lang: Initial implementation of the mgmt language

This is an initial implementation of the mgmt language. It is a
declarative (immutable) functional, reactive, domain specific
programming language. It is intended to be a language that is:

* safe
* powerful
* easy to reason about

With these properties, we hope this language, and the mgmt engine will
allow you to model the real-time systems that you'd like to automate.

This also includes a number of other associated changes. Sorry for the
large size of this patch.

gapi/deploy.go

@@ -0,0 +1,68 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package gapi
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/gob"
+
+	errwrap "github.com/pkg/errors"
+)
+
+func init() {
+	gob.Register(&Deploy{})
+}
+
+// Deploy represents a deploy action, include the type of GAPI to deploy, the
+// payload of that GAPI, and any deploy specific parameters that were chosen.
+// TODO: add staged rollout functionality to this struct
+// TODO: add proper authentication with gpg key signing
+type Deploy struct {
+	Name string // lang, hcl, puppet, yaml, yaml2, etc...
+	//Sync bool // wait for everyone to close previous GAPI before switching
+	Noop bool
+	Sema int // sema override
+	GAPI GAPI
+}
+
+// ToB64 encodes a deploy struct as a base64 encoded string.
+func (obj *Deploy) ToB64() (string, error) {
+	b := bytes.Buffer{}
+	e := gob.NewEncoder(&b)
+	err := e.Encode(&obj) // pass with &
+	if err != nil {
+		return "", errwrap.Wrapf(err, "gob failed to encode")
+	}
+	return base64.StdEncoding.EncodeToString(b.Bytes()), nil
+}
+
+// NewDeployFromB64 decodes a deploy struct from a base64 encoded string.
+func NewDeployFromB64(str string) (*Deploy, error) {
+	var deploy *Deploy
+	bb, err := base64.StdEncoding.DecodeString(str)
+	if err != nil {
+		return nil, errwrap.Wrapf(err, "base64 failed to decode")
+	}
+	b := bytes.NewBuffer(bb)
+	d := gob.NewDecoder(b)
+	if err := d.Decode(&deploy); err != nil { // pass with &
+		return nil, errwrap.Wrapf(err, "gob failed to decode")
+	}
+	return deploy, nil
+}

gapi/gapi.go

@@ -19,17 +19,39 @@
 package gapi
 
 import (
+	"encoding/gob"
+	"fmt"
+
 	"github.com/purpleidea/mgmt/pgraph"
 	"github.com/purpleidea/mgmt/resources"
+
+	"github.com/urfave/cli"
 )
 
+// RegisteredGAPIs is a global map of all possible GAPIs which can be used. You
+// should never touch this map directly. Use methods like Register instead.
+var RegisteredGAPIs = make(map[string]func() GAPI) // must initialize this map
+
+// Register takes a GAPI and its name and makes it available for use. There is
+// no matching Unregister function.
+func Register(name string, fn func() GAPI) {
+	if _, ok := RegisteredGAPIs[name]; ok {
+		panic(fmt.Sprintf("a GAPI named %s is already registered", name))
+	}
+	gob.Register(fn())
+	RegisteredGAPIs[name] = fn
+}
+
 // Data is the set of input values passed into the GAPI structs via Init.
 type Data struct {
+	Program       string // name of the originating program
 	Hostname      string // uuid for the host, required for GAPI
 	World         resources.World
 	Noop          bool
 	NoConfigWatch bool
 	NoStreamWatch bool
+	Debug         bool
+	Logf          func(format string, v ...interface{})
 	// NOTE: we can add more fields here if needed by GAPI endpoints
 }
 
@@ -48,6 +70,9 @@ type Next struct {
 
 // GAPI is a Graph API that represents incoming graphs and change streams.
 type GAPI interface {
+	Cli(c *cli.Context, fs resources.Fs) (*Deploy, error)
+	CliFlags() []cli.Flag
+
 	Init(Data) error               // initializes the GAPI and passes in useful data
 	Graph() (*pgraph.Graph, error) // returns the most recent pgraph
 	Next() chan Next               // returns a stream of switch events

gapi/helpers.go

@@ -0,0 +1,57 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package gapi
+
+import (
+	"io/ioutil"
+
+	"github.com/purpleidea/mgmt/resources"
+	"github.com/purpleidea/mgmt/util"
+
+	errwrap "github.com/pkg/errors"
+)
+
+// Umask is the default to use when none has been specified.
+// TODO: apparently using 0666 is equivalent to respecting the current umask
+const Umask = 0666
+
+// CopyFileToFs copies a file from src path on the local fs to a dst path on fs.
+func CopyFileToFs(fs resources.Fs, src, dst string) error {
+	data, err := ioutil.ReadFile(src)
+	if err != nil {
+		return errwrap.Wrapf(err, "can't read from file `%s`", src)
+	}
+	if err := fs.WriteFile(dst, data, Umask); err != nil {
+		return errwrap.Wrapf(err, "can't write to file `%s`", dst)
+	}
+	return nil
+}
+
+// CopyStringToFs copies a file from src path on the local fs to a dst path on
+// fs.
+func CopyStringToFs(fs resources.Fs, str, dst string) error {
+	if err := fs.WriteFile(dst, []byte(str), Umask); err != nil {
+		return errwrap.Wrapf(err, "can't write to file `%s`", dst)
+	}
+	return nil
+}
+
+// CopyDirToFs copies a dir from src path on the local fs to a dst path on fs.
+func CopyDirToFs(fs resources.Fs, src, dst string) error {
+	return util.CopyDiskToFs(fs, src, dst, false)
+}