Docker构建应用失败求助：DigitalOcean部署环境无进展

Hey there, let's figure out why your Docker Compose build is hanging on the app service—here are practical, step-by-step fixes to diagnose and resolve the issue:

• Get detailed build logs immediately
  The default build output hides most granular details, so run this command to see exactly what's happening during the app build:

  docker-compose build --no-cache --progress=plain app
  

  This will print every command being executed in your Dockerfile line by line, so you'll spot if it's stuck on dependency installation, a compile step, or waiting for user input that never comes.

• Check for network-related bottlenecks
  DigitalOcean droplets sometimes hit temporary network blips, or your app's package sources (like npm, pip, or apt) might be slow to respond. Try these quick checks:

  • Verify your droplet has outbound internet access (run curl google.com from the droplet terminal)
  • Temporarily switch to faster mirrors in your Dockerfile (e.g., use a regional apt mirror or a closer npm registry mirror)
  • Add timeout flags to package installation commands if supported (e.g., npm install --timeout=60000)

• Clear stale Docker cache
  Old cached layers can cause unexpected hangs or silent failures. Clean up unused Docker resources with:

  docker system prune -a
  

  This removes unused images, containers, volumes, and build cache—then try rebuilding your app service again from scratch.

• Fix interactive commands in your Dockerfile
  If your Dockerfile includes commands that require user input (like apt-get install without -y, or gem install prompts), the build will hang indefinitely waiting for a response. Make sure all commands are non-interactive:

  • Add -y to apt commands: RUN apt-get update && apt-get install -y your-package
  • Set the DEBIAN_FRONTEND=noninteractive environment variable for Debian/Ubuntu-based images to skip prompts:

    ENV DEBIAN_FRONTEND=noninteractive
    RUN apt-get update && apt-get install -y your-package
    

• Check droplet resource limits
  If your DigitalOcean droplet has limited CPU or memory, the build process might freeze under heavy load. Use these commands to monitor resource usage:

  • top to check overall CPU/memory usage on the droplet
  • docker stats to see resource usage specifically from Docker processes
    If resources are maxed out, consider upgrading your droplet's plan temporarily to complete the build.

• Isolate the app service build
  Since your other services (db, elasticsearch, redis) are using pre-built images and skipping, focus solely on the app service first. Run:

  docker-compose build app
  

  This eliminates any cross-service interference and lets you debug the app build in isolation.

Try these steps in order—the detailed plain-text logs from the first step will almost certainly point you to the exact cause of the hang.

内容的提问来源于stack exchange，提问作者Rails Developer