github.com/makyo/juju@v0.0.0-20160425123129-2608902037e9/worker/uniter/charm/charm.go (about)

     1  // Copyright 2012-2014 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package charm
     5  
     6  import (
     7  	"errors"
     8  	"net/url"
     9  
    10  	"github.com/juju/loggo"
    11  	"github.com/juju/utils"
    12  	"github.com/juju/utils/set"
    13  	"gopkg.in/juju/charm.v6-unstable"
    14  )
    15  
    16  var logger = loggo.GetLogger("juju.worker.uniter.charm")
    17  
    18  // CharmURLPath is the path within a charm directory to which Deployers
    19  // commonly write the charm URL of the latest deployed charm.
    20  const CharmURLPath = ".juju-charm"
    21  
    22  // Bundle allows access to a charm's files.
    23  type Bundle interface {
    24  
    25  	// Manifest returns a set of slash-separated strings representing files,
    26  	// directories, and symlinks stored in the bundle.
    27  	Manifest() (set.Strings, error)
    28  
    29  	// ExpandTo unpacks the entities referenced in the manifest into the
    30  	// supplied directory. If it returns without error, every file referenced
    31  	// in the charm must be present in the directory; implementations may vary
    32  	// in the details of what they do with other files present.
    33  	ExpandTo(dir string) error
    34  }
    35  
    36  // BundleInfo describes a Bundle.
    37  type BundleInfo interface {
    38  
    39  	// URL returns the charm URL identifying the bundle.
    40  	URL() *charm.URL
    41  
    42  	// ArchiveURLs returns the location(s) of the bundle data. ArchiveURLs
    43  	// may return multiple URLs; each should be tried until one succeeds.
    44  	ArchiveURLs() ([]*url.URL, error)
    45  
    46  	// ArchiveSha256 returns the hex-encoded SHA-256 digest of the bundle data.
    47  	ArchiveSha256() (string, error)
    48  }
    49  
    50  // BundleReader provides a mechanism for getting a Bundle from a BundleInfo.
    51  type BundleReader interface {
    52  
    53  	// Read returns the bundle identified by the supplied info. The abort chan
    54  	// can be used to notify an implementation that it need not complete the
    55  	// operation, and can immediately error out if it is convenient to do so.
    56  	Read(bi BundleInfo, abort <-chan struct{}) (Bundle, error)
    57  }
    58  
    59  // Deployer is responsible for installing and upgrading charms.
    60  type Deployer interface {
    61  
    62  	// Stage must be called to prime the Deployer to install or upgrade the
    63  	// bundle identified by the supplied info. The abort chan can be used to
    64  	// notify an implementation that it need not complete the operation, and
    65  	// can immediately error out if it convenient to do so. It must always
    66  	// be safe to restage the same bundle, or to stage a new bundle.
    67  	Stage(info BundleInfo, abort <-chan struct{}) error
    68  
    69  	// Deploy will install or upgrade the most recently staged bundle.
    70  	// Behaviour is undefined if Stage has not been called. Failures that
    71  	// can be resolved by user intervention will be signalled by returning
    72  	// ErrConflict.
    73  	Deploy() error
    74  
    75  	// NotifyRevert must be called when a conflicted deploy is abandoned, in
    76  	// preparation for a new upgrade.
    77  	NotifyRevert() error
    78  
    79  	// NotifyResolved must be called when the cause of a deploy conflict has
    80  	// been resolved, and a new deploy attempt will be made.
    81  	NotifyResolved() error
    82  }
    83  
    84  // ErrConflict indicates that an upgrade failed and cannot be resolved
    85  // without human intervention.
    86  var ErrConflict = errors.New("charm upgrade has conflicts")
    87  
    88  // ReadCharmURL reads a charm identity file from the supplied path.
    89  func ReadCharmURL(path string) (*charm.URL, error) {
    90  	surl := ""
    91  	if err := utils.ReadYaml(path, &surl); err != nil {
    92  		return nil, err
    93  	}
    94  	return charm.ParseURL(surl)
    95  }
    96  
    97  // WriteCharmURL writes a charm identity file into the supplied path.
    98  func WriteCharmURL(path string, url *charm.URL) error {
    99  	return utils.WriteYaml(path, url.String())
   100  }