respect "no_proxy" environment variable

[majewsky]

We are behind a corporate proxy and use a custom default source for our Chef cookbooks which is reachable without the proxy. My setup looks something like this:

$ export http_proxy=http;//proxy.$companyname.corp:$port
$ export no_proxy=.corp,localhost

$ cat Cheffile
site "http://supermarket.$companyname.corp/api/v1"
cookbook "myapplication"

In fact, I'm setting a bunch of additional environment variables to the same values, since some programs recognize upper-case env variables only, some check for a https proxy, and so on.

With this setup active, I'm seeing various errors during "librarian-chef install" (see example backtraces below). When I remove all the proxy environment variables, everything works fine. The error traces indicate that the proxy is being used, so http_proxy (or one of its various siblings) is being recognized, but no_proxy (or NO_PROXY) is not, since that one would cause librarian-chef to skip the proxy when talking to the configured default source.

Example backtraces (some values have been [redacted]):

$ git clean -dxf && bundle exec librarian-chef install
Installing build-essential (2.2.3)
Installing yum (3.5.3)
/Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:110:in `read': No such file or directory @ rb_sysopen - /Users/[username redacted]/[reponame redacted]/tmp/librarian/cache/source/chef/site/d72d2d4ed6e6fa75/yum/version/3.5.3 (Errno::ENOENT)
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:110:in `read'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:110:in `block in to_version_uri'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:381:in `memo'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:108:in `to_version_uri'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:211:in `cache_version_unpacked!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:30:in `install_version!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:437:in `install!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/manifest.rb:101:in `install!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:49:in `block in install_manifests'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:48:in `each'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:48:in `install_manifests'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:39:in `perform_installation'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:12:in `run'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:165:in `install!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/cli.rb:42:in `install'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor.rb:359:in `dispatch'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:26:in `block (2 levels) in bin!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:31:in `returning_status'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:26:in `block in bin!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:47:in `with_environment'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:26:in `bin!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/bin/librarian-chef:7:in `<top (required)>'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/bin/librarian-chef:23:in `load'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/bin/librarian-chef:23:in `<main>'


$ git clean -dxf && bundle exec librarian-chef install
Installing build-essential (2.2.3)
Installing yum (3.5.3)
/Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/net/http.rb:879:in `initialize': Operation timed out - connect(2) for "proxy.wdf.sap.corp" port 8080 (Errno::ETIMEDOUT)
    from /Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/net/http.rb:879:in `open'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/net/http.rb:879:in `block in connect'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/timeout.rb:76:in `timeout'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/net/http.rb:878:in `connect'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/net/http.rb:863:in `do_start'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/lib/ruby/2.1.0/net/http.rb:852:in `start'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:353:in `block in http_get'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:348:in `loop'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:348:in `http_get'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:238:in `cache_remote_object!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:228:in `cache_remote_json!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:180:in `cache_version_uri_metadata!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:81:in `block in version_uri_metadata'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:381:in `memo'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:80:in `version_uri_metadata'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:188:in `block in cache_version!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:187:in `each'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:187:in `cache_version!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:109:in `block in to_version_uri'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:381:in `memo'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:108:in `to_version_uri'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:211:in `cache_version_unpacked!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:30:in `install_version!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/source/site.rb:437:in `install!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/manifest.rb:101:in `install!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:49:in `block in install_manifests'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:48:in `each'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:48:in `install_manifests'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:39:in `perform_installation'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/action/install.rb:12:in `run'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:165:in `install!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/lib/librarian/chef/cli.rb:42:in `install'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor.rb:359:in `dispatch'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:26:in `block (2 levels) in bin!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:31:in `returning_status'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:26:in `block in bin!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:47:in `with_environment'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-0.1.2/lib/librarian/cli.rb:26:in `bin!'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/gems/librarian-chef-0.0.4/bin/librarian-chef:7:in `<top (required)>'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/bin/librarian-chef:23:in `load'
    from /Users/[username redacted]/.rbenv/versions/2.1.2/gemsets/[reponame redacted]/bin/librarian-chef:23:in `<main>'