apko as apk

Makefile

@@ -100,6 +100,10 @@ generate: ## Generates jsonschema for apko types.
 apko: $(SRCS) ## Builds apko
 	CGO_ENABLED=0 go build -trimpath -ldflags "$(LDFLAGS)" -o $@ ./
 
+.PHONY: apko-as-apk
+apko-as-apk: $(SRCS) ## Builds apko-as-apk
+	CGO_ENABLED=0 go build -trimpath -ldflags "$(LDFLAGS)" -o $@ ./cmd/apko-as-apk
+
 .PHONY: install
 install: $(SRCS) ## Builds and moves apko into BINDIR (default /usr/bin)
 	install -Dm755 apko ${DESTDIR}${BINDIR}/apko
@@ -147,9 +151,17 @@ lint: checkfmt golangci-lint ## Run linters and checks like golangci-lint
 test: ## Run go test
 	go test ./... -race
 
+.PHONY: test-apko-as-apk
+test-apko-as-apk: apko-as-apk ## Run unit tests for apko-as-apk
+	go test ./internal/cli/apkcompat/... -v
+
+.PHONY: test-apko-as-apk-container
+test-apko-as-apk-container: apko-as-apk ## Run container integration tests for apko-as-apk (requires docker)
+	go test -tags containerTest ./internal/cli/apkcompat/... -v -timeout 10m
+
 .PHONY: clean
 clean: ## Clean the workspace
-	rm -rf apko
+	rm -rf apko apko-as-apk
 	rm -rf bin/
 	rm -rf dist/
 

cmd/apko-as-apk/README.md

@@ -0,0 +1,193 @@
+# apko-as-apk
+
+`apko-as-apk` is an APK-compatible package manager that uses apko's existing functionality to provide a drop-in replacement for common `apk` commands.
+
+## Overview
+
+This binary leverages the extensive APK package management capabilities already built into apko, allowing it to operate directly on filesystem trees (including the root filesystem) rather than just building container images.
+
+## Building
+
+```bash
+make apko-as-apk
+```
+
+This creates a statically-linked binary (~27MB) in the project root.
+
+## Usage
+
+The tool is designed as a drop-in replacement for `apk` with compatible command-line flags:
+
+```bash
+# By default, operates on root filesystem (/)
+apko-as-apk [command] [flags]
+
+# Operate on an alternate root
+apko-as-apk --root /path/to/root [command] [flags]
+```
+
+## Implemented Commands
+
+### info
+Display information about installed packages.
+
+```bash
+# List all installed packages
+apko-as-apk info
+
+# List with versions
+apko-as-apk info -v
+
+# Show package details
+apko-as-apk info busybox
+
+# Show package contents
+apko-as-apk info -L busybox
+
+# Show dependencies
+apko-as-apk info -R busybox
+
+# Show all information
+apko-as-apk info -a busybox
+```
+
+**Status**: ✅ Fully functional
+
+### update
+Update repository indexes from configured repositories.
+
+```bash
+apko-as-apk update
+```
+
+**Status**: ✅ Fully functional
+
+### add
+Add packages and their dependencies to the system.
+
+```bash
+# Add a package
+apko-as-apk add curl
+
+# Initialize database and add package
+apko-as-apk add --initdb curl
+
+# Simulate without making changes
+apko-as-apk add --simulate curl
+```
+
+**Status**: ⚠️ Partially functional
+
+**Known Issue**: The `add` command currently has issues installing packages that contain install scripts. The command successfully:
+- Resolves dependencies correctly
+- Downloads packages
+- Reads package metadata
+
+However, it fails during installation for packages with install scripts with an error:
+```
+unable to update scripts.tar for pkg: unable to stat scripts file: file does not exist
+```
+
+This appears to be related to how apko's package installation code handles script extraction and would require further investigation into the `pkg/apk/apk/install.go` implementation.
+
+**Workaround**: The native `apk` command can still be used for package installation, while `apko-as-apk info` and `apko-as-apk update` work correctly alongside it.
+
+## Global Flags
+
+The tool supports the same global flags as `apk`:
+
+- `-p, --root ROOT` - Manage file system at ROOT (default: `/`)
+- `-v, --verbose` - Print more information (can be specified twice)
+- `-q, --quiet` - Print less information
+- `-X, --repository REPO` - Specify additional package repository
+- `--arch ARCH` - Temporarily override architecture
+- `--cache-dir DIR` - Override the cache directory
+- `--allow-untrusted` - Install packages with untrusted signatures
+- `--no-cache` - Do not use any local cache
+- `--keys-dir DIR` - Override directory of trusted keys
+- And more...
+
+## Architecture
+
+The implementation reuses apko's existing code:
+- **`pkg/apk/apk`** - Complete APK package management implementation
+- **`pkg/apk/fs`** - Filesystem abstraction supporting real filesystems
+- **`internal/cli/apkcompat`** - New CLI interface matching `apk` command structure
+
+No new APK parsing or installation code was needed - everything leverages battle-tested apko functionality.
+
+## Design Decisions
+
+1. **Default to root=/**: Unlike apko's image building mode, this tool defaults to operating on the live system root (`/`), matching `apk` behavior.
+
+2. **Reuse existing code**: The implementation deliberately reuses apko's `pkg/apk/apk` package rather than reimplementing APK operations.
+
+3. **Compatible interface**: Command-line flags and output formats match `apk` where possible for familiarity.
+
+## Testing
+
+### Unit Tests
+
+Run fast unit tests that don't require Docker:
+
+```bash
+make test-apko-as-apk
+```
+
+These tests cover:
+- Repository file parsing
+- Key installation logic
+- Package info formatting
+- Helper functions
+
+### Container Integration Tests
+
+Run integration tests that compare `apk` and `apko-as-apk` behavior in Docker containers:
+
+```bash
+make test-apko-as-apk-container
+```
+
+**Note**: Requires Docker to be running.
+
+These tests:
+- Compare `info` command output between `apk` and `apko-as-apk`
+- Verify `update` command updates repository indexes correctly
+- Test various command-line flags and options
+- Validate exit codes and error handling
+
+Tests use the `containerTest` build tag and can also be run directly:
+
+```bash
+go test -tags containerTest ./internal/cli/apkcompat/... -v
+```
+
+### Manual Testing
+
+Test in a container interactively:
+
+```bash
+# Start container with binary mounted
+docker run --rm -it \
+  --mount=type=bind,source=$PWD/apko-as-apk,destination=/usr/bin/apko-as-apk \
+  cgr.dev/chainguard/wolfi-base:latest \
+  sh
+
+# Inside container, compare commands:
+apk info
+apko-as-apk info
+
+apk info -v
+apko-as-apk info -v
+
+apk info busybox
+apko-as-apk info busybox
+```
+
+## Future Work
+
+- **Fix install script handling**: Investigate and resolve the script extraction issue in package installation
+- **Add more commands**: Implement additional `apk` subcommands (del, upgrade, fix, etc.)
+- **Add tests**: Create Go tests with `containerTest` build tag for integration testing
+- **Improve output formatting**: Match `apk` output more precisely in edge cases
+- **Virtual packages**: Implement support for the `--virtual` flag in `add` command

cmd/apko-as-apk/main.go

@@ -0,0 +1,37 @@
+// Copyright 2024 Chainguard, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"log"
+	"os"
+	"os/signal"
+
+	"chainguard.dev/apko/internal/cli/apkcompat"
+)
+
+func main() {
+	if err := mainE(); err != nil {
+		log.Fatalf("error during command execution: %v", err)
+	}
+}
+
+func mainE() error {
+	ctx, done := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer done()
+
+	return apkcompat.New().ExecuteContext(ctx)
+}