(untested) config for stinky and diff script.

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# Configuration Diff Tool
Tool to compare all NixOS host configurations between current working tree and HEAD commit.
## Purpose
Before committing changes (especially refactors), verify that you haven't accidentally broken existing host configurations. This tool:
- Builds all host configurations in current state (with uncommitted changes)
- Builds all host configurations at HEAD (last commit)
- Uses `nvd` to show readable diffs for each host
- Highlights which hosts changed and which didn't
## Usage
### Prerequisites
The script requires `nvd` to be in PATH. Use either:
**Option 1: direnv (recommended)**
```bash
# Allow direnv in the repository (one-time setup)
direnv allow
# direnv will automatically load the dev shell when you cd into the directory
cd /home/ppetru/projects/alo-cluster
# nvd is now in PATH
```
**Option 2: nix develop**
```bash
# Enter dev shell manually
nix develop
# Now run the script
./scripts/diff-configs.sh
```
### Quick Start
```bash
# Compare all hosts (summary)
./scripts/diff-configs.sh
# Compare with detailed path listing
./scripts/diff-configs.sh -v c1
# Compare with content diffs of changed files (deep mode)
./scripts/diff-configs.sh --deep c1
# Compare only x86_64 hosts (avoid slow ARM cross-compilation)
./scripts/diff-configs.sh c1 c2 c3 zippy chilly sparky
# Verbose mode with multiple hosts
./scripts/diff-configs.sh --verbose c1 c2 c3
# Via flake app
nix run .#diff-configs
# Show help
./scripts/diff-configs.sh --help
```
### Typical Workflow
```bash
# 1. Make changes to configurations
vim common/impermanence.nix
# 2. Stage changes (required for flake to see them)
git add common/impermanence.nix
# 3. Check what would change if you committed now
# For quick feedback, compare only x86_64 hosts first:
./scripts/diff-configs.sh c1 c2 c3 zippy chilly sparky
# 4. Review output, make adjustments if needed
# 5. If changes look good and affect ARM hosts, check those too:
./scripts/diff-configs.sh stinky alo-cloud-1
# 6. Commit when satisfied
git commit -m "Refactor impermanence config"
```
## Output Explanation
### No Changes
```
━━━ c1 ━━━
Building current... done
Building HEAD... done
✓ No changes
```
This host's configuration is identical between current and HEAD.
### Changes Detected
```
━━━ stinky ━━━
Building current... done
Building HEAD... done
⚠ Configuration changed
<<< /nix/store/abc-nixos-system-stinky-25.05 (HEAD)
>>> /nix/store/xyz-nixos-system-stinky-25.05 (current)
Version changes:
[C] octoprint: 1.9.3 -> 1.10.0
[A+] libcamera: ∅ -> 0.1.0
Closure size: 1500 -> 1520 (5 paths added, 2 paths removed, +3, +15.2 MB)
```
Legend:
- `[C]` - Changed package version
- `[A+]` - Added package
- `[R-]` - Removed package
- `[U.]` - Updated (same version, rebuilt)
### Verbose Mode (--verbose)
With `-v` or `--verbose`, also shows the actual store paths that changed:
```
━━━ c1 ━━━
Building current... done
Building HEAD... done
⚠ Configuration changed
[nvd summary as above]
Changed store paths:
Removed (17 paths):
- config.fish
- system-units
- home-manager-generation
- etc-fuse.conf
... and 13 more
Added (17 paths):
- config.fish
- system-units
- home-manager-generation
- etc-fuse.conf
... and 13 more
```
This is useful when nvd shows "No version changes" but paths still changed (e.g., refactors that rebuild config files).
### Deep Mode (--deep)
With `-d` or `--deep`, shows actual content diffs of changed files within store paths (implies verbose):
```
━━━ c1 ━━━
Building current... done
Building HEAD... done
⚠ Configuration changed
[nvd summary and path listing as above]
Content diffs of changed files:
▸ etc-fuse.conf
@@ -1,2 +1,2 @@
-user_allow_other
+#user_allow_other
mount_max = 1000
▸ nixos-system-c1-25.05
activate:
@@ -108,7 +108,7 @@
echo "setting up /etc..."
-/nix/store/...-perl/bin/perl /nix/store/...-setup-etc.pl /nix/store/abc-etc/etc
+/nix/store/...-perl/bin/perl /nix/store/...-setup-etc.pl /nix/store/xyz-etc/etc
▸ unit-dbus.service
dbus.service:
@@ -1,5 +1,5 @@
[Service]
+Environment="LD_LIBRARY_PATH=/nix/store/.../systemd/lib"
Environment="LOCALE_ARCHIVE=..."
```
**What it shows**:
- Matches changed paths by basename (e.g., both have "config.fish")
- Diffs important files: activate scripts, etc/*, *.conf, *.fish, *.service, *.nix
- Shows unified diff format (lines added/removed)
- Limits to first 50 lines per file
**When to use**:
- When you need to know **what exactly changed** in config files
- Debugging unexpected configuration changes
- Reviewing refactors that don't change package versions
- Understanding why a host rebuilt despite "No version changes"
### Build Failures
```
━━━ broken-host ━━━
Building current... FAILED
Error: attribute 'foo' missing
```
If a host fails to build, the error is shown and the script continues with other hosts.
## How It Works
1. **Discovers hosts**: Queries `deploy.nodes` from flake to get all configured hosts
2. **Creates worktree**: Uses `git worktree` to check out HEAD in a temporary directory
3. **Builds configurations**: Builds `config.system.build.toplevel` for each host in both locations
4. **Compares with nvd**: Runs `nvd diff` to show package-level changes
5. **Cleans up**: Removes temporary worktree automatically
## Important Notes
### Git Staging Required
Flakes only evaluate files that are tracked by git. To make changes visible:
```bash
# Stage new files
git add new-file.nix
# Stage changes to existing files
git add modified-file.nix
# Or stage everything
git add .
```
Unstaged changes to tracked files **are** visible (flake uses working tree content).
### Performance
- First run may be slow (building all configurations)
- Subsequent runs benefit from Nix evaluation cache
- Typical runtime: 1-5 minutes depending on changes
- **ARM cross-compilation is slow**: Use host filtering to avoid building ARM hosts when not needed
- Example: `./scripts/diff-configs.sh c1 c2 c3` (x86_64 only, fast)
- vs `./scripts/diff-configs.sh` (includes stinky/alo-cloud-1, slow)
### When to Use
**Good use cases**:
- Refactoring shared modules (like impermanence)
- Updating common configurations
- Before committing significant changes
- Verifying deploy target consistency
**Not needed for**:
- Adding a single new host
- Trivial one-host changes
- Documentation updates
## Troubleshooting
### "Not in a git repository"
```bash
cd /home/ppetru/projects/alo-cluster
./scripts/diff-configs.sh
```
### "No changes detected"
All changes are already committed. Stage some changes first:
```bash
git add .
```
### Build failures for all hosts
Check flake syntax:
```bash
nix flake check
```
### nvd not found
Install nvd:
```bash
nix profile install nixpkgs#nvd
```
(Already included in workstation-node.nix packages)
## Related Tools
- `nvd` - Package diff tool (used internally)
- `nix diff-closures` - Low-level closure diff
- `nix store diff-closures` - Alternative diff command
- `deploy-rs` - Actual deployment tool
## See Also
- `common/global/show-changelog.nix` - Shows changes during system activation
- `docs/RASPBERRY_PI_SD_IMAGE.md` - SD image building process

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# Raspberry Pi SD Image Building and Deployment
Guide for building and deploying NixOS SD card images for Raspberry Pi hosts (e.g., stinky).
## Overview
Raspberry Pi hosts use a different deployment strategy than regular NixOS hosts:
- **First deployment**: Build and flash an SD card image
- **Subsequent updates**: Use `deploy-rs` like other hosts
## Architecture
### Storage Layout
**Partition structure** (automatically created by NixOS):
- `/boot/firmware` - FAT32 partition (label: `FIRMWARE`)
- Contains Raspberry Pi firmware, U-Boot bootloader, device trees
- `/` - tmpfs (in-memory, ephemeral root)
- 2GB RAM disk, wiped on every boot
- `/nix` - ext4 partition (label: `NIXOS_SD`)
- Nix store and persistent data
- Contains `/nix/persist` directory for impermanence
### Impermanence with tmpfs
Unlike btrfs-based hosts that use `/persist`, Pi hosts use `/nix/persist`:
- Root filesystem is tmpfs (no disk writes, auto-wiped)
- Single ext4 partition mounted at `/nix`
- Persistent data stored in `/nix/persist/` (directory, not separate mount)
- Better for SD card longevity (fewer writes)
**Persisted paths**:
- `/nix/persist/var/lib/nixos` - System state
- `/nix/persist/home/ppetru` - User home directory
- `/nix/persist/etc` - SSH host keys, machine-id
- Service-specific: `/nix/persist/var/lib/octoprint`, etc.
## Building the SD Image
### Prerequisites
- ARM64 emulation enabled on build machine:
```nix
boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
```
(Already configured in `workstation-node.nix`)
### Build Command
```bash
# Build SD image for stinky
nix build .#stinky-sdImage
# Result location
ls -lh result/sd-image/
# nixos-sd-image-stinky-25.05-*.img.zst (compressed with zstd)
```
**Build location**: Defined in `flake.nix`:
```nix
packages.aarch64-linux.stinky-sdImage =
self.nixosConfigurations.stinky.config.system.build.sdImage;
```
## Flashing the SD Card
### Find SD Card Device
```bash
# Before inserting SD card
lsblk
# Insert SD card, then check again
lsblk
# Look for new device, typically:
# - /dev/sdX (USB SD card readers)
# - /dev/mmcblk0 (built-in SD card slots)
```
**Warning**: Double-check the device! Wrong device = data loss.
### Flash Image
```bash
# Decompress and flash in one command
zstd -d -c result/sd-image/*.img.zst | sudo dd of=/dev/sdX bs=4M status=progress conv=fsync
# Or decompress first, then flash
unzstd result/sd-image/*.img.zst
sudo dd if=result/sd-image/*.img of=/dev/sdX bs=4M status=progress conv=fsync
```
### Eject SD Card
```bash
sudo eject /dev/sdX
```