github.com/blixtra/rkt@v0.8.1-0.20160204105720-ab0d1add1a43/stage0/entrypoint.go (about)

     1  // Copyright 2015 The rkt Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  //+build linux
    16  
    17  package stage0
    18  
    19  import (
    20  	"encoding/json"
    21  	"errors"
    22  	"fmt"
    23  	"io/ioutil"
    24  
    25  	"github.com/appc/spec/schema"
    26  	"github.com/coreos/rkt/common"
    27  	"github.com/hashicorp/errwrap"
    28  )
    29  
    30  const (
    31  	enterEntrypoint = "coreos.com/rkt/stage1/enter"
    32  	runEntrypoint   = "coreos.com/rkt/stage1/run"
    33  	gcEntrypoint    = "coreos.com/rkt/stage1/gc"
    34  )
    35  
    36  // getStage1Entrypoint retrieves the named entrypoint from the stage1 manifest for a given pod
    37  func getStage1Entrypoint(cdir string, entrypoint string) (string, error) {
    38  	b, err := ioutil.ReadFile(common.Stage1ManifestPath(cdir))
    39  	if err != nil {
    40  		return "", errwrap.Wrap(errors.New("error reading pod manifest"), err)
    41  	}
    42  
    43  	s1m := schema.ImageManifest{}
    44  	if err := json.Unmarshal(b, &s1m); err != nil {
    45  		return "", errwrap.Wrap(errors.New("error unmarshaling stage1 manifest"), err)
    46  	}
    47  
    48  	if ep, ok := s1m.Annotations.Get(entrypoint); ok {
    49  		return ep, nil
    50  	}
    51  
    52  	return "", fmt.Errorf("entrypoint %q not found", entrypoint)
    53  }