weave-scope/report/mapping_functions.go

package report

import (
	"fmt"
	"strings"
)

// MappedNode is returned by the MapFuncs.
type MappedNode struct {
	ID    string
	Major string
	Minor string
	Rank  string
}

// MapFunc is anything which can take an arbitrary NodeMetadata, which is
// always one-to-one with nodes in a topology, and return a specific
// representation of the referenced node, in the form of a node ID and a
// human-readable major and minor labels.
//
// A single NodeMetadata can yield arbitrary many representations, including
// representations that reduce the cardinality of the set of nodes.
//
// If the final output parameter is false, the node shall be omitted from the
// rendered topology.
type MapFunc func(string, NodeMetadata, bool) (MappedNode, bool)

// PseudoFunc creates MappedNode representing pseudo nodes given the dstNodeID.
// The srcNode renderable node is essentially from MapFunc, representing one of
// the rendered nodes this pseudo node refers to. srcNodeID and dstNodeID are
// node IDs prior to mapping.
type PseudoFunc func(srcNodeID string, srcNode RenderableNode, dstNodeID string, grouped bool) (MappedNode, bool)

// ProcessPID takes a node NodeMetadata from a Process topology, and returns a
// representation with the ID based on the process PID and the labels based
// on the process name.
func ProcessPID(_ string, m NodeMetadata, grouped bool) (MappedNode, bool) {
	var (
		identifier = fmt.Sprintf("%s:%s:%s", "pid", m["domain"], m["pid"])
		minor      = fmt.Sprintf("%s (%s)", m["domain"], m["pid"])
		show       = m["pid"] != "" && m["name"] != ""
	)

	if grouped {
		identifier = m["name"] // flatten
		minor = ""             // nothing meaningful to put here?
	}

	return MappedNode{
		ID:    identifier,
		Major: m["name"],
		Minor: minor,
		Rank:  m["pid"],
	}, show
}

// ProcessContainer maps Process topology nodes to the containers they run in.
// We consider container and image IDs to be globally unique, and so don't
// scope them further by e.g. host. If no container metadata is found, nodes
// are grouped into the Uncontained node. If grouped is true, nodes with the
// same container image ID are merged together.
func ProcessContainer(_ string, m NodeMetadata, grouped bool) (MappedNode, bool) {
	var (
		containerID   = m["docker_id"]
		containerName = m["docker_name"]
		imageID       = m["docker_image_id"]
		imageName     = m["docker_image_name"]
		domain        = m["domain"]
	)

	var id, major, minor, rank string
	if containerID == "" {
		id, major, minor, rank = "uncontained", "Uncontained", "", "uncontained"
	} else if grouped {
		id, major, minor, rank = imageID, imageName, "", imageID
	} else {
		id, major, minor, rank = containerID, containerName, domain, imageID
	}

	return MappedNode{
		ID:    id,
		Major: major,
		Minor: minor,
		Rank:  rank,
	}, true
}

// NetworkHostname takes a node NodeMetadata from a Network topology, and
// returns a representation based on the hostname. Major label is the
// hostname, the minor label is the domain, if any.
func NetworkHostname(_ string, m NodeMetadata, _ bool) (MappedNode, bool) {
	var (
		name   = m["name"]
		domain = ""
		parts  = strings.SplitN(name, ".", 2)
	)

	if len(parts) == 2 {
		domain = parts[1]
	}

	return MappedNode{
		ID:    fmt.Sprintf("host:%s", name),
		Major: parts[0],
		Minor: domain,
		Rank:  parts[0],
	}, name != ""
}

// GenericPseudoNode contains heuristics for building sensible pseudo nodes.
// It should go away.
func GenericPseudoNode(src string, srcMapped RenderableNode, dst string, grouped bool) (MappedNode, bool) {
	var maj, min, outputID string

	if dst == TheInternet {
		outputID = dst
		maj, min = "the Internet", ""
	} else if grouped {
		// When grouping, emit one pseudo node per (srcNodeAddress, dstNodeAddr)
		dstNodeAddr, _ := trySplitAddr(dst)

		outputID = strings.Join([]string{"pseudo:", dstNodeAddr, srcMapped.ID}, ScopeDelim)
		maj, min = dstNodeAddr, ""
	} else {
		// Rule for non-internet psuedo nodes; emit 1 new node for each
		// dstNodeAddr, srcNodeAddr, srcNodePort.
		srcNodeAddr, srcNodePort := trySplitAddr(src)
		dstNodeAddr, _ := trySplitAddr(dst)

		outputID = strings.Join([]string{"pseudo:", dstNodeAddr, srcNodeAddr, srcNodePort}, ScopeDelim)
		maj, min = dstNodeAddr, ""
	}

	return MappedNode{
		ID:    outputID,
		Major: maj,
		Minor: min,
	}, true
}

// NoPseudoNode never creates a pseudo node.
func NoPseudoNode(string, RenderableNode, string, bool) (MappedNode, bool) {
	return MappedNode{}, false
}

func trySplitAddr(addr string) (string, string) {
	fields := strings.SplitN(addr, ScopeDelim, 3)
	if len(fields) == 3 {
		return fields[1], fields[2]
	}
	return fields[1], ""
}