It doesn't actually matter much for this if you use an OSS CI service like Gitlab: the hosted service is still dependent on the generosity/marketing of the company hosting it, and switching to self-hosting is much more effort than porting config from one CI service to another.
I had heard of CI testing, and sure it sounded good, but we had all been making due without it, and I didn't have time (and certainly the projects didn't have money) to set it up. But travis made it so damn easy and free to turn on, there was no reason not to try it. Once tried, there was no going back, we would never want to do otherwise.
Travis really defined this market and opened up CI testing to entire communities. We owe them (employees, former management) a debt of gratitude for that.
But then we come to depend upon it for sure. Which they had no obligation to supply it forever, and perhaps it wasn't even sustainable business to do so. So now what? Well, now we move over to other free options like Github Actions which fortunately exist.
But is it dangerous to depend on the largesse of for-profit companies? FOR SURE.
Is it, at this point, hard to figure out how to do otherwise? FOR SURE.
So, what could we do instead? In my dream world, we'd have a non-profit collaborative project to provide CI to open source on an ability-to-pay basis. Is that likely? I dunno, raising money for open source is already a problem. And it's a hard project. As long as there are companies providing it to us for free, it's definitely less likely.
You might hope you'd get a broader pool of companies paying in to the fund, so you're less dependent on any one company. But unless the donors throw almost infinite money at you, you would soon need to make some kind of restrictions on which projects can benefit and how much they can use per month.
The best I can think of to do is to make your CI config a relatively simple wrapper around generic tools, so it's easy to move when you need to. This is often a trade-off with things like parallelism and caching, but at least if you know it's a trade-off you can make sensible decisions.
https://docs.gitlab.com/ee/user/project/import/gitlab_com.ht...
hosting CI yourself is equally simple. The worker can be installed with few commands, and with a few extra you can configure autoscalling:
I don't think that's the issue. Large parts of Travis are open sourc, but no one uses it because they are too complex to set up; and there are better self-hosted solutions than Travis.
Travis was attractive, because it was free hosting, not just software. And worked with just a few clicks
It's certainly easy to get into these lassaiz-faire ad-hoc remote free solutions, it's harder to maintain your own CI, but if quality and consistency is important, it's not that hard.
OSS projects should not have dependencies on non-OSS infrastructure unless they are prepared for this eventuality. This has happened, in various forms, to most 'free as in beer' services given enough time. Companies typically provide the service as some combination of crush the competition / building goodwill / altruism / the prospect of eventual conversion of some small fraction of OSS projects to a paid version. The reasons tend to vary (in this case, new ownership) but eventually the bottom line tends to win out. Often you won't be given much time to transition when the free ride ends.