Convert android phone into linux server(bare metal performance)?

Question

I want to convert some old android phones(2017+) into SSH only servers, is it possible? My objectives are:

• run the phones 24/7 without a battery
• I don't want to use anything besides the motherboard and the wifi(or if possible to get internet from USB), and scrap display, battery, camera and other sensors for money
• bare metal performance, no android junk inside that eats cpu and ram
• root access, just like in a server
• run ubuntu server or debian

The scope of my project is being able to reuse old phones as linux servers and run stuff like nginx, posgresql, nodejs, ruby. And even docker if possible.

Answer 1

I want to convert some old android phones(2017+) into SSH only servers, is it possible?

Sure, Android is an operating system based on the Linux kernel, and you can run any user land on that. In fact, your average free alternative app store (e.g. fdroid) will have e.g. debian containers to execute.

run the phones 24/7 without a battery

Many phones' hardware won't boot without a battery. But you can definitely find phones that do.

I don't want to use anything besides the motherboard and the wifi(or if possible to get internet from USB), and scrap display, battery, camera and other sensors for money

your scrapping parts operation will have an expected negative return, forget about that. The cost of removing a screen doesn't justify the price you'll get for a used screen. What do you think a brightness sensor or an accelerometer costs from the manufacturer? We're talking cents here.

bare metal performance, no android junk inside that eats cpu and ram

Android is your operating system. This is like "I want to drive my car with bare metal performance, no motor control junk"… Android will very likely be necessary to get your phone into an operational state where you can execute anything that needs networking. So, forget about that too.

root access, just like in a server

You will need to have a phone that you can get root access to (many phones have a developer mode that you can enter more or less easily, by far not all) to do any of this.

The scope of my project is being able to reuse old phones as linux servers and run stuff like nginx, posgresql, nodejs, ruby. And even docker if possible.

Docker is the least of your problem – Linux namespaces work and are an important part of modern Android.

The rest makes absolutely no sense at all.

• nginx is a web server, but you've got a device that's only attached via wifi – whatever offers that wifi connection could just as well run that web server, and you could throw away your phone.
• postgresql is a database server. You'll find that a phone's storage is the opposite of what you want for a database server.
• nodejs: hm, that is a classically rather RAM-intense thing. You sure you want your old phone to run nodejs?
• Ruby: Well, that's just a popular scripting language. There's probably many android apps written in it. There's no reason this is any special.

In case you want to develop this into some kind of business: You're inventing slow, very power hungry, unreliable, expensive servers. A single ARM or x86_64 server box can host hundreds of virtual machines that would be more capable than what you could put up with the same number of phones. At a fraction of the hardware cost, at a fraction of the power consumption (mobile processors are not optimized for server workloads, and hundred USB supplies are less efficient than one ATX supply), and at way better maintainability. With the option to get server firmware updates.

I'll give you something to ponder: In Germany, electrical power is 0,34€ per kWh. That means 1W is ca 3€ over a year. A USB power supply (5V) offering 750 mA outputs 3.75 W. Typical power efficiency of these isn't very high – 80% would be good, so that's 4.7 W on the input side to run your phone at low load. That's 14€ a year.

For comparison: a small VM at azure, ionos, AWS or digital ocean costs about 24€ a year. That includes power, the hardware to run on, traffic cost, an IP address (which really dominates the price here - if you can home many servers behind the same IPv4 address, you get away much cheaper), the whole frigging data center with 24/7 staffing, cooling, multiply-redundant storage clusters powering your system... No way you can buy a used phone and operate it for long enough to even come close to that price.

Answer 2

Perhaps phone re-purposing isn't the most efficient way to host services for the money or power consumed, however probably more efficient than *pi pcb, but I believe there is coming a day when access will be controlled to cloud or otherwise remote hosted services. I don't want to be leveraged to do things I wouldn't do because my data sits on someone else's computer.

I've recently felt that our reliance of communication over the internet has become a huge leverage point over the masses. As much as I value the efficiency of centralized computing, in a world with opportunists seeking more power over the people I'm afraid to continue at the rate we're going will become our demise.

Is it faster or more reliable from the client's view to have my web host or web app sitting locally on my internet connection/lan/router? Probably not as upload speeds are usually tiny, but when there's Internet service interruption, digital ID requirements, etc, to access the net I will be glad my services are local and can be made available on a more local level should that day come. However to keep my internet up at the point will become a challenge to make available to the world, but at it brings the possible failure points to a minimum.

As of the moment without any data to go off of, my gut tells me our freedoms of liberty will gain traction if we all have the ability to self host on our own internet connections or at least disperse some to relieve any potential leveraging tactics of data. Messaging communications should be device to device and not fall apart whenever it can't reach a central service. This way they can adapt to getting messages to people through other means than internet, like say local mesh networking when the Internet blacks out all over or in certain regions fiber trunks become clipped.

It's a rather scary thought to think we've left walkie talkies behind to become hooked on a communication technology that's too easily manipulated to control the masses in doing what they ordinarily wouldn't do.

In the Philippines if we lose internet, communications will take a huge hit as everyone uses Facebook Messenger to communicate with or without an active promo.

Copies of a book held in possession of many keep the book from being altered. A book or article written on a web page in only one place can too easily be altered as the current paradigm shifts due to economic agendas uncontrolled by the people. Way Back Machine seemed a good way to record older versions of something on the net, but even that can be altered by the powers that be. Information in the hands of the people on a local level is, I feel, the better option to future freedom. The struggle to get those common folk to value and learn to manipulate their personal data and future freedoms is essential to being independent. And with independence comes a better chance of freedom.

I too was attracted to the small form factor *pi PCBs and what we could do, but the phones already have screens and generally more memory and CPU power. I think it would be great to use phones in IT before it becomes Information Tyranny.

Answer 3

I’ve been wanting to do the exact same thing, and I might be able to put you onto something if you’re ready to do a little bit of DIY stuff.

Some people in the answers told you that with most phones you can’t run them without a battery, and that’s… technically false.  Because they will refuse to boot if it does not detect any battery; however, there’s a way to power the phone exactly like the battery would.  You will have to open the phone, remove the battery and remove the long rectangular sheet down the battery where its cable is connected, and solder it to a buck converter set to 4.2 V, and then solder the input of the buck to a cable that’s connected to a phone charger.

The buck converter/charger (5 V / 9 V DC power supply) probably won’t be powerful enough to keep the phone turned on, as phones’ power draw is extremely fluctuating and if the power source can’t deliver the current that the phone requests, it’s gonna shut down brutally.  Plugging a USB-C cable into the charging port connected to a charger just like how you normally charge your phone will give it more current; therefore, it’s most likely not going to abruptly turn off.

I have tested this on an iPhone XR and it works pretty well, and theoretically it should also work with any smartphone, and I plan on doing it with a Galaxy S20 that has a damaged screen that I’m gonna use to host a server for my mobile app, probably.

I’m also doing some research on how to have the most lightweight/near bare Linux software to allow the phone to perform to its max (and that’s how I came across your post; LOL).  For now I have a few possibilities.  The one I’ll most likely do is to get the phone’s kernel/firmware from GitHub and modify it to remove all of the junk that’s uselessly filling up RAM/CPU.

I hope that might’ve helped.