{"id":5434,"date":"2018-10-09T01:45:23","date_gmt":"2018-10-09T01:45:23","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=5434"},"modified":"2021-11-17T09:51:59","modified_gmt":"2021-11-17T09:51:59","slug":"how-to-troubleshoot-docker-serverdaemon-and-containers","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/how-to-troubleshoot-docker-serverdaemon-and-containers\/","title":{"rendered":"How to troubleshoot Docker Server(daemon) and Containers?"},"content":{"rendered":"

How to troubleshoot Docker Server(daemon) and Containers?<\/strong><\/p>\n

There are following way using troubleshooting of Docker Server and Containers can be done. If you are running your container in -d (detached mode) or by docker remote API, you will not see any logs in console. To access running docker image or container logs you need to use docker logs command.<\/p>\n

Docker Containers Logs<\/strong><\/h3>\n

The docker logs command shows information logged by a running container.<\/strong><\/p>\n

[code]$ docker logs cont-id
\n$ docker container logs cont-id
\n$ docker logs –details CONTAINER
\n$ docker logs [OPTIONS] CONTAINER
\n$ docker container logs [OPTIONS] CONTAINER
\n$ docker help logs
\n# To follow docker log output or tail continuously
\n$ docker logs –follow ContainerName\/ContainerID<\/p>\n

# To see last n lines of logs
\n$ docker logs –tail 2500 ContainerName\/ContainerID<\/p>\n

# To see logs since particular date or timestamp
\n$ docker logs –since 2017-05-03 ContainerName\/ContainerID[\/code]<\/p>\n

The docker service logs command shows information logged by all containers participating in a service.<\/strong><\/p>\n

[code]$ docker service logs[\/code]<\/p>\n

    \n
  • If you use a logging driver which sends logs to a file, an external host, a database, or another logging back-end, docker logs may not show useful information.<\/li>\n
  • If your image runs a non-interactive process such as a web server or a database, that application may send its output to log files instead of STDOUT and STDERR.<\/li>\n<\/ul>\n

    Docker Events from Docker Server<\/strong><\/h3>\n

    To get real time events from the server, we can docker events commands. Information can include historical information and real-time information.<\/p>\n

    [code]$ docker events[\/code]<\/p>\n

    Docker containers will report the following events:<\/strong>
    \nattach, commit, copy, create, destroy, detach, die, exec_create, exec_detach, exec_start, export, kill, oom, pause, rename, resize, restart, start, stop, top, unpause, update<\/p>\n

    Docker images report the following events:<\/strong>
    \ndelete, import, load, pull, push, save, tag, untag<\/p>\n

    Docker volumes report the following events:<\/strong>
    \ncreate, mount, unmount, destroy<\/p>\n

    Docker networks report the following events:<\/strong>
    \ncreate, connect, disconnect, destroy<\/p>\n

    Docker Daemon Logs<\/h3>\n

    Docker daemon log depends on your OS. Here are the few locations, with commands for few Operating Systems:<\/p>\n

      \n
    • Ubuntu (old using upstart ) – \/var\/log\/upstart\/docker.log<\/li>\n
    • Ubuntu (new using systemd ) – sudo journalctl -fu docker.service<\/li>\n
    • Boot2Docker – \/var\/log\/docker.log<\/li>\n
    • Debian GNU\/Linux – \/var\/log\/daemon.log<\/li>\n
    • CentOS – \/var\/log\/daemon.log | grep docker<\/li>\n
    • CoreOS – journalctl -u docker.service<\/li>\n
    • Fedora – journalctl -u docker.service<\/li>\n
    • Red Hat Enterprise Linux Server – \/var\/log\/messages | grep docker<\/li>\n
    • OpenSuSE – journalctl -u docker.service<\/li>\n
    • OSX – ~\/Library\/Containers\/com.docker.docker\/Data\/com.docker.driver.amd64-linux\/log\/d\u200c\u200bocker.log<\/li>\n
    • Windows – Get-EventLog -LogName Application -Source Docker -After (Get-Date).AddMinutes(-5) | Sort-Object Time<\/li>\n<\/ul>\n

      If your OS is using systemd then you can view docker daemon log with:<\/strong>
      \n$ sudo journalctl -fu docker.service<\/p>\n

      Using CentOS7, logs are available using the command<\/strong>
      \n$ journalctl -u docker<\/p>\n

      For Docker Mac Native (without Boot2Docker or docker-machine, running your Docker installation without extra VirtualBox<\/strong>
      \n$ syslog -k Sender Docker<\/p>\n

      Docker for Mac (Beta)<\/strong>
      \n~\/Library\/Containers\/com.docker.docker\/Data\/com.docker.driver.amd64-linux\/log\/d\u200c\u200bocker.log<\/p>\n\n