Docker Debugger

Docker调试器

Instructions

使用说明

When debugging Docker issues:

Identify the problem type: Build, runtime, networking, or performance
Gather information using diagnostic commands
Analyze logs and errors
Apply fixes

调试Docker问题时，请遵循以下步骤：

确定问题类型：构建问题、运行时问题、网络问题或性能问题
使用诊断命令收集相关信息
分析日志与错误信息
应用对应修复方案

Diagnostic Commands

诊断命令

bash

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bash

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Check running containers

docker ps -a

View container logs

docker logs <container_id> --tail 100 -f

Inspect container

docker inspect <container_id>

Check resource usage

docker stats

View container processes

docker top <container_id>

Execute shell in running container

docker exec -it <container_id> /bin/sh

Check Docker disk usage

docker system df

View build history

docker history <image_name>

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docker history <image_name>

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Common Issues & Solutions

常见问题与解决方案

1. Container exits immediately

1. 容器启动后立即退出

bash

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bash

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Check exit code

docker inspect <container_id> --format='{{.State.ExitCode}}'

View last logs

docker logs <container_id>


**Fixes**:
- Ensure CMD/ENTRYPOINT runs a foreground process
- Check for missing dependencies
- Verify environment variables

docker logs <container_id>


**解决方案**:
- 确保CMD/ENTRYPOINT运行的是前台进程
- 检查是否缺少依赖
- 验证环境变量配置正确

2. Build fails

2. 构建失败

dockerfile

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dockerfile

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Use multi-stage builds for smaller images

FROM node:20-alpine AS builder WORKDIR /app COPY package*.json ./ RUN npm ci COPY . . RUN npm run build

FROM node:20-alpine AS runner WORKDIR /app COPY --from=builder /app/dist ./dist COPY --from=builder /app/node_modules ./node_modules CMD ["node", "dist/index.js"]

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FROM node:20-alpine AS builder WORKDIR /app COPY package*.json ./ RUN npm ci COPY . . RUN npm run build

FROM node:20-alpine AS runner WORKDIR /app COPY --from=builder /app/dist ./dist COPY --from=builder /app/node_modules ./node_modules CMD ["node", "dist/index.js"]

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3. Networking issues

3. 网络问题

bash

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bash

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List networks

docker network ls

Inspect network

docker network inspect <network_name>

Check container IP

docker inspect -f '{{range.NetworkSettings.Networks}}{{.IPAddress}}{{end}}' <container>

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docker inspect -f '{{range.NetworkSettings.Networks}}{{.IPAddress}}{{end}}' <container>

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4. Volume permission issues

4. 卷权限问题

dockerfile

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dockerfile

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Create non-root user

RUN addgroup -g 1001 -S appgroup &&
adduser -u 1001 -S appuser -G appgroup

Set ownership

COPY --chown=appuser:appgroup . .

USER appuser

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COPY --chown=appuser:appgroup . .

USER appuser

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Dockerfile Best Practices

Dockerfile最佳实践

dockerfile

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dockerfile

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1. Use specific tags, not :latest

FROM node:20.10-alpine

2. Set working directory

WORKDIR /app

3. Copy dependency files first (better caching)

COPY package*.json ./ RUN npm ci --only=production

4. Copy source after dependencies

COPY . .

5. Use non-root user

USER node

6. Set proper labels

LABEL maintainer="you@example.com" LABEL version="1.0"

7. Use HEALTHCHECK

HEALTHCHECK --interval=30s --timeout=3s
CMD wget -q --spider http://localhost:3000/health || exit 1

8. Expose ports

EXPOSE 3000

9. Use exec form for CMD

CMD ["node", "server.js"]

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CMD ["node", "server.js"]

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docker-compose Debugging

docker-compose调试

yaml

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yaml

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docker-compose.yml

services: app: build: context: . dockerfile: Dockerfile # Add for debugging stdin_open: true tty: true # Override command for debugging command: /bin/sh volumes: - .:/app environment: - DEBUG=true


```bash

services: app: build: context: . dockerfile: Dockerfile # Add for debugging stdin_open: true tty: true # Override command for debugging command: /bin/sh volumes: - .:/app environment: - DEBUG=true


```bash

Rebuild without cache

docker-compose build --no-cache

View logs

docker-compose logs -f app

Restart single service

docker-compose restart app

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docker-compose restart app

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docker-debugger

Original

Translation

Docker Debugger

Docker调试器

Instructions

使用说明

Diagnostic Commands

诊断命令

Check running containers

Check running containers

View container logs

View container logs

Inspect container

Inspect container

Check resource usage

Check resource usage

View container processes

View container processes

Execute shell in running container

Execute shell in running container

Check Docker disk usage

Check Docker disk usage

View build history

View build history

Common Issues & Solutions

常见问题与解决方案

1. Container exits immediately

1. 容器启动后立即退出

Check exit code

Check exit code

View last logs

View last logs

2. Build fails

2. 构建失败

Use multi-stage builds for smaller images

Use multi-stage builds for smaller images

3. Networking issues

3. 网络问题

List networks

List networks

Inspect network

Inspect network

Check container IP

Check container IP

4. Volume permission issues

4. 卷权限问题

Create non-root user

Create non-root user

Set ownership

Set ownership

Dockerfile Best Practices

Dockerfile最佳实践

1. Use specific tags, not :latest

1. Use specific tags, not :latest

2. Set working directory

2. Set working directory

3. Copy dependency files first (better caching)

3. Copy dependency files first (better caching)

4. Copy source after dependencies

4. Copy source after dependencies

5. Use non-root user

5. Use non-root user

6. Set proper labels

6. Set proper labels

7. Use HEALTHCHECK

7. Use HEALTHCHECK

8. Expose ports

8. Expose ports

9. Use exec form for CMD

9. Use exec form for CMD

docker-compose Debugging

docker-compose调试

docker-compose.yml

docker-compose.yml

Rebuild without cache

Rebuild without cache

View logs

View logs

Restart single service