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gapi.go
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gapi.go
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// 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 yamlgraph2
import (
"fmt"
"log"
"sync"
"github.com/purpleidea/mgmt/gapi"
"github.com/purpleidea/mgmt/pgraph"
"github.com/purpleidea/mgmt/recwatch"
"github.com/purpleidea/mgmt/resources"
errwrap "github.com/pkg/errors"
"github.com/urfave/cli"
)
const (
// Name is the name of this frontend.
Name = "yaml2"
// Start is the entry point filename that we use. It is arbitrary.
Start = "/start.yaml"
)
func init() {
gapi.Register(Name, func() gapi.GAPI { return &GAPI{} }) // register
}
// GAPI implements the main yamlgraph GAPI interface.
type GAPI struct {
InputURI string // input URI of file system containing yaml graph to use
data gapi.Data
initialized bool
closeChan chan struct{}
wg sync.WaitGroup // sync group for tunnel go routines
configWatcher *recwatch.ConfigWatcher
}
// Cli takes a cli.Context, and returns our GAPI if activated. All arguments
// should take the prefix of the registered name. On activation, if there are
// any validation problems, you should return an error. If this was not
// activated, then you should return a nil GAPI and a nil error.
func (obj *GAPI) Cli(c *cli.Context, fs resources.Fs) (*gapi.Deploy, error) {
if s := c.String(Name); c.IsSet(Name) {
if s == "" {
return nil, fmt.Errorf("input yaml is empty")
}
// single file input only
if err := gapi.CopyFileToFs(fs, s, Start); err != nil {
return nil, errwrap.Wrapf(err, "can't copy yaml from `%s` to `%s`", s, Start)
}
return &gapi.Deploy{
Name: Name,
Noop: c.GlobalBool("noop"),
Sema: c.GlobalInt("sema"),
GAPI: &GAPI{
InputURI: fs.URI(),
// TODO: add properties here...
},
}, nil
}
return nil, nil // we weren't activated!
}
// CliFlags returns a list of flags used by this deploy subcommand.
func (obj *GAPI) CliFlags() []cli.Flag {
return []cli.Flag{
cli.StringFlag{
Name: Name,
Value: "",
Usage: "yaml graph definition to run (parser v2)",
},
}
}
// Init initializes the yamlgraph GAPI struct.
func (obj *GAPI) Init(data gapi.Data) error {
if obj.initialized {
return fmt.Errorf("already initialized")
}
if obj.InputURI == "" {
return fmt.Errorf("the InputURI param must be specified")
}
obj.data = data // store for later
obj.closeChan = make(chan struct{})
obj.initialized = true
obj.configWatcher = recwatch.NewConfigWatcher()
return nil
}
// Graph returns a current Graph.
func (obj *GAPI) Graph() (*pgraph.Graph, error) {
if !obj.initialized {
return nil, fmt.Errorf("%s: GAPI is not initialized", Name)
}
fs, err := obj.data.World.Fs(obj.InputURI) // open the remote file system
if err != nil {
return nil, errwrap.Wrapf(err, "can't load yaml from file system `%s`", obj.InputURI)
}
b, err := fs.ReadFile(Start) // read the single file out of it
if err != nil {
return nil, errwrap.Wrapf(err, "can't read yaml from file `%s`", Start)
}
config := ParseConfigFromFile(b)
if config == nil {
return nil, fmt.Errorf("%s: ParseConfigFromFile returned nil", Name)
}
g, err := config.NewGraphFromConfig(obj.data.Hostname, obj.data.World, obj.data.Noop)
return g, err
}
// Next returns nil errors every time there could be a new graph.
func (obj *GAPI) Next() chan gapi.Next {
ch := make(chan gapi.Next)
obj.wg.Add(1)
go func() {
defer obj.wg.Done()
defer close(ch) // this will run before the obj.wg.Done()
if !obj.initialized {
next := gapi.Next{
Err: fmt.Errorf("%s: GAPI is not initialized", Name),
Exit: true, // exit, b/c programming error?
}
ch <- next
return
}
startChan := make(chan struct{}) // start signal
close(startChan) // kick it off!
var watchChan chan error
if obj.data.NoStreamWatch {
watchChan = nil
} else {
watchChan = obj.data.World.ResWatch()
}
for {
var err error
var ok bool
select {
case <-startChan: // kick the loop once at start
startChan = nil // disable
// pass
case err, ok = <-watchChan:
if !ok {
return
}
case <-obj.closeChan:
return
}
log.Printf("%s: Generating new graph...", Name)
next := gapi.Next{
//Exit: true, // TODO: for permanent shutdown!
Err: err,
}
select {
case ch <- next: // trigger a run (send a msg)
// TODO: if the error is really bad, we could:
//if err != nil {
// return
//}
// unblock if we exit while waiting to send!
case <-obj.closeChan:
return
}
}
}()
return ch
}
// Close shuts down the yamlgraph GAPI.
func (obj *GAPI) Close() error {
if !obj.initialized {
return fmt.Errorf("%s: GAPI is not initialized", Name)
}
obj.configWatcher.Close()
close(obj.closeChan)
obj.wg.Wait()
obj.initialized = false // closed = true
return nil
}