🐳 How to Push Docker Image to Docker Registries – Complete Guide with FAQs

Pushing Docker images to registries is a crucial step in sharing, deploying, or backing up your containers. Whether you’re using Docker Hub, a private registry, or a cloud service like AWS ECR, this guide will walk you through the process.

By the end of this article, you’ll know exactly how to tag, authenticate, and push Docker images to any registry with ease.

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🔹 What is Pushing in Docker?

Pushing a Docker image means uploading it from your local system to a Docker registry so it can be shared, stored, or deployed on other systems.

Registries can be:

• ✅ Public (e.g., Docker Hub)
• 🔐 Private (e.g., self-hosted, AWS ECR, GCR)

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🚀 How to Push Docker Image – Step-by-Step

✅ 1. Build Your Docker Image (If Not Already Built)

Before pushing, you must have a built image.

docker build -t myimage:latest .

📝 Note: Replace myimage:latest with your preferred name and tag.

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✅ 2. Tag the Image for the Registry

You must tag your image with the full registry path.

docker tag <local-image> <registry-url>/<username>/<image-name>:<tag>

Example for Docker Hub:

docker tag myimage:latest docker.io/myusername/myimage:latest

Example for Private Registry:

docker tag myimage:latest myregistrydomain.com/myimage:latest

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✅ 3. Log in to the Registry

You must be authenticated before pushing.

docker login <registry-url>

Examples:

Docker Hub:

docker login

Private Registry:

docker login myregistrydomain.com

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✅ 4. Push the Image

Once authenticated and tagged, push the image:

docker push <registry-url>/<username>/<image-name>:<tag>

Example for Docker Hub:

docker push docker.io/myusername/myimage:latest

Example for Private Registry:

docker push myregistrydomain.com/myimage:latest

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☁️ Pushing to Cloud Registries

🔸 AWS ECR (Elastic Container Registry)

Step 1: Authenticate via AWS CLI

aws ecr get-login-password --region <region> | docker login --username AWS --password-stdin <aws_account_id>.dkr.ecr.<region>.amazonaws.com

Step 2: Tag the image

docker tag myimage:latest <aws_account_id>.dkr.ecr.<region>.amazonaws.com/myimage:latest

Step 3: Push the image

docker push <aws_account_id>.dkr.ecr.<region>.amazonaws.com/myimage:latest

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🔸 Google Container Registry (GCR)

Step 1: Authenticate

gcloud auth configure-docker

Step 2: Tag the image

docker tag myimage gcr.io/<project-id>/myimage:latest

Step 3: Push the image

docker push gcr.io/<project-id>/myimage:latest

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🔸 GitHub Container Registry (GHCR)

Step 1: Authenticate

echo <your-token> | docker login ghcr.io -u <your-username> --password-stdin

Step 2: Tag the image

docker tag myimage ghcr.io/<your-username>/myimage:latest

Step 3: Push the image

docker push ghcr.io/<your-username>/myimage:latest

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🔍 Verifying the Image

After pushing, you can:

• 🔄 Pull the image on another system
• 📦 View it in your registry’s web UI (Docker Hub, ECR Console, etc.)
• 🔐 Set permissions if needed (for private/public access)

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Final Thought

Now you know how to push Docker images to any registry — whether public, private, or cloud-hosted. This workflow is essential for modern DevOps, CI/CD pipelines, and cloud-native development.

By mastering tagging, authentication, and registry-specific steps, you ensure your images are easily shareable and deployable across environments. 🔧✨

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❓ Frequently Asked Questions (FAQs)

🔸 Q1: What happens if I push an image with the same tag?

Docker will overwrite the existing image tag in the registry with your newly pushed image.

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🔸 Q2: Can I push images to multiple registries?

Yes! Simply tag the image for each registry and push accordingly:

docker tag myimage ghcr.io/user/myimage:latest
docker push ghcr.io/user/myimage:latest

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🔸 Q3: Why do I get “denied: requested access to the resource is denied”?

This usually means:

• You’re not logged in
• You don’t have permission to push to the repository
• The image name or tag is incorrect

Make sure you:

• Log in to the correct registry
• Use the correct tag format
• Have permission (especially for org-owned repos)

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🔸 Q4: How do I make my image public?

• For Docker Hub, go to the image’s settings and set its visibility to Public
• For GitHub, go to the package settings and change the visibility

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🔸 Q5: Do I need to re-tag an image for every push?

Yes. Each registry requires the image to be tagged with its own domain format. Use:

docker tag <image> <registry-url>/<image-name>:<tag>

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🔸 Q6: How can I automate image builds and pushes?

Use tools like:

• ✅ Dockerfiles + shell scripts
• ⚙️ GitHub Actions
• 🚀 CI/CD pipelines in Jenkins, GitLab, etc.

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