[cli] Await port/service expose

[randomir]

The problem

How to make sure service/port is exposed before accessing it from browser/simple-browser.

Consider something like this:

$ port=8000
$ python -m http.server $port & gp await-port $port && gp preview $(gp url $port)

In roughly one out of three runs, this fails with:

The proposal

We need a way to sync on port exposed. Something like gp await-port, but for exposed (proxied) ports/services.

For example:

$ python -m http.server $port & gp await-port $port --external && gp preview $(gp url $port)

(note the --external flag)

Considered alternative

Naive sleep(t_delay). Problems with this approach:

1. introduces unwanted delay
2. no upper bound on t_delay

Additional context

Using enterprise self-hosting version (GP 0.9.x).

[axonasif]

Hey @randomir, gp await-port should work. Do you have an example repo where we can reproduce your issue?

[randomir]

Hey @axonasif, I checked the source of gp await-port before opening this issue, and saw it's simply checking /proc/net/tcp for <port> to be in listen state (and then pausing for 2s even if port is opened!)

After a port is opened on localhost, it has to be exposed by ws-proxy, and that takes some time, right?

Are you saying the upper bound for port expose via ws-proxy is 2 seconds?

FYI, I wasn't able to verify this issue on gitpod.io, as login via GH was broken at the time of filing. I tried reproducing it on gitpod.io today and was not able to. I can still reproduce it on our self-hosted install.

[randomir]

Let me rephrase my question: why 2 seconds in L50 of the await-port?

https://github.com/gitpod-io/gitpod/blob/bd3ba7cdecf78efb2e36d1665e3dc692460b0a33/components/gitpod-cli/cmd/await-port.go#L50

I would like to get to the bottom of why the difference in behavior on our self-hosted version (based on gitpod 0.9 / f496a745a08e9b8a2be23d8c0b5a326af09b69bc) and on gitpod.io?

A quick way to reproduce the problem described above (with high probability on our install) is:

$ test() { python -m http.server $1 & gp await-port $1 && gp preview $(gp url $1); }
$ test 8000
$ test 8001
$ test 8002
...

I wanted to direct this question to the author of the await-port.go, but git blame is obfuscated during gitpod open-sourcing, and changes hidden behind the "Initial commit". But if I were to take a wild guess, I'd say @geropl, @jankeromnes or @csweichel can answer this.. :wink:

[csweichel]

The await-port code is very old. When it was written the port exposure did take some time because of DNS and the use Kubernetes services. None of those things plays a role anymore, we simply haven't come 'round to updating the await-port command :)

[randomir]

Ok, cool, thanks for the super quick answer.

Is there something we can do (I'm guessing on the infra side) on our self-hosted install (GKE, gitpod 0.9), to ensure the port is exposed within some <insert-upper-bound>? Currently, not even those 2 seconds from the await-port are always sufficient..

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.