README
¶
go-dmflakey
Go bindings for the dm-flakey device.
Key Features
-
AllowWrites: The device is available for<up interval>seconds. -
DropWrites: All write I/O is silently ignored for<down interval>seconds. Read I/O is handled correctly. -
ErrorWrites: All write I/O is failed with an error signalled for<down interval>seconds. Read I/O is handled correctly.
Both <up> and <down> interval can be configured by WithIntervalFeatOpt(interval).
TODO: ErrorReads, CorruptBIOByte, RandomReadCorrupt, RandomWriteCorrupt.
Example
- Simulate power failure and cause data loss
// init flakey device named by /dev/mapper/go-dmflakey with empty ext4 filesystem
flakey, _ := InitFlakey("go-dmflakey", workDir, FSTypeEXT4)
flakeyDevice := flakey.DevicePath()
// mount that flakey device into temp dir
args := []string{"mount", flakeyDevice, targetDir}
exec.Command(args[0], args[1:]).Run()
// write file in targetDir without syncfs/fsync/fdatasync
// ...
// drop all write IO created by previous step
flakey.DropWrites()
// remount and allow all write IO to simulate power failure
exec.Command("umount", targetDir)
flakey.AllowWrites()
exec.Command(args[0], args[1:]).Run()
// check the file
- How to cause data loss during
bbolt bench?
Checkout contrib-test-boltdb.
- What if power failure after pulling image?
It's reproducer for container not starting in few nodes "standard_init_linux.go:219: exec user process caused: exec format error".
Checkout contrib-test-containerd.
Requirements
The package needs to invoke the following commands to init flakey device:
All of them are supported by most of linux distributions.
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type FeatOpt ¶
type FeatOpt func(*featCfg)
FeatOpt is used to configure failure feature.
func WithIntervalFeatOpt ¶
WithIntervalFeatOpt updates the up time for the feature.
func WithSyncFSFeatOpt ¶
WithSyncFSFeatOpt is to determine if the caller wants to synchronize filesystem before inject failure.
type Flakey ¶
type Flakey interface {
// DevicePath returns the flakey device path.
DevicePath() string
// Filesystem returns filesystem's type.
Filesystem() FSType
// AllowWrites allows write I/O.
AllowWrites(opts ...FeatOpt) error
// DropWrites drops all write I/O silently.
DropWrites(opts ...FeatOpt) error
// ErrorWrites drops all write I/O and returns error.
ErrorWrites(opts ...FeatOpt) error
// ErrorReads makes all read I/O is failed with an error signalled.
ErrorReads(opts ...FeatOpt) error
// CorruptBIOByte corruptes one byte in write bio.
CorruptBIOByte(nth int, read bool, value uint8, flags int, opts ...FeatOpt) error
// RandomReadCorrupt replaces random byte in a read bio with a random value.
RandomReadCorrupt(probability int, opts ...FeatOpt) error
// RandomWriteCorrupt replaces random byte in a write bio with a random value.
RandomWriteCorrupt(probability int, opts ...FeatOpt) error
// Teardown releases the flakey device.
Teardown() error
}
Flakey is to inject failure into device.
func InitFlakey ¶
InitFlakey creates an filesystem on a loopback device and returns Flakey on it.
The device-mapper device will be /dev/mapper/$flakeyDevice. And the filesystem image will be created at $dataStorePath/$flakeyDevice.img. By default, the device is available for 2 minutes and size is 10 GiB.
Source Files
Directories