github.com/stackdocker/rkt@v0.10.1-0.20151109095037-1aa827478248/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  	"fmt"
    22  	"io/ioutil"
    23  
    24  	"github.com/coreos/rkt/Godeps/_workspace/src/github.com/appc/spec/schema"
    25  	"github.com/coreos/rkt/common"
    26  )
    27  
    28  const (
    29  	enterEntrypoint = "coreos.com/rkt/stage1/enter"
    30  	runEntrypoint   = "coreos.com/rkt/stage1/run"
    31  	gcEntrypoint    = "coreos.com/rkt/stage1/gc"
    32  )
    33  
    34  // getStage1Entrypoint retrieves the named entrypoint from the stage1 manifest for a given pod
    35  func getStage1Entrypoint(cdir string, entrypoint string) (string, error) {
    36  	b, err := ioutil.ReadFile(common.Stage1ManifestPath(cdir))
    37  	if err != nil {
    38  		return "", fmt.Errorf("error reading pod manifest: %v", err)
    39  	}
    40  
    41  	s1m := schema.ImageManifest{}
    42  	if err := json.Unmarshal(b, &s1m); err != nil {
    43  		return "", fmt.Errorf("error unmarshaling stage1 manifest: %v", err)
    44  	}
    45  
    46  	if ep, ok := s1m.Annotations.Get(entrypoint); ok {
    47  		return ep, nil
    48  	}
    49  
    50  	return "", fmt.Errorf("entrypoint %q not found", entrypoint)
    51  }