Create ipfs.add flag for specifying base of produced CID

[lidel]

This is a small, but important piece on the road to CIDv1 in Base32: https://github.com/ipfs/ipfs/issues/337
IMO it should happen before anything else:

To make migration easier, it should be possible for user to opt-in for different base when adding files:

ipfs add --cid-base=base32 (use of --cid-base should imply --cid-version 1)

Note: it is a separate thing from "specifying full default cidv1 parameters", which is tracked in #5230

cc @kevina @kyledrake @alanshaw (for parity with js-ipfs – ipfs/js-ipfs#1440)

[kevina]

Actually what I plan to implement is a little different. It is a global mbase option. We output CIDs in nearly every command so a global option makes more sense. This option does not imply that newly added files are CIDv1 it simply changes the output (when fully implemented) of all go-ipfs commands to output CIDv1 in the given base.

[kevina]

Note that it doesn't imply CIDv1 because it makes sense to decouple the base used to display CIDv1 and the CID version of newly added files.

[lidel]

@kevina Global flag for default base of outputted CIDs across entire app is a good idea, IIUC it would mitigate issue raised in #5234 👍

Note that it does not remove the need for opt-in --cid-base= parameter in ipfs add, it is a complementary UX feature. Perhaps it should be a separate issue?

Users should have an option to change the default base via ad-hoc command to enable batch scripting that outputs different base depending on added content. I see some scenarios where hashes for some files need to be as short as possible, while others need to conform to some standard or limitation, eg. be URL and Origin-safe. Having --cid-base= parameter in ipfs add will make it easy to handle it programmatically without need for conversion step in userland.

[kevina]

Users should have an option to change the default base via ad-hoc command to enable batch scripting that outputs different base depending on added content.

By a global flag I mean a command line flags that can be used with all ipfs command, not just ipfs add. This is separate from a config option. ipfs add. ipfs add --mbase=base32 --cid-version=1 will be identical to ipfs add --cid-base=base32.

[lidel]

Ack, finally got it, if it is a global commandline param, it brings much more value.
It solves UX around base encoding across all APIs and makes all sorts of scripting easier:

ipfs add --cid-version=1 --mbase=base32 
ipfs resolve /ipns/docs.ipfs.io --mbase=base32
ipfs files ls -l --mbase=base32

👍 from me, as long we implement the same in js-ipfs (cc @alanshaw)

[hsanjuan]

(subscribing)