Example: Launch tmux session to run a command as a desired user

"su -l -c 'tmux new -d -s sesion_name \"cd /somewhere && command_to_execute\"' desired_username"

Borrowed from an example I saw from David Gao

Rails Generator Examples

Cheatsheet for common rails generator examples

Create a new model:

rails g model Invoice name:string order:integer

Create a join table between 2 existing models:

rails generate migration CreateJoinTableCustomerInvoice customer invoice

Using {{link-to}} with Bootstrap requires some extra work for expected Bootstrap Navigation Styling. (ember-cli-active-link-wrapper Addon solves issue)

Using {{link-to}} with Bootstrap requires some extra work.

Bootstrap expects

Additionally bootstrap expects a class="active" attribute on the <li>

Ember.js will mark the class="active" on the <a> when you use {{link-to}}

This will break the boostrap styling.

You can use the below ember add-on to make this easier, essentially it introduce a new component {{active-link}}

You use {{active-link}} instead of <li>

https://github.com/alexspeller/ember-cli-active-link-wrapper

<ul class="nav nav-tabs" role="tablist">
{{#active-link}}
  {{#link-to "foo" }}Foo{{/link-to}}
{{/active-link}}
{{#active-link}}
  {{#link-to "bar" }}Bar{{/link-to}}
{{/active-link}}
</ul>

Building RHEL Box for Vagrant

Libvirt:

Example script for building a libvirt box based on RHEL to use with Vagrant

https://github.com/jwmatthews/fusor_vm_env/blob/master/boxes/el7/rhel7/build.sh

Virtual Box

Example of building a RHEL 7 box for VirtualBox and Vagrant

Referenced Blog Post:

http://dtucker.co.uk/hack/creating-a-vagrant-base-box-for-rhel-with-bento.html

Assumunptions:

we are building this on OSX
we have already downloaded an ISO for RHEL 7.2

Versions tested with:

VirtualBox 5.0.16
Packer 0.9.0

Steps:

brew install packer
git clone https://github.com/chef/bento.git
cd bento
mkdir -p iso/rhel
Modify rhel-7.2-x86_64.json

Update 'iso_name' so it points to the correct ISO

Copy your downloaded ISO to ./iso/rhel
$ time packer build -only=virtualbox-iso -var 'mirror=file:///git/vagrant/bento/iso' rhel-7.2-x86_64.json

update the mirror variable to point to the correct directory, for me I'm running out of /git/vagrant/bento
took ~10 minutes to finish on my Macbook Pro

vagrant box add rhel72_test builds/rhel-7.2.virtualbox.box

Converting an existing qcow2 image to VirtualBox format:

qemu-img convert -O vdi vda.img vda.vdi

Note: For Vagrant usage, we wouldn't want to just convert an existing libvirt image to virtualbox format, we will want to also install virtualbox guest additions to shared folders will function in vagrant<->virtualbox

Sed example: update a value in a block of a config file

Sed example for updating a value in a block in a config file

Thanks to Jason Montleon for the example

[jmontleo@jmontleo ~]$ cat alpha.txt 
[lazy]
#enabled: false

[foo]
#enabled: false
[jmontleo@jmontleo ~]$ sed -i '/^\[lazy\]$/{$!{N;s/^\[lazy\]\n#enabled: false$/[lazy]\n#enabled: true/;ty;P;D;:y}}' alpha.txt
[jmontleo@jmontleo ~]$ cat alpha.txt 
[lazy]
#enabled: true

[foo]
#enabled: false

Reference: http://unix.stackexchange.com/questions/26284/how-can-i-use-sed-to-replace-a-multi-line-string

Building 'pg' gem on OSX when using Postgres.app

Error seen during "gem install pg"

Installing pg 0.18.3 with native extensions

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /Users/jmatthews/.rvm/rubies/ruby-2.2.2/bin/ruby -r ./siteconf20160219-13102-1ygzen8.rb extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/Users/jmatthews/.rvm/rubies/ruby-2.2.2/bin/$(RUBY_BASE_NAME)
	--with-pg
	--without-pg
	--enable-windows-cross
	--disable-windows-cross
	--with-pg-config
	--without-pg-config
	--with-pg_config
	--without-pg_config
	--with-pg-dir
	--without-pg-dir
	--with-pg-include
	--without-pg-include=${pg-dir}/include
	--with-pg-lib
	--without-pg-lib=${pg-dir}/lib

extconf failed, exit code 1

Gem files will remain installed in /Users/jmatthews/.rvm/gems/ruby-2.2.2/gems/pg-0.18.3 for inspection.
Results logged to /Users/jmatthews/.rvm/gems/ruby-2.2.2/extensions/x86_64-darwin-14/2.2.0-static/pg-0.18.3/gem_make.out

Solution

$ gem install pg -- --with-pg-config=/Applications/Postgres.app/Contents/Versions/9.4/bin/pg_config
Building native extensions with: '--with-pg-config=/Applications/Postgres.app/Contents/Versions/9.4/bin/pg_config'
This could take a while...
Successfully installed pg-0.18.4
Parsing documentation for pg-0.18.4
Installing ri documentation for pg-0.18.4
Done installing documentation for pg after 3 seconds
1 gem installed

With Bundler

bundle config build.pg --with-pg-config=/Applications/Postgres.app/Contents/Versions/9.4/bin/pg_config
bundle install

FrontEnd Development Links

https://developer.mozilla.org/en-US/docs/Web

ember-cli examples

ember g model my-model name:string

ember generate route my-route-name

ember generate controller name-of-my-route

ember g http-mock room_attributes

ember g route admin/room_attributes/room_attribute --path=':id'

ember g route admin/room_attributes/index

ember g controller "admin/items/item"

ember g controller "admin/room-elements/room-element"

ember g route admin/styles

ember g route admin/styles/style --path=':style_id'

ember g http-mock style

ember g model style

Ruby + Ember.js: ActiveModelSerializers

Notes on configuring Ruby on Rails to use ActiveModelSerializers with Ember.js

Ruby Notes:

Configure ActiveModelSerializers to use 'embed = :ids, embed_in_root = true'

Ember will expect the response to be in a format like this:

{

  "famous_person": {
    "id": 1,
    "first_name": "Barack",
    "last_name": "Obama",
    "occupation": "President"
  }
}

Controller needs to reflect that the JSON parameters will be included in a hash of the object's name

Example:

        desc 'Create a widget.'
        params do
          requires :widget, type: Hash do
            requires :name, type: String, desc: 'Widget name'
          end
        end
        post do
          widget_params = params["widget"]
          Widget.create!({
            name: widget_params[:name],
          })
        end