Orchestration for starting ipfs daemon without port conflicts

[lidel]

Requirements

Native support in Brave (brave/brave-browser#10220) requires a way of starting daemon without worrying about user having the default ports taken.

Specific needs are:

• $IPFS_PATH/config should be the source of truth about Swarm, API and Gateway ports
• Conflict avoidance should be future-proof, meaning if current port gets taken by something else in the future, daemon will automatically pick next one and update source of truth

Note that setting ports to 0 is not feasible:

• it is meant to be used in tests, reading config tells us nothing about Gateway port, produces different port every time, and it is hard to read randomly-picked ports without capturing stout of ipfs daemon
• we don't want gateway URLs to change all the time, as that would mean Origins are different every time daemon restarts, which breaks web storage on websites. it should change only if there is a conflict.

Proposed implementation

Add a parameter ipfs daemon --update-ports-if-taken
(or --find-free-ports ? suggestions? 🚲 🏚️ )

This new parameter should enable additional checks before ipfs daemon starts:

• check if ports defined in $IPFS_PATH/config are free before starting (Swarm, API, Gateway)
  • if not
    • increase them +1 and retry until all are free
    • save new values to $IPFS_PATH/config
    • start regular ipfs daemon

cc @autonome @aschmahmann

[tysonzero]

On a related note would it be reasonable to change the default ports? Port collisions seem unnecessarily common due to the current choice of fairly popular ports. I know I've run into collisions locally.

[Stebalien]

See #874.

[Geo25rey]

It might be worth while to add a config option to randomly select available ports at launch instead of requiring application of the "randomports" profile for each port change.

Edit: Something like this:

// Open the repo
repo, err := fsrepo.Open(repoPath)
if err != nil {
	return nil, err
}

cfg, err := repo.Config()

// Sets swarm ports to random - helps with port conflicts
maxTries := 3
err = config.Profiles["randomports"].Transform(cfg)
for i := 0; i < maxTries; i++ {
	if err == nil {
		break
	}
	err = config.Profiles["randomports"].Transform(cfg)
}
if err != nil {
	return nil, err
}

err = repo.SetConfig(cfg)
if err != nil {
	return nil, err
}

// Construct the node

nodeOptions := &core.BuildCfg{
	Online:  true,
	Routing: libp2p.DHTOption, 
	Repo: repo,
}

node, err := core.NewNode(ctx, nodeOptions)
if err != nil {
	return nil, err
}

// Attach the Core API to the constructed node
return coreapi.NewCoreAPI(node)

[Stebalien]

There are two sets of ports:

• Ports used to communicate with other libp2p nodes. This is what "randomports" randomizes. If you want a new random external port on every restart, just set them to zero.
• Ports used on the by the API and the gateway. That's what this issue is about. It's again possible to do this by setting the port to 0 in the config and it's possible to learn the API port by reading the ~/.ipfs/api file. However, there's no "good" way to learn the chosen gateway port, other than to capture stdout (as noted in the first post).

[Stebalien]

This new parameter should enable additional checks before ipfs daemon starts:

@lidel I'm very wary about modifying the config this way. The config is something that should generally be managed by the user.

What about exiting with a special code indicating the port conflict? That would let the caller decide how it wants to handle the issue (e.g., by modifying the config). That would also allow the application to tell the user "hey, you appear to have something else running on your IPFS gateway port, try on port XYZ?".

[Geo25rey]

Why not add a ~/.ipfs/gateway file?

[Stebalien]

We can do that, but that doesn't solve the problem here about picking a _stable_ port. The goal isn't to pick a random port, it's to pick a new port if and only if the normal port doesn't work.

[Geo25rey]

Perhaps port 8008 as a gateway port alternative. It's a less common http server port, and most of its use cases in software are heavily dated, according to wikipedia.

[RubenKelevra]

I was wondering if this is still an issue since brave/brave-browser#10220 was closed and the brave browser released the native support 🥳

Regardless of what the brave support needs, I think IPFS should change the default port - which is still 8080 as far as I can tell :)

In #874 we have had two ideas how to "encode" the characters of IPFS into a port number and got 4737 from @jbenet and 6437 from @ruverav - see #874 (comment).

[Stebalien]

@lidel I assume we found some way to work around this?