Tail and grep docker logs

Question

How can I both tail and grep Docker logs? I've tried the following:

sudo docker logs -f my_container | grep foo

This should tail all lines with foo from the container's logs, but instead shows everything.

Answer 1

Here's what I did:

sudo docker logs -f my_container &> log.log & tail -f log.log | grep foo

docker logs -f my_container &> log.log tails all the containers logs while also outputting to file log.log. In parallel, which is what the & by itself does, tail -f log.log | grep foo tails that file and greps, which a common way to grep tailed output.

The downside is that file log.log is created, but there was no other way to do this.