aottr.dev
Pull-based GitOps-style Docker Compose deployer: polls a (private) Git repo, detects changed stacks and reconciles only the affected
feat: init repo with current state
Signed-off-by: A. Ottr <alex@otter.foo>
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.gitignore
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.gitignore
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README.md
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README.md
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# compose-sync
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A tool to automatically sync and deploy Docker Compose stacks from a git repository, with multi-host support.
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## Overview
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compose-sync pulls changes from a git repository containing Docker Compose files and only deploys stacks that:
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1. Have changed since the last pull
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2. Are assigned to the current host
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## Repository Structure
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Your git repository should have the following structure:
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```
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stacks/
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traefik/compose.yml
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uptime-kuma/compose.yml
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home-assistant/compose.yml
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...
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inventory.yml
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```
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The `inventory.yml` file at the root contains all hosts and their assigned stacks. For example:
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```yaml
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hosts:
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vps-1:
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- traefik
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- uptime-kuma
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nas-1:
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- home-assistant
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- nextcloud
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```
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This format is compatible with Ansible inventory structures and provides a centralized view of all host assignments.
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## Installation
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```bash
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go install github.com/aottr/compose-sync@latest
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```
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#### Alternatively build from source
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1. Clone this repository
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2. Build the application:
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```bash
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go build -o compose-sync
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```
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## Configuration
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1. Copy `config.yml.example` to `config.yml`
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2. Edit `config.yml` and set `repo_path` to the local path of your git repository
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## Usage
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### Basic Usage
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```bash
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./compose-sync
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```
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This will:
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- Detect the current hostname
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- Pull the latest changes from git
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- Find changed stacks
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- Deploy only changed stacks assigned to this host
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### Dry Run
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To see what would be deployed without actually deploying:
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```bash
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./compose-sync -dry-run
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```
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### Custom Config Path
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```bash
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./compose-sync -config /path/to/config.yml
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```
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## How It Works
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1. **Host Detection**: The tool uses the system hostname to identify the current host
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2. **Stack Assignment**: Reads `inventory.yml` to determine which stacks should be deployed on this host
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3. **Change Detection**: Compares git commits before and after pulling to find changed stacks
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4. **Selective Deployment**: Only deploys stacks that both changed AND are assigned to this host
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## Requirements
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- Go 1.21 or later
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- Git
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- Docker and Docker Compose
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- A git repository with the structure described above
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## License
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MIT
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config.yml.example
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config.yml.example
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go.mod
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go.mod
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go.sum
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go.sum
···
···
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
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gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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main.go
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main.go
···
···
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package main
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import (
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"flag"
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"fmt"
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"log"
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"os"
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"path/filepath"
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"slices"
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)
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func main() {
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configPath := flag.String("config", "config.yml", "Path to configuration file")
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dryRun := flag.Bool("dry-run", false, "Show what would be deployed without actually deploying")
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flag.Parse()
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cfg, err := loadConfig(*configPath)
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if err != nil {
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log.Fatalf("Failed to load config: %v", err)
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}
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// Acquire file lock to prevent concurrent sync jobs
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lockPath := filepath.Join(cfg.RepoPath, ".compose-sync.lock")
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releaseLock, err := acquireLock(lockPath)
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if err != nil {
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log.Fatalf("Failed to acquire lock: %v", err)
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}
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defer func() {
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if err := releaseLock(); err != nil {
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log.Printf("Warning: failed to release lock: %v", err)
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}
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}()
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currentHost, err := detectHost()
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if err != nil {
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log.Fatalf("Failed to detect host: %v", err)
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}
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fmt.Printf("Detected host: %s\n", currentHost)
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assignedStacks, err := getAssignedStacks(cfg.RepoPath, currentHost)
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if err != nil {
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log.Fatalf("Failed to get assigned stacks: %v", err)
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}
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fmt.Printf("Stacks assigned to this host: %v\n", assignedStacks)
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fmt.Println("Pulling git repository...")
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changedStacks, err := pullAndDetectChanges(cfg.RepoPath)
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if err != nil {
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log.Fatalf("Failed to pull or detect changes: %v", err)
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}
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if len(changedStacks) == 0 {
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fmt.Println("No changes detected.")
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return
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}
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fmt.Printf("Changed stacks: %v\n", changedStacks)
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// Filter to only stacks assigned to this host
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stacksToDeploy := []string{}
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for _, stack := range changedStacks {
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if slices.Contains(assignedStacks, stack) {
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stacksToDeploy = append(stacksToDeploy, stack)
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}
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}
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if len(stacksToDeploy) == 0 {
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fmt.Println("No changed stacks are assigned to this host.")
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return
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}
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fmt.Printf("Stacks to deploy: %v\n", stacksToDeploy)
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if *dryRun {
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fmt.Println("DRY RUN: Would deploy the following stacks:")
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for _, stack := range stacksToDeploy {
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fmt.Printf(" - %s\n", stack)
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}
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return
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}
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// Deploy each stack
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for _, stack := range stacksToDeploy {
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composePath := filepath.Join(cfg.RepoPath, "stacks", stack, "compose.yml")
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if _, err := os.Stat(composePath); os.IsNotExist(err) {
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composePath = filepath.Join(cfg.RepoPath, "stacks", stack, "compose.yaml")
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}
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fmt.Printf("Deploying stack: %s\n", stack)
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if err := deployStack(composePath); err != nil {
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log.Printf("Failed to deploy stack %s: %v", stack, err)
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continue
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}
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fmt.Printf("Successfully deployed stack: %s\n", stack)
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}
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}
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sync.go
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sync.go
···
···
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package main
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import (
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"errors"
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"fmt"
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"os"
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"os/exec"
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"path/filepath"
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"strings"
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"syscall"
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"gopkg.in/yaml.v3"
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)
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type config struct {
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RepoURL string `yaml:"repo_url"`
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RepoPath string `yaml:"repo_path"`
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}
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func loadConfig(path string) (*config, error) {
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data, err := os.ReadFile(path)
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if err != nil {
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return nil, fmt.Errorf("failed to read config file: %w", err)
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}
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var cfg config
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if err := yaml.Unmarshal(data, &cfg); err != nil {
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return nil, fmt.Errorf("failed to parse config: %w", err)
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}
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if cfg.RepoPath == "" {
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return nil, fmt.Errorf("repo_path is required in config")
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}
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return &cfg, nil
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}
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func acquireLock(lockPath string) (func() error, error) {
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f, err := os.OpenFile(lockPath, os.O_CREATE|os.O_RDWR, 0644)
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if err != nil {
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return nil, err
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}
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if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
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_ = f.Close()
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return nil, errors.New("another compose-sync is already running")
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}
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return func() error {
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if err := syscall.Flock(int(f.Fd()), syscall.LOCK_UN); err != nil {
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f.Close()
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return err
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}
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if err := f.Close(); err != nil {
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return err
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}
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return os.Remove(lockPath)
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}, nil
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}
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func detectHost() (string, error) {
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hostname, err := os.Hostname()
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if err != nil {
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return "", fmt.Errorf("failed to get hostname: %w", err)
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}
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return hostname, nil
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}
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type inventory struct {
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Hosts map[string][]string `yaml:"hosts"`
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}
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func getAssignedStacks(repoPath, hostname string) ([]string, error) {
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inventoryFile := filepath.Join(repoPath, "inventory.yml")
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data, err := os.ReadFile(inventoryFile)
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if err != nil {
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return nil, fmt.Errorf("failed to read inventory file %s: %w", inventoryFile, err)
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}
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var inv inventory
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if err := yaml.Unmarshal(data, &inv); err != nil {
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return nil, fmt.Errorf("failed to parse inventory file %s: %w", inventoryFile, err)
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}
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stacks, exists := inv.Hosts[hostname]
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if !exists {
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return []string{}, nil // Host not in inventory, no stacks assigned
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}
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return stacks, nil
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}
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func pullAndDetectChanges(repoPath string) ([]string, error) {
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if _, err := os.Stat(repoPath); os.IsNotExist(err) {
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return nil, fmt.Errorf("repository path does not exist: %s", repoPath)
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}
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if _, err := os.Stat(fmt.Sprintf("%s/.git", repoPath)); os.IsNotExist(err) {
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return nil, fmt.Errorf("path is not a git repository: %s", repoPath)
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}
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prevHead, err := getGitHead(repoPath)
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if err != nil {
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return nil, fmt.Errorf("failed to get previous HEAD: %w", err)
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}
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if err := gitPull(repoPath); err != nil {
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return nil, fmt.Errorf("failed to pull: %w", err)
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}
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newHead, err := getGitHead(repoPath)
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if err != nil {
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return nil, fmt.Errorf("failed to get new HEAD: %w", err)
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}
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// If HEAD didnt change, no changes were pulled
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if prevHead == newHead {
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return []string{}, nil
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}
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changedStacks, err := findChangedStacks(repoPath, prevHead, newHead)
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if err != nil {
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return nil, fmt.Errorf("failed to find changed stacks: %w", err)
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}
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return changedStacks, nil
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}
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func gitPull(repoPath string) error {
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cmd := exec.Command("git", "pull")
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cmd.Dir = repoPath
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output, err := cmd.CombinedOutput()
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if err != nil {
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return fmt.Errorf("git pull failed: %s, %w", string(output), err)
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}
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return nil
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}
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func getGitHead(repoPath string) (string, error) {
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cmd := exec.Command("git", "rev-parse", "HEAD")
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cmd.Dir = repoPath
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output, err := cmd.Output()
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if err != nil {
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return "", fmt.Errorf("failed to get HEAD: %w", err)
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}
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return strings.TrimSpace(string(output)), nil
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}
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func findChangedStacks(repoPath, oldCommit, newCommit string) ([]string, error) {
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// Get list of changed files between the two commits
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cmd := exec.Command("git", "diff", "--name-only", oldCommit, newCommit)
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cmd.Dir = repoPath
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output, err := cmd.Output()
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if err != nil {
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return nil, fmt.Errorf("failed to get changed files: %w", err)
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}
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// Parse changed files and get stack names
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changedFiles := strings.Split(strings.TrimSpace(string(output)), "\n")
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stackSet := make(map[string]bool)
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for _, file := range changedFiles {
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if file == "" {
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continue
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}
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// Check if file is in the stacks directory
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// Format: stacks/<stack-name>/compose.yml
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if strings.HasPrefix(file, "stacks/") {
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parts := strings.Split(file, "/")
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if len(parts) >= 2 {
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stackName := parts[1]
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// filter out unknown files
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if len(parts) >= 3 && (parts[2] == "compose.yml" || parts[2] == "compose.yaml") {
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stackSet[stackName] = true
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}
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}
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}
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}
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stacks := make([]string, 0, len(stackSet))
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for stack := range stackSet {
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stacks = append(stacks, stack)
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}
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return stacks, nil
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}
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func deployStack(composePath string) error {
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if _, err := os.Stat(composePath); os.IsNotExist(err) {
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return fmt.Errorf("compose file does not exist: %s", composePath)
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}
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composeDir := filepath.Dir(composePath)
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cmd := exec.Command("docker", "compose", "-f", composePath, "up", "-d")
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cmd.Dir = composeDir
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output, err := cmd.CombinedOutput()
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if err != nil {
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return fmt.Errorf("docker compose up failed: %s, %w", string(output), err)
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}
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return nil
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}