Customize the fallback order of IPFS providers

[lidel]

There should be a way to customize the order in which providers are tried.
For example, if I want to ensure my app tries remote API before falling back to window.ipfs and embedded js-ipfs, I should be able to specify providers via ordered list:

const { ipfs, provider } = await getIpfs({
  fallbackOrder: ['api','window.ipfs', 'js-ipfs']  // strings? import enums?
  apiAddress:    '/ip4/10.1.1.1/tcp/5002'
  jsIpfsOpts:    {}
})

Additional notes:

• Providing ordered list of providers should take precedence over individual flags such as tryApi: false
• cc @parkan for thoughts and suggestions for use cases at Internet Archive

[parkan]

hi, sorry this slipped past me back in June

thoughts:

• having multiple control mechanisms for whether providers should be tried and in what order is difficult to reason about (would need to read docs to understand inclusion in fallbackOrder takes precedence over tryThing, for ex.)

  using fallbackOrder alone (with a healthy default) is sufficient to signify both, though (1) you need a way to enumerate legal values to know what to put in there (2) any new providers added in an update would not be enabled if you have a custom fallbackOrder set (though maybe that’s for the best)

• another way could be to use a Map that signifies order (key order) and enabled/disabled state (bool values), though of course we still don’t have a nice looking Map literal syntax 😢

• re: IA, it’s probably best to sync up with Mitra as to their current thinking

[lidel]

Idea: providers – a predefined Map of Symbols:

import { getIpfs, providers } from 'ipfs-provider'
const { httpClient, windowIpfs, jsIpfs } = providers
const { ipfs, provider } = await getIpfs({
  fallbackOrder: [ httpClient, windowIpfs, jsIpfs ]
  apiAddress:    '/ip4/10.1.1.1/tcp/5002'
  jsIpfsOpts:    {}
})

[parkan]

what are the value in this example?

[lidel]

I was thinking along these lines:

const providers = Object.freeze({ 
  httpClient: Symbol('httpClient')
  windowIpfs: Symbol('windowIpfs')
  jsIpfs: Symbol('jsIpfs')
})

cc @hugomrdias if there is a better/more intuitive way to do this

[hugomrdias]

// providers.js

export {
	httpClient : (options = {}) => { 
		options = mergeOptions(defaults, options)
		return 'everything needed'
	},
	windowIpfs : (options = {}) => { 
		options = mergeOptions(defaults, options)
		return 'everything needed'
	},
	jsIpfs : (options = {}) => { 
		options = mergeOptions(defaults, options)
		return 'everything needed'
	},
}

import { getIpfs, providers } from 'ipfs-provider'
const { httpClient, windowIpfs, jsIpfs } = providers
const { ipfs, provider } = await getIpfs([ 
	httpClient({apiAddress: '/ip4/10.1.1.1/tcp/5002'}), 
	windowIpfs(), 
	jsIpfs({})
])

i would do it like this

[parkan]

@hugomrdias that looks good, one concern is that even though the provider-specific options are better encapsulated this way, we may still have some global options, so I’d pass the array as a named parameter to the constructor

another comment would be that the provider constructors here need to be lazy: don’t want to start up all the nodes before picking one to actually use

[lidel]

Below should address:

• lazy constructors
• support global options

// providers.js

export {
	httpClient : (options = {}) => { 
		options = mergeOptions(defaults, options)
		return () => 'everything needed'
	},
	windowIpfs : (options = {}) => { 
		options = mergeOptions(defaults, options)
		return () => 'everything needed'
	},
	jsIpfs : (options = {}) => { 
		options = mergeOptions(defaults, options)
		return () => 'everything needed'
	},
}

// sample use

import { getIpfs, providers } from 'ipfs-provider'
const { httpClient, windowIpfs, jsIpfs } = providers
const { ipfs, provider } = await getIpfs({
	providers: [ 
		httpClient({ apiAddress: '/ip4/10.1.1.1/tcp/5002' }), 
		windowIpfs({ commands: ['add','cat'] }), 
		jsIpfs({
			getJsIpfs: () => import('ipfs'),
			jsIpfsOpts: { /* advanced config */ }
		})
	],
    someGlobalOption: 'some value'
})

Y/n? Anything missing?

[parkan]

lgtm!