debug: add version constraint to avoid pprof panic

.changelog/12807.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+cli: `operator debug` command now skips generating pprofs to avoid a panic on Nomad 0.11.2. 0.11.1, and 0.11.0
+```

command/operator_debug.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/hashicorp/go-cleanhttp"
 	"github.com/hashicorp/go-multierror"
+	goversion "github.com/hashicorp/go-version"
 	"github.com/hashicorp/nomad/api"
 	"github.com/hashicorp/nomad/api/contexts"
 	"github.com/hashicorp/nomad/helper"
@@ -54,14 +55,17 @@ type OperatorDebugCommand struct {
 	cancel        context.CancelFunc
 	opts          *api.QueryOptions
 	verbose       bool
+	members       *api.ServerMembers
+	nodes         []*api.NodeListStub
 }
 
 const (
-	userAgent   = "nomad operator debug"
-	clusterDir  = "cluster"
-	clientDir   = "client"
-	serverDir   = "server"
-	intervalDir = "interval"
+	userAgent                     = "nomad operator debug"
+	clusterDir                    = "cluster"
+	clientDir                     = "client"
+	serverDir                     = "server"
+	intervalDir                   = "interval"
+	minimumVersionPprofConstraint = ">= 0.11.0, <= 0.11.2"
 )
 
 func (c *OperatorDebugCommand) Help() string {
@@ -502,6 +506,16 @@ func (c *OperatorDebugCommand) Run(args []string) int {
 		AuthToken:  c.Meta.token,
 	}
 
+	// Get complete list of client nodes
+	c.nodes, _, err = client.Nodes().List(c.queryOpts())
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("Error querying node info: %v", err))
+		return 1
+	}
+
+	// Write nodes to file
+	c.writeJSON(clusterDir, "nodes.json", c.nodes, err)
+
 	// Search all nodes If a node class is specified without a list of node id prefixes
 	if c.nodeClass != "" && nodeIDs == "" {
 		nodeIDs = "all"
@@ -565,17 +579,17 @@ func (c *OperatorDebugCommand) Run(args []string) int {
 	}
 
 	// Resolve servers
-	members, err := client.Agent().MembersOpts(c.queryOpts())
+	c.members, err = client.Agent().MembersOpts(c.queryOpts())
 	if err != nil {
 		c.Ui.Error(fmt.Sprintf("Failed to retrieve server list; err: %v", err))
 		return 1
 	}
 
 	// Write complete list of server members to file
-	c.writeJSON(clusterDir, "members.json", members, err)
+	c.writeJSON(clusterDir, "members.json", c.members, err)
 
 	// Filter for servers matching criteria
-	c.serverIDs, err = filterServerMembers(members, serverIDs, c.region)
+	c.serverIDs, err = filterServerMembers(c.members, serverIDs, c.region)
 	if err != nil {
 		c.Ui.Error(fmt.Sprintf("Failed to parse server list; err: %v", err))
 		return 1
@@ -584,8 +598,8 @@ func (c *OperatorDebugCommand) Run(args []string) int {
 	serversFound := 0
 	serverCaptureCount := 0
 
-	if members != nil {
-		serversFound = len(members.Members)
+	if c.members != nil {
+		serversFound = len(c.members.Members)
 	}
 	if c.serverIDs != nil {
 		serverCaptureCount = len(c.serverIDs)
@@ -900,9 +914,31 @@ func (c *OperatorDebugCommand) collectAgentHost(path, id string, client *api.Cli
 
 func (c *OperatorDebugCommand) collectPeriodicPprofs(client *api.Client) {
 
+	pprofNodeIDs := []string{}
+	pprofServerIDs := []string{}
+
+	// threadcreate pprof causes a panic on Nomad 0.11.0 to 0.11.2 -- skip those versions
+	for _, serverID := range c.serverIDs {
+		version := c.getNomadVersion(serverID, "")
+		err := checkVersion(version, minimumVersionPprofConstraint)
+		if err != nil {
+			c.Ui.Warn(fmt.Sprintf("Skipping pprof: %v", err))
+		}
+		pprofServerIDs = append(pprofServerIDs, serverID)
+	}
+
+	for _, nodeID := range c.nodeIDs {
+		version := c.getNomadVersion("", nodeID)
+		err := checkVersion(version, minimumVersionPprofConstraint)
+		if err != nil {
+			c.Ui.Warn(fmt.Sprintf("Skipping pprof: %v", err))
+		}
+		pprofNodeIDs = append(pprofNodeIDs, nodeID)
+	}
+
 	// Take the first set of pprofs synchronously...
 	c.Ui.Output("    Capture pprofInterval 0000")
-	c.collectPprofs(client, 0)
+	c.collectPprofs(client, pprofServerIDs, pprofNodeIDs, 0)
 	if c.pprofInterval == c.pprofDuration {
 		return
 	}
@@ -921,7 +957,7 @@ func (c *OperatorDebugCommand) collectPeriodicPprofs(client *api.Client) {
 				return
 			case <-timer.C:
 				c.Ui.Output(fmt.Sprintf("    Capture pprofInterval %04d", pprofIntervalCount))
-				c.collectPprofs(client, pprofIntervalCount)
+				c.collectPprofs(client, pprofServerIDs, pprofNodeIDs, pprofIntervalCount)
 				timer.Reset(c.pprofInterval)
 				pprofIntervalCount++
 			}
@@ -930,12 +966,12 @@ func (c *OperatorDebugCommand) collectPeriodicPprofs(client *api.Client) {
 }
 
 // collectPprofs captures the /agent/pprof for each listed node
-func (c *OperatorDebugCommand) collectPprofs(client *api.Client, interval int) {
-	for _, n := range c.nodeIDs {
+func (c *OperatorDebugCommand) collectPprofs(client *api.Client, serverIDs, nodeIDs []string, interval int) {
+	for _, n := range nodeIDs {
 		c.collectPprof(clientDir, n, client, interval)
 	}
 
-	for _, n := range c.serverIDs {
+	for _, n := range serverIDs {
 		c.collectPprof(serverDir, n, client, interval)
 	}
 }
@@ -987,12 +1023,6 @@ func (c *OperatorDebugCommand) collectPprof(path, id string, client *api.Client,
 	c.savePprofProfile(path, "heap", opts, client)         // A sampling of memory allocations of live objects. You can specify the gc GET parameter to run GC before taking the heap sample.
 	c.savePprofProfile(path, "allocs", opts, client)       // A sampling of all past memory allocations
 	c.savePprofProfile(path, "threadcreate", opts, client) // Stack traces that led to the creation of new OS threads
-
-	// This profile is disabled by default -- Requires runtime.SetBlockProfileRate to enable
-	// c.savePprofProfile(path, "block", opts, client)        // Stack traces that led to blocking on synchronization primitives
-
-	// This profile is disabled by default -- Requires runtime.SetMutexProfileFraction to enable
-	// c.savePprofProfile(path, "mutex", opts, client)        // Stack traces of holders of contended mutexes
 }
 
 // savePprofProfile retrieves a pprof profile and writes to disk
@@ -1714,3 +1744,53 @@ func isRedirectError(err error) bool {
 	const redirectErr string = `invalid character '<' looking for beginning of value`
 	return strings.Contains(err.Error(), redirectErr)
 }
+
+// getNomadVersion fetches the version of Nomad running on a given server/client node ID
+func (c *OperatorDebugCommand) getNomadVersion(serverID string, nodeID string) string {
+	if serverID == "" && nodeID == "" {
+		return ""
+	}
+
+	version := ""
+	if serverID != "" {
+		for _, server := range c.members.Members {
+			// Raft v2 server
+			if server.Name == serverID {
+				version = server.Tags["build"]
+			}
+
+			// Raft v3 server
+			if server.Tags["id"] == serverID {
+				version = server.Tags["version"]
+			}
+		}
+	}
+
+	if nodeID != "" {
+		for _, node := range c.nodes {
+			if node.ID == nodeID {
+				version = node.Version
+			}
+		}
+	}
+
+	return version
+}
+
+// checkVersion verifies that version satisfies the constraint
+func checkVersion(version string, versionConstraint string) error {
+	v, err := goversion.NewVersion(version)
+	if err != nil {
+		return fmt.Errorf("error: %v", err)
+	}
+
+	c, err := goversion.NewConstraint(versionConstraint)
+	if err != nil {
+		return fmt.Errorf("error: %v", err)
+	}
+
+	if !c.Check(v) {
+		return nil
+	}
+	return fmt.Errorf("unsupported version=%s matches version filter %s", version, minimumVersionPprofConstraint)
+}

command/operator_debug_test.go

@@ -578,6 +578,36 @@ func TestDebug_Fail_Pprof(t *testing.T) {
 	require.Contains(t, ui.OutputWriter.String(), "Created debug archive")   // Archive should be generated anyway
 }
 
+// TestDebug_PprofVersionCheck asserts that only versions < 0.12.0 are
+// filtered by the version constraint.
+func TestDebug_PprofVersionCheck(t *testing.T) {
+	cases := []struct {
+		version string
+		errMsg  string
+	}{
+		{"0.8.7", ""},
+		{"0.11.1", "unsupported version=0.11.1 matches version filter >= 0.11.0, <= 0.11.2"},
+		{"0.11.2", "unsupported version=0.11.2 matches version filter >= 0.11.0, <= 0.11.2"},
+		{"0.11.2+ent", "unsupported version=0.11.2+ent matches version filter >= 0.11.0, <= 0.11.2"},
+		{"0.11.3", ""},
+		{"0.11.3+ent", ""},
+		{"0.12.0", ""},
+		{"1.3.0", ""},
+		{"foo.bar", "error: Malformed version: foo.bar"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.version, func(t *testing.T) {
+			err := checkVersion(tc.version, minimumVersionPprofConstraint)
+			if tc.errMsg == "" {
+				require.NoError(t, err, "expected no error from %s", tc.version)
+			} else {
+				require.EqualError(t, err, tc.errMsg)
+			}
+		})
+	}
+}
+
 func TestDebug_StringToSlice(t *testing.T) {
 	ci.Parallel(t)