mirror clone: Improve handling of latest versions

[dveeden]

What problem does this PR solve?

When running tiup mirror clone ... v5.0.0 it may download a different version of a component if there
is no v5.0.0 for that component.

If you specify "v9999" it will cause tiup mirror clone to download the latest version of all components.

What is changed and how it works?

1. Print a message when falling back on the latest version for a component
2. Allow the user to specify "latest" as version to get the latest version.

Check List

Tests

• Manual test (add detailed scripts or steps below)

Try tiup mirror clone /path/to/tiup-mirror --os linux --arch amd64 latest and tiup mirror clone /path/to/tiup-mirror --os linux --arch amd4 v5.0.0.

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

Allow specifying "latest" as version for `tiup mirror clone`

[AstroProfundis]

I think it should be "latest" available version by default, so I'm not sure if it's necessary to add an alias to specify "latest". PTAL @lucklove

[dveeden]

I think it should be "latest" available version by default, so I'm not sure if it's necessary to add an alias to specify "latest". PTAL @lucklove

Making "latest" the default would be ok with me as that is probably what people want if they don't specify --full. However that's not how it works now as you need to specify a version.

[dvaneeden@dve-carbon ~]$ tiup mirror clone ~/tiup-mirror/ --arch=amd64 --os=linux
Start to clone mirror, targetDir is /home/dvaneeden/tiup-mirror/, selectedVersions are []
If this does not meet expectations, please abort this process, read `tiup mirror clone --help` and run again
Arch [amd64]
OS [linux]
download https://tiup-mirrors.pingcap.com/tiup-linux-amd64.tar.gz 6.71 MiB / 6.71 MiB 100.00% 7.66 MiB p/s                                                                                    
[dvaneeden@dve-carbon ~]$ tiup mirror clone ~/tiup-mirror/ --arch=amd64 --os=linux v99
Start to clone mirror, targetDir is /home/dvaneeden/tiup-mirror/, selectedVersions are [v99]
If this does not meet expectations, please abort this process, read `tiup mirror clone --help` and run again
Arch [amd64]
OS [linux]
download https://tiup-mirrors.pingcap.com/alertmanager-v0.17.0-linux-amd64.tar.gz 22.54 MiB / 22.54 MiB 100.00% 15.71 MiB p/s                                                                 
download https://tiup-mirrors.pingcap.com/bench-v1.4.1-linux-amd64.tar.gz 7.84 MiB / 7.84 MiB 100.00% 8.94 MiB p/s                                                                            
download https://tiup-mirrors.pingcap.com/blackbox_exporter-v0.12.0-linux-amd64.tar.gz 4.72 MiB / 4.72 MiB 100.00% 6.12 MiB p/s                                                               
download https://tiup-mirrors.pingcap.com/br-v5.0.0-linux-amd64.tar.gz 41.08 MiB / 41.08 MiB 100.00% 23.98 MiB p/s                                                                            
download https://tiup-mirrors.pingcap.com/client-v1.4.1-linux-amd64.tar.gz 4.50 MiB / 4.50 MiB 100.00% 5.11 MiB p/s                                                                           
download https://tiup-mirrors.pingcap.com/cluster-v1.4.1-linux-amd64.tar.gz 8.05 MiB / 8.05 MiB 100.00% 187.73 MiB p/s                                                                        
download https://tiup-mirrors.pingcap.com/dm-v1.4.1-linux-amd64.tar.gz 7.73 MiB / 7.73 MiB 100.00% 69.69 MiB p/s                                                                              
download https://tiup-mirrors.pingcap.com/dm-master-v2.0.2-linux-amd64.tar.gz 1.19 MiB / 31.44 MiB 3.77% 1.92 MiB p/s                                                                         ^C

[dvaneeden@dve-carbon ~]$ tiup mirror clone ~/tiup-mirror/ --arch=amd64 --os=linux --tidb-lightning
Error: flag needs an argument: --tidb-lightning
[dvaneeden@dve-carbon ~]$ tiup mirror clone ~/tiup-mirror/ --arch=amd64 --os=linux --tidb-lightning=v999
Start to clone mirror, targetDir is /home/dvaneeden/tiup-mirror/, selectedVersions are []
If this does not meet expectations, please abort this process, read `tiup mirror clone --help` and run again
Arch [amd64]
OS [linux]
download https://tiup-mirrors.pingcap.com/tiup-linux-amd64.tar.gz 6.71 MiB / 6.71 MiB 100.00% 489.30 MiB p/s   

[AstroProfundis]

Oh I see, that's an issue of how clone parses the argument list.

[lucklove]

Clever implementation!!!

[lucklove]

/lgtm

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[lucklove]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 2c09edd

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@dveeden: Your PR was out of date, I have automatically updated it for you.

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[dveeden]

/merge

[ti-chi-bot]

@dveeden: /merge is only allowed for the committers in list.

In response to this:

/merge

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[AstroProfundis]

/merge