(puppetlabsGH-2125) Read command from a file or stdin

This adds support for reading a command from a file or `stdin` using
the `bolt command run` command. To read a command from a file,
pass the path to the file with the `@` symbol:

```shell
$ bolt command run @script.sh --targets targets
```

The filepath is expanded relative to the current working directory.

To read a command from `stdin`, pass a single dash `-` as the command
and then pipe the command to Bolt:

```shell
$ echo whoami | bolt command run - --targets targets
```

!feature

* **Read command from a file or `stdin` using `bolt command run`**
  ([puppetlabs#2125](puppetlabs#2125))

  The `bolt command run` command can now read a command from a file or
  `stdin`.

documentation/running_bolt_commands.md

@@ -14,11 +14,13 @@ across those systems.
     ```shell script
     bolt command run <COMMAND> --targets <TARGET NAME>,<TARGET NAME>,<TARGET NAME>
     ```
+
 -   To run a command on WinRM targets, indicate the WinRM protocol in the
     targets string:
     ```shell script
     bolt command run <COMMAND> --targets winrm://<WINDOWS.TARGET> --user <USERNAME> --password <PASSWORD>
     ```
+
 -   To run a command that contains spaces or shell special characters, wrap the
     command in single quotation marks:
     ```shell script
@@ -27,14 +29,41 @@ across those systems.
     ```shell script
     bolt command run "netstat -an | grep 'tcp.*LISTEN'" --targets web5.mydomain.edu,web6.mydomain.edu
     ```
+
 -   To run a cross-platform command:
     ```shell script
     bolt command run "echo 'hello world'"
     ```
 
-    **Note:** When connecting to Bolt hosts over WinRM that have not configured
-    SSL for port 5986, passing the `--no-ssl` switch is required to connect to
-    the default WinRM port 5985.
+-   To read a command from a file, pass the command as an `@` symbol followed by
+    the path to the file:
+
+    ```
+    bolt command run @command.txt --targets servers
+    ```
+
+    For Windows PowerShell, add single quotation marks to define the file:
+
+    ```
+    bolt command run '@command.txt' --targets servers
+    ```
+
+-   To read a command from `stdin`, pass the command as a single dash `-` and
+    pipe the command to Bolt:
+
+    ```
+    <COMMAND> | bolt command run - --targets servers
+    ```
+
+    For example, if you have a command in a text file:
+
+    ```
+    cat command.txt | bolt command run - --targets servers
+    ```
+
+> **Note:** When connecting to Bolt hosts over WinRM that have not configured
+> SSL for port 5986, passing the `--no-ssl` switch is required to connect to
+> the default WinRM port 5985.
 
 
 ## Running commands with redirection or pipes

lib/bolt/bolt_option_parser.rb

@@ -746,7 +746,7 @@ def initialize(options)
              'For SSH, port defaults to `22`',
              'For WinRM, port defaults to `5985` or `5986` based on the --[no-]ssl setting') do |targets|
         @options[:targets] ||= []
-        @options[:targets] << get_arg_input(targets)
+        @options[:targets] << Bolt::Util.get_arg_input(targets)
       end
       define('-q', '--query QUERY', 'Query PuppetDB to determine the targets') do |query|
         @options[:query] = query
@@ -985,27 +985,10 @@ def update
     end
 
     def parse_params(params)
-      json = get_arg_input(params)
+      json = Bolt::Util.get_arg_input(params)
       JSON.parse(json)
     rescue JSON::ParserError => e
       raise Bolt::CLIError, "Unable to parse --params value as JSON: #{e}"
     end
-
-    def get_arg_input(value)
-      if value.start_with?('@')
-        file = value.sub(/^@/, '')
-        read_arg_file(file)
-      elsif value == '-'
-        $stdin.read
-      else
-        value
-      end
-    end
-
-    def read_arg_file(file)
-      File.read(File.expand_path(file))
-    rescue StandardError => e
-      raise Bolt::FileError.new("Error attempting to read #{file}: #{e}", file)
-    end
   end
 end

lib/bolt/cli.rb

@@ -107,6 +107,11 @@ def parse_command
 
       options[:object] = remaining.shift
 
+      # Handle reading a command from a file
+      if options[:subcommand] == 'command'
+        options[:object] = Bolt::Util.get_arg_input(options[:object])
+      end
+
       # Only parse task_options for task or plan
       if %w[task plan].include?(options[:subcommand])
         task_options, remaining = remaining.partition { |s| s =~ /.+=/ }

lib/bolt/util.rb

@@ -3,6 +3,31 @@
 module Bolt
   module Util
     class << self
+      # Gets input for an argument.
+      def get_arg_input(value)
+        if value.start_with?('@')
+          file = value.sub(/^@/, '')
+          read_arg_file(file)
+        elsif value == '-'
+          $stdin.read
+        else
+          value
+        end
+      end
+
+      # Reads a file passed as an argument to a command.
+      def read_arg_file(file)
+        file = File.expand_path(file)
+
+        unless File.exist?(file)
+          raise Bolt::FileError.new("File #{file} does not exist", file)
+        end
+
+        File.read(File.expand_path(file))
+      rescue StandardError => e
+        raise Bolt::FileError.new("Error attempting to read #{file}: #{e}", file)
+      end
+
       def read_yaml_hash(path, file_name)
         require 'yaml'
 

spec/bolt/cli_spec.rb

@@ -1043,6 +1043,25 @@ def stub_config(file_content = {})
         cli = Bolt::CLI.new(%w[command run --targets foo whoami --env-var POP=TARTS])
         expect(cli.parse[:env_vars]).to eq({ 'POP' => 'TARTS' })
       end
+
+      it "reads from a file when command starts with @" do
+        command = 'whoami'
+
+        with_tempfile_containing('command', command) do |file|
+          cli = Bolt::CLI.new(%W[command run @#{file.path}])
+          options = cli.parse
+          expect(options[:object]).to eq(command)
+        end
+      end
+
+      it "reads from stdin when command is '-'" do
+        command = 'whoami'
+
+        cli = Bolt::CLI.new(%w[command run - --targets localhost])
+        allow($stdin).to receive(:read).and_return(command)
+        options = cli.parse
+        expect(options[:object]).to eq(command)
+      end
     end
 
     it "distinguishes subcommands" do