adebisi-fa
8d42faf707
Bundle selection is now architecture-aware, not just codename-aware, and the no-compatible-bundle failure names the host architecture. Merged into the fpagent-installer spec and archived the change.
73 lines
3.2 KiB
Markdown
73 lines
3.2 KiB
Markdown
# Design: fpagent-installer-multiarch
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## Context
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The hosted installer (`tools/public/fpagent/install.sh`) runs on the field
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laptop and proxies the private release through `tools.yrka.app`. It resolves
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the release's asset names with a small `python3` snippet and hardcodes the
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x86_64 suffix. fingerprint-agent v1.5.0 added an i386 build:
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- online: `fpagent-<version>-linux-x86_64.tar.gz`, `fpagent-<version>-linux-i386.tar.gz`
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- offline: `fpagent-<version>-ubuntu-<release>-x86_64.tar.gz` (x86_64 only)
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The bundle's own installer already refuses a binary whose ELF class does not
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match the host, so the hosted installer only has to pick the right asset.
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## Goals / Non-goals
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- Goal: on any supported host (x86_64, i386) pick the release bundle built for
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that architecture, and record its version.
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- Non-goal: changing `tools/server.js`. It proxies whatever the release lists,
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and asset filtering/naming is unchanged.
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- Non-goal: i386 offline (codename) bundles. fingerprint-agent ships those
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x86_64-only; i386 hosts fall back to the generic online bundle whose
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installer apt-get's libfprint.
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- Non-goal: adding a production environment knob for the architecture. The
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host's own `uname -m` is the source of truth.
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## Decisions
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### Architecture from `uname -m`, resolved once
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Map `x86_64|amd64` → `x86_64`, `i386|i486|i586|i686` → `i386`, anything else →
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fail before any download. This mirrors `deploy/install.sh` in fingerprint-agent
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so the hosted and bundled installers agree on what is supported.
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### Selection order: codename bundle, then generic, both arch-scoped
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With `codename` from `/etc/os-release`:
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1. `-ubuntu-<codename>-<arch>.tar.gz`
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2. `-linux-<arch>.tar.gz`
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The codename attempt is skipped when the host has no codename. Because offline
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bundles are x86_64-only, an i386 host simply finds no codename asset and falls
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to step 2. The suffix match keeps one architecture's bundle from ever matching
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another's (`-linux-i386` does not end with `-linux-x86_64`).
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### Version regex derived from the architecture
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The version is the git hash embedded in the asset name. The existing regex only
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listed the x86_64 endings, so it produced an empty version for an i386 bundle
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and nothing was recorded. The regex must accept the same set of endings the
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selection can produce: `linux-x86_64`, `linux-i386` and
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`ubuntu-<codename>-x86_64`.
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### Tests stub `uname`
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The installer takes the architecture from the host, so a test cannot assert the
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i386 path on an x86_64 CI box by running the real `uname`. A test prepends a
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temp directory holding a fake `uname` to `PATH`, which is contained and needs no
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production-only override. Assertions are made on the gateway requests the script
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makes (which asset it asks for), the way the existing `--tag` test does.
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## Risks / trade-offs
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- A 64-bit userland on a 32-bit kernel is exotic; `uname -m` is the documented
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choice for the bundled installer, so the hosted one follows it rather than
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trying a second heuristic. `ponytail:` if such hosts appear, add a
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`getconf LONG_BIT` fallback in both installers at once.
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- The generated `install.sh --help` text duplicates the bundle installer's
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flags list. It can drift again; keeping it short and pointing at the bundle
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installer's own help limits the cost.
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