Docker Build Failed in CI

# Docker Build Failed in CI

Common Error Patterns

Docker build failures in CI typically show:

ERROR: failed to solve: failed to compute cache key

Cannot connect to the Docker daemon at unix:///var/run/docker.sock

denied: requested access to the resource is denied

failed to register layer: Error processing tar file

COPY failed: file not found in build context

Root Causes and Solutions

1. Docker Daemon Not Available

CI runner cannot connect to Docker daemon.

Solution:

For GitHub Actions, use Docker executor:

jobs:
  build:
    runs-on: ubuntu-latest
    container:
      image: docker:24
      options: --privileged
      volumes:
        - /var/run/docker.sock:/var/run/docker.sock
    steps:
      - name: Build image
        run: docker build -t myapp .

Or use Docker action:

```yaml - name: Set up Docker Buildx uses: docker/setup-buildx-action@v3

• name: Build and push
• uses: docker/build-push-action@v5
• with:
• context: .
• push: true
• tags: myapp:latest
• `

For Jenkins with Docker agent:

pipeline {
  agent {
    docker {
      image 'docker:24'
      args '-v /var/run/docker.sock:/var/run/docker.sock --privileged'
    }
  }
  stages {
    stage('Build') {
      steps {
        sh 'docker build -t myapp .'
      }
    }
  }
}

2. Dockerfile Build Context Issues

Files not in build context or wrong path.

Solution:

Verify build context:

# GitHub Actions
- name: Build
  uses: docker/build-push-action@v5
  with:
    context: .  # Current directory
    file: ./Dockerfile  # Dockerfile path

Common Dockerfile errors:

```dockerfile # WRONG - File outside build context COPY ../src /app

# CORRECT - File in build context COPY src /app

# WRONG - Path doesn't exist COPY package.json /app/

# CORRECT - Verify path exists COPY ./package.json ./package-lock.json /app/ ```

Test Dockerfile locally:

```bash # Build with verbose output docker build --progress=plain -t myapp .

# Check build context ls -la .dockerignore cat .dockerignore ```

3. Registry Authentication Failure

Cannot push to container registry.

Solution:

For Docker Hub:

```yaml # GitHub Actions - name: Login to Docker Hub uses: docker/login-action@v3 with: username: ${{ secrets.DOCKERHUB_USERNAME }} password: ${{ secrets.DOCKERHUB_TOKEN }}

• name: Build and push
• uses: docker/build-push-action@v5
• with:
• push: true
• tags: username/myapp:latest
• `

For AWS ECR:

```yaml - name: Configure AWS credentials uses: aws-actions/configure-aws-credentials@v4 with: role-to-assume: arn:aws:iam::123456789012:role/my-role aws-region: us-east-1

• name: Login to Amazon ECR
• id: login-ecr
• uses: aws-actions/amazon-ecr-login@v2

• name: Build, tag, and push image
• env:
• ECR_REGISTRY: ${{ steps.login-ecr.outputs.registry }}
• ECR_REPOSITORY: myapp
• IMAGE_TAG: ${{ github.sha }}
• run: |
• docker build -t $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG .
• docker push $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG
• `

For GCR:

```yaml - name: Authenticate to Google Cloud uses: google-github-actions/auth@v2 with: credentials_json: ${{ secrets.GCP_CREDENTIALS }}

• name: Configure Docker
• run: gcloud auth configure-docker gcr.io

• name: Build and push
• run: |
• docker build -t gcr.io/my-project/myapp:${{ github.sha }} .
• docker push gcr.io/my-project/myapp:${{ github.sha }}
• `

4. Layer Caching Not Working

Build cache not utilized, slow builds.

Solution:

Enable BuildKit caching:

```yaml # GitHub Actions with Docker Buildx - name: Set up Docker Buildx uses: docker/setup-buildx-action@v3

• name: Cache Docker layers
• uses: actions/cache@v4
• with:
• path: /tmp/.buildx-cache
• key: ${{ runner.os }}-buildx-${{ github.sha }}
• restore-keys: |
• ${{ runner.os }}-buildx-

• name: Build with cache
• uses: docker/build-push-action@v5
• with:
• context: .
• cache-from: type=local,src=/tmp/.buildx-cache
• cache-to: type=local,dest=/tmp/.buildx-cache-new,mode=max
• `

Optimize Dockerfile for caching:

```dockerfile # BAD - Changes often, breaks cache COPY . /app RUN npm install

# GOOD - Layers that change less frequently first COPY package*.json /app/ RUN npm install COPY . /app/ RUN npm run build ```

5. Out of Disk Space

CI runner disk full during build.

Solution:

Clean up before build:

```yaml steps: - name: Free disk space run: | sudo rm -rf /usr/share/dotnet sudo rm -rf /opt/ghc sudo rm -rf /usr/local/lib/android docker system prune -af --volumes

• name: Build image
• run: docker build -t myapp .
• `

Use multi-stage builds to reduce image size:

```dockerfile # Build stage FROM node:18 AS builder WORKDIR /app COPY package*.json ./ RUN npm install COPY . . RUN npm run build

# Production stage (smaller) FROM node:18-alpine WORKDIR /app COPY --from=builder /app/dist ./dist COPY --from=builder /app/node_modules ./node_modules CMD ["node", "dist/index.js"] ```

6. Network Issues During Build

Cannot download packages during build.

Solution:

Use proxy or mirror:

```dockerfile # Use npm mirror RUN npm config set registry https://registry.npmmirror.com && \ npm install

# Use apt mirror RUN sed -i 's/archive.ubuntu.com/mirrors.aliyun.com/g' /etc/apt/sources.list && \ apt-get update && apt-get install -y package ```

Or pre-download dependencies:

```yaml steps: - name: Download dependencies run: | npm install # Copy node_modules into build context

• name: Build image
• run: docker build --build-arg NODE_MODULES=$(pwd)/node_modules -t myapp .
• `

7. Permission Denied in Build

Container user lacks permissions.

Solution:

Handle permissions in Dockerfile:

# Create user and set permissions
FROM node:18
WORKDIR /app
RUN chown -R node:node /app
USER node
COPY --chown=node:node . .
RUN npm install

For rootless Docker:

# GitHub Actions
- name: Build with rootless Docker
  run: |
    docker build --build-arg USER_ID=$(id -u) -t myapp .

8. Base Image Not Found

Cannot pull base image.

Solution:

Check image exists:

docker pull node:18
docker pull node:18-alpine

Use specific version:

```dockerfile # BAD - Latest may break or not exist FROM my-org/base:latest

# GOOD - Pin specific version FROM my-org/base:v1.2.3

# GOOD - Use digest for exact match FROM my-org/base@sha256:abc123... ```

Dockerfile Best Practices

Layer Order for Caching

```dockerfile # 1. Base image (changes least) FROM node:18-alpine

# 2. System packages RUN apk add --no-cache git curl

# 3. Dependencies WORKDIR /app COPY package*.json ./ RUN npm ci --only=production

# 4. Application code (changes most) COPY . . RUN npm run build

# 5. Runtime configuration ENV NODE_ENV=production EXPOSE 3000 CMD ["node", "dist/index.js"] ```

Minimize Layers

```dockerfile # BAD - Multiple layers RUN apt-get update RUN apt-get install -y git RUN apt-get install -y curl RUN apt-get clean

# GOOD - Single layer RUN apt-get update && \ apt-get install -y git curl && \ apt-get clean && \ rm -rf /var/lib/apt/lists/* ```

Use .dockerignore

# .dockerignore
node_modules
npm-debug.log
.git
.gitignore
.env
.env.*
*.md
test/
tests/
*.test.js
Dockerfile*
.dockerignore

Debugging Commands

```bash # Build with verbose output docker build --progress=plain --no-cache -t myapp .

# Debug specific stage docker build --target builder -t myapp-builder .

# Inspect image docker inspect myapp:latest

# Check image size docker images myapp:latest

# Run container interactively docker run -it --rm myapp:latest sh

# Check container logs docker logs container-id ```

Quick Reference

Prevention Tips

1. 1.Use multi-stage builds for smaller images
2. 2.Order Dockerfile layers for optimal caching
3. 3.Pin base image versions, not latest
4. 4.Use .dockerignore to reduce build context
5. 5.Enable BuildKit for better caching
6. 6.Test Dockerfile locally before pushing

Related Articles

• [Jenkins Build Failed](#)
• [GitHub Actions Workflow Failed](#)
• [Kubernetes Deployment Failed in CI](#)