func addCharm(st *state.State, curl *charm.URL, ch charm.Charm) (*state.Charm, error) {
var f *os.File
name := charm.Quote(curl.String())
switch ch := ch.(type) {
case *charm.Dir:
var err error
if f, err = ioutil.TempFile("", name); err != nil {
return nil, err
}
defer os.Remove(f.Name())
defer f.Close()
err = ch.BundleTo(f)
if err != nil {
return nil, fmt.Errorf("cannot bundle charm: %v", err)
}
if _, err := f.Seek(0, 0); err != nil {
return nil, err
}
case *charm.Bundle:
var err error
if f, err = os.Open(ch.Path); err != nil {
return nil, fmt.Errorf("cannot read charm bundle: %v", err)
}
defer f.Close()
default:
return nil, fmt.Errorf("unknown charm type %T", ch)
}
digest, size, err := utils.ReadSHA256(f)
if err != nil {
return nil, err
}
if _, err := f.Seek(0, 0); err != nil {
return nil, err
}
cfg, err := st.EnvironConfig()
if err != nil {
return nil, err
}
env, err := environs.New(cfg)
if err != nil {
return nil, err
}
stor := env.Storage()
if err := stor.Put(name, f, size); err != nil {
return nil, fmt.Errorf("cannot put charm: %v", err)
}
ustr, err := stor.URL(name)
if err != nil {
return nil, fmt.Errorf("cannot get storage URL for charm: %v", err)
}
u, err := url.Parse(ustr)
if err != nil {
return nil, fmt.Errorf("cannot parse storage URL: %v", err)
}
sch, err := st.AddCharm(ch, curl, u, digest)
if err != nil {
return nil, fmt.Errorf("cannot add charm: %v", err)
}
return sch, nil
}
// PutCharm uploads the given charm to provider storage, and adds a
// state.Charm to the state. The charm is not uploaded if a charm with
// the same URL already exists in the state.
// If bumpRevision is true, the charm must be a local directory,
// and the revision number will be incremented before pushing.
func (conn *Conn) PutCharm(curl *charm.URL, repo charm.Repository, bumpRevision bool) (*state.Charm, error) {
if curl.Revision == -1 {
rev, err := charm.Latest(repo, curl)
if err != nil {
return nil, fmt.Errorf("cannot get latest charm revision: %v", err)
}
curl = curl.WithRevision(rev)
}
ch, err := repo.Get(curl)
if err != nil {
return nil, fmt.Errorf("cannot get charm: %v", err)
}
if bumpRevision {
chd, ok := ch.(*charm.Dir)
if !ok {
return nil, fmt.Errorf("cannot increment revision of charm %q: not a directory", curl)
}
if err = chd.SetDiskRevision(chd.Revision() + 1); err != nil {
return nil, fmt.Errorf("cannot increment revision of charm %q: %v", curl, err)
}
curl = curl.WithRevision(chd.Revision())
}
if sch, err := conn.State.Charm(curl); err == nil {
return sch, nil
}
return conn.addCharm(curl, ch)
}
// AddCharm adds the ch charm with curl to the state. bundleURL must
// be set to a URL where the bundle for ch may be downloaded from. On
// success the newly added charm state is returned.
func (st *State) AddCharm(ch charm.Charm, curl *charm.URL, bundleURL *url.URL, bundleSha256 string) (stch *Charm, err error) {
// The charm may already exist in state as a placeholder, so we
// check for that situation and update the existing charm record
// if necessary, otherwise add a new record.
var existing charmDoc
err = st.charms.Find(bson.D{{"_id", curl.String()}, {"placeholder", true}}).One(&existing)
if err == mgo.ErrNotFound {
cdoc := &charmDoc{
URL: curl,
Meta: ch.Meta(),
Config: ch.Config(),
Actions: ch.Actions(),
BundleURL: bundleURL,
BundleSha256: bundleSha256,
}
err = st.charms.Insert(cdoc)
if err != nil {
return nil, fmt.Errorf("cannot add charm %q: %v", curl, err)
}
return newCharm(st, cdoc)
} else if err != nil {
return nil, err
}
return st.updateCharmDoc(ch, curl, bundleURL, bundleSha256, stillPlaceholder)
}
func (br *bundleReader) AddBundle(c *gc.C, url *corecharm.URL, bundle charm.Bundle) charm.BundleInfo {
if br.bundles == nil {
br.bundles = map[string]charm.Bundle{}
}
br.bundles[url.String()] = bundle
return &bundleInfo{nil, url}
}
// addCharmViaAPI calls the appropriate client API calls to add the
// given charm URL to state. Also displays the charm URL of the added
// charm on stdout.
func addCharmViaAPI(client *api.Client, ctx *cmd.Context, curl *charm.URL, repo charm.Repository) (*charm.URL, error) {
if curl.Revision < 0 {
latest, err := charm.Latest(repo, curl)
if err != nil {
return nil, err
}
curl = curl.WithRevision(latest)
}
switch curl.Schema {
case "local":
ch, err := repo.Get(curl)
if err != nil {
return nil, err
}
stateCurl, err := client.AddLocalCharm(curl, ch)
if err != nil {
return nil, err
}
curl = stateCurl
case "cs":
err := client.AddCharm(curl)
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("unsupported charm URL schema: %q", curl.Schema)
}
ctx.Infof("Added charm %q to the environment.", curl)
return curl, nil
}
// DeleteCharm deletes the charms matching url. If no revision is specified,
// all revisions of the charm are deleted.
func (s *Store) DeleteCharm(url *charm.URL) ([]*CharmInfo, error) {
logger.Debugf("deleting charm %s", url)
infos, err := s.getRevisions(url, 0)
if err != nil {
return nil, err
}
if len(infos) == 0 {
return nil, ErrNotFound
}
session := s.session.Copy()
defer session.Close()
var deleted []*CharmInfo
for _, info := range infos {
err := session.Charms().Remove(
bson.D{{"urls", url.WithRevision(-1)}, {"revision", info.Revision()}})
if err != nil {
logger.Errorf("failed to delete metadata for charm %s: %v", url, err)
return deleted, err
}
err = session.CharmFS().RemoveId(info.fileId)
if err != nil {
logger.Errorf("failed to delete GridFS file for charm %s: %v", url, err)
return deleted, err
}
deleted = append(deleted, info)
}
return deleted, err
}
// storeManifest stores, into dataPath, the supplied manifest for the supplied charm.
func (d *manifestDeployer) storeManifest(url *charm.URL, manifest set.Strings) error {
if err := os.MkdirAll(d.DataPath(manifestsDataPath), 0755); err != nil {
return err
}
name := charm.Quote(url.String())
path := filepath.Join(d.DataPath(manifestsDataPath), name)
return utils.WriteYaml(path, manifest.SortedValues())
}
// PrepareLocalCharmUpload must be called before a local charm is
// uploaded to the provider storage in order to create a charm
// document in state. It returns the chosen unique charm URL reserved
// in state for the charm.
//
// The url's schema must be "local" and it must include a revision.
func (st *State) PrepareLocalCharmUpload(curl *charm.URL) (chosenUrl *charm.URL, err error) {
// Perform a few sanity checks first.
if curl.Schema != "local" {
return nil, fmt.Errorf("expected charm URL with local schema, got %q", curl)
}
if curl.Revision < 0 {
return nil, fmt.Errorf("expected charm URL with revision, got %q", curl)
}
// Get a regex with the charm URL and no revision.
noRevURL := curl.WithRevision(-1)
curlRegex := "^" + regexp.QuoteMeta(noRevURL.String())
for attempt := 0; attempt < 3; attempt++ {
// Find the highest revision of that charm in state.
var docs []charmDoc
err = st.charms.Find(bson.D{{"_id", bson.D{{"$regex", curlRegex}}}}).Select(bson.D{{"_id", 1}}).All(&docs)
if err != nil {
return nil, err
}
// Find the highest revision.
maxRevision := -1
for _, doc := range docs {
if doc.URL.Revision > maxRevision {
maxRevision = doc.URL.Revision
}
}
// Respect the local charm's revision first.
chosenRevision := curl.Revision
if maxRevision >= chosenRevision {
// More recent revision exists in state, pick the next.
chosenRevision = maxRevision + 1
}
chosenUrl = curl.WithRevision(chosenRevision)
uploadedCharm := &charmDoc{
URL: chosenUrl,
PendingUpload: true,
}
ops := []txn.Op{{
C: st.charms.Name,
Id: uploadedCharm.URL,
Assert: txn.DocMissing,
Insert: uploadedCharm,
}}
// Run the transaction, and retry on abort.
if err = st.runTransaction(ops); err == txn.ErrAborted {
continue
} else if err != nil {
return nil, err
}
break
}
if err != nil {
return nil, ErrExcessiveContention
}
return chosenUrl, nil
}
// Charm returns the charm with the given URL.
func (st *State) Charm(curl *charm.URL) (*Charm, error) {
if curl == nil {
return nil, fmt.Errorf("charm url cannot be nil")
}
return &Charm{
st: st,
url: curl.String(),
}, nil
}
func handleEvent(ctx *cmd.Context, curl *charm.URL, event *charm.EventResponse) error {
switch event.Kind {
case "published":
curlRev := curl.WithRevision(event.Revision)
logger.Infof("charm published at %s as %s", event.Time, curlRev)
fmt.Fprintln(ctx.Stdout, curlRev)
case "publish-error":
return fmt.Errorf("charm could not be published: %s", strings.Join(event.Errors, "; "))
default:
return fmt.Errorf("unknown event kind %q for charm %s", event.Kind, curl)
}
return nil
}
// AddStoreCharmPlaceholder creates a charm document in state for the given charm URL which
// must reference a charm from the store. The charm document is marked as a placeholder which
// means that if the charm is to be deployed, it will need to first be uploaded to env storage.
func (st *State) AddStoreCharmPlaceholder(curl *charm.URL) (err error) {
// Perform sanity checks first.
if curl.Schema != "cs" {
return fmt.Errorf("expected charm URL with cs schema, got %q", curl)
}
if curl.Revision < 0 {
return fmt.Errorf("expected charm URL with revision, got %q", curl)
}
for attempt := 0; attempt < 3; attempt++ {
// See if the charm already exists in state and exit early if that's the case.
var doc charmDoc
err = st.charms.Find(bson.D{{"_id", curl.String()}}).Select(bson.D{{"_id", 1}}).One(&doc)
if err != nil && err != mgo.ErrNotFound {
return err
}
if err == nil {
return nil
}
// Delete all previous placeholders so we don't fill up the database with unused data.
var ops []txn.Op
ops, err = st.deleteOldPlaceholderCharmsOps(curl)
if err != nil {
return nil
}
// Add the new charm doc.
placeholderCharm := &charmDoc{
URL: curl,
Placeholder: true,
}
ops = append(ops, txn.Op{
C: st.charms.Name,
Id: placeholderCharm.URL.String(),
Assert: txn.DocMissing,
Insert: placeholderCharm,
})
// Run the transaction, and retry on abort.
if err = st.runTransaction(ops); err == txn.ErrAborted {
continue
} else if err != nil {
return err
}
break
}
if err != nil {
return ErrExcessiveContention
}
return nil
}
// SetCharmURL marks the unit as currently using the supplied charm URL.
// An error will be returned if the unit is dead, or the charm URL not known.
func (u *Unit) SetCharmURL(curl *charm.URL) error {
if curl == nil {
return fmt.Errorf("charm URL cannot be nil")
}
var result params.ErrorResults
args := params.EntitiesCharmURL{
Entities: []params.EntityCharmURL{
{Tag: u.tag.String(), CharmURL: curl.String()},
},
}
err := u.st.call("SetCharmURL", args, &result)
if err != nil {
return err
}
return result.OneError()
}
// serviceSetCharm1dot16 sets the charm for the given service in 1.16
// compatibility mode. Remove this when support for 1.16 is dropped.
func (c *Client) serviceSetCharm1dot16(service *state.Service, curl *charm.URL, force bool) error {
if curl.Schema != "cs" {
return fmt.Errorf(`charm url has unsupported schema %q`, curl.Schema)
}
if curl.Revision < 0 {
return fmt.Errorf("charm url must include revision")
}
err := c.AddCharm(params.CharmURL{curl.String()})
if err != nil {
return err
}
ch, err := c.api.state.Charm(curl)
if err != nil {
return err
}
return service.SetCharm(ch, force)
}
// LatestPlaceholderCharm returns the latest charm described by the
// given URL but which is not yet deployed.
func (st *State) LatestPlaceholderCharm(curl *charm.URL) (*Charm, error) {
noRevURL := curl.WithRevision(-1)
curlRegex := "^" + regexp.QuoteMeta(noRevURL.String())
var docs []charmDoc
err := st.charms.Find(bson.D{{"_id", bson.D{{"$regex", curlRegex}}}, {"placeholder", true}}).All(&docs)
if err != nil {
return nil, fmt.Errorf("cannot get charm %q: %v", curl, err)
}
// Find the highest revision.
var latest charmDoc
for _, doc := range docs {
if latest.URL == nil || doc.URL.Revision > latest.URL.Revision {
latest = doc
}
}
if latest.URL == nil {
return nil, errors.NotFoundf("placeholder charm %q", noRevURL)
}
return newCharm(st, &latest)
}
// AddStoreCharmPlaceholder creates a charm document in state for the given charm URL which
// must reference a charm from the store. The charm document is marked as a placeholder which
// means that if the charm is to be deployed, it will need to first be uploaded to env storage.
func (st *State) AddStoreCharmPlaceholder(curl *charm.URL) (err error) {
// Perform sanity checks first.
if curl.Schema != "cs" {
return fmt.Errorf("expected charm URL with cs schema, got %q", curl)
}
if curl.Revision < 0 {
return fmt.Errorf("expected charm URL with revision, got %q", curl)
}
buildTxn := func(attempt int) ([]txn.Op, error) {
// See if the charm already exists in state and exit early if that's the case.
var doc charmDoc
err := st.charms.Find(bson.D{{"_id", curl.String()}}).Select(bson.D{{"_id", 1}}).One(&doc)
if err != nil && err != mgo.ErrNotFound {
return nil, err
}
if err == nil {
return nil, jujutxn.ErrNoOperations
}
// Delete all previous placeholders so we don't fill up the database with unused data.
ops, err := st.deleteOldPlaceholderCharmsOps(curl)
if err != nil {
return nil, err
}
// Add the new charm doc.
placeholderCharm := &charmDoc{
URL: curl,
Placeholder: true,
}
ops = append(ops, txn.Op{
C: st.charms.Name,
Id: placeholderCharm.URL.String(),
Assert: txn.DocMissing,
Insert: placeholderCharm,
})
return ops, nil
}
return st.run(buildTxn)
}
// getRevisions returns at most the last n revisions for charm at url,
// in descending revision order. For limit n=0, all revisions are returned.
func (s *Store) getRevisions(url *charm.URL, n int) ([]*CharmInfo, error) {
session := s.session.Copy()
defer session.Close()
logger.Debugf("retrieving charm info for %s", url)
rev := url.Revision
url = url.WithRevision(-1)
charms := session.Charms()
var cdocs []charmDoc
var qdoc interface{}
if rev == -1 {
qdoc = bson.D{{"urls", url}}
} else {
qdoc = bson.D{{"urls", url}, {"revision", rev}}
}
q := charms.Find(qdoc).Sort("-revision")
if n > 0 {
q = q.Limit(n)
}
if err := q.All(&cdocs); err != nil {
logger.Errorf("failed to find charm %s: %v", url, err)
return nil, ErrNotFound
}
var infos []*CharmInfo
for _, cdoc := range cdocs {
infos = append(infos, &CharmInfo{
cdoc.Revision,
cdoc.Digest,
cdoc.Sha256,
cdoc.Size,
cdoc.FileId,
cdoc.Meta,
cdoc.Config,
cdoc.Actions,
})
}
return infos, nil
}
// deleteOldPlaceholderCharmsOps returns the txn ops required to delete all placeholder charm
// records older than the specified charm URL.
func (st *State) deleteOldPlaceholderCharmsOps(curl *charm.URL) ([]txn.Op, error) {
// Get a regex with the charm URL and no revision.
noRevURL := curl.WithRevision(-1)
curlRegex := "^" + regexp.QuoteMeta(noRevURL.String())
var docs []charmDoc
err := st.charms.Find(
bson.D{{"_id", bson.D{{"$regex", curlRegex}}}, {"placeholder", true}}).Select(bson.D{{"_id", 1}}).All(&docs)
if err != nil {
return nil, err
}
var ops []txn.Op
for _, doc := range docs {
if doc.URL.Revision >= curl.Revision {
continue
}
ops = append(ops, txn.Op{
C: st.charms.Name,
Id: doc.URL.String(),
Assert: stillPlaceholder,
Remove: true,
})
}
return ops, nil
}
// repackageAndUploadCharm expands the given charm archive to a
// temporary directoy, repackages it with the given curl's revision,
// then uploads it to providr storage, and finally updates the state.
func (h *charmsHandler) repackageAndUploadCharm(archive *charm.Bundle, curl *charm.URL) error {
// Create a temp dir to contain the extracted charm
// dir and the repackaged archive.
tempDir, err := ioutil.TempDir("", "charm-download")
if err != nil {
return errors.Annotate(err, "cannot create temp directory")
}
defer os.RemoveAll(tempDir)
extractPath := filepath.Join(tempDir, "extracted")
repackagedPath := filepath.Join(tempDir, "repackaged.zip")
repackagedArchive, err := os.Create(repackagedPath)
if err != nil {
return errors.Annotate(err, "cannot repackage uploaded charm")
}
defer repackagedArchive.Close()
// Expand and repack it with the revision specified by curl.
archive.SetRevision(curl.Revision)
if err := archive.ExpandTo(extractPath); err != nil {
return errors.Annotate(err, "cannot extract uploaded charm")
}
charmDir, err := charm.ReadDir(extractPath)
if err != nil {
return errors.Annotate(err, "cannot read extracted charm")
}
// Bundle the charm and calculate its sha256 hash at the
// same time.
hash := sha256.New()
err = charmDir.BundleTo(io.MultiWriter(hash, repackagedArchive))
if err != nil {
return errors.Annotate(err, "cannot repackage uploaded charm")
}
bundleSHA256 := hex.EncodeToString(hash.Sum(nil))
size, err := repackagedArchive.Seek(0, 2)
if err != nil {
return errors.Annotate(err, "cannot get charm file size")
}
// Now upload to provider storage.
if _, err := repackagedArchive.Seek(0, 0); err != nil {
return errors.Annotate(err, "cannot rewind the charm file reader")
}
storage, err := environs.GetStorage(h.state)
if err != nil {
return errors.Annotate(err, "cannot access provider storage")
}
name := charm.Quote(curl.String())
if err := storage.Put(name, repackagedArchive, size); err != nil {
return errors.Annotate(err, "cannot upload charm to provider storage")
}
storageURL, err := storage.URL(name)
if err != nil {
return errors.Annotate(err, "cannot get storage URL for charm")
}
bundleURL, err := url.Parse(storageURL)
if err != nil {
return errors.Annotate(err, "cannot parse storage URL")
}
// And finally, update state.
_, err = h.state.UpdateUploadedCharm(archive, curl, bundleURL, bundleSHA256)
if err != nil {
return errors.Annotate(err, "cannot update uploaded charm in state")
}
return nil
}
func (s *LocalRepoSuite) checkNotFoundErr(c *gc.C, err error, charmURL *charm.URL) {
expect := `charm not found in "` + s.repo.Path + `": ` + charmURL.String()
c.Check(err, gc.ErrorMatches, expect)
}
// WriteCharmURL writes a charm identity file into the supplied path.
func WriteCharmURL(path string, url *charm.URL) error {
return utils.WriteYaml(path, url.String())
}
// bundleURLPath returns the path to the location where the verified charm
// bundle identified by url will be, or has been, saved.
func (d *BundlesDir) bundleURLPath(url *charm.URL) string {
return path.Join(d.path, charm.Quote(url.String()))
}
// Run connects to the specified environment and starts the charm
// upgrade process.
func (c *UpgradeCharmCommand) Run(ctx *cmd.Context) error {
client, err := juju.NewAPIClientFromName(c.EnvName)
if err != nil {
return err
}
defer client.Close()
oldURL, err := client.ServiceGetCharmURL(c.ServiceName)
if err != nil {
return err
}
attrs, err := client.EnvironmentGet()
if err != nil {
return err
}
conf, err := config.New(config.NoDefaults, attrs)
if err != nil {
return err
}
var newURL *charm.URL
if c.SwitchURL != "" {
newURL, err = resolveCharmURL(c.SwitchURL, client, conf)
if err != nil {
return err
}
} else {
// No new URL specified, but revision might have been.
newURL = oldURL.WithRevision(c.Revision)
}
repo, err := charm.InferRepository(newURL.Reference, ctx.AbsPath(c.RepoPath))
if err != nil {
return err
}
repo = config.SpecializeCharmRepo(repo, conf)
// If no explicit revision was set with either SwitchURL
// or Revision flags, discover the latest.
explicitRevision := true
if newURL.Revision == -1 {
explicitRevision = false
latest, err := charm.Latest(repo, newURL)
if err != nil {
return err
}
newURL = newURL.WithRevision(latest)
}
if *newURL == *oldURL {
if explicitRevision {
return fmt.Errorf("already running specified charm %q", newURL)
} else if newURL.Schema == "cs" {
// No point in trying to upgrade a charm store charm when
// we just determined that's the latest revision
// available.
return fmt.Errorf("already running latest charm %q", newURL)
}
}
addedURL, err := addCharmViaAPI(client, ctx, newURL, repo)
if err != nil {
return err
}
return client.ServiceSetCharm(c.ServiceName, addedURL.String(), c.Force)
}
// AddLocalCharm prepares the given charm with a local: schema in its
// URL, and uploads it via the API server, returning the assigned
// charm URL. If the API server does not support charm uploads, an
// error satisfying params.IsCodeNotImplemented() is returned.
func (c *Client) AddLocalCharm(curl *charm.URL, ch charm.Charm) (*charm.URL, error) {
if curl.Schema != "local" {
return nil, fmt.Errorf("expected charm URL with local: schema, got %q", curl.String())
}
// Package the charm for uploading.
var archive *os.File
switch ch := ch.(type) {
case *charm.Dir:
var err error
if archive, err = ioutil.TempFile("", "charm"); err != nil {
return nil, fmt.Errorf("cannot create temp file: %v", err)
}
defer os.Remove(archive.Name())
defer archive.Close()
if err := ch.BundleTo(archive); err != nil {
return nil, fmt.Errorf("cannot repackage charm: %v", err)
}
if _, err := archive.Seek(0, 0); err != nil {
return nil, fmt.Errorf("cannot rewind packaged charm: %v", err)
}
case *charm.Bundle:
var err error
if archive, err = os.Open(ch.Path); err != nil {
return nil, fmt.Errorf("cannot read charm archive: %v", err)
}
defer archive.Close()
default:
return nil, fmt.Errorf("unknown charm type %T", ch)
}
// Prepare the upload request.
url := fmt.Sprintf("%s/charms?series=%s", c.st.serverRoot, curl.Series)
req, err := http.NewRequest("POST", url, archive)
if err != nil {
return nil, fmt.Errorf("cannot create upload request: %v", err)
}
req.SetBasicAuth(c.st.tag, c.st.password)
req.Header.Set("Content-Type", "application/zip")
// Send the request.
// BUG(dimitern) 2013-12-17 bug #1261780
// Due to issues with go 1.1.2, fixed later, we cannot use a
// regular TLS client with the CACert here, because we get "x509:
// cannot validate certificate for 127.0.0.1 because it doesn't
// contain any IP SANs". Once we use a later go version, this
// should be changed to connect to the API server with a regular
// HTTP+TLS enabled client, using the CACert (possily cached, like
// the tag and password) passed in api.Open()'s info argument.
resp, err := utils.GetNonValidatingHTTPClient().Do(req)
if err != nil {
return nil, fmt.Errorf("cannot upload charm: %v", err)
}
if resp.StatusCode == http.StatusMethodNotAllowed {
// API server is 1.16 or older, so charm upload
// is not supported; notify the client.
return nil, ¶ms.Error{
Message: "charm upload is not supported by the API server",
Code: params.CodeNotImplemented,
}
}
// Now parse the response & return.
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("cannot read charm upload response: %v", err)
}
defer resp.Body.Close()
var jsonResponse params.CharmsResponse
if err := json.Unmarshal(body, &jsonResponse); err != nil {
return nil, fmt.Errorf("cannot unmarshal upload response: %v", err)
}
if jsonResponse.Error != "" {
return nil, fmt.Errorf("error uploading charm: %v", jsonResponse.Error)
}
return charm.MustParseURL(jsonResponse.CharmURL), nil
}
// AddCharm adds the given charm URL (which must include revision) to
// the environment, if it does not exist yet. Local charms are not
// supported, only charm store URLs. See also AddLocalCharm() in the
// client-side API.
func (c *Client) AddCharm(curl *charm.URL) error {
args := params.CharmURL{URL: curl.String()}
return c.call("AddCharm", args, nil)
}