Only redact the non-sensitive bits of build args and env vars.

* `-e [REDACTED]` → `-e SOME_SECRET=[REDACTED]`
* Replaces `Utils.redact` with `Utils.sensitive` to clarify that we're
  indicating redactability, not actually performing redaction.
* Redacts from YAML output, including `mrsk config` (fixes basecamp#96)

lib/mrsk/cli/main.rb

@@ -119,7 +119,7 @@ def audit
   desc "config", "Show combined config (including secrets!)"
   def config
     run_locally do
-      puts MRSK.config.to_h.to_yaml
+      puts Mrsk::Utils.redacted(MRSK.config.to_h).to_yaml
     end
   end
 

lib/mrsk/commands/base.rb

@@ -1,6 +1,6 @@
 module Mrsk::Commands
   class Base
-    delegate :redact, :argumentize, to: Mrsk::Utils
+    delegate :sensitive, :argumentize, to: Mrsk::Utils
 
     attr_accessor :config
 

lib/mrsk/commands/builder/base.rb

@@ -28,7 +28,7 @@ def build_labels
     end
 
     def build_args
-      argumentize "--build-arg", args, redacted: true
+      argumentize "--build-arg", args, sensitive: true
     end
 
     def build_secrets

lib/mrsk/commands/registry.rb

@@ -2,7 +2,7 @@ class Mrsk::Commands::Registry < Mrsk::Commands::Base
   delegate :registry, to: :config
 
   def login
-    docker :login, registry["server"], "-u", redact(lookup("username")), "-p", redact(lookup("password"))
+    docker :login, registry["server"], "-u", sensitive(lookup("username")), "-p", sensitive(lookup("password"))
   end
 
   def logout

lib/mrsk/utils.rb

@@ -2,11 +2,12 @@ module Mrsk::Utils
   extend self
 
   # Return a list of escaped shell arguments using the same named argument against the passed attributes (hash or array).
-  def argumentize(argument, attributes, redacted: false)
+  def argumentize(argument, attributes, sensitive: false)
     Array(attributes).flat_map do |key, value|
       if value.present?
-        escaped_pair = [ key, escape_shell_value(value) ].join("=")
-        [ argument, redacted ? redact(escaped_pair) : escaped_pair ]
+        attr = "#{key}=#{escape_shell_value(value)}"
+        attr = self.sensitive(attr, redaction: "#{key}=[REDACTED]") if sensitive
+        [ argument, attr]
       else
         [ argument, key ]
       end
@@ -17,7 +18,7 @@ def argumentize(argument, attributes, redacted: false)
   # but redacts and expands secrets.
   def argumentize_env_with_secrets(env)
     if (secrets = env["secret"]).present?
-      argumentize("-e", secrets.to_h { |key| [ key, ENV.fetch(key) ] }, redacted: true) + argumentize("-e", env["clear"])
+      argumentize("-e", secrets.to_h { |key| [ key, ENV.fetch(key) ] }, sensitive: true) + argumentize("-e", env["clear"])
     else
       argumentize "-e", env.fetch("clear", env)
     end
@@ -39,9 +40,37 @@ def flatten_args(args)
     args.flat_map { |key, value| value.try(:map) { |entry| [key, entry] } || [ [ key, value ] ] }
   end
 
-  # Copied from SSHKit::Backend::Abstract#redact to be available inside Commands classes
-  def redact(arg) # Used in execute_command to hide redact() args a user passes in
-    arg.to_s.extend(SSHKit::Redaction) # to_s due to our inability to extend Integer, etc
+  # Marks sensitive values for redaction in logs and human-visible output.
+  # Pass `redaction:` to change the default `"[REDACTED]"` redaction, e.g.
+  # `sensitive "#{arg}=#{secret}", redaction: "#{arg}=xxxx"
+  def sensitive(...)
+    Mrsk::Utils::Sensitive.new(...)
+  end
+
+  def redacted(value)
+    case
+    when value.respond_to?(:redaction)
+      value.redaction
+    when value.respond_to?(:transform_values)
+      value.transform_values { |value| redacted value }
+    when value.respond_to?(:map)
+      value.map { |element| redacted element }
+    else
+      value
+    end
+  end
+
+  def unredacted(value)
+    case
+    when value.respond_to?(:unredacted)
+      value.unredacted
+    when value.respond_to?(:transform_values)
+      value.transform_values { |value| unredacted value }
+    when value.respond_to?(:map)
+      value.map { |element| unredacted element }
+    else
+      value
+    end
   end
 
   # Escape a value to make it safe for shell use.

lib/mrsk/utils/sensitive.rb

@@ -0,0 +1,19 @@
+require "active_support/core_ext/module/delegation"
+
+class Mrsk::Utils::Sensitive
+  # So SSHKit knows to redact these values.
+  include SSHKit::Redaction
+
+  attr_reader :unredacted, :redaction
+  delegate :to_s, to: :unredacted
+  delegate :inspect, to: :redaction
+
+  def initialize(value, redaction: "[REDACTED]")
+    @unredacted, @redaction = value, redaction
+  end
+
+  # Sensitive values won't leak into YAML output.
+  def encode_with(coder)
+    coder.represent_scalar nil, redaction
+  end
+end

test/configuration/accessory_test.rb

@@ -112,8 +112,11 @@ class ConfigurationAccessoryTest < ActiveSupport::TestCase
 
   test "env args with secret" do
     ENV["MYSQL_ROOT_PASSWORD"] = "secret123"
-    assert_equal ["-e", "MYSQL_ROOT_PASSWORD=\"secret123\"", "-e", "MYSQL_ROOT_HOST=\"%\""], @config.accessory(:mysql).env_args
-    assert @config.accessory(:mysql).env_args[1].is_a?(SSHKit::Redaction)
+
+    @config.accessory(:mysql).env_args.tap do |env_args|
+      assert_equal ["-e", "MYSQL_ROOT_PASSWORD=\"secret123\"", "-e", "MYSQL_ROOT_HOST=\"%\""], Mrsk::Utils.unredacted(env_args)
+      assert_equal ["-e", "MYSQL_ROOT_PASSWORD=[REDACTED]", "-e", "MYSQL_ROOT_HOST=\"%\""], Mrsk::Utils.redacted(env_args)
+    end
   ensure
     ENV["MYSQL_ROOT_PASSWORD"] = nil
   end

test/configuration/role_test.rb

@@ -97,7 +97,10 @@ class ConfigurationRoleTest < ActiveSupport::TestCase
     ENV["REDIS_PASSWORD"] = "secret456"
     ENV["DB_PASSWORD"] = "secret&\"123"
 
-    assert_equal ["-e", "REDIS_PASSWORD=\"secret456\"", "-e", "DB_PASSWORD=\"secret&\\\"123\"", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], @config_with_roles.role(:workers).env_args
+    @config_with_roles.role(:workers).env_args.tap do |env_args|
+      assert_equal ["-e", "REDIS_PASSWORD=\"secret456\"", "-e", "DB_PASSWORD=\"secret&\\\"123\"", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], Mrsk::Utils.unredacted(env_args)
+      assert_equal ["-e", "REDIS_PASSWORD=[REDACTED]", "-e", "DB_PASSWORD=[REDACTED]", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], Mrsk::Utils.redacted(env_args)
+    end
   ensure
     ENV["REDIS_PASSWORD"] = nil
     ENV["DB_PASSWORD"] = nil
@@ -116,7 +119,10 @@ class ConfigurationRoleTest < ActiveSupport::TestCase
 
     ENV["DB_PASSWORD"] = "secret123"
 
-    assert_equal ["-e", "DB_PASSWORD=\"secret123\"", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], @config_with_roles.role(:workers).env_args
+    @config_with_roles.role(:workers).env_args.tap do |env_args|
+      assert_equal ["-e", "DB_PASSWORD=\"secret123\"", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], Mrsk::Utils.unredacted(env_args)
+      assert_equal ["-e", "DB_PASSWORD=[REDACTED]", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], Mrsk::Utils.redacted(env_args)
+    end
   ensure
     ENV["DB_PASSWORD"] = nil
   end
@@ -133,7 +139,10 @@ class ConfigurationRoleTest < ActiveSupport::TestCase
 
     ENV["REDIS_PASSWORD"] = "secret456"
 
-    assert_equal ["-e", "REDIS_PASSWORD=\"secret456\"", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], @config_with_roles.role(:workers).env_args
+    @config_with_roles.role(:workers).env_args.tap do |env_args|
+      assert_equal ["-e", "REDIS_PASSWORD=\"secret456\"", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], Mrsk::Utils.unredacted(env_args)
+      assert_equal ["-e", "REDIS_PASSWORD=[REDACTED]", "-e", "REDIS_URL=\"redis://a/b\"", "-e", "WEB_CONCURRENCY=\"4\""], Mrsk::Utils.redacted(env_args)
+    end
   ensure
     ENV["REDIS_PASSWORD"] = nil
   end

test/configuration_test.rb

@@ -113,12 +113,13 @@ class ConfigurationTest < ActiveSupport::TestCase
 
   test "env args with clear and secrets" do
     ENV["PASSWORD"] = "secret123"
+
     config = Mrsk::Configuration.new(@deploy.tap { |c| c.merge!({
       env: { "clear" => { "PORT" => "3000" }, "secret" => [ "PASSWORD" ] }
     }) })
 
-    assert_equal [ "-e", "PASSWORD=\"secret123\"", "-e", "PORT=\"3000\"" ], config.env_args
-    assert config.env_args[1].is_a?(SSHKit::Redaction)
+    assert_equal [ "-e", "PASSWORD=\"secret123\"", "-e", "PORT=\"3000\"" ], Mrsk::Utils.unredacted(config.env_args)
+    assert_equal [ "-e", "PASSWORD=[REDACTED]", "-e", "PORT=\"3000\"" ], Mrsk::Utils.redacted(config.env_args)
   ensure
     ENV["PASSWORD"] = nil
   end
@@ -133,12 +134,13 @@ class ConfigurationTest < ActiveSupport::TestCase
 
   test "env args with only secrets" do
     ENV["PASSWORD"] = "secret123"
+
     config = Mrsk::Configuration.new(@deploy.tap { |c| c.merge!({
       env: { "secret" => [ "PASSWORD" ] }
     }) })
 
-    assert_equal [ "-e", "PASSWORD=\"secret123\"" ], config.env_args
-    assert config.env_args[1].is_a?(SSHKit::Redaction)
+    assert_equal [ "-e", "PASSWORD=\"secret123\"" ], Mrsk::Utils.unredacted(config.env_args)
+    assert_equal [ "-e", "PASSWORD=[REDACTED]" ], Mrsk::Utils.redacted(config.env_args)
   ensure
     ENV["PASSWORD"] = nil
   end

test/utils_test.rb

@@ -8,13 +8,16 @@ class UtilsTest < ActiveSupport::TestCase
 
   test "argumentize with redacted" do
     assert_kind_of SSHKit::Redaction, \
-      Mrsk::Utils.argumentize("--label", { foo: "bar" }, redacted: true).last
+      Mrsk::Utils.argumentize("--label", { foo: "bar" }, sensitive: true).last
   end
 
   test "argumentize_env_with_secrets" do
     ENV.expects(:fetch).with("FOO").returns("secret")
-    assert_equal [ "-e", "FOO=\"secret\"", "-e", "BAZ=\"qux\"" ], \
-      Mrsk::Utils.argumentize_env_with_secrets({ "secret" => [ "FOO" ], "clear" => { BAZ: "qux" } })
+
+    args = Mrsk::Utils.argumentize_env_with_secrets({ "secret" => [ "FOO" ], "clear" => { BAZ: "qux" } })
+
+    assert_equal [ "-e", "FOO=[REDACTED]", "-e", "BAZ=\"qux\"" ], Mrsk::Utils.redacted(args)
+    assert_equal [ "-e", "FOO=\"secret\"", "-e", "BAZ=\"qux\"" ], Mrsk::Utils.unredacted(args)
   end
 
   test "optionize" do
@@ -27,9 +30,20 @@ class UtilsTest < ActiveSupport::TestCase
       Mrsk::Utils.optionize({ foo: "bar", baz: "qux", quux: true }, with: "=")
   end
 
-  test "redact" do
-    assert_kind_of SSHKit::Redaction, Mrsk::Utils.redact("secret")
-    assert_equal "secret", Mrsk::Utils.redact("secret")
+  test "no redaction from #to_s" do
+    assert_equal "secret", Mrsk::Utils.sensitive("secret").to_s
+  end
+
+  test "redact from #inspect" do
+    assert_equal "[REDACTED]".inspect, Mrsk::Utils.sensitive("secret").inspect
+  end
+
+  test "redact from SSHKit output" do
+    assert_kind_of SSHKit::Redaction, Mrsk::Utils.sensitive("secret")
+  end
+
+  test "redact from YAML output" do
+    assert_equal "--- ! '[REDACTED]'\n", YAML.dump(Mrsk::Utils.sensitive("secret"))
   end
 
   test "escape_shell_value" do