pastbedti.me » Mathias Stjernström

Change PATH environment with Rails and Capistrano

Mathias Stjernström — Wed, 01 Jun 2011 20:09:49 +0000

Note to self.

When deploying my RubyOnRails applications with Capistrano and I get errors like this one

1
2
3
4
5

servers: ["app.myserver.com"]
[app.myserver.com] executing command
** [out :: app.myserver.com] sh: bundle: command not found
command finished in 31ms
servers: ["app.myserver.com"] [app.myserver.com] executing command ** [out :: app.myserver.com] sh: bundle: command not found command finished in 31ms

Capistrano executes the commands in a very basic shell so the $PATH environment are not the same as when you login through SSH.

One way to solve this is by setting PermitUserEnvironment to yes in /etc/sshd_config and then add the correct PATH to ~/.ssh/environment

I just found another way that was much easier

In you config/deploy.rb add the following snippet

1
2
3

set :default_environment, {
'PATH' => "/opt/ruby-enterprise/bin/:$PATH"
}

Thats it!

Cheers!

Batch rename files with spaces in linux/bash

Mathias Stjernström — Wed, 20 Oct 2010 07:55:04 +0000

A reminder for myself how to batch rename files with spaces in bash.

This is how i rename files with space to have underscores instead. DO NOT blame me if this commando erases all your files I found several examples how to do this when googling but they all failed. Some of them did nothing and some erased half my filenames. SO IF YOU USE THIS, PLEASE TRY IT IN A FOLDER WITHOUT IMPORTANT FILES FIRST.

1	for f in ' '; do mv "$f" "`echo $f \| sed -e 's/ /_/g'`"; done

Cheers!

Nokogiri quote

Mathias Stjernström — Fri, 02 Apr 2010 20:12:14 +0000

I just have to share this funny quote from the nokogiri website (for those of you that does not know 鋸 it’s a reeeeeeeeaaally good and fast HTML, XML, SAX, and Reader parser).

XML is like violence – if it doesn’t solve your problems, you are not using enough of it. – http://nokogiri.org/

Cheers!

Deploying a Sinatra app with Apache and Phusion Passenger a.k.a. mod_rack

Mathias Stjernström — Mon, 30 Nov 2009 22:01:30 +0000

My Sinatra + Apache + Passenger setup did not just run

Deploying a simple Sinatra rack application under Apache and Phusion Passenger turned out not work out of the box for me.

I already had a virtual host so I decided to deploy with passengers sub URI (sub URI documentation).

To make this work you’ll need Apache installed with Phusion Passenger setup (Passenger installation)

This is what I started with

This is my folders for the already existing website.

1
2
3
4

# Existing homedir
/home/my_web/
# Current webroot
/home/my_web/htdocs

Creating folders and files for Sinatra

The first thing you want to do is to create folders and files for Sinatra.

1	mkdir /home/my_web/sinatra

1
2
3
4
5
6

cd /home/my_web/sinatra
mkdir tmp
mkdir logs
mkdir public
touch app.rb
touch config.ru

Create symlink

Create a symbolic link from our current webroot to the new Sinatra app so that apache/passenger can find it.

1	ln -s /home/my_web/sinatra/public /home/my_web/htdocs/app

Creating the application

We also need a Sinatra application for this to work so lets fill those files.

File: config.ru

1
2
3
4
5
6
7
8
9
10
11

require 'app'

set :environment, ENV['RACK_ENV'].to_sym
set :app_file, 'app.rb'
disable :run

log = File.new("logs/sinatra.log", "a")
STDOUT.reopen(log)
STDERR.reopen(log)

run Sinatra::Application

File: app.rb

1
2
3
4
5
6
7
8
9
10
11

require 'rubygems'
require 'sinatra'

before do
# Strip the last / from the path
request.env['PATH_INFO'].gsub!(/\/$/, '')
end

get '' do
"Hello world"
end

Apache configuration

Now we need to setup apache so that it can find our Sinatra app and load it.

The only thing you need to do is add the following line to your existing VirtualHost block:

1	RackBaseURI /app

This line will tell passenger to look into our existing webroot for a symlink thats named app and which points to our rack app. (RackBaseURI documentation)

Virtual host entry

1
2
3
4
5
6
7
8
9
10
11
12

<VirtualHost *:80>
ServerName www.example.com
ServerAlias example.com
DocumentRoot /home/my_web/htdocs/
RackBaseURI /app

<Directory "/home/my_web/htdocs/">
Order allow,deny
Allow from all
AllowOverride All
Directory>
VirtualHost>

The best part is that you are allowed to specify this option multiple times. So you can easily setup multiple apps under the same virtual host.

Cheers!

Grouping a timestamp field by date in Ruby On Rails / PostgreSQL

Mathias Stjernström — Sun, 08 Nov 2009 00:55:09 +0000

Recently I’ve been working a lot with dates and tonight I had a hard time finding information about how to group a model by date when the model only have a timestamp column.

Lets pretend we have a user model with a created_at attribute which is stored as a timestamp.

If we want to plot a simple graph showing signups per date this is the way to extract them:

1	User.count(:group => "DATE(created_at)")

Thats all there is to it. From this you will get an OrderedHash containing the date and count of users for each date.

One small thing to remember if you are using PostgreSQL. You will need the DATE() function in any ORDER/SELECT statements because PostgreSQL will only select/order by fields thats in the GROUP BY statement and this is a pretty healthy behavior that many databases (no names here) don’t care about. Think about it. If you are grouping all users by date and use * as selector how would the database know which username or email address to display?

This is what happens if you try to group by created_at without DATE() ->

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

>> User.count(:order => 'created_at DESC', :group => ["DATE(created_at)"])
ActiveRecord::StatementInvalid: PGError: ERROR: column "users.created_at" must appear in the GROUP BY clause or be used in an aggregate function
: SELECT count(*) AS count_all, DATE(created_at) AS date_created_at FROM "users" GROUP BY DATE(created_at) ORDER BY created_at DESC
from /tmp/app/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:212:in `log'
from /tmp/app/vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb:507:in `execute'
from /tmp/app/vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb:985:in `select_raw'
from /tmp/app/vendor/rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb:972:in `select'
from /tmp/app/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all_without_query_cache'
from /tmp/app/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:62:in `select_all'
from /tmp/app/vendor/rails/activerecord/lib/active_record/calculations.rb:255:in `execute_grouped_calculation'
from /tmp/app/vendor/rails/activerecord/lib/active_record/calculations.rb:132:in `calculate'
from /tmp/app/vendor/rails/activerecord/lib/active_record/calculations.rb:130:in `catch'
from /tmp/app/vendor/rails/activerecord/lib/active_record/calculations.rb:130:in `calculate'
from /tmp/app/vendor/rails/activerecord/lib/active_record/calculations.rb:48:in `count'
from (irb):18

And this is the right way to do it:

1
2

>> User.count(:order => 'DATE(created_at) DESC', :group => ["DATE(created_at)"])
=> #22, "2009-10-25"=>4, "2009-11-04"=>8, "2009-10-15"=>9, "2009-10-26"=>16, "2009-11-05"=>9, "2009-10-16"=>193, "2009-10-27"=>14, "2009-11-06"=>9, "2009-10-17"=>49, "2009-10-28"=>15, "2009-11-07"=>6, "2009-10-18"=>36, "2009-10-29"=>8, "2009-10-19"=>116, "2009-10-30"=>15>

As you may notice the Hash does not look ordered. But if you loop over it you will get them in order:

1
2
3
4
5
6
7
8
9
10
11
12

>> User.count(:order => 'DATE(created_at) DESC', :group => ["DATE(created_at)"]).each {|u| puts "#{u[0]} -> #{u[1]}" }
2009-11-07 -> 6
2009-11-06 -> 9
2009-11-05 -> 9
2009-11-04 -> 8
2009-11-03 -> 14
2009-11-02 -> 20
2009-11-01 -> 10
2009-10-31 -> 6
2009-10-30 -> 15
2009-10-29 -> 8
..

And thats how you group a timestamp field with just its date part.

Cheers!

5-10 second delay when launching Terminal.app in OSX

Mathias Stjernström — Fri, 11 Sep 2009 20:29:36 +0000

A couple of days ago my Terminal.app (console) got a really annoying feature. When launching the console or when I created a new tab it got stuck for about 5-10 seconds before I got my prompt.

If you are like me and are spending most of your time in Terminal.app you understand how annoying this is/was.

I tried to rename .profile, .inputrc and evey other startup script I had in my home folder but the problem did not go away.

Then I found an OSX user which had his Terminal crash when started. He solved his problem by cleaning up some OSX systemlogs. So I thought I try the same trick.

The logfiles which he removed where the asl files under /private/var/log/asl/

I read about them here: http://macosx.com/tech-support/can-i-deleteasl-log/24223.html

But I figured I’d just remove them all

1	sudo rm -rf /private/var/log/asl/*

When all asl files where removed my Terminal went back to normal again and I am sooooooo relieved.

This worked for me BUT I do not recommend you to remove anything if you do not know what you are doing!!!

Cheers!

Running couchdb under an unprivileged user account.

Mathias Stjernström — Fri, 10 Apr 2009 18:23:55 +0000

When helping a friend last night with couchdb a got stuck when trying to start it as an unprivileged user. The error messages you get from couchdb is far from easy to understand.

This is my way of solving it.

1
2
3
4
5
6
7

$ couchdb
kernel-poll not supported; "K" parameter ignored
Apache CouchDB 0.9.0 (LogLevel=info) is starting.
{"init terminating in do_boot",{{badmatch,{error,shutdown}},[{couch_server_sup,start_server,1},{erl_eval,do_apply,5},{erl_eval,exprs,5},{init,start_it,1},{init,start_em,1}]}}

Crash dump was written to: erl_crash.dump
init terminating in do_boot ()

Even with debug turned on it’s pretty hard to understand.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44

kernel-poll not supported; "K" parameter ignored
Apache CouchDB 0.9.0 (LogLevel=debug) is starting.
Configuration Settings ["./couchdb/local.ini"]:
[Couch] BindAddress="127.0.0.1"
[Couch] ConsoleStartupMsg="Apache CouchDB is starting."
[Couch] DbRootDir="/home/mathias/couchdb"
[Couch] DocumentRoot="/home/mathias/couchdb/www"
[Couch] LogFile="/home/mathias/couchdb/couch.log"
[Couch] LogLevel="debug"
[Couch] Port="5984"
[Couch] UtilDriverDir="/usr/local/lib/couchdb/erlang/lib/couch-0.8.1-incubating/priv/lib"
[Couch Query Servers] javascript="/usr/local/bin/couchjs /usr/local/share/couchdb/server/main.js"
[couchdb] database_dir="/home/mathias/couchdb"
[couchdb] view_index_dir="/home/mathias/couchdb"
[httpd] bind_address="127.0.0.1"
[httpd] port="5984"
[log] level="debug"
[error] [<0.41.0>] {error_report,<0.21.0>,
{<0.41.0>,crash_report,
[[{pid,<0.41.0>},
{registered_name,couch_server},
{error_info,
{exit,
{badarg,
[{erlang,list_to_integer,[undefined]},
{couch_server,init,1},
{gen_server,init_it,6},
{proc_lib,init_p_do_apply,3}]},
[{gen_server,init_it,6},{proc_lib,init_p_do_apply,3}]}},
{initial_call,{couch_server,init,['Argument__1']}},
{ancestors,[couch_primary_services,couch_server_sup,<0.1.0>]},
{messages,[]},
{links,[<0.36.0>]},
{dictionary,[]},
{trap_exit,false},
{status,running},
{heap_size,233},
{stack_size,23},
{reductions,113}],
[]]}}
{"init terminating in do_boot",{{badmatch,{error,shutdown}},[{couch_server_sup,start_server,1},{erl_eval,do_apply,5},{erl_eval,exprs,5},{init,start_it,1},{init,start_em,1}]}}

Crash dump was written to: erl_crash.dump
init terminating in do_boot ()

When running things as unprivileged users the usual problems are that you do not have access to read/write files or binding to the lower ports A.K.A. “well known ports”. With that in mind I located the original config files for couchdb with the plan of copying or overriding them.

My config files where located under /usr/local/etc/couchdb/

1
2
3

$ ls -lsa /usr/local/etc/couchdb/
4 -rw-r--r-- 1 root root 2626 2009-04-10 11:58 default.ini
4 -rw-r--r-- 1 root root 847 2009-04-10 14:17 local.ini

Reading the documentation I found out that local.ini is just for overriding stuff and local.ini will never be overwritten by any upgrades. The config files contain lots of settings, but my aim is just to get it to start so I focus on the things that I think is the problem and thats all the PATH settings.

In my unprivileged users home folder I created a folder named couchdb to hold my config and datafiles. I also created a www folder inside it.

After that I create my local.ini to override my settings:

1
2
3
4
5
6
7
8
9
10
11
12
13

$ cat couchdb/local.ini

[couchdb]
database_dir = ./couchdb
view_index_dir = ./couchdb

[httpd]
port = 5984
bind_address = 127.0.0.1

[log]
level = info
file=./couchdb/couch.log

When our new config is in place we can try to start couchdb again.

1 2	$ couchdb -C ./couchdb/local.ini -p ./couchdb/couch.pid -b Apache CouchDB has started, time to relax.

-C means use configuration FILE (chainable, does not reset system default). If we do not want to use the system config at all we can use a lowercase -c but we want to keep our overridden config as small as possible right now.

-p is the path to our pid file and -b tells couchdb to spawn in the background.

If you are on your local machine you can just launch your browser and point it to http://127.0.0.1:5984/

1	{"couchdb":"Welcome","version":"0.9.0"}

or you can access the admin gui trough: http://127.0.0.1:5984/_utils/index.html.

After I started to write this blogpost I did found a page on the Couchdb wiki that explains Error messages and solutions and here it is: http://wiki.apache.org/couchdb/Error_messages.

Happy haxxing!

I have this great device but I cannot use it, thanks to TeliaSonera!

Mathias Stjernström — Fri, 10 Apr 2009 12:25:22 +0000

The iPhone is a really great device. It lacks a few basic features that I misses from ericsson or nokia but overall it’s a really great device.

Where it really kicks ass is when you are out of town and need to find a location or restaurant. This have been great when I am still in the same country but earlier this week I when to Glasgow/scotland and the first thing you get is a welcome SMS from one of the local mobile network operators and here is when the problem arise.

The problem is that the SMS is more of a warning than a welcome message or even a HAHA-turn-roaming-on-and-we-gone-make-you-cry-message.

My problem here is the data traffic. They charge you 40 SEK/MB and that is almost $5/MB. So Starting my facebook application or loading some maps in the iPhone would cost me loooots of money. If I use it all day it would be cheeper to hire a private guide all day and this really pisses me off. The phone operators makes so much money on dataroaming that they have no reasons at all to change it. As long as they all agree and charge the same price. In sweden this is not even legal.

As a reference to the price we charge our customers (list price) 15 SEK / GB and thats almost $2 for ONE GB. We are a really small operator and we pay for all our traffic. The big operators like Telia/Orange/O2 and the rest they do not pay for all they traffic and probably they only pay for a small part of the traffic.

And what makes me even more angry is that I think that the operators will lose money in the end. If the price where not a rip-off I would have spent a couple of hundreds just to have the luxury of a GPS and my emails. But during my stay I did not roam a single time.

I REALLY RELLY HATE GREED!!!

Internet is a virtual share-your-stuff-machine.

Mathias Stjernström — Thu, 02 Apr 2009 14:43:47 +0000

I do not usually blog about this tuff. Hell I do not blog much at all But I think this was pretty cool.

Internet is a virtual share-your-stuff-machine.
On YouTube you share you creativity.
On Facebook you share you life.
On Second Life you share your dreams.
On Wikipedia you share you knowledge.
On Ebay you share your belongings.

Translated from a swedish blogpost reacting to the new Swedish IPRED law (http://micco.se/2009/03/delning-blir-en-multimiljardindustri/)

A pretty weak google translation of the page

Painful experience with rails InvalidAuthenticityToken

Mathias Stjernström — Mon, 23 Mar 2009 19:22:25 +0000

Today I had a really painful experience with rails InvalidAuthenticityToken. It turned out not to have anything to do with rails at all and there is where the painful part come in to play.

We had an application which needed a staging environment. When everything where setup and after the first deploy to the new environment everything seemed fine at first but when we tried to login we got these fine messages:

1
2
3
4
5
6
7
8
9
10

ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken):
/vendor/rails/actionpack/lib/action_controller/request_forgery_protection.rb:86:in `verify_authenticity_token'
/vendor/rails/activesupport/lib/active_support/callbacks.rb:178:in `send'
/vendor/rails/activesupport/lib/active_support/callbacks.rb:178:in `evaluate_method'
/vendor/rails/activesupport/lib/active_support/callbacks.rb:166:in `call'
/vendor/rails/actionpack/lib/action_controller/filters.rb:225:in `call'
/vendor/rails/actionpack/lib/action_controller/filters.rb:629:in `run_before_filters'
/vendor/rails/actionpack/lib/action_controller/filters.rb:615:in `call_filters'
/vendor/rails/actionpack/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark'
/vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'

After about two hours of troubleshooting the only problem left where that the browser did not get the cookie. We used telnet to check the headers and the cookie where there… ok, the browser is broken…. sure…

Then, finally it came to me… what if,… the hostname is broken? Broken hostname you tell me? Just for fun I changed the hostname and bada-bong bada-bing everything is working…. Now I get this creepy feeling of the big mistake I have made…

The thing is that I have worked with domains for many years and I know very well that you CANNOT have underscores in your domains. But my peanut brain do not think of subdomains as a domain-name. So we had a sub-domain with an underscore. Putting a underscore in the domainname makes Safari and some versions of Explorer not to accept cookies and that makes rails AuthenticityToken to treat me as a hacker….

As a punishment I will force myself to read RFC 1035 (http://tools.ietf.org/html/rfc1035).

Over and out….