run the vm instance creation tasks.

ansible-playbook site.yml -i ‘devstack.testing.ansible.com,` -vvvv –tags “devstack_nova”

Beaglebone + Ubuntu

  

We can install Ubuntu 2-ways.

  1. To the external SDCARD
  2. To the internal MMC

Installing to the internal MMC requires an SDCARD to install, but the sdcard is not required after that. The process is mostly the same. The MMC setup vs. the SDCARD setup depends on which image you download.

Installing Ubuntu


MMC: Download the latest file of the form BBB-eMMC-flasher-ubuntu-xx.xx-xxxx-xx-xx.img.xz
SDCARD: Download the latest file of the form ubuntu-12.10-console-armhf-xxxx-xx-xx.tar.xz

Extract the image

sudo apt-get install xz
xz -d *.img.xz

Insert the sdcard into your desktop and note the device path. In my case the device is at /dev/sdc.

meyers@mcbeefy:~/beaglebone$ dmesg
[ 1659.900631] usb 3-1: USB disconnect, device number 3
[ 2664.433700] usb 3-1: new high-speed USB device number 4 using xhci_hcd
[ 2664.709199] scsi7 : usb-storage 3-1:1.0
[ 2665.706903] scsi 7:0:0:0: Direct-Access Generic- SD/MMC 1.00 PQ: 0 ANSI: 0 CCS
[ 2665.707747] sd 7:0:0:0: Attached scsi generic sg3 type 0
[ 2666.334388] sd 7:0:0:0: [sdc] 15519744 512-byte logical blocks: (7.94 GB/7.40 GiB)
[ 2666.334770] sd 7:0:0:0: [sdc] Write Protect is off
[ 2666.334775] sd 7:0:0:0: [sdc] Mode Sense: 03 00 00 00
[ 2666.335066] sd 7:0:0:0: [sdc] No Caching mode page present
[ 2666.335071] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 2666.336660] sd 7:0:0:0: [sdc] No Caching mode page present
[ 2666.336667] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 2666.337339] sdc: sdc1 sdc2
[ 2666.338721] sd 7:0:0:0: [sdc] No Caching mode page present
[ 2666.338726] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 2666.338730] sd 7:0:0:0: [sdc] Attached SCSI removable disk
[ 2666.821868] EXT4-fs (sdc2): mounted filesystem with ordered data mode. Opts: (null)

Flash the image to the sdcard. Substitute <mmc_or_sdcard>.img and /dev/sdX accordingly.

sudo dd if=<mmc_or_sdcard>.img of=/dev/sdX bs=1M

Upon completion remove the sdcard and perform the following:

  • Ensure the beaglebone is off
  • If you plan on powering the beaglebone with usb, ensure the ethernet is unplugged.
  • Insert the sdcard into the beaglebone
  • Hold down the button that is by itself near the SDCARD
  • Insert the USB power or barrel jack power
  • Once the lights begin blinking blue you may release the button
  • Wait =~ 45 minutes until all the lights are blue 

Once all the lights turn solid blue the MMC is successfully flashed and you may power down your beaglebone (unplug the power), remove the sdcard. Wait a couple seconds, then plug the power back in and the system will boot Ubuntu.

Verifying Ubuntu Install

Find the ip of your beaglebone on your network.

meyers@mcbeefy:~$ sudo nmap -sP 192.168.1.*
Starting Nmap 5.21 ( http://nmap.org ) at 2013-06-30 14:13 EDT
Nmap scan report for 192.168.1.1
Host is up (0.00086s latency).
MAC Address: 00:23:69:0E:20:D7 (Cisco-Linksys)
Nmap scan report for 192.168.1.2
Host is up (0.076s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.103
Host is up (0.065s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.106
Host is up (0.00023s latency).
MAC Address: 3C:07:71:24:21:4B (Unknown)
Nmap scan report for 192.168.1.107
Host is up.
Nmap scan report for 192.168.1.112
Host is up (0.075s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.114
Host is up (0.062s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.116
Host is up (0.00072s latency).
MAC Address: C8:A0:30:B2:8E:5D (Unknown)
Nmap scan report for 192.168.1.118
Host is up (0.017s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap done: 256 IP addresses (9 hosts up) scanned in 6.18 seconds

ssh to your beaglebone.

ssh ubuntu@192.168.1.116
ubuntu@192.168.1.116′s password: temppwd

Raspberry Pi + MSP430 + SPI

  

This tutorial will explain how to communicate from the Raspberry Pi to an MSP430 Launchpad board (M430G2553 chip) using SPI.

Requirements

  • 1 Raspberry pi (running Raspbian)
  • 1 MSP430 TI Launchpad
  • 3 wires

Your raspberry pi should be running the newest version of Raspbian.  To ensure your system is up-to-date please download and run rpi-update.

Wiring

 

MSP430

Flash the below code to your MSP430 chip. Please see this tutorial for information on compiling and programming your MSP430.

MSP430 Code

Raspberry Pi

With your updated rasbian system you should have the drivers that you need. Now it’s time to load them.

modprobe spi_bcm2708
modprobe spidev

Check to be sure the modules loaded:

lsmod
Module Size Used by
spidev 5944 0
spi_bcm2708 5350 0
snd_bcm2835 21681 0
snd_pcm 81170 1 snd_bcm2835
snd_seq 59528 0
snd_timer 21602 2 snd_seq,snd_pcm
snd_seq_device 6924 1 snd_seq
snd 57427 5 snd_seq_device,snd_timer,snd_seq,snd_pcm,snd_bcm2835
snd_page_alloc 5343 1 snd_pcm
i2c_bcm2708 3822 0

Raspberry Pi Code

Save the below code as spidev_test.c on to your Raspberry Pi and compile it

gcc spidev_test.c -o spidev_test

Running

The MSP430 board LED1 will blink 3 times upon recognition of the SPI clock. After this initial sequence, when you SPI data “HELLO WORLD\n” to the MSP430 it will turn on the LED1 light.
On your Raspberry Pi run the previously compiled program. The -s options sets the frequency of the clock when performing the SPI communication.

sudo ./spidev_test -s 120000

Again, a successful sending of “HELLO WORLD\n” will be denoted by LED1 lighting up on the MSP430 board.

Raspberry Pi + Arduino + SPI

  

This tutorial will show you how to communicate from your raspberry pi to your arduino using 3-wire SPI.

Requirements

  • 1 Raspberry pi (running Raspbian)
  • 1 Arduino
  • 4 wires

Your raspberry pi should be running the newest version of Raspbian.  To ensure your system is up-to-date please download and run rpi-update.

Wiring

 

Arduino

Open your Arduino ide and flash the below code to your Arduino.

Arduino code

Raspberry Pi

With your updated rasbian system you should have the drivers that you need. Now it’s time to load them.

modprobe spi_bcm2708
modprobe spidev

Check to be sure the modules loaded:

lsmod
Module Size Used by
spidev 5944 0
spi_bcm2708 5350 0
snd_bcm2835 21681 0
snd_pcm 81170 1 snd_bcm2835
snd_seq 59528 0
snd_timer 21602 2 snd_seq,snd_pcm
snd_seq_device 6924 1 snd_seq
snd 57427 5 snd_seq_device,snd_timer,snd_seq,snd_pcm,snd_bcm2835
snd_page_alloc 5343 1 snd_pcm
i2c_bcm2708 3822 0

Raspberry Pi Code

Save the below code as spidev_test.c on to your Raspberry Pi and compile it

gcc spidev_test.c -o spidev_test

Running

Plug your Arduino to your desktop via the serial cable. Open the arduino Serial Monitor and set the bitrate to 115200. Now, on the Raspberry Pi, run the compiled code

sudo ./spidev_test

You should see HELLO WORLD print in the Arduino IDE Serial Monitor.

Debugging

    • Make sure that your kernel has the required drivers (spi-bcm2708.ko and spidev.ko)

pi@raspberrypi ~/spi $ ls -al /lib/modules/`uname -r`/kernel/drivers/spi/
total 64
drwxrwxr-x 2 pi pi 4096 Aug 10 10:53 .
drwxrwxr-x 23 pi pi 4096 Aug 10 10:53 ..
-rw-rw-r– 1 pi pi 14428 Aug 10 10:53 spi-bcm2708.ko
-rw-rw-r– 1 pi pi 10852 Aug 10 10:53 spi-bitbang.ko
-rw-rw-r– 1 pi pi 15803 Aug 10 10:53 spidev.ko
-rw-rw-r– 1 pi pi 10693 Aug 10 10:53 spi-gpio.ko

Thanks to Nick Gammon for the SPI slave code.

Thanks to Anton Vorontsov for the kernel Documentation spidev_test.c example code.