Allow the ability to specify branch when deploying charms

The following is the initial work for deploying charms with channel
branches. As channel branches are non-discoverable it means that both
arch and series (platform) are required when using a branch in a
channel.

The code was pretty much wired up for this already, it was just about
exposing this via the api parameters.

api/common/charm/charmorigin.go

@@ -42,6 +42,8 @@ type Origin struct {
 	Revision *int
 	// Track is a CharmHub channel track.
 	Track *string
+	// Branch is the CharmHub channel branch
+	Branch *string
 	// Architecture describes the architecture intended to be used by the charm.
 	Architecture string
 	// OS describes the OS intended to be used by the charm.
@@ -69,9 +71,14 @@ func (o Origin) CharmChannel() charm.Channel {
 	if o.Track != nil {
 		track = *o.Track
 	}
+	var branch string
+	if o.Branch != nil {
+		branch = *o.Branch
+	}
 	return charm.Channel{
-		Track: track,
-		Risk:  charm.Risk(o.Risk),
+		Track:  track,
+		Risk:   charm.Risk(o.Risk),
+		Branch: branch,
 	}
 }
 
@@ -86,6 +93,7 @@ func (o Origin) ParamsCharmOrigin() params.CharmOrigin {
 		Revision:     o.Revision,
 		Risk:         o.Risk,
 		Track:        o.Track,
+		Branch:       o.Branch,
 		Architecture: o.Architecture,
 		OS:           o.OS,
 		Series:       o.Series,
@@ -99,11 +107,16 @@ func (o Origin) CoreCharmOrigin() corecharm.Origin {
 	if o.Track != nil {
 		track = *o.Track
 	}
+	var branch string
+	if o.Branch != nil {
+		branch = *o.Branch
+	}
 	var channel *charm.Channel
 	if o.Risk != "" {
 		channel = &charm.Channel{
-			Risk:  charm.Risk(o.Risk),
-			Track: track,
+			Risk:   charm.Risk(o.Risk),
+			Track:  track,
+			Branch: branch,
 		}
 	}
 	return corecharm.Origin{
@@ -133,6 +146,7 @@ func APICharmOrigin(origin params.CharmOrigin) Origin {
 		Risk:         origin.Risk,
 		Revision:     origin.Revision,
 		Track:        origin.Track,
+		Branch:       origin.Branch,
 		Architecture: origin.Architecture,
 		OS:           origin.OS,
 		Series:       origin.Series,
@@ -151,6 +165,10 @@ func CoreCharmOrigin(origin corecharm.Origin) Origin {
 	if ch.Track != "" {
 		track = &ch.Track
 	}
+	var branch *string
+	if ch.Branch != "" {
+		branch = &ch.Branch
+	}
 	return Origin{
 		Source:       OriginSource(origin.Source),
 		Type:         origin.Type,
@@ -159,6 +177,7 @@ func CoreCharmOrigin(origin corecharm.Origin) Origin {
 		Revision:     origin.Revision,
 		Risk:         string(ch.Risk),
 		Track:        track,
+		Branch:       branch,
 		Architecture: origin.Platform.Architecture,
 		OS:           origin.Platform.OS,
 		Series:       origin.Platform.Series,

api/common/charm/charmorigin_test.go

@@ -16,13 +16,16 @@ var _ = gc.Suite(&originSuite{})
 
 func (originSuite) TestCoreChannel(c *gc.C) {
 	track := "latest"
+	branch := "foo"
 	origin := commoncharm.Origin{
-		Risk:  "edge",
-		Track: &track,
+		Risk:   "edge",
+		Track:  &track,
+		Branch: &branch,
 	}
 	c.Assert(origin.CharmChannel(), gc.DeepEquals, charm.Channel{
-		Risk:  charm.Edge,
-		Track: "latest",
+		Risk:   charm.Edge,
+		Track:  "latest",
+		Branch: "foo",
 	})
 }
 

apiserver/facades/client/charms/clientnormalize_test.go

@@ -19,11 +19,13 @@ var _ = gc.Suite(&clientNormalizeOriginSuite{})
 
 func (s *clientNormalizeOriginSuite) TestNormalizeCharmOriginNoAll(c *gc.C) {
 	track := "1.0"
+	branch := "foo"
 	origin := params.CharmOrigin{
 		Source:       "charm-hub",
 		Type:         "charm",
 		Risk:         "edge",
 		Track:        &track,
+		Branch:       &branch,
 		Architecture: "all",
 		OS:           "all",
 		Series:       "all",

apiserver/facades/client/charms/conversions.go

@@ -15,6 +15,10 @@ func convertOrigin(origin corecharm.Origin) params.CharmOrigin {
 	if origin.Channel != nil && origin.Channel.Track != "" {
 		track = &origin.Channel.Track
 	}
+	var branch *string
+	if origin.Channel != nil && origin.Channel.Branch != "" {
+		branch = &origin.Channel.Branch
+	}
 	var risk string
 	if origin.Channel != nil {
 		risk = string(origin.Channel.Risk)
@@ -27,6 +31,7 @@ func convertOrigin(origin corecharm.Origin) params.CharmOrigin {
 		Risk:         risk,
 		Revision:     origin.Revision,
 		Track:        track,
+		Branch:       branch,
 		Architecture: origin.Platform.Architecture,
 		OS:           origin.Platform.OS,
 		Series:       origin.Platform.Series,
@@ -39,15 +44,20 @@ func convertParamsOrigin(origin params.CharmOrigin) corecharm.Origin {
 	if origin.Track != nil {
 		track = *origin.Track
 	}
+	var branch string
+	if origin.Branch != nil {
+		branch = *origin.Branch
+	}
 	return corecharm.Origin{
 		Source:   corecharm.Source(origin.Source),
 		Type:     origin.Type,
 		ID:       origin.ID,
 		Hash:     origin.Hash,
 		Revision: origin.Revision,
 		Channel: &charm.Channel{
-			Track: track,
-			Risk:  charm.Risk(origin.Risk),
+			Track:  track,
+			Risk:   charm.Risk(origin.Risk),
+			Branch: branch,
 		},
 		Platform: corecharm.Platform{
 			Architecture: origin.Architecture,

apiserver/facades/schema.json

@@ -3164,6 +3164,9 @@
                         "architecture": {
                             "type": "string"
                         },
+                        "branch": {
+                            "type": "string"
+                        },
                         "hash": {
                             "type": "string"
                         },
@@ -15732,6 +15735,9 @@
                         "architecture": {
                             "type": "string"
                         },
+                        "branch": {
+                            "type": "string"
+                        },
                         "hash": {
                             "type": "string"
                         },
@@ -39275,6 +39281,9 @@
                         "architecture": {
                             "type": "string"
                         },
+                        "branch": {
+                            "type": "string"
+                        },
                         "hash": {
                             "type": "string"
                         },

cmd/juju/application/utils/origin.go

@@ -55,6 +55,10 @@ func DeduceOrigin(url *charm.URL, channel charm.Channel, platform corecharm.Plat
 		if channel.Track != "" {
 			track = &channel.Track
 		}
+		var branch *string
+		if channel.Branch != "" {
+			branch = &channel.Branch
+		}
 		var revision *int
 		if url.Revision != -1 {
 			revision = &url.Revision
@@ -64,6 +68,7 @@ func DeduceOrigin(url *charm.URL, channel charm.Channel, platform corecharm.Plat
 			Revision:     revision,
 			Risk:         string(channel.Risk),
 			Track:        track,
+			Branch:       branch,
 			Architecture: architecture,
 			OS:           platform.OS,
 			Series:       platform.Series,

core/charm/repository/charmhub.go

@@ -523,6 +523,11 @@ func (c *CharmHubRepository) selectNextBasesFromReleases(releases []transport.Re
 		return nil, errors.Errorf("no releases available")
 	}
 	if origin.Platform.Series == "" {
+		// If the user passed in a branch, but not enough information about the
+		// arch and series, then we can help by giving a better error message.
+		if origin.Channel != nil && origin.Channel.Branch != "" {
+			return nil, errors.Errorf("ambiguous arch and series with channel track/risk/branch. specify both arch and series along with channel.")
+		}
 		// If the origin is empty, then we want to help the user out
 		// by display a series of suggestions to try.
 		suggestions := c.composeSuggestions(releases, origin)

rpc/params/applications.go

@@ -34,6 +34,7 @@ type CharmOrigin struct {
 	// Revision is the charm revision number.
 	Revision *int    `json:"revision,omitempty"`
 	Track    *string `json:"track,omitempty"`
+	Branch   *string `json:"branch,omitempty"`
 
 	Architecture string `json:"architecture,omitempty"`
 	OS           string `json:"os,omitempty"`