Feature Proposal: new Pull command

[marc0der]

Text copied here for convenience from the pull.feature Cucumber spec. Please note, the feature file is the authoritave source so the text below may be out of date.

Versions of SDKMAN prior to 6.0.0 were very reliant on being connected to the internet. For most this has not been a problem, but for those with limited bandwidth or unreliable internet connectivity this has rendered the CLI unusable.

One of the steps that was taken previously was to introduce an offline mode, allowing the CLI to continue working even when no internet connection was present. The intent was to cause the CLI to degrade gracefully when:

• no internet connectivity was available
• when the sdk offline enable command was issued

Despite this being a noble effort, the implementation of this was troublesome due to the limitations of bash and curl. To date this functionality still has serious issues.

This leads us to re-evaluating our options given a blank canvas. Looking at tools like Debian's Apt and DVCS systems like Git, they all have functions that explicitly pull down remote state. In the case of Apt we have an apt update, in the case of Git we have git pull.

The proposal is to follow this line of thinking, preventing continual API access on every command. Instead, an explicit command such as sdk pull or sdk update should be issued in order to fetch remote state. If the sdk command has not been updated in while, it should warn the user that their local state is out of date.