How to clear the logs properly for a Docker container

Question

I use docker logs  container-name  to see the logs of a specific container   Is there an elegant way to clear these logs

User · Answer

Docker4Mac  a 2018 solution   LOGPATH   docker inspect --format     LogPath     lt container name or id gt   docker run -it --rm --privileged --pid host alpine latest nsenter -t 1 -m -u -n -i -- truncate -s0  LOGPATH   The first line gets the log file path  similar to the accepted answer   The second line uses nsenter that allows you to run commands in the xhyve VM that servers as the host for all the docker containers under Docker4Mac  The command we run is the familiar truncate -s0  LOGPATH from non-Mac answers   If you re using docker-compose  the first line becomes   local LOGPATH   docker inspect --format     LogPath      docker-compose ps -q  lt service gt      and  lt service gt  is the service name from your docker-compose yml file   Thanks to https   github com justincormack nsenter1 for the nsenter trick

User · Answer

On my Ubuntu servers even as sudo I would get Cannot open     var lib docker containers    -json log    for writing  No such file or directory  But combing the docker inspect and truncate answers worked    sudo truncate -s 0  docker inspect --format     LogPath     lt container gt

User · Answer

You can set up logrotate to clear the logs periodically   Example file in  etc logrotate d docker-logs   var lib docker containers     log    rotate 7  daily  compress  size 50M  missingok  delaycompress  copytruncate

User · Answer

You can t do this directly through a Docker command   You can either limit the log s size  or use a script to delete logs related to a container  You can find scripts examples here  read from the bottom   Feature  Ability to clear log history  1083  Check out the logging section of the docker-compose file reference  where you can specify options  such as log rotation and log size limit  for some logging drivers

User · Answer

To remove clear  docker container logs we can use below command    docker inspect  container id grep  quot LogPath quot  cut -d  quot  quot  quot  -f4  or   docker inspect  container name grep  quot LogPath quot  cut -d  quot  quot  quot  -f4

User · Answer

Not sure if this is helpful for you  but removing the container always helps  So  if you use docker-compose for your setup  you can simply use docker-compose down  amp  amp  docker-compose up instead of docker-compose restart  With a proper setup  make sure to use volume mounts for persistent data   you don t lose any data this way  Sure  this is more than the OP requested  But there are various situations where the other answers cannot help  if using a remote docker server or working on a Windows machine  accessing the underlying filesystem is proprietary and difficult

User · Answer

I needed something I could run as one command  instead of having to write docker ps and copying over each Container ID and running the command multiple times  I ve adapted BMitch s answer and thought I d share in case someone else may find this useful  Mixing xargs seems to pull off what I need here  docker ps --format     ID          xargs -I    sh -c  echo  gt    docker inspect --format  quot    LogPath   quot        This grabs each Container ID listed by docker ps  will erase your logs for any container on that list    pipes it into xargs and then echoes a blank string to replace the log path of the container

User · Answer

Here is a cross platform solution to clearing docker container logs  docker run --rm -v  var lib docker  var lib docker alpine sh -c  quot echo     gt    docker inspect --format     LogPath    CONTAINER NAME  quot   Paste this into your terminal and change CONTAINER NAME to desired container name or id

User · Answer

On Docker for Windows and Mac  and probably others too  it is possible to use the tail option  For example   docker logs -f --tail 100   This way  only the last 100 lines are shown  and you don t have first to scroll through 1M lines      And thus  deleting the log is probably unnecessary

User · Answer

Use   truncate -s 0  var lib docker containers    -json log   You may need sudo   sudo sh -c  truncate -s 0  var lib docker containers    -json log    ref  Jeff S  How to clear the logs properly for a Docker container   Reference  Truncating a file while it  39 s being used  Linux

User · Answer

sudo find  var lib docker containers  -type f -name  quot   log quot  -delete

User · Answer

First the bad answer  From this question there s a one-liner that you can run  echo  quot  quot   gt    docker inspect --format     LogPath     lt container name or id gt    instead of echo  there s the simpler     gt    docker inspect --format     LogPath     lt container name or id gt    or there s the truncate command  truncate -s 0   docker inspect --format     LogPath     lt container name or id gt     I m not a big fan of either of those since they modify Docker s files directly  The external log deletion could happen while docker is writing json formatted data to the file  resulting in a partial line  and breaking the ability to read any logs from the docker logs cli  For an example of that happening  see this comment on duketwo s answer Instead  you can have Docker automatically rotate the logs for you  This is done with additional flags to dockerd if you are using the default JSON logging driver  dockerd     --log-opt max-size 10m --log-opt max-file 3  You can also set this as part of your daemon json file instead of modifying your startup scripts       quot log-driver quot    quot json-file quot      quot log-opts quot     quot max-size quot    quot 10m quot    quot max-file quot    quot 3 quot      These options need to be configured with root access  Make sure to run a systemctl reload docker after changing this file to have the settings applied  This setting will then be the default for any newly created containers  Note  existing containers need to be deleted and recreated to receive the new log limits   Similar log options can be passed to individual containers to override these defaults  allowing you to save more or fewer logs on individual containers  From docker run this looks like  docker run --log-driver json-file --log-opt max-size 10m --log-opt max-file 3      or in a compose file  version   3 7  services    app      image          logging        options          max-size   quot 10m quot          max-file   quot 3 quot    For additional space savings  you can switch from the json log driver to the  quot local quot  log driver  It takes the same max-size and max-file options  but instead of storing in json it uses a binary syntax that is faster and smaller  This allows you to store more logs in the same sized file  The daemon json entry for that looks like       quot log-driver quot    quot local quot      quot log-opts quot     quot max-size quot    quot 10m quot    quot max-file quot    quot 3 quot      The downside of the local driver is external log parsers forwarders that depended on direct access to the json logs will no longer work  So if you use a tool like filebeat to send to Elastic  or Splunk s universal forwarder  I d avoid the  quot local quot  driver  I ve got a bit more on this in my Tips and Tricks presentation

User · Answer

As a root user  try to run the following    gt    var lib docker containers    -json log   or  cat  dev null  gt   var lib docker containers    -json log   or  echo     gt   var lib docker containers    -json log

User · Answer

sudo sh -c  truncate -s 0  var lib docker containers    -json log

User · Answer

You can also supply the log-opts parameters on the docker run command line  like this   docker run --log-opt max-size 10m --log-opt max-file 5 my-app latest   or in a docker-compose yml like this  my-app  image  my-app latest logging      driver   json-file      options          max-file   5          max-size  10m   Credits  https   medium com  Quigley Ja rotating-docker-logs-keeping-your-overlay-folder-small-40cfa2155412  James Quigley

User · Answer

Docker for Mac users  here is the solution     Find log file path by      docker inspect   grep log   SSH into the docker machine  suppose the name is default  if not  run docker-machine ls to find out       docker-machine ssh default   Change to root user reference       sudo -i   Delete the log file content     echo     gt  log file path from step1

User · Answer

I do prefer this one  from solutions above    truncate -s 0  var lib docker containers    -json log   However I m running several systems  Ubuntu 18 x Bionic for example   where this path does not work as expected  Docker is installed through Snap  so the path to containers is more like   truncate -s 0  var snap docker common var-lib-docker containers    -json log

[docker] How to clear the logs properly for a Docker container?

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