Applications (expr) topology

app/api_topologies_test.go

@@ -16,7 +16,7 @@ func TestAPITopology(t *testing.T) {
 	if err := json.Unmarshal(body, &topologies); err != nil {
 		t.Fatalf("JSON parse error: %s", err)
 	}
-	equals(t, 3, len(topologies))
+	equals(t, 4, len(topologies))
 
 	for _, topology := range topologies {
 		is200(t, ts, topology.URL)

app/router.go

@@ -12,6 +12,7 @@ import (
 	"github.com/gorilla/mux"
 
 	"github.com/weaveworks/scope/render"
+	"github.com/weaveworks/scope/render/dsl"
 	"github.com/weaveworks/scope/report"
 	"github.com/weaveworks/scope/xfer"
 )
@@ -137,6 +138,21 @@ var topologyRegistry = map[string]topologyView{
 		parent:   "",
 		renderer: render.FilterUnconnected(render.ProcessWithContainerNameRenderer{}),
 	},
+	"applications-expr": {
+		human:  "Applications (expr)",
+		parent: "",
+		renderer: render.CustomRenderer{
+			Renderer: render.Map{
+				Renderer: render.SelectAll,
+				MapFunc:  render.MapIdentity,
+			},
+			RenderFunc: dsl.ParseExpressions(
+				"ALL GROUPBY {{pid}}",
+				"NOT WITH {{pid}} REMOVE",
+				"NOT CONNECTED REMOVE",
+			).Eval,
+		},
+	},
 	"applications-by-name": {
 		human:    "by name",
 		parent:   "applications",

render/dsl/expression.go

@@ -341,7 +341,11 @@ func cp(dst render.RenderableNodes, src render.RenderableNodes, id string) {
 }
 
 func merge(dst render.RenderableNodes, dstID string, src render.RenderableNodes, srcID string) {
-	dst[dstID] = dst[dstID].Merge(src[srcID])
+	dstNode, ok := dst[dstID]
+	if !ok {
+		dstNode = render.NewRenderableNode(dstID)
+	}
+	dst[dstID] = dstNode.Merge(src[srcID])
 
 	// Every transform that calls merge must call shift at the end, to update
 	// adjacency lists and edge metadatas.

render/dsl/parser.go

@@ -95,7 +95,7 @@ func ParseExpressions(strs ...string) Expressions {
 	for _, str := range strs {
 		expr, err := ParseExpression(str)
 		if err != nil {
-			log.Printf("%s: %v", str, err)
+			log.Printf("%q: %v", str, err)
 			continue
 		}
 		exprs = append(exprs, expr)

render/mapping.go

@@ -31,6 +31,11 @@ const (
 // If the output is empty, the node shall be omitted from the rendered topology.
 type MapFunc func(RenderableNode, report.Networks) RenderableNodes
 
+// MapIdentity returns a perfect identity mapping of the input domain.
+func MapIdentity(n RenderableNode, _ report.Networks) RenderableNodes {
+	return RenderableNodes{n.ID: n}
+}
+
 // MapEndpointIdentity maps an endpoint topology node to a single endpoint
 // renderable node. As it is only ever run on endpoint topology nodes, we
 // expect that certain keys are present.

render/selectors.go

@@ -86,4 +86,15 @@ var (
 	SelectHost = TopologySelector(func(r report.Report) RenderableNodes {
 		return MakeRenderableNodes(r.Host)
 	})
+
+	// SelectAll merges all topologies.
+	SelectAll = TopologySelector(func(r report.Report) RenderableNodes {
+		rns := RenderableNodes{}
+		for _, t := range r.Topologies() {
+			for id, rn := range MakeRenderableNodes(t) {
+				rns[id] = rn
+			}
+		}
+		return rns
+	})
 )