{"id":48372,"date":"2025-02-08T08:15:57","date_gmt":"2025-02-08T08:15:57","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=48372"},"modified":"2025-07-12T05:38:45","modified_gmt":"2025-07-12T05:38:45","slug":"docker-port","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/docker-port\/","title":{"rendered":"Docker commands Guide – docker port with examples"},"content":{"rendered":"\n

Here\u2019s a complete tutorial<\/strong> on the docker port<\/code> command, including how it works<\/strong>, use cases<\/strong>, and a comprehensive list of examples<\/strong>.<\/p>\n\n\n\n

\n\n\n\n

What is docker port<\/code>?<\/strong><\/h2>\n\n\n\n

docker port<\/code> is a Docker command used to list the port mappings<\/strong> for a container. It shows how the container\u2019s internal ports<\/strong> (e.g., port 80<\/code>) are mapped to the host machine\u2019s ports<\/strong> (e.g., port 8080<\/code>). This is particularly useful for understanding and debugging networking configurations.<\/p>\n\n\n\n

Key Features:<\/strong><\/h3>\n\n\n\n
    \n
  • Displays port mappings<\/strong> for a container.<\/li>\n\n\n\n
  • Useful for verifying published ports<\/strong>.<\/li>\n\n\n\n
  • Helps in debugging connectivity<\/strong> issues.<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    Basic Syntax<\/strong><\/h2>\n\n\n
    docker<\/span> port<\/span> CONTAINER<\/span> [PRIVATE_PORT]<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
    Arguments:<\/strong><\/h3>\n\n\n\n
      \n
    • CONTAINER<\/code>: The container\u2019s name or ID.<\/li>\n\n\n\n
    • PRIVATE_PORT<\/code>: The internal port inside the container (optional). If specified, it only shows the mapping for that port.<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      Examples of docker port<\/code><\/strong><\/h2>\n\n\n\n
      1. List All Port Mappings for a Container<\/strong><\/h3>\n\n\n
      docker port my_container\n<\/code><\/span><\/pre>\n\n\n
      Example Output:<\/strong><\/p>\n\n\n
      80\/tcp -> 0.0.0.0:8080\n443\/tcp -> 0.0.0.0:8443\n<\/code><\/span><\/pre>\n\n\n
      This shows that port 80<\/code> in the container is mapped to port 8080<\/code> on the host, and port 443<\/code> is mapped to 8443<\/code>.<\/p>\n\n\n\n
      \n\n\n\n
      2. Show the Mapping for a Specific Port<\/strong><\/h3>\n\n\n
      docker port my_container 80\n<\/code><\/span><\/pre>\n\n\n
      Example Output:<\/strong><\/p>\n\n\n
      0.0<\/span>.0<\/span>.0<\/span>:8080<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
      This indicates that the container\u2019s port 80<\/code> is accessible on port 8080<\/code> of the host machine.<\/p>\n\n\n\n
      \n\n\n\n
      3. Use a Container ID Instead of a Name<\/strong><\/h3>\n\n\n
      docker port a1b2c3d4e5f6 443\n<\/code><\/span><\/pre>\n\n\n
      This returns the mapping for port 443<\/code> on the container with ID a1b2c3d4e5f6<\/code>.<\/p>\n\n\n\n
      \n\n\n\n
      4. Check Port Mapping for Multiple Containers<\/strong><\/h3>\n\n\n
      docker ps -q | xargs -n 1 docker port\n<\/code><\/span><\/pre>\n\n\n
      This lists the port mappings for all running containers.<\/p>\n\n\n\n
      \n\n\n\n
      5. Verify a Random Port Mapping<\/strong><\/h3>\n\n\n\n
      If you published a container with a random port (-p 0:80<\/code>), use docker port<\/code> to find the assigned host port:<\/p>\n\n\n
      docker port my_container 80\n<\/code><\/span><\/pre>\n\n\n
      Example Output:<\/strong><\/p>\n\n\n
      0.0<\/span>.0<\/span>.0<\/span>:32768<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
      The random port 32768<\/code> on the host is mapped to the container\u2019s port 80<\/code>.<\/p>\n\n\n\n
      \n\n\n\n
      6. Combine docker port<\/code> with curl<\/code> to Test Connectivity<\/strong><\/h3>\n\n\n
      curl<\/span> localhost<\/span>:8080<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
      You can verify if the mapped port is responding by sending a request to it.<\/p>\n\n\n\n
      \n\n\n\n
      7. Check Port Mapping for a Stopped Container<\/strong><\/h3>\n\n\n\n
      Even after a container stops, docker port<\/code> still shows its previous mappings:<\/p>\n\n\n
      docker port stopped_container\n<\/code><\/span><\/pre>\n\n\n
      \n\n\n\n
      Use Cases for docker port<\/code><\/strong><\/h2>\n\n\n\n
      1. Verifying Port Mappings<\/strong><\/h3>\n\n\n\n
        \n
      • Ensure that ports are correctly exposed and accessible from the host.<\/li>\n\n\n\n
      • Check which random ports were assigned when using -p 0:PORT<\/code>.<\/li>\n<\/ul>\n\n\n\n
        2. Debugging Connectivity Issues<\/strong><\/h3>\n\n\n\n
          \n
        • Use docker port<\/code> to identify whether the correct ports are mapped.<\/li>\n\n\n\n
        • Combine with curl<\/code> or telnet<\/code> to check if a service is responding.<\/li>\n<\/ul>\n\n\n\n
          3. Auditing Network Configuration<\/strong><\/h3>\n\n\n\n
            \n
          • Regularly list port mappings to monitor network exposure for security.<\/li>\n\n\n\n
          • Detect conflicts between containers using the same host port.<\/li>\n<\/ul>\n\n\n\n
            4. Multi-Service Environments<\/strong><\/h3>\n\n\n\n
              \n
            • Quickly check how multiple services (e.g., web, database, caching) are mapped to different host ports.<\/li>\n<\/ul>\n\n\n\n
              5. Dynamic Port Mapping<\/strong><\/h3>\n\n\n\n
                \n
              • When using Docker Swarm<\/strong> or Kubernetes<\/strong>, where services often use random port mappings, docker port<\/code> is useful for finding the actual host ports.<\/li>\n<\/ul>\n\n\n\n
                \n\n\n\n
                List of Common docker port<\/code> Commands<\/strong><\/h2>\n\n\n\n
                Command<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
                docker port my_container<\/code><\/td>List all port mappings for the container<\/td><\/tr>
                docker port my_container 80<\/code><\/td>Show the host mapping for port 80 in the container<\/td><\/tr>
                docker port $(docker ps -q)<\/code><\/td>List port mappings for all running containers<\/td><\/tr>
                docker port stopped_container<\/code><\/td>Check port mappings for a stopped container<\/td><\/tr>
                docker port container_id 443<\/code><\/td>Show the mapping for port 443 using a container ID<\/td><\/tr>
                `docker ps -q<\/td>xargs -n 1 docker port`<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                \n\n\n\n
                Best Practices for Using docker port<\/code>:<\/strong><\/h2>\n\n\n\n
                  \n
                1. Verify port mappings before deploying<\/strong> to avoid conflicts.<\/li>\n\n\n\n
                2. Use docker port<\/code> in scripts<\/strong> to automate port checks for health monitoring.<\/li>\n\n\n\n
                3. Combine with firewalls and security tools<\/strong> to audit exposed ports.<\/li>\n\n\n\n
                4. Check for random port mappings<\/strong> in dynamically assigned setups (-p 0:PORT<\/code>).<\/li>\n<\/ol>\n\n\n\n
                  \n\n\n\n
                  Common Errors and Solutions<\/strong><\/h2>\n\n\n\n
                    \n
                  1. “Error: No such container”<\/strong>
                    \u2192 Ensure the container is running or exists by checking with docker ps<\/code> or docker ps -a<\/code>.<\/li>\n\n\n\n
                  2. No Output for docker port<\/code><\/strong>
                    \u2192 The container may not have any ports published. Check how it was started: docker inspect --format='{{ .HostConfig.PortBindings }}' my_container<\/code><\/li>\n\n\n\n
                  3. Service Not Responding on Mapped Port<\/strong>
                    \u2192 Verify the service is running inside the container: docker exec -it my_container ps aux<\/code><\/li>\n<\/ol>\n\n\n\n
                    \n\n\n\n
                    <\/p>\n","protected":false},"excerpt":{"rendered":"
                    Here\u2019s a complete tutorial on the docker port command, including how it works, use cases, and a comprehensive list of examples. What is docker port? docker port is a Docker… <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_joinchat":[],"footnotes":""},"categories":[4862],"tags":[],"class_list":["post-48372","post","type-post","status-publish","format-standard","hentry","category-docker"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48372","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=48372"}],"version-history":[{"count":2,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48372\/revisions"}],"predecessor-version":[{"id":48374,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48372\/revisions\/48374"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=48372"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=48372"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=48372"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}