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CoreOS Kubernetes logging to Graylog

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# kube-gelf

[Fluentd](https://www.fluentd.org/) [CoreOS](https://coreos.com/) Kubernetes container logs & [journald](https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html) log collector with [Graylog](https://www.graylog.org/) output.
Configurable through [ConfigMap](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/) and with provided cron example to mitigate some fluentd bugs as well as providing option for config reloads

## Notes

This project is automaticly built at [Docker Hub](https://hub.docker.com/r/roffe/kube-gelf/)

This image has only been tested with CoreOS but should work with any other distribution as long as the paths in fluent.conf & the daemonset is adjusted accordingly.

## Installation

```sh
kubectl create -f rbac.yaml

kubectl create configmap \
    --namespace kube-system kube-gelf \
    --from-file fluent.conf \
    --from-literal GELF_HOST=<server address> \
    --from-literal GELF_PORT=12201 \
    --from-literal GELF_PROTOCOL=<udp|tcp>

kubectl create -f daemonset.yaml

# optional, see notes below
kubectl create -f cron.yaml
```

After updating the configmap reloading fluentd config on all pods can be done with kubectl access.
Please allow atleast a minute to pass before issuing the command due to Kubernetes not real-time syncing configmap updates to volumes.

```sh
for POD in `kubectl get pod --namespace kube-system -l app=kube-gelf | tail -n +2 | awk '{print $1}'`; do echo RELOAD ${POD}; kubectl exec --namespace kube-system ${POD} -- /bin/sh -c 'kill -1 1'; done
```

## Cron

As of Kubernetes 1.8 batch/v1beta1 is enabled by default and no additional changes are needed.

If you are on < 1.8:

Enable `batch/v2alpha1=true` in the apiserver(s) `--runtime-config=` & restart apiservers + controller-manager.
Also change the apiVersion from `batch/v1beta1` to `batch/v2alpha1`

The cron.yaml can be used to deploy a cronJob that periodicly tells kube-gelf to reload it's configuration to also works around some fluend bugs.

I have several images made for different Kubernetes versions and you could adapt your cron.yaml by using any of my avail image tags here: <https://hub.docker.com/r/roffe/kubectl/tags/>

## Fluentd Bugs

in_tail prevents docker from removing container
<https://github.com/fluent/fluentd/issues/1680>.

in_tail removes untracked file position during startup phase. It means the content of pos_file is growing until restart when you tails lots of files with dynamic path setting. I will fix this problem in the future. Check this issue.
<https://github.com/fluent/fluentd/issues/1126>.

## Changelog

### 1.2

* Introduced new ENV variable GELF_PROTOCOL for protocol selection. Valid values are "udp" or "tcp". This requires a update of you configmap from earlier verisons
* Changed output plugin to <https://github.com/bodhi-space/fluent-plugin-gelf-hs>

### 1.1

Got rid of hostNetwork and added a NODENAME env variable utilizing the downward api. All log entries will contain the field `hostname: <your nodename in kubernetes>`

kube-gelf

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