The `ctr image usage` can display the usage of snapshots with a given
image ref. It's easy for user to get chain snapshot IDs and unpack
usage. And according to the [discuss][1], this subcommand can be used to
ensure if snapshot's pagecache has been discarded in a unexpected
reboot.
How to use it:
```bash
$ bin/ctr image usage --snapshotter native docker.io/library/golang:1.19.3
ctr: image docker.io/library/golang:1.19.3 isn't unpacked in snapshotter native
$ bin/ctr image usage --snapshotter overlayfs docker.io/library/golang:1.19.3
KEY SIZE INODES
sha256:28114d8403bac6352c3e09cb23e37208138a0cd9d309edf3df38e57be8075a1d 16.0 KiB 4
sha256:f162c02ce6b9b594757cd76eda1c1dd119b88e69e882cb645bf7ad528b54f0d2 476.2 MiB 13660
sha256:a5b9faceaa495819b9ba7011b7276c4ffaffe6c7b9de0889e11abc1113f7b5ca 225.5 MiB 3683
sha256:412b2615d27d6b0090558d25b201b60a7dff2a40892a7e7ca868b80bf5e5de41 159.8 MiB 6196
sha256:dbce1593502d39c344ce089f98187999f294de5182a7106dcb6c9d04ce0c7265 19.4 MiB 502
sha256:8953bf5d24149e9b2236abc76bd0aa14b73828f1b63e816cb4b457249f6125bc 12.2 MiB 958
sha256:ccba29d6937047c719a6c048a7038d3907590fbb8556418d119469b2ad4f95bc 134.7 MiB 7245
$ bin/ctr image usage --snapshotter overlayfs docker.io/library/golang:1.19
ctr: failed to ensure if image docker.io/library/golang:1.19 exists: image "docker.io/library/golang:1.19": not found
```
[1]: <https://github.com/containerd/containerd/issues/5854#issuecomment-1415915765>
Signed-off-by: Wei Fu <fuweid89@gmail.com>
- Add Target to mount.Mount.
- Add UnmountMounts to unmount a list of mounts in reverse order.
- Add UnmountRecursive to unmount deepest mount first for a given target, using
moby/sys/mountinfo.
Signed-off-by: Edgar Lee <edgarhinshunlee@gmail.com>
This adds in a simple flag to control what platform the spec it generates
is for. Useful to easily get a glance at whats the default across platforms.
Signed-off-by: Danny Canter <danny@dcantah.dev>
Go 1.18 and up now provides a strings.Cut() which is better suited for
splitting key/value pairs (and similar constructs), and performs better:
```go
func BenchmarkSplit(b *testing.B) {
b.ReportAllocs()
data := []string{"12hello=world", "12hello=", "12=hello", "12hello"}
for i := 0; i < b.N; i++ {
for _, s := range data {
_ = strings.SplitN(s, "=", 2)[0]
}
}
}
func BenchmarkCut(b *testing.B) {
b.ReportAllocs()
data := []string{"12hello=world", "12hello=", "12=hello", "12hello"}
for i := 0; i < b.N; i++ {
for _, s := range data {
_, _, _ = strings.Cut(s, "=")
}
}
}
```
BenchmarkSplit
BenchmarkSplit-10 8244206 128.0 ns/op 128 B/op 4 allocs/op
BenchmarkCut
BenchmarkCut-10 54411998 21.80 ns/op 0 B/op 0 allocs/op
While looking at occurrences of `strings.Split()`, I also updated some for alternatives,
or added some constraints; for cases where an specific number of items is expected, I used `strings.SplitN()`
with a suitable limit. This prevents (theoretical) unlimited splits.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
