Save docker-compose logs to a file

Question

I have unit tests running on my build server and would like to capture the log results for analysis when something fails. I have yet to find a way to redirect the output of

Answer 1

The solution I made is based on Chris McKinnel's answer with some enhancements.

I needed to dump last 1MIO records from my nginx container and docker-compose logs --tail 1000000 nginx > last1mio.log was too slow and the output was not exactly the same as usual nginx files have.

This is solution that works for me:

docker inspect --format='{{.LogPath}}' nginx-1 \
| xargs tail -n 1000000 \
| jq -r -j .log > last1mio.log 2>&1

Notes:

• you need to know your container name, in my case is nginx-1 - I use docker-compose option container_name: for having this constant
• I am using JQ utility to parse json - with some special options to get the format the same as original nginx log files usually have.

In my case dump of last 1mio lines of nginx log takes cca 10s.