Add devenv.sh feature

[Copilot]

Adds a devcontainer feature for devenv.sh — a Nix-based developer environment manager by Cachix.

Changes

• src/devenv.sh/devcontainer-feature.json — feature metadata with version option (default: latest)
• src/devenv.sh/install.sh — installs devenv via Nix: installs the Nix package manager if not already present (using the Determinate Systems installer, same approach as the nixos.org feature), starts the Nix daemon, then installs devenv from the devenv.cachix.org binary cache via nix profile install github:cachix/devenv[/v{version}]#devenv; supports both latest and specific version tags (e.g. 2.0.4); symlinks the devenv binary to /usr/local/bin/devenv
• src/devenv.sh/README.md — auto-generated format documentation
• test/devenv.sh/test.sh — verifies binary is installed and functional
• .github/workflows/test.yaml — added devenv.sh to both the test-autogenerated and test-scenarios CI matrices

Usage

"features": {
    "ghcr.io/devcontainer-community/devcontainer-features/devenv.sh:1": {}
}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add feature devenv.sh</issue_title>
<issue_description></issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add feature devenv.sh #41

---

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[sebst]

@copilot New features need to be added to .github/workflows/test.yaml

[Copilot]

@copilot New features need to be added to .github/workflows/test.yaml

Added devenv.sh to both the test-autogenerated and test-scenarios matrices in .github/workflows/test.yaml (commit 6fd902c).

[sebst]

tests are failing

[sebst]

Tests are still failing:

[2026-03-16T15:32:38.968Z] ERROR: failed to build: failed to solve: process "/bin/sh -c cp -ar /tmp/build-features-src/devenv.sh_0 /tmp/dev-container-features && chmod -R 0755 /tmp/dev-container-features/devenv.sh_0 && cd /tmp/dev-container-features/devenv.sh_0 && chmod +x ./devcontainer-features-install.sh && ./devcontainer-features-install.sh && rm -rf /tmp/dev-container-features/devenv.sh_0" did not complete successfully: exit code: 1

[Copilot]

tests are failing

The tests were failing because devenv doesn't publish standalone binary releases to GitHub — the download URL was always a 404. Fixed in commit 5aa30ae by rewriting install.sh to install devenv via Nix instead: it installs the Nix package manager (using the same Determinate Systems approach as the nixos.org feature), starts the Nix daemon, then installs devenv from the devenv.cachix.org binary cache via nix profile install github:cachix/devenv#devenv.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• devenv.sh
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)
• https://api.github.com/repos/cachix/devenv/releases/295917499/assets
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (http block)
• https://api.github.com/repos/cachix/devenv/releases/tags/v1.3.1
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[Copilot]

Tests are still failing:

...

The error shown is from the run before my fix — the new CI run (triggered by commit 5aa30ae, now 158bac0) shows action_required and hasn't run yet.

The root cause of the original failure: devenv doesn't publish standalone binary releases — the download URL was always a 404. I've replaced the entire approach: install.sh now installs Nix via the Determinate Systems installer (same as the nixos.org feature), starts the nix-daemon, then installs devenv from the devenv.cachix.org binary cache via nix profile install github:cachix/devenv#devenv, and symlinks the result to /usr/local/bin/devenv.