Prefetch flake inputs with retries in CI - #2567
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GitHub's tarball API intermittently returns 503s, which fails any job during flake input fetching before the build even starts. Prefetch all inputs with nix flake archive inside the same retry wrapper the attic setup already uses, so transient GitHub outages are absorbed instead of failing the run. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01FoVmjH7WSaK69bYy8xhVW7
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palfrey
approved these changes
Jul 17, 2026
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Problem
CI jobs have been failing intermittently with HTTP 503s from GitHub's tarball API while Nix fetches flake inputs (e.g.
hercules-ci/flake-parts), before the actual build starts:Nix's own retry gives up within seconds, so a brief GitHub blip fails the whole job. The requests are already authenticated (
nix-installer-actionauto-configuresaccess-tokensfromGITHUB_TOKEN), so this is server-side flakiness, not rate limiting.Fix
Add a
nix flake archiveprefetch step to the sharedprepare-nixaction, wrapped in the samenick-fields/retryaction (5 attempts, 30s apart) the attic setup already uses. All flake inputs land in the store before anynix develop/nix buildstep runs, so transient 503s are ridden out instead of failing the run.The step deliberately fails (rather than skips) if GitHub is hard-down for the full retry window — a build job that can't fetch its inputs can't do anything meaningful, and skipping would report green without building.
🤖 Generated with Claude Code
https://claude.ai/code/session_01FoVmjH7WSaK69bYy8xhVW7
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