`npm ping` to test registry reachability

[othiym23]

As described by @yorkie and @timoxley on #5743, it would be very useful to have a simple command that ensures that the registry (either the default, or selectable via --registry) is reachable (and, optionally, that your credentials for that registry are valid).

This would be very useful to have as a troubleshooting tool available to npm report (#5214).

[yorkie]

haha, that's great :)

[tjwebb]

Yea, someone host npm-report.herokuapp.com. badabing, independent npm registry status

[othiym23]

npm, Inc. is already using pingdom and Nagios and a bunch of other checks to verify registry availability, but that doesn't help you at all if you're running the CLI from behind a dodgy proxy or over a flaky connection. npm ping, as described, is a troubleshooting tool for end users, rather than an availability monitoring tool.

[michaelnisi]

Which existing HTTP endpoint of the registry (or client function) do you suggest to use for pinging?

[michaelnisi]

Just getting familiar with npm's source, I naively assumed I could just write a quick npm-ping module:

var RegClient = require('npm-registry-client')
  , npmconf = require('npmconf')
  ;

module.exports.ping = ping

function conf (cb) {
  var loaded = npmconf.loaded
  loaded ? cb(null, loaded) : npmconf.load(cb)
}

function ping (cb) {
  conf(function (er, conf) {
    var client = new RegClient(conf)
      , reg = conf.get('registry')
      ;
    client.whoami(reg, function (er, who) {
      cb(er, who)
    })
  })
}

/* Example */
ping(function (er, res) {
  console.log(res) 
  // results in a 404 (er = null, res = undefined)
})

Well, not really—hints welcome.

[othiym23]

whoami is currently an endpoint that isn't on the main npm registry, but in general, if you can fetch the info on a package using npm-registry-client (and it parses as valid JSON), npm's probably going to work. If you can fetch that info with ?write=true, your credentials are set correctly. Look at lib/star.js in npm-registry-client for an example.

Eventually, I'd like to have a safe ping endpoint in the registry, as well as a corresponding command in npm-registry-client, but something a little looser like what you've started working on is a good place to start. Thank you, and let me know if you need further help!

[tjwebb]

I'm not sure what a designated ping endpoint would tell us besides whether the designated ping endpoint is working or not. Unless it then polls the internal infrastructure for status?

[othiym23]

It would tell you that your installation of npm can reach the registry, and that your credentials are valid. This may not seem like very much, but it's a hugely valuable tool for front-line support, especially when helping newer users who are unfamiliar with npm and node and looking to get their setup dialed in.

[tjwebb]

Yea, +1 front line support. What comes to my mind is the npmjs.org status page, on which I've never seen anything but glowing success, even when I'm having connectivity issues with the registry. As long as npm ping is clear as to what it should convince me of, it sounds like a helpful debug/sanity tool.

[michaelnisi]

Thanks, I'll see what I can do.

[mreinstein]

Could we instead improve the error messages when there are npm failures of this kind? Having to build a debug subcommand just to tell us why things are going wrong seems like a heavy workaround for better error messages in the cli.

[othiym23]

That is also a thing we want to do! But having a separate troubleshooting command will be very useful for support and remote help.