While Docker manager simplifies container deployment, you might occasionally encounter issues. This guide covers the most common problems and their solutions, helping you quickly resolve deployment or runtime issues.<\/p>
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Before troubleshooting, it’s essential to know how to access detailed deployment logs:<\/p>
Click the Browser terminal<\/b> button in the top right corner<\/p>\n<\/li>\n Navigate to your project’s build log:<\/p>\n Replace Review the output for error messages or warnings<\/p>\n<\/li>\n<\/ol> These logs contain valuable information about image pulling, container creation, and startup processes.<\/p> \n<\/p> Symptoms<\/b>: Deployment fails with a message about port conflicts<\/p> Solutions<\/b>:<\/p> Check which ports are in use: <\/p>\n Either:<\/p>\n Choose a different port in your configuration<\/p>\n<\/li>\n Stop the conflicting service<\/p>\n<\/li>\n Modify your port mapping (e.g., change Symptoms<\/b>: Docker cannot pull the specified image<\/p> Solutions<\/b>:<\/p> Verify the image name and tag:<\/p>\n Correct format: Check for typos<\/p>\n<\/li>\n<\/ul>\n<\/li>\n Ensure the image exists on Docker Hub or the specified registry<\/p>\n<\/li>\n For private images, ensure authentication is configured<\/p>\n<\/li>\n<\/ol> Symptoms<\/b>: Container shows as “Exited” or keeps restarting<\/p> Solutions<\/b>:<\/p> Check container logs via browser terminal: <\/p>\n Common causes:<\/p>\n Missing environment variables<\/p>\n<\/li>\n Incorrect startup command<\/p>\n<\/li>\n Application crashes on startup<\/p>\n<\/li>\n<\/ul>\n<\/li>\n Verify all required environment variables are set<\/p>\n<\/li>\n Check if the application needs specific file permissions<\/p>\n<\/li>\n<\/ol> Symptoms<\/b>: Application seems to be running, but the web browser shows a connection error<\/p> Solutions<\/b>:<\/p> Verify the correct port mapping:<\/p>\n Check if you’re using the VPS port, not the container port<\/p>\n<\/li>\n URL format: Check firewall rules: <\/p>\n Ensure the application is listening on the correct interface (0.0.0.0, not localhost)<\/p>\n<\/li>\n<\/ol> Symptoms<\/b>: Container crashes with “OOMKilled” status or the application becomes unresponsive<\/p> Solutions<\/b>:<\/p> Check container resource usage:<\/p>\n Monitor VPS resources via the control panel<\/p>\n<\/li>\n Consider:<\/p>\n Upgrading your VPS plan<\/p>\n<\/li>\n Optimizing your application<\/p>\n<\/li>\n Setting memory limits in your compose file<\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ol> Symptoms<\/b>: Database or uploaded files disappear after container updates<\/p> Solutions<\/b>:<\/p> Ensure you’ve configured volumes correctly:<\/p>\n Format: Use absolute paths on the host<\/p>\n<\/li>\n<\/ul>\n<\/li>\n Check volume permissions: <\/p>\n Verify volumes are properly mounted: <\/p>\n Symptoms<\/b>: Deployment fails with parsing errors<\/p> Solutions<\/b>:<\/p> Use the YAML preview pane to spot issues<\/p>\n<\/li>\n Common YAML mistakes:<\/p>\n Incorrect indentation (use spaces, not tabs)<\/p>\n<\/li>\n Missing colons after keys<\/p>\n<\/li>\n Improper quotes around values<\/p>\n<\/li>\n<\/ul>\n<\/li>\n Validate your YAML using online tools before deployment<\/p>\n<\/li>\n<\/ol> Symptoms<\/b>: Application can’t find configuration values<\/p> Solutions<\/b>:<\/p> Check environment variable format:<\/p>\n Correct: No spaces around the equals sign<\/p>\n<\/li>\n<\/ul>\n<\/li>\n For multi-line values, use proper YAML syntax: <\/p>\n Verify inside container: <\/p>\n Symptoms<\/b>: Multi-container applications fail to connect to each other<\/p> Solutions<\/b>:<\/p> Ensure containers are in the same compose project<\/p>\n<\/li>\n Use service names for internal communication:<\/p>\n Not: Correct: Check if containers are on the same network: <\/p>\n Symptoms<\/b>: Container can’t resolve external domains<\/p> Solutions<\/b>:<\/p> Check DNS configuration: <\/p>\n Test DNS resolution: <\/p>\n Configure custom DNS servers if needed in your compose file<\/p>\n<\/li>\n<\/ol> Symptoms<\/b>: Containers take unusually long to start<\/p> Solutions<\/b>:<\/p> Check if images are cached locally: bash<\/p>\n Monitor download speed during image pull<\/p>\n<\/li>\n Consider using smaller base images (e.g., Ensure your VPS has sufficient resources<\/p>\n<\/li>\n<\/ol> Symptoms<\/b>: Application responds but performance is poor<\/p> Solutions<\/b>:<\/p> Monitor resource usage: bash<\/p>\n Check for:<\/p>\n CPU throttling<\/p>\n<\/li>\n Memory swapping<\/p>\n<\/li>\n Disk I\/O bottlenecks<\/p>\n<\/li>\n<\/ul>\n<\/li>\n Optimize your application or upgrade VPS resources<\/p>\n<\/li>\n<\/ol> Access these commands via the browser terminal:<\/p> Test locally first<\/b>: Deploy on your local machine before VPS<\/p>\n<\/li>\n Start simple<\/b>: Begin with single containers before multi-container setups<\/p>\n<\/li>\n Use version tags<\/b>: Specify exact versions instead of Monitor resources<\/b>: Keep an eye on VPS resource usage<\/p>\n<\/li>\n Regular backups<\/b>: Backup your volumes and configurations<\/p>\n<\/li>\n Document changes<\/b>: Keep track of what works for your setup<\/p>\n<\/li>\n<\/ol> Remember, most Docker manager issues have straightforward solutions. Start with the deployment logs and work through the relevant troubleshooting steps.<\/p>\n","protected":false},"excerpt":{"rendered":" Troubleshooting your Docker containers on Hostinger Docker manager<\/p>\n","protected":false},"author":581,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"include_on_kodee":true,"footnotes":""},"categories":[297],"tags":[],"class_list":["post-263","post","type-post","status-publish","format-standard","hentry","category-docker-manager"],"hreflangs":[{"locale":"en-US","link":"https:\/\/www.hostinger.com\/support\/12040867-troubleshooting-common-docker-manager-issues\/","default":1}],"include_on_kodee":true,"_links":{"self":[{"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/posts\/263","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/users\/581"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/comments?post=263"}],"version-history":[{"count":0,"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/posts\/263\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/media?parent=263"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/categories?post=263"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hostinger.com\/support\/wp-json\/wp\/v2\/tags?post=263"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}cat \/docker\/[project-name]\/.build.log<\/code><\/pre>\n[project-name]<\/code> with your actual project name<\/p>\n<\/li>\nCommon deployment issues<\/h2>
Issue 1: “Port already in use” error<\/h3>
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sudo netstat -tlnp<\/code><\/pre>\n<\/li>\n\n
80:80<\/code> to 8080:80<\/code>)<\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ol>Issue 2: “Image not found” error<\/h3>
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image:tag<\/code> (e.g., nginx:latest<\/code>)<\/p>\n<\/li>\nIssue 3: Container starts but immediately stops<\/h3>
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docker logs [container-name]<\/code><\/pre>\n<\/li>\n\n
Common runtime issues<\/h2>
Issue 4: Cannot access the application via browser<\/h3>
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http:\/\/your-vps-ip:vps-port<\/code><\/p>\n<\/li>\n<\/ul>\n<\/li>\nsudo ufw status<\/code><\/pre>\n<\/li>\nIssue 5: Container running out of memory<\/h3>
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docker stats [container-name]<\/code><\/pre>\n<\/li>\n\n
Issue 6: Persistent data lost after container restart<\/h3>
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\/host\/path:\/container\/path<\/code><\/p>\n<\/li>\nls -la \/path\/to\/volume<\/code><\/pre>\n<\/li>\ndocker inspect [container-name] | grep -A 10 Mounts<\/code><\/pre>\n<\/li>\n<\/ol>Configuration issues<\/h2>
Issue 7: Invalid YAML syntax<\/h3>
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Issue 8: Environment variables not working<\/h3>
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KEY=value<\/code><\/p>\n<\/li>\nenvironment:
- KEY=value
- MULTILINE_KEY=|
line1
line2<\/code><\/pre>\n<\/li>\ndocker exec [container-name] env<\/code><\/pre>\n<\/li>\n<\/ol>Networking issues<\/h2>
Issue 9: Containers can’t communicate<\/h3>
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localhost:3306<\/code><\/p>\n<\/li>\nmysql:3306<\/code> (where mysql<\/code> is the service name)<\/p>\n<\/li>\n<\/ul>\n<\/li>\ndocker network ls docker inspect [network-name]<\/code><\/pre>\n<\/li>\n<\/ol>Issue 10: DNS resolution problems<\/h3>
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docker exec [container-name] cat \/etc\/resolv.conf<\/code><\/pre>\n<\/li>\ndocker exec [container-name] nslookup google.com<\/code><\/pre>\n<\/li>\nPerformance issues<\/h2>
Issue 11: Slow container startup<\/h3>
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docker images<\/code><\/pre>\n<\/li>\nalpine<\/code> variants)<\/p>\n<\/li>\nIssue 12: Application running slowly<\/h3>
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docker stats htop<\/code><\/pre>\n<\/li>\n\n
Debugging commands cheat sheet<\/h2>
# View all containers
docker ps -a
# Check container logs
docker logs [container-name] --tail 50 -f
# Access container shell
docker exec -it [container-name] \/bin\/sh
# View deployment logs
cat \/docker\/[project-name]\/.build.log
# Check system resources
free -h
df -h
top
# Inspect container configuration
docker inspect [container-name]
# View Docker daemon logs
journalctl -u docker -n 100<\/code><\/pre>Best practices to avoid issues<\/h2>
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latest<\/code><\/p>\n<\/li>\n