Executing a task once locally, but copying to all remote hosts

[Robin Bowes]

Hi,

I'm using railsless deploy, and have this task to generate a config file
locally, and copy it to all hosts:

desc <<-DESC
Create config file & copy to release path
DESC
task :create_copy_config_file, :roles => [:web] do
print " Creating config file.\n"
file = 'files/counter.php'
system "scripts/create_config #{file}"
print " Copying config file.\n"
upload(file, "#{release_path}/www/counter.php")
end

I suspect that will re-create the config file once for every host?

If so, how would I just generate the config file once locally, then copy
to all hosts?

It's not so bad for this simple case but I have another task to write
that grabs ~200M of GeoIP updates and I only want to execute that once!

R.

[Lee Hambley]

You're doing it wrong, try this

def generate_config_file
     # implement me in pure, standard ruby!
     file_generated ||= system('script/system')
end

-- Lee Hambley

Twitter: @leehambley | @capistranorb

[Robin Bowes]

On 02/12/09 14:16, Lee Hambley wrote:
> You're doing it wrong, try this
>
> def generate_config_file
> # implement me in pure, standard ruby!
> file_generated ||= system('script/system')
> end

I don't know ruby all that well, but I suspect that will not re-generate
the file when the deploy runs if it already exists?

Also, that just generates the file - how do I tie that in to
distributing it?

Thanks!

R.

[Robin Bowes]

On 02/12/09 13:24, Robin Bowes wrote:

> It's not so bad for this simple case but I have another task to write
> that grabs ~200M of GeoIP updates and I only want to execute that once!

In this case, what I need to do is run the following commands:

# First make sure /usr/share/GeoIP/ is up-to-date locally
geoippudate
# Then update twenty nodes
for node in node${seq -w 1 20} ; do
rsync -avn /usr/share/GeoIP/ root@$node:/usr/share/GeoIP
done

How can I capify this?

R.

[Lee Hambley]

The idea would be that file_generated would be boolean,

# deploy.rb

@file_generated = false

def generate_config_file
     # implement me in pure, standard ruby!

     @file_generated ||= system('script/system')
end

System, should - once generate the file

-- Lee Hambley

Twitter: @leehambley | @capistranorb

Blog: http://lee.hambley.name/
Working with Rails: http://is.gd/1s5W1

2009/12/2 Robin Bowes <robin...@robinbowes.com>

R.

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[Robin Bowes]

On 02/12/09 15:04, Lee Hambley wrote:
> The idea would be that file_generated would be boolean,
>
> # deploy.rb
>
> @file_generated = false
>
> def generate_config_file
> # implement me in pure, standard ruby!
> @file_generated ||= system('script/system')
> end
>
> System, should - once generate the file

You appear to be answering the question before last :)

Thanks - I'll give that a go.

> In this case, what I need to do is run the following commands:
>
> # First make sure /usr/share/GeoIP/ is up-to-date locally
> geoippudate
> # Then update twenty nodes
> for node in node${seq -w 1 20} ; do
> rsync -avn /usr/share/GeoIP/ root@$node:/usr/share/GeoIP
> done
>
> How can I capify this?

How about this?

R.

[Lee Hambley]

I'd have something like this:

task :upload_config_file, :roles => [:all] do
   generate_config_file
   put() # see our docs for put.
end

-- Lee Hambley

Twitter: @leehambley | @capistranorb
Blog: http://lee.hambley.name/
Working with Rails: http://is.gd/1s5W1

2009/12/2 Robin Bowes <robin...@robinbowes.com>

On 02/12/09 15:04, Lee Hambley wrote:

R.

[Donovan Bray]

Memoize the block around the system call

http://6brand.com/ruby-speedup-memoize-those-methods.html

On Dec 2, 2009, at 5:24 AM, Robin Bowes <robin...@robinbowes.com>
wrote:

[Robin Bowes]

OK, this seems to work:

@file_generated = false
def generate_config_file
# implement me in pure, standard ruby!

@file_generated ||= system("scripts/create_config
files/counter.php")
end

desc <<-DESC
Create counter.php config file & copy to release path
DESC
task :update_config_file, :roles => [:web] do
generate_config_file

print " Copying config file.\n"

upload("files/counter.php", "#{release_path}/www/counter.php")
end


However, you'll noticed that the scratch file name (files/counter.php)
is specified in two places. Can I somehow define that in a var that can
be used un the system call *and* in the cap upload command?

R.

[Robin Bowes]

On 02/12/09 18:17, Lee Hambley wrote:
> Yes, of course, just make it a local variable
>

[taking back to list]

Er, "just make it a local variable" ? For example... ?

R.

[Lee Hambley]

Robin https://gist.github.com/f9aca125524fa03c45ef

[Robin Bowes]

On 02/12/09 19:15, Lee Hambley wrote:
> Robin https://gist.github.com/f9aca125524fa03c45ef

Hmmm, I could've sworn I tried that.

Thanks!

R.

[Lee Hambley]

Yep, but these things happen!