View container logs
docker logs command shows information logged by a running container. The
docker service logs command shows information logged by all containers
participating in a service. The information that is logged and the format of the
log depends almost entirely on the container’s endpoint command.
docker logs or
docker service logs shows the command’s output
just as it would appear if you ran the command interactively in a terminal. UNIX
and Linux commands typically open three I/O streams when they run, called
STDIN is the command’s input stream, which
may include input from the keyboard or input from another command.
usually a command’s normal output, and
STDERR is typically used to output
error messages. By default,
docker logs shows the command’s
STDERR. To read more about I/O and Linux, see the
Linux Documentation Project article on I/O redirection.
In some cases,
docker logs may not show useful information unless you take
- If you use a logging driver which sends logs to a file, an
external host, a database, or another logging back-end, and have “dual logging”
docker logsmay not show useful information.
- 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
In the first case, your logs are processed in other ways and you may choose not
docker logs. In the second case, the official
nginx image shows one
workaround, and the official Apache
httpd image shows another.
nginx image creates a symbolic link from
/dev/stdout, and creates another symbolic link
/dev/stderr, overwriting the log files and
causing logs to be sent to the relevant special device instead. See the
httpd driver changes the
httpd application’s configuration to
write its normal output directly to
/proc/self/fd/1 (which is
its errors to
/proc/self/fd/2 (which is
STDERR). See the
- Configure logging drivers.
- Write a Dockerfile.