add option to reverse buildchains

contrib/completions/bash/oadm

@@ -1553,6 +1553,7 @@ _oadm_build-chain()
     flags+=("--all")
     flags+=("--output=")
     two_word_flags+=("-o")
+    flags+=("--reverse")
     flags+=("--trigger-only")
     flags+=("--api-version=")
     flags+=("--certificate-authority=")

contrib/completions/bash/oc

@@ -4398,6 +4398,7 @@ _oc_adm_build-chain()
     flags+=("--all")
     flags+=("--output=")
     two_word_flags+=("-o")
+    flags+=("--reverse")
     flags+=("--trigger-only")
     flags+=("--api-version=")
     flags+=("--certificate-authority=")

contrib/completions/bash/openshift

@@ -2130,6 +2130,7 @@ _openshift_admin_build-chain()
     flags+=("--all")
     flags+=("--output=")
     two_word_flags+=("-o")
+    flags+=("--reverse")
     flags+=("--trigger-only")
     flags+=("--api-version=")
     flags+=("--certificate-authority=")
@@ -7949,6 +7950,7 @@ _openshift_cli_adm_build-chain()
     flags+=("--all")
     flags+=("--output=")
     two_word_flags+=("-o")
+    flags+=("--reverse")
     flags+=("--trigger-only")
     flags+=("--api-version=")
     flags+=("--certificate-authority=")
@@ -14690,6 +14692,7 @@ _openshift_ex_build-chain()
     flags+=("--all")
     flags+=("--output=")
     two_word_flags+=("-o")
+    flags+=("--reverse")
     flags+=("--trigger-only")
     flags+=("--api-version=")
     flags+=("--certificate-authority=")

pkg/api/graph/graph.go

@@ -434,6 +434,17 @@ func RemoveInboundEdges(nodes []graph.Node) EdgeFunc {
 	}
 }
 
+func RemoveOutboundEdges(nodes []graph.Node) EdgeFunc {
+	return func(g Interface, from, to graph.Node, edgeKinds sets.String) bool {
+		for _, node := range nodes {
+			if node == from {
+				return false
+			}
+		}
+		return true
+	}
+}
+
 // EdgeSubgraph returns the directed subgraph with only the edges that match the
 // provided function.
 func (g Graph) EdgeSubgraph(edgeFn EdgeFunc) Graph {

pkg/cmd/cli/describe/chaindescriber.go

@@ -23,9 +23,9 @@ import (
 )
 
 // NotFoundErr is returned when the imageStreamTag (ist) of interest cannot
-// be found in the graph. This doesn't mean though that the ist does not
+// be found in the graph. This doesn't mean though that the IST does not
 // exist. A user may have an image stream without a build configuration
-// pointing at it. In that case, the ist of interest simply doesn't have
+// pointing at it. In that case, the IST of interest simply doesn't have
 // other dependant ists
 type NotFoundErr string
 
@@ -79,7 +79,7 @@ func (d *ChainDescriber) MakeGraph() (osgraph.Graph, error) {
 // image stream tag (name:tag) in namespace. Namespace is needed here
 // because image stream tags with the same name can be found across
 // different namespaces.
-func (d *ChainDescriber) Describe(ist *imageapi.ImageStreamTag, includeInputImages bool) (string, error) {
+func (d *ChainDescriber) Describe(ist *imageapi.ImageStreamTag, includeInputImages, reverse bool) (string, error) {
 	g, err := d.MakeGraph()
 	if err != nil {
 		return "", err
@@ -96,8 +96,13 @@ func (d *ChainDescriber) Describe(ist *imageapi.ImageStreamTag, includeInputImag
 		buildInputEdgeKinds = append(buildInputEdgeKinds, buildedges.BuildInputImageEdgeKind)
 	}
 
-	// Partition down to the subgraph containing the ist of interest
-	partitioned := partition(g, istNode, buildInputEdgeKinds)
+	// Partition down to the subgraph containing the imagestreamtag of interest
+	var partitioned osgraph.Graph
+	if reverse {
+		partitioned = partitionReverse(g, istNode, buildInputEdgeKinds)
+	} else {
+		partitioned = partition(g, istNode, buildInputEdgeKinds)
+	}
 
 	switch strings.ToLower(d.outputFormat) {
 	case "dot":
@@ -107,7 +112,7 @@ func (d *ChainDescriber) Describe(ist *imageapi.ImageStreamTag, includeInputImag
 		}
 		return string(data), nil
 	case "":
-		return d.humanReadableOutput(partitioned, d.namer, istNode), nil
+		return d.humanReadableOutput(partitioned, d.namer, istNode, reverse), nil
 	}
 
 	return "", fmt.Errorf("unknown specified format %q", d.outputFormat)
@@ -124,7 +129,7 @@ func partition(g osgraph.Graph, root graph.Node, buildInputEdgeKinds []string) o
 	edgeFn := osgraph.EdgesOfKind(edgeKinds...)
 	sub := g.Subgraph(nodeFn, edgeFn)
 
-	// Filter out inbound edges to the ist of interest
+	// Filter out inbound edges to the IST of interest
 	edgeFn = osgraph.RemoveInboundEdges([]graph.Node{root})
 	sub = sub.Subgraph(nodeFn, edgeFn)
 
@@ -144,11 +149,46 @@ func partition(g osgraph.Graph, root graph.Node, buildInputEdgeKinds []string) o
 	return sub.SubgraphWithNodes(desired, osgraph.ExistingDirectEdge)
 }
 
+// partitionReverse the graph down to a subgraph starting from the given root
+func partitionReverse(g osgraph.Graph, root graph.Node, buildInputEdgeKinds []string) osgraph.Graph {
+	// Filter out all but BuildConfig and ImageStreamTag nodes
+	nodeFn := osgraph.NodesOfKind(buildgraph.BuildConfigNodeKind, imagegraph.ImageStreamTagNodeKind)
+	// Filter out all but BuildInputImage and BuildOutput edges
+	edgeKinds := []string{}
+	edgeKinds = append(edgeKinds, buildInputEdgeKinds...)
+	edgeKinds = append(edgeKinds, buildedges.BuildOutputEdgeKind)
+	edgeFn := osgraph.EdgesOfKind(edgeKinds...)
+	sub := g.Subgraph(nodeFn, edgeFn)
+
+	// Filter out inbound edges to the IST of interest
+	edgeFn = osgraph.RemoveOutboundEdges([]graph.Node{root})
+	sub = sub.Subgraph(nodeFn, edgeFn)
+
+	// Check all paths leading from the root node, collect any
+	// node found in them, and create the desired subgraph
+	desired := []graph.Node{root}
+	paths := path.DijkstraAllPaths(sub)
+	for _, node := range sub.Nodes() {
+		if node == root {
+			continue
+		}
+		path, _, _ := paths.Between(node, root)
+		if len(path) != 0 {
+			desired = append(desired, node)
+		}
+	}
+	return sub.SubgraphWithNodes(desired, osgraph.ExistingDirectEdge)
+}
+
 // humanReadableOutput traverses the provided graph using DFS and outputs it
 // in a human-readable format. It starts from the provided root, assuming it
 // is an imageStreamTag node and continues to the rest of the graph handling
 // only imageStreamTag and buildConfig nodes.
-func (d *ChainDescriber) humanReadableOutput(g osgraph.Graph, f osgraph.Namer, root graph.Node) string {
+func (d *ChainDescriber) humanReadableOutput(g osgraph.Graph, f osgraph.Namer, root graph.Node, reverse bool) string {
+	if reverse {
+		g = g.EdgeSubgraph(osgraph.ReverseExistingDirectEdge)
+	}
+
 	var singleNamespace bool
 	if len(d.namespaces) == 1 && !d.namespaces.Has(kapi.NamespaceAll) {
 		singleNamespace = true

pkg/cmd/cli/describe/chaindescriber_test.go

@@ -19,6 +19,7 @@ func TestChainDescriber(t *testing.T) {
 		testName         string
 		namespaces       sets.String
 		output           string
+		reverse          bool
 		defaultNamespace string
 		name             string
 		tag              string
@@ -161,6 +162,24 @@ func TestChainDescriber(t *testing.T) {
 				"\t\tistag/parent3img:latest":    1,
 			},
 		},
+		{
+			testName:         "human readable - multiple triggers - triggeronly - reverse",
+			name:             "child2img",
+			reverse:          true,
+			defaultNamespace: "test",
+			tag:              "latest",
+			path:             "../../../../pkg/cmd/experimental/buildchain/test/multiple-trigger-bcs.yaml",
+			namespaces:       sets.NewString("test"),
+			humanReadable: map[string]int{
+				"istag/child2img:latest":               1,
+				"\tbc/child2":                          1,
+				"\t\tistag/parent1img:latest":          1,
+				"\t\t\tbc/parent1":                     1,
+				"\t\t\t\tistag/ruby-22-centos7:latest": 2,
+				"\t\tistag/parent3img:latest":          1,
+				"\t\t\tbc/parent3":                     1,
+			},
+		},
 	}
 
 	for _, test := range tests {
@@ -174,7 +193,7 @@ func TestChainDescriber(t *testing.T) {
 		oc, _ := testclient.NewFixtureClients(o)
 		ist := imagegraph.MakeImageStreamTagObjectMeta(test.defaultNamespace, test.name, test.tag)
 
-		desc, err := NewChainDescriber(oc, test.namespaces, test.output).Describe(ist, test.includeInputImg)
+		desc, err := NewChainDescriber(oc, test.namespaces, test.output).Describe(ist, test.includeInputImg, test.reverse)
 		t.Logf("%s: output:\n%s\n\n", test.testName, desc)
 		if err != test.expectedErr {
 			t.Fatalf("%s: error mismatch: expected %v, got %v", test.testName, test.expectedErr, err)

pkg/cmd/experimental/buildchain/buildchain.go

@@ -49,6 +49,7 @@ type BuildChainOptions struct {
 	namespaces       sets.String
 	allNamespaces    bool
 	triggerOnly      bool
+	reverse          bool
 
 	output string
 
@@ -77,6 +78,7 @@ func NewCmdBuildChain(name, fullName string, f *clientcmd.Factory, out io.Writer
 
 	cmd.Flags().BoolVar(&options.allNamespaces, "all", false, "Build dependency tree for the specified image stream tag across all namespaces")
 	cmd.Flags().BoolVar(&options.triggerOnly, "trigger-only", true, "If true, only include dependencies based on build triggers. If false, include all dependencies.")
+	cmd.Flags().BoolVar(&options.reverse, "reverse", false, "If true, show the istags dependencies instead of its dependants.")
 	cmd.Flags().StringVarP(&options.output, "output", "o", "", "Output format of dependency tree")
 	return cmd
 }
@@ -160,7 +162,7 @@ func (o *BuildChainOptions) Validate() error {
 func (o *BuildChainOptions) RunBuildChain() error {
 	ist := imagegraph.MakeImageStreamTagObjectMeta2(o.defaultNamespace, o.name)
 
-	desc, err := describe.NewChainDescriber(o.c, o.namespaces, o.output).Describe(ist, !o.triggerOnly)
+	desc, err := describe.NewChainDescriber(o.c, o.namespaces, o.output).Describe(ist, !o.triggerOnly, o.reverse)
 	if err != nil {
 		if _, isNotFoundErr := err.(describe.NotFoundErr); isNotFoundErr {
 			name, tag, _ := imageapi.SplitImageStreamTag(o.name)