Allow for configuration policies

Summary:
Implements a rough interface for validating configuration against
arbitrary policy rules. Policies are provided as YAML and passed via the
command line as file paths or remote URIs.

The format of policies is:

    enforcements:
      - path: <path>
        rule: <rule>

Where `<path>` is a YAML-ish path to a config field and `<rule>` is any
expression our config validator understands (expressions built in by the
validator library and custom tags defined in `config.validation.go`).

Example policy:

    enforcements:
      - path: variants.production.base
        rule: oneof=debian:jessie debian:stretch
      - path: variants.production.runs.as
        rule: ne=foo
      - path: variants.production.node.dependencies
        rule: isfalse

Command flag parsing was implemented in `main.go` to support the new
`--policy=uri` flag and improve existing handling of `--version` and the
usage statement.

Test Plan: Run `go test ./...`.

Reviewers: thcipriani, demon, hashar, mmodell, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D999

1 files changed, 63 insertions, 0 deletions

diff --git a/vendor/github.com/pborman/getopt/var.go b/vendor/github.com/pborman/getopt/var.go
new file mode 100644
index 0000000..fd816b9
--- /dev/null
+++ b/vendor/github.com/pborman/getopt/var.go
@@ -0,0 +1,63 @@
+// Copyright 2013 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package getopt
+
+import (
+	"fmt"
+	"runtime"
+)
+
+// Value is the interface to the dynamic value stored in a flag. (The default
+// value is represented as a string.)  Set is passed the string to set the
+// value to as well as the Option that is being processed.
+type Value interface {
+	Set(string, Option) error
+	String() string
+}
+
+// Var creates an option of the specified name. The type and value of the option
+// are represented by the first argument, of type Value, which typically holds a
+// user-defined implementation of Value.  All options are ultimately created
+// as a Var.
+func Var(p Value, name rune, helpvalue ...string) Option {
+	return CommandLine.VarLong(p, "", name, helpvalue...)
+}
+
+func VarLong(p Value, name string, short rune, helpvalue ...string) Option {
+	return CommandLine.VarLong(p, name, short, helpvalue...)
+}
+
+func (s *Set) Var(p Value, name rune, helpvalue ...string) Option {
+	return s.VarLong(p, "", name, helpvalue...)
+}
+
+func (s *Set) VarLong(p Value, name string, short rune, helpvalue ...string) Option {
+	opt := &option{
+		short:  short,
+		long:   name,
+		value:  p,
+		defval: p.String(),
+	}
+
+	switch len(helpvalue) {
+	case 2:
+		opt.name = helpvalue[1]
+		fallthrough
+	case 1:
+		opt.help = helpvalue[0]
+	case 0:
+	default:
+		panic("Too many strings for String helpvalue")
+	}
+	if _, file, line, ok := runtime.Caller(1); ok {
+		opt.where = fmt.Sprintf("%s:%d", file, line)
+	}
+	if opt.short == 0 && opt.long == "" {
+		fmt.Fprintf(stderr, opt.where+": no short or long option given")
+		exit(1)
+	}
+	s.AddOption(opt)
+	return opt
+}