SyncerD

SyncerD is a lightweight Go tool that copies Docker images from Docker Hub into your private registries — AWS ECR, Azure ACR, Google GCR, and GitHub Container Registry — automatically and without manual intervention.

Repository: clouddrove/SyncerD

Why it exists: Docker Hub's rate limits (100–200 pulls per 6 hours for free accounts) can break CI pipelines and Kubernetes node pulls. SyncerD mirrors the images you care about into registries you control, so your infrastructure never hits Docker Hub directly.

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Features

• Multi-registry support — sync to ECR, ACR, GCR, and GHCR simultaneously from one config file
• Automatic tag detection — monitors source tags and syncs only new images
• Three deployment modes — CLI, GitHub Action, or Kubernetes CronJob
• Stateless by default — no database required; optionally tracks state to a file
• Slack notifications — alerts for sync completions and failures
• Secure auth — Docker Hub via env vars; destinations use the standard Docker credential chain

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Installation

Method	Command
Go install	go install github.com/clouddrove/syncerd@latest
Build from source	git clone https://github.com/clouddrove/SyncerD.git && cd SyncerD && go build -o syncerd ./main.go
Docker	docker run ghcr.io/clouddrove/syncerd:latest syncerd sync --once
GitHub Releases	Download from the releases page

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Quick start

1. Write a config file

# syncerd.yaml
source:
  type: dockerhub
  registry: docker.io

destinations:
  - name: my-ecr
    type: ecr
    registry: 123456789012.dkr.ecr.us-east-1.amazonaws.com
    region: us-east-1

images:
  - name: library/nginx
    watch_tags: true
  - name: library/redis
    watch_tags: true

2. Set credentials

export SYNCERD_SOURCE_USERNAME=your-dockerhub-username
export SYNCERD_SOURCE_PASSWORD=your-dockerhub-token

For destinations, authenticate with the standard Docker CLI:

# ECR
aws ecr get-login-password --region us-east-1 | \
  docker login --username AWS --password-stdin 123456789012.dkr.ecr.us-east-1.amazonaws.com

# GHCR
echo $GITHUB_TOKEN | docker login ghcr.io --username $GITHUB_USER --password-stdin

3. Run

# One-time sync
./syncerd sync --once

# Continuous mode (uses `schedule` from config)
./syncerd sync

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Deployment modes

GitHub Actions

- uses: clouddrove/SyncerD@v1
  with:
    config: syncerd.yaml
    once: "true"
  env:
    SYNCERD_SOURCE_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
    SYNCERD_SOURCE_PASSWORD: ${{ secrets.DOCKERHUB_TOKEN }}

Kubernetes CronJob (Helm)

helm install syncerd ./_helm/syncerd \
  --namespace syncerd \
  --create-namespace

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Configuration reference

Top-level fields

Field	Description
source	Docker Hub connection (type, registry)
destinations	List of target registries
images	Images to sync with optional tag filters
schedule	Cron expression for continuous mode (e.g., 0 */6 * * *)
state_path	File path to track already-synced tags
slack.webhook_url	Slack webhook for notifications
fail_fast	Stop on first error (true) or continue (false)

Environment variable overrides

All config values can be overridden with the SYNCERD_ prefix:

Variable	Description
SYNCERD_SOURCE_USERNAME	Docker Hub username
SYNCERD_SOURCE_PASSWORD	Docker Hub password or PAT
SYNCERD_SOURCE_TOKEN	Docker Hub personal access token
SYNCERD_STATE_PATH	Path to state file
SYNCERD_SLACK_WEBHOOK_URL	Slack webhook URL
SYNCERD_SLACK_CHANNEL	Slack channel
SYNCERD_FAIL_FAST	true or false

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Multi-destination example

Sync the same image to ECR, ACR, and GHCR simultaneously:

source:
  type: dockerhub
  registry: docker.io

destinations:
  - name: aws-ecr
    type: ecr
    registry: 123456789012.dkr.ecr.us-east-1.amazonaws.com
    region: us-east-1

  - name: azure-acr
    type: acr
    registry: mycompany.azurecr.io

  - name: github-ghcr
    type: ghcr
    registry: ghcr.io/myorg

images:
  - name: library/nginx
    watch_tags: true
  - name: library/postgres
    tags: ["15", "15-alpine"]

schedule: "0 */6 * * *"

slack:
  webhook_url: https://hooks.slack.com/services/xxx/yyy/zzz

fail_fast: false