Add the ability to delete an etcd snapshot locally or from S3

[briandowns]

Proposed Changes

This change introduces the ability to perform a deletion of an etcd snapshot from either local storage or an S3 compatible object store.

A subcommand has been added to etcd-snapshot called "delete" that triggers this new behavior and takes all of the same flags as it's parent, allowing for the same default overrides and S3 access.

The "delete" subcommand is depend upon positional arguments being the name of the snapshots to be removed. If none are provided, it errors out.

Types of Changes

This change will require a documentation update. I will do that when the rest of the etcd snapshot CLI CRUD operations are complete.

Verification

For locally stored etcd snapshots:

Create a snapshot

k3s etcd-snapshot  

Get the name of the snapshot from the output.

k3s etcd-snapshot  delete <SNAPSHOT_NAME>

For etcd snapshots stored in s3:

Create a snapshot

k3s etcd-snapshot --s3 --s3-bucket=k3s-snapshots --s3-access-key=<REDACTED> --s3-secret-key=<REDACTED> 

Get the name of the snapshot from the output.

k3s etcd-snapshot delete --s3 --s3-bucket=k3s-snapshots --s3-access-key=<REDACTED> --s3-secret-key=<REDACTED> <SNAPSHOT_NAME>

Linked Issues

#3240

Further Comments

[dweomer]

Prefer the old func NewEtcdSnapshotCommand(action func(*cli.Context) error) signature. Use it to create the snapshot command and then modify the result by hanging the sub-command onto it. I think this would read cleaner in a PR and in general.

[briandowns]

That was the preferred route but doing so resulted in the binary being bloated passed the checked limit.

[dweomer]

double-you-tee-eff-dot-gif

[brandond]

Yeah, we need to use the command factory pattern to bind different actions to the command and subcommands.
For the 'real' binaries we use the actual functions (Run, Delete, etc) as the command actions; for the self-extracting wrapper we need to bind the internalCLIAction to the command and subcommands so that it can (if necessary) extract out the real binaries and then exec them.

Remediated