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Use stable random generator for temporary instance name #12568

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merged 2 commits into from
Nov 28, 2023
Merged

Use stable random generator for temporary instance name #12568

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33b66f5
lxd/instance: Use stable random generator for temporary instance name
roosterfish Oct 9, 2023
b31242b
lxd/instance: Improve error message
roosterfish Nov 23, 2023
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34 changes: 27 additions & 7 deletions lxd/instance/instance_utils.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ import (
"github.com/canonical/lxd/lxd/seccomp"
"github.com/canonical/lxd/lxd/state"
"github.com/canonical/lxd/lxd/sys"
"github.com/canonical/lxd/lxd/util"
"github.com/canonical/lxd/shared"
"github.com/canonical/lxd/shared/api"
"github.com/canonical/lxd/shared/idmap"
Expand Down Expand Up @@ -1049,9 +1050,18 @@ func NextSnapshotName(s *state.State, inst Instance, defaultPattern string) (str
return pattern, nil
}

// temporaryName concatenates the move prefix and instUUID for a temporary instance.
func temporaryName(instUUID string) string {
return fmt.Sprintf("lxd-move-of-%s", instUUID)
// temporaryName returns the temporary instance name using a stable random generator.
// The returned string is a valid DNS name.
func temporaryName(instUUID string) (string, error) {
r, err := util.GetStableRandomGenerator(instUUID)
if err != nil {
return "", err
}

// The longest temporary name is lxd-move-18446744073709551615 which has a length
// of 30 characters since 18446744073709551615 is the biggest value for an uint64.
// The prefix is attached to have a valid DNS name that doesn't start with numbers.
return fmt.Sprintf("lxd-move-%d", r.Uint64()), nil
}

// MoveTemporaryName returns a name derived from the instance's volatile.uuid, to use when moving an instance
Expand All @@ -1064,11 +1074,11 @@ func MoveTemporaryName(inst Instance) (string, error) {
instUUID = uuid.New().String()
err := inst.VolatileSet(map[string]string{"volatile.uuid": instUUID})
if err != nil {
return "", fmt.Errorf("Failed generating instance UUID: %w", err)
return "", fmt.Errorf("Failed setting volatile.uuid to %s: %w", instUUID, err)
}
}

return temporaryName(instUUID), nil
return temporaryName(instUUID)
}

// IsSameLogicalInstance returns true if the supplied Instance and db.Instance have the same project and name or
Expand All @@ -1083,12 +1093,22 @@ func IsSameLogicalInstance(inst Instance, dbInst *db.InstanceArgs) bool {
if dbInst.Config["volatile.uuid"] == inst.LocalConfig()["volatile.uuid"] {
// Accommodate moving instances between storage pools.
// Check temporary copy against source.
if dbInst.Name == temporaryName(inst.LocalConfig()["volatile.uuid"]) {
tempName, err := temporaryName(inst.LocalConfig()["volatile.uuid"])
if err != nil {
return false
}

if dbInst.Name == tempName {
return true
}

// Check source against temporary copy.
if inst.Name() == temporaryName(dbInst.Config["volatile.uuid"]) {
tempName, err = temporaryName(dbInst.Config["volatile.uuid"])
if err != nil {
return false
}

if inst.Name() == tempName {
return true
}

Expand Down
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