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Feb 23, 2018
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[enterprise-3.7] Clarified support for journald per BZ #7923

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73 changes: 66 additions & 7 deletions install_config/aggregate_logging.adoc
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Expand Up @@ -42,15 +42,23 @@ administrators can view all logs, but application developers can only view logs
for projects they have permission to view. The stack components communicate
securely.

[NOTE]
====
xref:../install_config/install/host_preparation.adoc#managing-docker-container-logs[Managing
Docker Container Logs] discusses the use of `json-file` logging driver options
Aggregated logging is supported using the `json-file` or `journald` driver in Docker.
The Docker log driver is set to `journald` as the default for all nodes. See
xref:fluentd-upgrade-source[Updating Fluentd's Log Source After a Docker Log
Driver Update] for more information about switching between `json-file` and `journald`.
Fluentd automatically determines which log driver (`journald` or `json-file`) the container runtime is using.

When the log driver is set to `journald`, Fluentd reads journald logs. When set to `json-file` Fluentd reads from *_/var/log/containers_*.

See xref:../install_config/install/host_preparation.adoc#managing-docker-container-logs[Managing
Docker Container Logs] for information on `json-file` logging driver options
to manage container logs and prevent filling node disks.

Aggregated logging is only supported using the `journald` driver in Docker. See
xref:fluentd-upgrade-source[Updating Fluentd's Log Source After a Docker Log
Driver Update] for more information.

[IMPORTANT]
====
If Docker log-driver is set to journald, there is no log rate throttling with the `journald` driver.
As a result, there is a risk of denial-of-service attacks from rogue containers.
====

[[aggregate-logging-pre-deployment-configuration]]
Expand Down Expand Up @@ -1762,6 +1770,57 @@ $ curl --key /etc/elasticsearch/secret/admin-key \
----
====

[[fluentd-update-source]]
== Changing the Aggregated Logging Driver

By default, aggregated logging uses the `journald` log driver
xref:../install_config/install/advanced_install.adoc#configuring-host-variables[unless `json-file` was specified during installation]. You can change the log driver between `journald` and `json-file` as needed.

[IMPORTANT]
====
When using the `json-file` driver, ensure that your Docker version is Docker version *docker-1.12.6-55.gitc4618fb.el7_4 now*
or later.
====

Fluentd determines the driver Docker is using by checking the *_/etc/docker/daemon.json_* and *_/etc/sysconfig/docker_* files.

You can determine which driver Docker is using with the `docker info` command:

----
# docker info | grep Logging

Logging Driver: journald
----

To change between `json-file` and `journald` after installation:

. Modify either the *_/etc/sysconfig/docker_* or *_/etc/docker/daemon.json_* files.
+
For example:
+
[source,json]
----
# cat /etc/sysconfig/docker
OPTIONS=' --selinux-enabled --log-driver=json-file --log-opt max-size=1M --log-opt max-file=3 --signature-verification=False'

cat /etc/docker/daemon.json
{
"log-driver": "json-file",
"log-opts": {
"max-size": "1M",
"max-file": "1"
}
}
----

. Restart the Docker service:
+
----
systemctl restart docker
----

. Update the xref:fluentd-upgrade-source[Fluentd log source].

[[fluentd-upgrade-source]]
== Updating Fluentd's Log Source After a Docker Log Driver Update

Expand Down
12 changes: 9 additions & 3 deletions install_config/install/advanced_install.adoc
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Expand Up @@ -463,10 +463,16 @@ which may cause invalid configurations. Example usage:
*{'image-gc-high-threshold': ['90'],'image-gc-low-threshold': ['80']}*.

|`openshift_docker_options`
|This variable configures additional `docker` options within
a|This variable configures additional `docker` options within
*_/etc/sysconfig/docker_*, such as options used in
xref:../../install_config/install/host_preparation.adoc#managing-docker-container-logs[Managing Container Logs]. Example usage: *"--log-driver json-file --log-opt max-size=1M
--log-opt max-file=3"*. Do not use when
xref:../../install_config/install/host_preparation.adoc#managing-docker-container-logs[Managing Container Logs].
Use `json-file` or `journald`. The default is `journald`.
Example usage:
----
"--log-driver json-file --log-opt max-size=1M --log-opt max-file=3"
"--log-driver journald"
----
Do not use when
xref:advanced-install-docker-system-container[running `docker` as a system container].

|`openshift_schedulable`
Expand Down
7 changes: 0 additions & 7 deletions install_config/install/host_preparation.adoc
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Expand Up @@ -579,13 +579,6 @@ container is running) can increase to a problematic size. You can manage this by
configuring Docker's `json-file` logging driver to restrict the size and number
of log files.

[IMPORTANT]
====
Aggregated logging is only supported using the `journald` driver in Docker. See
xref:../../install_config/aggregate_logging.adoc#fluentd-upgrade-source[Updating
Fluentd's Log Source After a Docker Log Driver Update] for more information.
====

[options="header"]
|===

Expand Down