The title of this article is the opposite of what the article says.
He made almost no money with open source. He made tons of money by withholding features from the open source library and instead only offering them under a commercial license as an add-on. Since this is itself a violation of the LGPL, anyone using the Pro version isn't even using open source at all, as both the original and Pro enhancements are at that point licensed with a commercial license.
An accurate title would be:
"How to make $100K by writing an open source library, waiting for a lot of people to build a product using it, then holding back essential features until they pay you money, which they will do because they are suffering lock-in and it's way cheaper to pay you than pay a developer for dozens of hours of work to adopt an open source solution."
Something can be pay for use and open source. What he did here was totally fine. Sidkiq is amazing, and what it replaces is kludgy. If Sidkiq or Riak want to make a version that is specially geared for people that need software to scale then everybody wins.
The people at scale win because they buy the software for peanuts and they were able to do so only after hitting product-market fit. The people starting startups win, since they get well designed software from someone that has self-interest to keep it going.
I see no problem with this whatsoever. It isn't like the at-scale version of Sidekiq would ever have been built if it hadn't been for the cash. The only thing I would add would be that maybe he puts a sunset clause in there that auto-frees the source in a year or two. That way people won't waste time rebuilding the at-scale components.
There's nothing at all wrong with what he did - it's just not 'making money from open source' per se. I guess you can argue he would not have made money were it not for the open source project, but the actual money is coming from what he's holding back.
He tried selling support and failed miserably, he made no money. So, he issued a better version of the same software under a commercial license, and that sold well.
RedHat does not do that. Everything they do is available in CentOS, or is available freely. They make money selling support.
Redhat's strategy is a bit more complex than that:
They only support the official Redhat release, but that contains Redhat's trademarks, which you are not free to copy/modify/etc... and indeed, you have to pay for the official release.
I think it ends up being that if you need the official Redhat, you pretty much have to buy it, and buy a long-term-ish support contract.
In any event, support is not a public good along the lines of software: it's very much rivalrous and excludable.
In other words, redhat doesnt make money from open source. But nobody ever complains when they're held up as the poster child for how to make money from open source.
If a lot of people were able to build products based on his open source library, it seems wrong to claim that anything he held back was truly essential.
Sure, this is possible. However, this author is not violating it.
For example, if the regular version were issued with the Pro version merged into it, the author would have to provide an unmodified version in the same distribution lest he violate the LGPL. There isn't much consequence to this, unless he felt the need to sue himself.
However, since the author here also owns the rights to both the regular and Pro versions, he can just license both to the user under a commercial license when including the Pro version, which is what he does. At that point, neither is 'free as in speech' from the perspective of the person who bought the license, even though lots of the bits are the same. The user is using a non-free commercial license. The user could also use the free version under the LGPL, but that would be redundant, since they have the same code under a license they can use from buying the commercial license.
In this case the author says he relicenses both for users who can't use LGPL code.
No, this is wrong. The author's code is licensed to the author under a "license" that allows him to do whatever he wants, since he owns the copyright.
Just because he chooses to extend the LGPL to others doesn't mean he is himself bound by its constraints.
In the model you're proposing (where things have one and only one set of copyright terms that apply to everyone), how would things like Libreoffice be offered under multiple licenses simultaneously?
In which case, maybe it's classified as a derivative work of the original OS project? This is how WordPress tries to classify third-party themes and plugins, meaning they should "thus inherit the GPL license". See: http://www.wordpress.org/about/license/
Yes and it's standard for contributing to pretty much any open source project that's run by a company. The contributor's agreement you'll sign has you assign them full copyright for your patches, so they can do whatever they want, including make a non-GPL version.
He made almost no money with open source. He made tons of money by withholding features from the open source library and instead only offering them under a commercial license as an add-on. Since this is itself a violation of the LGPL, anyone using the Pro version isn't even using open source at all, as both the original and Pro enhancements are at that point licensed with a commercial license.
An accurate title would be: "How to make $100K by writing an open source library, waiting for a lot of people to build a product using it, then holding back essential features until they pay you money, which they will do because they are suffering lock-in and it's way cheaper to pay you than pay a developer for dozens of hours of work to adopt an open source solution."