VI mode indicator in ZSH prompt

Here is my take on VI mode indicator in zsh’s prompt. This is useful only for people who use the vi mode (bindkey -v) in ZSH.

vim_ins_mode="%{$fg[cyan]%}[INS]%{$reset_color%}"
vim_cmd_mode="%{$fg[green]%}[CMD]%{$reset_color%}"
vim_mode=$vim_ins_mode

function zle-keymap-select {
  vim_mode="${${KEYMAP/vicmd/${vim_cmd_mode}}/(main|viins)/${vim_ins_mode}}"
  zle reset-prompt
}
zle -N zle-keymap-select

function zle-line-finish {
  vim_mode=$vim_ins_mode
}
zle -N zle-line-finish

# Fix a bug when you C-c in CMD mode and you'd be prompted with CMD mode indicator, while in fact you would be in INS mode
# Fixed by catching SIGINT (C-c), set vim_mode to INS and then repropagate the SIGINT, so if anything else depends on it, we will not break it
# Thanks Ron! (see comments)
function TRAPINT() {
  vim_mode=$vim_ins_mode
  return $(( 128 + $1 ))
} 

And then it’s a matter of adding ${vim_mode} somewhere in your prompt. For example like this:

RPROMPT='${vim_mode}'

Other examples on the web use zle reset-prompt in the zle-line-init, which has a very nasty side effect of deleting last couple of lines on mode change (when going from ins to cmd mode) when using multi-line prompt. Using zle-line-finish works around that.

Also see my current ~/.zshrc, which includes those tweaks (and many others!).

ZSH vi mode with emacs keybindings

This is my attempt at bringing emacs-style keybindings to vi mode in ZSH:

# VI MODE KEYBINDINGS (ins mode)                                      
bindkey -M viins '^a'    beginning-of-line                            
bindkey -M viins '^e'    end-of-line                                  
bindkey -M viins '^k'    kill-line                                    
bindkey -M viins '^r'    history-incremental-pattern-search-backward  
bindkey -M viins '^s'    history-incremental-pattern-search-forward   
bindkey -M viins '^p'    up-line-or-history                           
bindkey -M viins '^n'    down-line-or-history                         
bindkey -M viins '^y'    yank                                         
bindkey -M viins '^w'    backward-kill-word                           
bindkey -M viins '^u'    backward-kill-line                           
bindkey -M viins '^h'    backward-delete-char                         
bindkey -M viins '^?'    backward-delete-char                         
bindkey -M viins '^_'    undo                                         
bindkey -M viins '^x^r'  redisplay                                    
bindkey -M viins '\eOH'  beginning-of-line # Home                     
bindkey -M viins '\eOF'  end-of-line       # End                      
bindkey -M viins '\e[2~' overwrite-mode    # Insert                   
bindkey -M viins '\ef'   forward-word      # Alt-f                    
bindkey -M viins '\eb'   backward-word     # Alt-b                    
bindkey -M viins '\ed'   kill-word         # Alt-d                    
                                                                      
                                                                      
# VI MODE KEYBINDINGS (cmd mode)                                      
bindkey -M vicmd '^a'    beginning-of-line                            
bindkey -M vicmd '^e'    end-of-line                                  
bindkey -M vicmd '^k'    kill-line                                    
bindkey -M vicmd '^r'    history-incremental-pattern-search-backward  
bindkey -M vicmd '^s'    history-incremental-pattern-search-forward   
bindkey -M vicmd '^p'    up-line-or-history                           
bindkey -M vicmd '^n'    down-line-or-history                         
bindkey -M vicmd '^y'    yank                                         
bindkey -M vicmd '^w'    backward-kill-word                           
bindkey -M vicmd '^u'    backward-kill-line                           
bindkey -M vicmd '/'     vi-history-search-forward                    
bindkey -M vicmd '?'     vi-history-search-backward                   
bindkey -M vicmd '^_'    undo                                         
bindkey -M vicmd '\ef'   forward-word                      # Alt-f    
bindkey -M vicmd '\eb'   backward-word                     # Alt-b    
bindkey -M vicmd '\ed'   kill-word                         # Alt-d    
bindkey -M vicmd '\e[5~' history-beginning-search-backward # PageUp   
bindkey -M vicmd '\e[6~' history-beginning-search-forward  # PageDown 

You know, so that your muscle memory can rest in peace. Also see the commit adding the above emacs style keybindings to my dotfiles.

Testing CSRF protection in Rails

Ever wanted to test your CSRF protection in a Rails app? For example, in a situation when you have a custom “remember me” cookie set and you need to overwrite Rails’ handle_unverified_request to clear it so it does not open a big security hole in your app? I know I did and it took me a while to find out how to do that, so I figured it would be good to write about it.

Here’s how to do it (in Test::Unit, but it’s the same for RSpec):

setup do                                                           
  # Enable CSRF protection in this test                            
  ActionController::Base.allow_forgery_protection = true           
end                                                                
                                                                   
teardown do                                                        
  # Disable CSRF protection for all other tests                    
  ActionController::Base.allow_forgery_protection = false          
end                                                                

Adding the above will make it so that the authenticity_token is added to each generated <form> element and will be required to be sent with each non GET request.

Heroku memory quota killing machine

When I was migrating a suite of Exvo apps to Heroku‘s Cedar stack I’ve noticed a very strange behaviour. For two apps during first “run” the main process spun out of control, trying to consume way too much memory. After doing a manual restart everything went back to normal and the problem was basically gone (we haven’t seen it reoccuring).

Here is the log of such an out of control worker:

2012-04-02T11:52:32+00:00 heroku[worker.1]: Process running mem=550M(107.5%)
2012-04-02T11:52:32+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:52:52+00:00 heroku[worker.1]: Process running mem=811M(158.5%)
2012-04-02T11:52:52+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:53:12+00:00 heroku[worker.1]: Process running mem=858M(167.7%)
2012-04-02T11:53:12+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:53:32+00:00 heroku[worker.1]: Process running mem=1099M(214.8%)
2012-04-02T11:53:32+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:53:52+00:00 heroku[worker.1]: Process running mem=1539M(300.6%)
2012-04-02T11:53:52+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:54:12+00:00 heroku[worker.1]: Process running mem=1580M(308.7%)
2012-04-02T11:54:12+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:54:32+00:00 heroku[worker.1]: Process running mem=1709M(333.8%)
2012-04-02T11:54:32+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:54:53+00:00 heroku[worker.1]: Process running mem=2115M(413.1%)
2012-04-02T11:54:53+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:55:13+00:00 heroku[worker.1]: Process running mem=2301M(449.6%)
2012-04-02T11:55:13+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:55:33+00:00 heroku[worker.1]: Process running mem=2302M(449.6%)
2012-04-02T11:55:33+00:00 heroku[worker.1]: Error R14 (Memory quota exceeded)
2012-04-02T11:55:53+00:00 heroku[worker.1]: Process running mem=2747M(536.6%)
2012-04-02T11:55:53+00:00 heroku[worker.1]: Error R15 (Memory quota vastly exceeded)
2012-04-02T11:55:53+00:00 heroku[worker.1]: Stopping process with SIGKILL
2012-04-02T11:55:54+00:00 heroku[worker.1]: Process exited with status 137

This is just a worker, but I’ve observed the same for web processes as well. Be aware that as soon as your application starts serving R14/R15 errors it stops processing any new requests (they simply time out).

Previously: Introduction to Heroku H12 timeouts.

Compromised

This blog has been. But no more! Now restored from the dead (i.e. fresh installation and customization of the Kubrick template).

It seems that running and outdated WordPress installation is not a very bright idea. Who would have thought?

Oh WordPress and PHP…
how much I loathe thee!

Introduction to Heroku H12 timeouts

At Exvo we were experiencing problems while trying to send an email to all of our 150K+ users. This lead to a careful investigation of what is exactly happening during this process. So we setup our loggers (heroku logs -t | tee output.log), run heroku consoles, increased to 20 dynos and 10 workers and begun the sending process.

It all started with a POST request to send those emails:

app[web.10]: Started POST ...

Which timed out and there was no:

app[web.10]: Completed 200 OK ...

or similar log entry later on, just silence.

This is Heroku’s killing machine in action. It silently kills every process, which runs for longer than 30 seconds (we’re using the Bamboo stack). This is more or less how Heroku deals with long running requests. I don’t blame them for this behavior, even though I very much dislike it. But I digress.

When Heroku kills such process it does so in a very nice way, i.e. it lets it finish its business first. In other words the process will continue in the background and after finishing it will just die/stop/restart. Our email collecting job (selecting 150K users from the database…) run uninterrupted for over 40 minutes. So this is the good part.

The bad part is that when this killed process is still running in the background the dyno which it was connected to will stop serving new requests until this process finally dies, but Heroku will keep sending new requests to it! This is observed by the infamous H12 timeouts:

heroku[router]: Error H12 (Request timeout) -> GET auth.exvo.com/users/sign_in dyno=web.10 queue= wait= service=30000ms status=503 bytes=0

Also notice the 503 error code (Unavailable), which is returned by the Heroku router.

So this is really bad as all sorts of different/random web requests will just keep failing without you knowing what’s going on.

So while I greatly appreciate that Heroku lets such processes still run in the background, I really don’t like that it still keeps sending traffic their way.

PS: Yes, sending emails should be done as a background action by the Heroku workers. I know. But it’s not. Yet.

Ruby 1.9.2 via rvm installation woes

I’ve just had to upgrade Ruby to 1.9.2 (from 1.8.7) on the EC2 instance, but ran into a weird error while running rvm install 1.9.2:

Compiling yaml in /home/ubuntu/.rvm/src/yaml-0.1.4.
ERROR: Error running 'make ', please read /home/ubuntu/.rvm/log/ruby-1.9.2-p290/yaml/make.log
Installing yaml to /home/ubuntu/.rvm/usr
ERROR: Error running 'make install', please read /home/ubuntu/.rvm/log/ruby-1.9.2-p290/yaml/make.install.log

and in the log:

src/Makefile.am:2: Libtool library used but `LIBTOOL' is undefined
src/Makefile.am:2:   The usual way to define `LIBTOOL' is to add `AC_PROG_LIBTOOL'
src/Makefile.am:2:   to `configure.ac' and run `aclocal' and `autoconf' again.
src/Makefile.am:2:   If `AC_PROG_LIBTOOL' is in `configure.ac', make sure
src/Makefile.am:2:   its definition is in aclocal's search path.

Fortunately the solution was rather simple, although Google was not really that helpful this time, hence this post:

sudo aptitude install libtool

Basically the libtool library was not installed.