Install postmarketOS on Android phone and use Docker as a home server

Original Article ↗ Hacker News Discussion ↗

Repurposing old Android phones as low-power home servers is appealing, especially when flashing Linux-based systems like postmarketOS or Mobian and running Docker containers on them. Commenters weigh this against simply using Android with Termux, raising concerns about Android’s aggressive process killing, outdated kernels and firmware, and the safety and lifespan of lithium batteries left on constant charge—often recommending battery removal or charge limiting. Many conclude it’s a fun, resource-efficient reuse of idle hardware if you already own a suitable device, but not a clear substitute for purpose-built SBCs or mini PCs in terms of reliability, I/O, or long-term maintainability.

Scope of the Article / Title Confusion

  • Many note the article is really about flashing postmarketOS (Alpine/musl) and then installing Docker, not “Docker on Android.”
  • Some find that less exciting (“just Linux on a small computer”), others like it as a way to reuse old phones.

Android vs. Linux for Phone-as-Server

  • Android is seen as problematic for servers due to:
    • Aggressive background OOM killing that can terminate services like sshd or containers.
    • Lack of swap and difficulty marking critical services as non-killable.
  • Several argue you can “play by Android rules” (foreground services, root workarounds, system flags) or use Termux to run long-lived services, including Docker.
  • Others counter that a proper Linux distro (postmarketOS, Mobian, etc.) gives more predictable server behavior and mainline kernels.

Battery Life, Degradation, and Safety

  • Strong concern about leaving phone batteries on charge 24/7:
    • Repeated anecdotes of swollen batteries over years of continuous power.
    • Comparison to UPS batteries: lead-acid tolerates float charge; phone Li-ion does not.
  • Suggestions: remove battery entirely, fake the battery electrically, or use phones with configurable charge limits (e.g., 60–80%).
  • Coulomb counting and BMS behavior are discussed; partial charge + occasional full cycles may help, but long-term accuracy is tricky.
  • Some describe hardware “chargers/limiters” and timers; others call crude timer-based cycling unsafe and destructive.

Security and Firmware Concerns

  • Avoiding Android is also framed as a kernel-security and firmware issue:
    • Old Android devices often have outdated kernels.
    • Many proprietary firmware blobs (baseband, Wi-Fi, BT, etc.) stop receiving updates; this is seen as a risk if exposed to the internet.
  • Using mainline Linux (postmarketOS, Mobian) can improve kernel support, but firmware blobs largely remain closed and unmaintained.

Linux Phone OSes and Practicality

  • Status of Linux phones (PinePhone, Librem 5, SailfishOS) is mixed:
    • They can work as daily drivers for some, but hardware (battery life, modem reliability, performance) is often the bottleneck.
    • Android remains far more power-efficient and has better app availability.
  • Many conclude phone-as-server is appealing mainly for hardware reuse and ultra-low power, not as a general replacement for SBCs or mini PCs.