Do snapshot now

[halleyshx]

support do snapshot immediately

$./etcdctl -h
NAME:
        etcdctl - A simple command line client for etcd3.

USAGE:
        etcdctl [flags]

VERSION:
        3.5.0

API VERSION:
        3.5

COMMANDS:
        ...
        **snapshot donow          DoSnapshotNow do an auto snapshot immediately**
        snapshot restore        Restores an etcd member snapshot to an etcd directory
        snapshot save           Stores an etcd node backend snapshot to a given file
        snapshot status         [deprecated] Gets backend snapshot status of a given file
        ...

How to use

# all endpoint
$./etcdctl snapshot donow --cluster
Set doSnapshotNow conf passed, endpoint: http://127.0.0.1:2379
Set doSnapshotNow conf passed, endpoint: http://127.0.0.1:22379
Set doSnapshotNow conf passed, endpoint: http://127.0.0.1:32379
doSnapshotNow success

# one endpoint
$./etcdctl snapshot donow --cluster
Set doSnapshotNow conf passed, endpoint: 127.0.0.1:2379
doSnapshotNow success

[stale]

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