Do not assume type of private key

The only type of private key supported at the moment are RSA keys.
Since there are multiple types (RSA, DSA, EC ...), it would be best
not to assume.

Seems like the OpenSSL::PKey.read(string [,pwd]) does exactly what
we need to have that abstraction:

  Reads a DER or PEM encoded string from string or io and returns an
  instance of the appropriate PKey class.

CHANGELOG.md

@@ -6,6 +6,7 @@ This CHANGELOG follows the format listed at [Keep A Changelog](http://keepachang
 ## [Unreleased]
 ### Changed
 - Updated Travis configuration to include Ruby 2.4.1
+- Updated to be compatible with other type of private keys than RSA
 
 ### Removed
 - Ruby 1.9.3 from deploy-time testing (@eheydrick)

bin/check-etcd-peer-count.rb

@@ -87,7 +87,7 @@ def run
     r = RestClient::Resource.new("#{protocol}://#{config[:server]}:#{config[:port]}/v2/members",
                                  timeout: 5,
                                  ssl_client_cert: (OpenSSL::X509::Certificate.new(File.read(config[:cert])) unless config[:cert].nil?),
-                                 ssl_client_key: (OpenSSL::PKey::RSA.new(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?),
+                                 ssl_client_key: (OpenSSL::PKey.read(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?),
                                  ssl_ca_file:  config[:ca],
                                  verify_ssl:  config[:insecure] ? 0 : 1).get
     peers = JSON.parse(r.to_str)['members'].length

bin/check-etcd.rb

@@ -124,7 +124,7 @@ def request(path, server)
     RestClient::Resource.new("#{protocol}://#{server}:#{config[:port]}/#{path}",
                              timeout: 5,
                              ssl_client_cert: (OpenSSL::X509::Certificate.new(File.read(config[:cert])) unless config[:cert].nil?),
-                             ssl_client_key: (OpenSSL::PKey::RSA.new(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?),
+                             ssl_client_key: (OpenSSL::PKey.read(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?),
                              ssl_ca_file:  config[:ca],
                              verify_ssl:  config[:insecure] ? 0 : 1).get
   end

bin/check-flannel-subnet-count.rb

@@ -122,7 +122,7 @@ def request(path, server)
       "#{protocol}://#{server}:#{config[:port]}/#{path}",
       timeout: 5,
       ssl_client_cert: (OpenSSL::X509::Certificate.new(File.read(config[:cert])) unless config[:cert].nil?),
-      ssl_client_key: (OpenSSL::PKey::RSA.new(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?),
+      ssl_client_key: (OpenSSL::PKey.read(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?),
       ssl_ca_file:  config[:ca],
       verify_ssl:  config[:insecure] ? 0 : 1
     ).get

bin/metrics-etcd.rb

@@ -96,7 +96,7 @@ def run
         verify_mode: (config[:insecure] ? OpenSSL::SSL::VERIFY_NONE : OpenSSL::SSL::VERIFY_PEER),
         ca_file: config[:ca],
         ssl_cert: (OpenSSL::X509::Certificate.new(File.read(config[:cert])) unless config[:cert].nil?),
-        ssl_key:  (OpenSSL::PKey::RSA.new(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?)
+        ssl_key:  (OpenSSL::PKey.read(File.read(config[:key]), config[:passphrase]) unless config[:key].nil?)
       )
     else
       client = Etcd.client(host: config[:etcd_host], port: config[:etcd_port])