Trying to set custom SCM on Capistrano 3.8.1 - ruby

Question

I am configuring a custom SCM because i don't need the default git in the development local environment, but i would like to trigger a custom logic, mainly based on creating a release starting from a source_directory.
As described in the documentation (http://capistranorb.com/documentation/advanced-features/custom-scm/) i wrote a module that extends the Capistrano::Plugin, and set required methods to handle the custom SCM implementation used by deploy Capistrano flow.
Besides this, when i put in my config/deploy/<environment>.rb the entry:
set :scm, :<custom plugin name>
Capistrano keeps to use the default git scm, even if is not declared.
in my Capfile there are loaded both as follow:
require_relative 'scm/local.rb'
install_plugin Capistrano::LocalPlugin
require 'capistrano/git
install_plugin Capistrano::SCM::Git
Here also the module of custom SCM :
require 'capistrano/scm/plugin'
module Capistrano
class Capistrano::SCM::LocalPlugin < ::Capistrano::Plugin
def set_defaults
set_if_empty :source_dir, 'non-exisisting-dir'
end
def define_tasks
namespace :local do
task :create_release do
run_locally do
execute :mkdir, '-p', :'tmp'
execute "cd #{fetch(:source_dir)} && tar -cz --exclude tests --exclude vendor --exclude .git --exclude node_modules --exclude tmp/#{fetch(:release_timestamp)}.tar.gz -f tmp/#{fetch(:release_timestamp)}.tar.gz ."
end
on release_roles :all do
execute :mkdir, '-p', release_path
upload! "tmp/#{fetch(:release_timestamp)}.tar.gz", "#{release_path}/#{fetch(:release_timestamp)}.tar.gz"
execute "tar -xvf #{release_path}/#{fetch(:release_timestamp)}.tar.gz --directory #{release_path}"
execute "rm #{release_path}/#{fetch(:release_timestamp)}.tar.gz"
end
run_locally do
execute "rm -rf tmp"
end
end
desc 'Determine the revision that will be deployed'
task :set_current_revision do
run_locally do
set :current_revision, capture(:git, " --git-dir #{fetch(:source_dir)}/.git rev-parse --short #{fetch(:branch)}")
end
end
end
end
def register_hooks
after 'deploy:new_release_path', 'local:create_release'
end
end
end
Does anyone know which is the black magic to use in order to say to Capistrano to use my scm instead of the default git one ?

Answer 1

set :scm, 'myscm' is deprecated. Until the next major version of Capistrano (4.0), there is a class which checks for an SCM having been installed via install_plugin, and if not, checks for the set :scm definition. If install_plugin has been called, then set :scm is ignored and deleted.
install_plugin only registers the plugin. It looks to me from the code that Capistrano will run both plugins if two are installed.
So, in a nutshell, Capistrano doesn't support selecting multiple SCMs based on environment. The closest thing to that you could try is using an environment variable to conditionally load the SCM in your Capfile. Something like:
if ENV['CAP_SCM'] == 'local'
require_relative 'scm/local.rb'
install_plugin Capistrano::LocalPlugin
else
require 'capistrano/git'
install_plugin Capistrano::SCM::Git
end
This is all documented here: https://github.com/capistrano/capistrano/blob/master/UPGRADING-3.7.md