{"id":48400,"date":"2025-02-08T08:23:44","date_gmt":"2025-02-08T08:23:44","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=48400"},"modified":"2025-07-12T05:38:44","modified_gmt":"2025-07-12T05:38:44","slug":"docker-update","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/docker-update\/","title":{"rendered":"Docker commands Guide – docker update with examples"},"content":{"rendered":"\n

Here\u2019s a complete tutorial<\/strong> on docker update<\/code>, covering what it does<\/strong>, examples<\/strong>, and use cases<\/strong>.<\/p>\n\n\n\n

\n\n\n\n

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

docker update<\/code> is a Docker command used to modify the resource limits<\/strong> or configuration settings<\/strong> of one or more running containers<\/strong>. Unlike docker run<\/code>, which sets these limits at container creation, docker update<\/code> allows you to adjust them on the fly<\/strong> without stopping the container.<\/p>\n\n\n\n

Key Features:<\/strong><\/p>\n\n\n\n

    \n
  • Adjust CPU, memory, block I\/O, and restart policies<\/strong> for running containers.<\/li>\n\n\n\n
  • Helps manage resource allocation<\/strong> dynamically.<\/li>\n\n\n\n
  • Supports updating multiple containers at once<\/strong>.<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    Basic Syntax<\/strong><\/h2>\n\n\n
    docker<\/span> update<\/span> [OPTIONS]<\/span> CONTAINER<\/span> [CONTAINER...]<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
    Common Options:<\/strong><\/h3>\n\n\n\n
      \n
    • --cpus<\/code>: Limit the CPU usage<\/strong> for the container (e.g., --cpus=\"1.5\"<\/code>).<\/li>\n\n\n\n
    • --memory<\/code>: Set the maximum memory<\/strong> the container can use (e.g., --memory=\"512m\"<\/code>).<\/li>\n\n\n\n
    • --memory-swap<\/code>: Set the total memory plus swap<\/strong> for the container.<\/li>\n\n\n\n
    • --restart<\/code>: Update the restart policy<\/strong> (no<\/code>, always<\/code>, on-failure<\/code>, or unless-stopped<\/code>).<\/li>\n\n\n\n
    • --blkio-weight<\/code>: Set the block I\/O weight<\/strong> (relative I\/O priority).<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      Examples of docker update<\/code><\/strong><\/h2>\n\n\n\n
      1. Limit CPU Usage for a Running Container<\/strong><\/h3>\n\n\n
      docker update --cpus=\"1.5\"<\/span> my_container\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      This limits the container to 1.5 CPU cores<\/strong>.<\/p>\n\n\n\n
      \n\n\n\n
      2. Set a Maximum Memory Limit<\/strong><\/h3>\n\n\n
      docker update --memory=\"512m\"<\/span> my_container\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      This limits the container\u2019s memory usage to 512MB<\/strong>.<\/p>\n\n\n\n
      \n\n\n\n
      3. Adjust Memory Swap Limit<\/strong><\/h3>\n\n\n
      docker update --memory=\"1g\"<\/span> --memory-swap=\"2g\"<\/span> my_container\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      This sets the container\u2019s memory limit to 1GB<\/strong> and total memory + swap to 2GB<\/strong>.<\/p>\n\n\n\n
      \n\n\n\n
      4. Change the Restart Policy<\/strong><\/h3>\n\n\n
      docker update --restart=always my_container\n<\/code><\/span><\/pre>\n\n\n
      This updates the container\u2019s restart policy to always<\/strong>, ensuring it restarts automatically if it stops.<\/p>\n\n\n\n
      \n\n\n\n
      5. Set Block I\/O Weight<\/strong><\/h3>\n\n\n
      docker update --blkio-weight=500 my_container\n<\/code><\/span><\/pre>\n\n\n
      This sets the block I\/O priority<\/strong> for the container, with values ranging from 10 (low priority) to 1000 (high priority). The default is 500.<\/p>\n\n\n\n
      \n\n\n\n
      6. Update Multiple Containers at Once<\/strong><\/h3>\n\n\n
      docker update --memory=\"1g\"<\/span> container1 container2 container3\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      This applies the same memory limit to multiple containers.<\/p>\n\n\n\n
      \n\n\n\n
      7. Increase CPU Allocation Dynamically<\/strong><\/h3>\n\n\n
      docker update --cpus=\"2.0\"<\/span> my_container\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      If a running container needs more CPU power, you can increase its limit without stopping it.<\/p>\n\n\n\n
      \n\n\n\n
      8. Remove a Restart Policy<\/strong><\/h3>\n\n\n
      docker update --restart=no my_container\n<\/code><\/span><\/pre>\n\n\n
      This removes the restart policy, meaning the container won\u2019t automatically restart if it stops.<\/p>\n\n\n\n
      \n\n\n\n
      9. Use docker update<\/code> in a Shell Script<\/strong><\/h3>\n\n\n
      #!\/bin\/bash<\/span>\ndocker update --memory=\"512m\"<\/span> --cpus=\"1\"<\/span> web_container\ndocker update --memory=\"1g\"<\/span> --cpus=\"2\"<\/span> db_container\necho<\/span> \"Resource limits updated for web and database containers.\"<\/span>\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
      This script updates memory and CPU limits for two specific containers.<\/p>\n\n\n\n
      \n\n\n\n
      Use Cases for docker update<\/code><\/strong><\/h2>\n\n\n\n
      1. Dynamic Resource Management<\/strong><\/h3>\n\n\n\n
        \n
      • Adjust resource limits for containers based on system load or performance requirements<\/strong>.<\/li>\n\n\n\n
      • Example: Increase memory for a database container during peak usage.<\/li>\n<\/ul>\n\n\n\n
        2. Performance Tuning<\/strong><\/h3>\n\n\n\n
          \n
        • Optimize CPU and I\/O allocation for critical containers to ensure consistent performance<\/strong>.<\/li>\n\n\n\n
        • Example: Give high-priority services more CPU and I\/O resources.<\/li>\n<\/ul>\n\n\n\n
          3. System Recovery and Stability<\/strong><\/h3>\n\n\n\n
            \n
          • Prevent system crashes by limiting memory usage for containers that consume too much memory.<\/li>\n\n\n\n
          • Example: Set a strict memory limit for a container running a resource-intensive task.<\/li>\n<\/ul>\n\n\n\n
            4. Temporary Scaling<\/strong><\/h3>\n\n\n\n
              \n
            • Increase CPU or memory limits temporarily to handle high traffic<\/strong> and reduce them later.<\/li>\n\n\n\n
            • Example: Allocate more resources to a web server during a flash sale.<\/li>\n<\/ul>\n\n\n\n
              5. Restart Policy Updates<\/strong><\/h3>\n\n\n\n
                \n
              • Change the restart policy for containers in production environments<\/strong> to ensure high availability.<\/li>\n\n\n\n
              • Example: Set the restart policy to always<\/code> for critical services.<\/li>\n<\/ul>\n\n\n\n
                6. Batch Processing and Background Tasks<\/strong><\/h3>\n\n\n\n
                  \n
                • Manage CPU and memory usage for batch jobs or data processing<\/strong> to avoid overloading the host system.<\/li>\n<\/ul>\n\n\n\n
                  \n\n\n\n
                  List of Common docker update<\/code> Commands<\/strong><\/h2>\n\n\n\n
                  Command<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
                  docker update --cpus=\"1.5\" my_container<\/code><\/td>Limit CPU usage to 1.5 cores<\/td><\/tr>
                  docker update --memory=\"512m\" my_container<\/code><\/td>Set a maximum memory limit of 512MB<\/td><\/tr>
                  docker update --memory=\"1g\" --memory-swap=\"2g\" my_container<\/code><\/td>Limit memory to 1GB with 2GB total (including swap)<\/td><\/tr>
                  docker update --restart=always my_container<\/code><\/td>Set restart policy to always<\/code><\/td><\/tr>
                  docker update --blkio-weight=800 my_container<\/code><\/td>Set block I\/O priority to 800<\/td><\/tr>
                  docker update --cpus=\"2\" container1 container2<\/code><\/td>Increase CPU limit for multiple containers<\/td><\/tr>
                  docker update --restart=no my_container<\/code><\/td>Remove the restart policy<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                  \n\n\n\n
                  Best Practices for Using docker update<\/code>:<\/strong><\/h2>\n\n\n\n
                    \n
                  1. Monitor resource usage<\/strong> (docker stats<\/code>) before adjusting limits to avoid unintended performance degradation.<\/li>\n\n\n\n
                  2. Apply limits cautiously<\/strong>, especially for memory and swap, to prevent container crashes.<\/li>\n\n\n\n
                  3. Use --restart=always<\/code><\/strong> for critical services to ensure high availability.<\/li>\n\n\n\n
                  4. Combine with orchestration tools<\/strong> (Docker Swarm, Kubernetes) for automated resource scaling.<\/li>\n\n\n\n
                  5. Regularly review resource limits<\/strong> and adjust based on application requirements.<\/li>\n<\/ol>\n\n\n\n
                    \n\n\n\n
                    Common Errors and Solutions<\/strong><\/h2>\n\n\n\n
                      \n
                    1. “Error response from daemon: Cannot update a stopped container”<\/strong>
                      \u2192 Ensure the container is running. Start it with docker start<\/code>.<\/li>\n\n\n\n
                    2. “Error: Cannot set memory limit below current usage”<\/strong>
                      \u2192 Check the container\u2019s current memory usage and set a higher limit.<\/li>\n\n\n\n
                    3. “Permission denied”<\/strong>
                      \u2192 Ensure you have sufficient privileges. Use sudo<\/code> if necessary.<\/li>\n\n\n\n
                    4. “Restart policy update failed”<\/strong>
                      \u2192 Verify the container\u2019s status and ensure it is running before updating the restart policy.<\/li>\n<\/ol>\n\n\n\n
                      \n\n\n\n
                      Combining docker update<\/code> with Monitoring<\/strong><\/h2>\n\n\n\n
                        \n
                      1. Monitor Resource Usage with docker stats<\/code>:<\/strong> docker stats my_container<\/code><\/li>\n\n\n\n
                      2. Update CPU or Memory Limits Dynamically:<\/strong> docker update --cpus=\"2\" --memory=\"1g\" my_container<\/code><\/li>\n<\/ol>\n\n\n\n
                        \n\n\n\n
                        <\/p>\n","protected":false},"excerpt":{"rendered":"
                        Here\u2019s a complete tutorial on docker update, covering what it does, examples, and use cases. What is docker update? docker update is a Docker command used to modify the resource… <\/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-48400","post","type-post","status-publish","format-standard","hentry","category-docker"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48400","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=48400"}],"version-history":[{"count":2,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48400\/revisions"}],"predecessor-version":[{"id":48402,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48400\/revisions\/48402"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=48400"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=48400"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=48400"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}