---
description: Learn how to use the Journald logging driver with Docker Engine
keywords: journald, systemd-journald, docker, logging, driver
title: Journald logging driver
aliases:
- /engine/reference/logging/journald/
- /engine/admin/logging/journald/
- /config/containers/logging/journald/
---
The `journald` logging driver sends container logs to the
[`systemd` journal](https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html).
Log entries can be retrieved using the `journalctl` command, through use of the
`journal` API, or using the `docker logs` command.
In addition to the text of the log message itself, the `journald` log driver
stores the following metadata in the journal with each message:
| Field | Description |
| :----------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------- |
| `CONTAINER_ID` | The container ID truncated to 12 characters. |
| `CONTAINER_ID_FULL` | The full 64-character container ID. |
| `CONTAINER_NAME` | The container name at the time it was started. If you use `docker rename` to rename a container, the new name isn't reflected in the journal entries. |
| `CONTAINER_TAG`, `SYSLOG_IDENTIFIER` | The container tag ([log tag option documentation](log_tags.md)). |
| `CONTAINER_PARTIAL_MESSAGE` | A field that flags log integrity. Improve logging of long log lines. |
| `IMAGE_NAME` | The name of the container image. |
## Usage
To use the `journald` driver as the default logging driver, set the `log-driver`
and `log-opts` keys to appropriate values in the `daemon.json` file, which is
located in `/etc/docker/` on Linux hosts or
`C:\ProgramData\docker\config\daemon.json` on Windows Server. For more about
configuring Docker using `daemon.json`, see
[daemon.json](/reference/cli/dockerd.md#daemon-configuration-file).
The following example sets the log driver to `journald`:
```json
{
"log-driver": "journald"
}
```
Restart Docker for the changes to take effect.
To configure the logging driver for a specific container, use the `--log-driver`
flag on the `docker run` command.
```console
$ docker run --log-driver=journald ...
```
## Options
Use the `--log-opt NAME=VALUE` flag to specify additional `journald` logging
driver options.
| Option | Required | Description |
| :------------- | :------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `tag` | optional | Specify template to set `CONTAINER_TAG` and `SYSLOG_IDENTIFIER` value in journald logs. Refer to [log tag option documentation](log_tags.md) to customize the log tag format. |
| `labels` | optional | Comma-separated list of keys of labels, which should be included in message, if these labels are specified for the container. |
| `labels-regex` | optional | Similar to and compatible with labels. A regular expression to match logging-related labels. Used for advanced [log tag options](log_tags.md). |
| `env` | optional | Comma-separated list of keys of environment variables, which should be included in message, if these variables are specified for the container. |
| `env-regex` | optional | Similar to and compatible with `env`. A regular expression to match logging-related environment variables. Used for advanced [log tag options](log_tags.md). |
If a collision occurs between `label` and `env` options, the value of the `env`
takes precedence. Each option adds additional fields to the attributes of a
logging message.
The following is an example of the logging options required to log to journald.
```console
$ docker run \
--log-driver=journald \
--log-opt labels=location \
--log-opt env=TEST \
--env "TEST=false" \
--label location=west \
your/application
```
This configuration also directs the driver to include in the payload the label
location, and the environment variable `TEST`. If the `--env "TEST=false"`
or `--label location=west` arguments were omitted, the corresponding key would
not be set in the journald log.
## Note regarding container names
The value logged in the `CONTAINER_NAME` field is the name of the container that
was set at startup. If you use `docker rename` to rename a container, the new
name isn't reflected in the journal entries. Journal entries continue
to use the original name.
## Retrieve log messages with `journalctl`
Use the `journalctl` command to retrieve log messages. You can apply filter
expressions to limit the retrieved messages to those associated with a specific
container:
```console
$ sudo journalctl CONTAINER_NAME=webserver
```
You can use additional filters to further limit the messages retrieved. The `-b`
flag only retrieves messages generated since the last system boot:
```console
$ sudo journalctl -b CONTAINER_NAME=webserver
```
The `-o` flag specifies the format for the retrieved log messages. Use `-o json`
to return the log messages in JSON format.
```console
$ sudo journalctl -o json CONTAINER_NAME=webserver
```
### View logs for a container with a TTY enabled
If TTY is enabled on a container you may see `[10B blob data]` in the output
when retrieving log messages.
The reason for that is that `\r` is appended to the end of the line and
`journalctl` doesn't strip it automatically unless `--all` is set:
```console
$ sudo journalctl -b CONTAINER_NAME=webserver --all
```
## Retrieve log messages with the `journal` API
This example uses the `systemd` Python module to retrieve container
logs:
```python
import systemd.journal
reader = systemd.journal.Reader()
reader.add_match('CONTAINER_NAME=web')
for msg in reader:
print '{CONTAINER_ID_FULL}: {MESSAGE}'.format(**msg)
```