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rkt: Don't require port_map with host networking #3615

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merged 1 commit into from
Dec 4, 2017
Merged

rkt: Don't require port_map with host networking #3615

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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@ BUG FIXES:
* client: Fix allocation accounting in GC and trigger GCs on allocation
updates [GH-3445]
* driver/rkt: Remove pods on shutdown [GH-3562]
* driver/rkt: Don't require port maps when using host networking [GH-3615]
* template: Fix issue where multiple environment variable templates would be
parsed incorrectly when contents of one have changed after the initial
rendering [GH-3529]
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25 changes: 16 additions & 9 deletions client/driver/rkt.go
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Original file line number Diff line number Diff line change
Expand Up @@ -529,6 +529,9 @@ func (d *RktDriver) Start(ctx *ExecContext, task *structs.Task) (*StartResponse,
if len(driverConfig.PortMap) > 0 {
return nil, fmt.Errorf("Trying to map ports but no network interface is available")
}
} else if network == "host" {
// Port mapping is skipped when host networking is used.
d.logger.Println("[DEBUG] driver.rkt: Ignoring port_map when using --net=host")
} else {
// TODO add support for more than one network
network := task.Resources.Networks[0]
Expand Down Expand Up @@ -657,15 +660,19 @@ func (d *RktDriver) Start(ctx *ExecContext, task *structs.Task) (*StartResponse,
}
go h.run()

d.logger.Printf("[DEBUG] driver.rkt: retrieving network information for pod %q (UUID %s) for task %q", img, uuid, d.taskName)
driverNetwork, err := rktGetDriverNetwork(uuid, driverConfig.PortMap)
if err != nil && !pluginClient.Exited() {
d.logger.Printf("[WARN] driver.rkt: network status retrieval for pod %q (UUID %s) for task %q failed. Last error: %v", img, uuid, d.taskName, err)

// If a portmap was given, this turns into a fatal error
if len(driverConfig.PortMap) != 0 {
pluginClient.Kill()
return nil, fmt.Errorf("Trying to map ports but driver could not determine network information")
// Only return a driver network if *not* using host networking
var driverNetwork *cstructs.DriverNetwork
if network != "host" {
d.logger.Printf("[DEBUG] driver.rkt: retrieving network information for pod %q (UUID %s) for task %q", img, uuid, d.taskName)
driverNetwork, err = rktGetDriverNetwork(uuid, driverConfig.PortMap)
if err != nil && !pluginClient.Exited() {
d.logger.Printf("[WARN] driver.rkt: network status retrieval for pod %q (UUID %s) for task %q failed. Last error: %v", img, uuid, d.taskName, err)

// If a portmap was given, this turns into a fatal error
if len(driverConfig.PortMap) != 0 {
pluginClient.Kill()
return nil, fmt.Errorf("Trying to map ports but driver could not determine network information")
}
}
}

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I am concerned about nil pointer dereferencing in downstream code like

nomad/command/agent/consul/client.go

Line 575 in a52cb34

if net.Advertise() {
that use the DriverNetwork struct, isn't that going to panic when network == "host" ?

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So I have regrets about how I implemented DriverNetwork, but it was designed to gracefully handle nils since the vast majority of drivers don't implement it (so they return nil).

nomad/client/driver/driver.go

Lines 199 to 201 in 730e2aa

// Network may be nil as not all drivers or configurations create
// networks.
Network *cstructs.DriverNetwork

And if you look at each of the methods on DriverNetwork they handle nil:

nomad/client/structs/structs.go

Lines 134 to 186 in 730e2aa

// DriverNetwork is the network created by driver's (eg Docker's bridge
// network) during Prestart.
type DriverNetwork struct {
// PortMap can be set by drivers to replace ports in environment
// variables with driver-specific mappings.
PortMap map[string]int
// IP is the IP address for the task created by the driver.
IP string
// AutoAdvertise indicates whether the driver thinks services that
// choose to auto-advertise-addresses should use this IP instead of the
// host's. eg If a Docker network plugin is used
AutoAdvertise bool
}
// Advertise returns true if the driver suggests using the IP set. May be
// called on a nil Network in which case it returns false.
func (d *DriverNetwork) Advertise() bool {
return d != nil && d.AutoAdvertise
}
// Copy a DriverNetwork struct. If it is nil, nil is returned.
func (d *DriverNetwork) Copy() *DriverNetwork {
if d == nil {
return nil
}
pm := make(map[string]int, len(d.PortMap))
for k, v := range d.PortMap {
pm[k] = v
}
return &DriverNetwork{
PortMap: pm,
IP: d.IP,
AutoAdvertise: d.AutoAdvertise,
}
}
// Hash the contents of a DriverNetwork struct to detect changes. If it is nil,
// an empty slice is returned.
func (d *DriverNetwork) Hash() []byte {
if d == nil {
return []byte{}
}
h := md5.New()
io.WriteString(h, d.IP)
io.WriteString(h, strconv.FormatBool(d.AutoAdvertise))
for k, v := range d.PortMap {
io.WriteString(h, k)
io.WriteString(h, strconv.Itoa(v))
}
return h.Sum(nil)
}

Definitely something worth changing/fixing in the future, but I think it's out of scope for this PR.

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Agreed, thanks for the explain.

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66 changes: 66 additions & 0 deletions client/driver/rkt_test.go
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Expand Up @@ -519,6 +519,72 @@ func TestRktDriver_PortsMapping(t *testing.T) {
}
}

// TestRktDriver_PortsMapping_Host asserts that port_map isn't required when
// host networking is used.
func TestRktDriver_PortsMapping_Host(t *testing.T) {
if !testutil.IsTravis() {
t.Parallel()
}
if os.Getenv("NOMAD_TEST_RKT") == "" {
t.Skip("skipping rkt tests")
}

ctestutils.RktCompatible(t)
task := &structs.Task{
Name: "etcd",
Driver: "rkt",
Config: map[string]interface{}{
"image": "docker://redis:latest",
"net": []string{"host"},
},
LogConfig: &structs.LogConfig{
MaxFiles: 10,
MaxFileSizeMB: 10,
},
Resources: &structs.Resources{
MemoryMB: 256,
CPU: 512,
Networks: []*structs.NetworkResource{
{
IP: "127.0.0.1",
ReservedPorts: []structs.Port{{Label: "main", Value: 8080}},
},
},
},
}

ctx := testDriverContexts(t, task)
defer ctx.AllocDir.Destroy()
d := NewRktDriver(ctx.DriverCtx)

if _, err := d.Prestart(ctx.ExecCtx, task); err != nil {
t.Fatalf("error in prestart: %v", err)
}
resp, err := d.Start(ctx.ExecCtx, task)
if err != nil {
t.Fatalf("err: %v", err)
}
if resp.Network != nil {
t.Fatalf("No network should be returned with --net=host but found: %#v", resp.Network)
}

failCh := make(chan error, 1)
go func() {
time.Sleep(1 * time.Second)
if err := resp.Handle.Kill(); err != nil {
failCh <- err
}
}()

select {
case err := <-failCh:
t.Fatalf("failed to kill handle: %v", err)
case <-resp.Handle.WaitCh():
case <-time.After(time.Duration(testutil.TestMultiplier()*15) * time.Second):
t.Fatalf("timeout")
}
}

func TestRktDriver_HandlerExec(t *testing.T) {
if !testutil.IsTravis() {
t.Parallel()
Expand Down