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Sumo Logic

Kubernetes

Information on using the Sumo Kubernetes Fluentd plugin to collect logs from Kubernetes.


To monitor Kubernetes, Sumo recommends using the open source FluentD agent to collect log data, rather than a Sumo collector.  

FluentD, with its ability to integrate metadata from the Kubernetes master, is the dominant approach for collecting logs from Kubernetes environments. We have developed a FluentD plugin that sends data directly to Sumo Logic, and for ease of deployment, we have containerized a preconfigured package of FluentD and the Sumo Fluentd plugin. 
For ease of implementation, we provide a Kubernetes Helm Chart for the Sumo-FluentD integration. 

This page describes the Sumo Kubernetes Fluentd plugin, available at https://github.com/SumoLogic/fluentd-kubernetes-sumologic.

The plugin runs as a Kubernetes DaemonSet; it runs an instance of the plugin on each host in a cluster. Each plugin instance pulls system, kubelet, docker daemon, and container logs from the host and sends them, in JSON or text format, to an HTTP endpoint on a hosted collector in the Sumo service.

kubernetes2.png

Step 1: Create hosted collector and HTTP source in Sumo

In this step you create, on the Sumo service, an HTTP endpoint to receive your logs. This process involves creating an HTTP source on a hosted collector in Sumo. In Sumo, collectors use sources to receive data.

  1. If you don’t already have a Sumo account, you can create one by clicking the Free Trial button on https://www.sumologic.com/.
  2. Create a hosted collector, following the instructions on Configure a Hosted Collector in Sumo help. (If you already have a Sumo hosted collector that you want to use, skip this step.)
  3. Create an HTTP source on the collector you created in the previous step. For instructions, see HTTP Logs and Metrics Source in Sumo help.
  4. When you have configured the HTTP source, Sumo will display the URL of the HTTP endpoint. Make a note of the URL. You will use it when you configure the Kubernetes service to send data to Sumo.

Step 2: Create a Kubernetes secret

Create a secret in Kubernetes with the HTTP source URL. If you want to change the secret name, you must modify the Kubernetes manifest accordingly.

kubectl create secret generic sumologic --from-literal=collector-url=INSERT_HTTP_URL

You should see the confirmation message:

secret "sumologic" created

Step 3: Install the Sumo Kubernetes FluentD plugin

Follow the instructions in Option A below to install the plugin using kubectl. If you prefer to use a Helm chart, see Option B.

Before you start, see Environment variables for information about settings you can customize, and how to use annotations to override selected environment variables and exclude data from being sent to Sumo.

Option A: Install plugin using kubectl

See the sample Kubernetes DaemonSet and Role in fluentd.yaml.

  1. Clone the GitHub repo.
  2. In fluentd-kubernetes-sumologic, install the chart using kubectl.

Which .yaml file you should use depends on whether or not you are running RBAC for authorization. RBAC is enabled by default as of Kubernetes 1.6.

Non-RBAC (Kubernetes 1.5 and below)

kubectl create -f /daemonset/nonrbac/fluentd.yaml

RBAC (Kubernetes 1.6 and above) 

kubectl create -f /daemonset/rbac/fluentd.yaml

Example headline

Option B: Helm chart

If you use Helm to manage your Kubernetes resources, there is a Helm chart for the plugin at https://github.com/kubernetes/charts/tree/master/stable/sumologic-fluentd.

Logs should begin flowing into Sumo within a few minutes of plugin installation.

Environment variables

Environment variables may not apply to all Fluentd sources. See the table following the environment variable definitions for information about which Fluentd sources are affected by each variable.

Environment variable  Description
CONCAT_SEPARATOR The character to use to delimit lines within the final concatenated message. Most multi-line messages contain a newline at the end of each line.

Default: ""
EXCLUDE_CONTAINER_REGEX A regular expression for containers. Matching containers will be excluded from Sumo. The logs will still be sent to Fluentd.
EXCLUDE_FACILITY_REGEX A regular expression for syslog facilities. Matching facilities will be excluded from Sumo. The logs will still be sent to Fluentd.
EXCLUDE_HOST_REGEX     A regular expression for hosts. Matching hosts will be excluded from Sumo. The logs will still be sent to Fluentd.
EXCLUDE_NAMESPACE_REGEX A regular expression for namespaces. Matching namespaces will be excluded from Sumo. The logs will still be sent to Fluentd.
EXCLUDE_PATH Files matching this pattern will be ignored by the in_tail plugin, and will not be sent to Kubernetes or Sumo. This can be a comma-separated list as well. See in_tail documentation for more information.

For example, defining EXCLUDE_PATH as shown below excludes all files matching /var/log/containers/*.log
 
...

env:
  - name: EXCLUDE_PATH
  value: "[\"/var/log/containers/*.log\"]"

EXCLUDE_POD_REGEX A regular expression for pods. Matching pods will be excluded from Sumo. The logs will still be sent to Fluentd.
EXCLUDE_PRIORITY_REGEX A regular expression for syslog priorities. Matching priorities will be excluded from Sumo. The logs will still be sent to Fluentd.
EXCLUDE_UNIT_REGEX A regular expression for systemd units. Matching units will be excluded from Sumo. The logs will still be sent to Fluentd.
FLUENTD_SOURCE Fluentd can tail files or query systemd. Allowable values: file, systemd.

Default: file
FLUENTD_USER_CONFIG_DIR     A directory of user-defined Fluentd configuration files, which must be in the *.conf directory in the container.
FLUSH_INTERVAL How frequently to push logs to Sumo.

Default: 5s
KUBERNETES_META Include or exclude Kubernetes metadata such as namespace and pod_name if using JSON log format.

Default: true
LOG_FORMAT Format in which to post logs to Sumo. Allowable values:
  • text—Logs will appear in SumoLogic in text format.
  • json—Logs will appear in SumoLogic in json format.
  • json_merge—Same as json but if the container logs in json format to stdout it will merge in the container json log at the root level and remove the log field.
Default: json
MULTILINE_START_REGEXP The regular expression for the concat plugin to use when merging multi-line messages. Defaults to Julian dates, for example, Jul 29, 2017.
NUM_THREADS Set the number of HTTP threads to Sumo. It might be necessary to do so in heavy-logging clusters.

Default: 1
READ_FROM_HEAD Start to read the logs from the head of file, not bottom. Only applies to containers log files. See in_tail doc for more information.

Default: true
SOURCE_CATEGORY Set the _sourceCategory metadata field in Sumo.

Default: "%{namespace}/%{pod_name}"
SOURCE_CATEGORY_PREFIX Prepends a string that identifies the cluster to the _sourceCategory metadata field in Sumo.

Default: kubernetes/
SOURCE_CATEGORY_REPLACE_DASH Used to replace a dash (-) character with another character.

Default: /

For example, a Pod called travel-nginx-3629474229-dirmo within namespace app will appear in Sumo with _sourceCategory=app/travel/nginx.
SOURCE_HOST Set the _sourceHost metadata field in Sumo.

Default: ""
SOURCE_NAME Set the _sourceName metadata field in Sumo.

Default: "%{namespace}.%{pod}.%{container}"

The following table show which environment variables affect which Fluentd sources.

Environment Variable Containers Docker     Kubernetes Systemd
EXCLUDE_CONTAINER_REGEX
EXCLUDE_FACILITY_REGEX
EXCLUDE_HOST_REGEX
EXCLUDE_NAMESPACE_REGEX
EXCLUDE_PATH
EXCLUDE_PRIORITY_REGEX
EXCLUDE_POD_REGEX
EXCLUDE_UNIT_REGEX

Override environment variables using annotations

You can override the LOG_FORMAT, SOURCE_CATEGORY, and SOURCE_NAME environment variables, per pod, using Kubernetes annotations. For example:

apiVersion: v1
kind: ReplicationController
metadata:
  name: nginx
spec:
  replicas: 1
  selector:
    app: mywebsite
  template:
    metadata:
      name: nginx
      labels:
        app: mywebsite
      annotations:
        sumologic.com/format: "text"
        sumologic.com/sourceCategory: "mywebsite/nginx"
        sumologic.com/sourceName: "mywebsite_nginx"
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80

Exclude data using annotations

You can also use the sumologic.com/exclude annotation to exclude data from Sumo. This data is sent to Fluentd, but not to Sumo.

apiVersion: v1
kind: ReplicationController
metadata:
  name: nginx
spec:
  replicas: 1
  selector:
    app: mywebsite
  template:
    metadata:
      name: nginx
      labels:
        app: mywebsite
      annotations:
        sumologic.com/format: "text"
        sumologic.com/sourceCategory: "mywebsite/nginx"
        sumologic.com/sourceName: "mywebsite_nginx"
        sumologic.com/exclude: "true"
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80

Step 4: Set up Heapster for metric collection

The recommended way to collect metrics from Kubernetes clusters is to use Heapster and a Sumo collector with a Graphite source.

Heapster aggregates metrics across a Kubenetes cluster. Heapster runs as a pod in the cluster, and discovers all nodes in the cluster and queries usage information from each node's kubelet—the on-machine Kubernetes agent.

Heapster provides metrics at the cluster, node and pod level.

Install Heapster in your Kubernetes cluster and configure a Graphite Sink to send the data in Graphite format to Sumo. For instructions, see https://github.com/kubernetes/heapster/blob/master/docs/sink-configuration.md#graphitecarbon.

Use the Sumo Docker container. For instructions, see https://hub.docker.com/r/sumologic/collector/.

The following sections contain an example configmap, which contains the sources.json configuration, an example service, and an example deployment. Create these manifests in Kubernetes using kubectl.

Kubernetes configMap

kind: ConfigMap
apiVersion: v1
metadata:
  name: "sumo-sources"
data:
  sources.json: |-
    {
      "api.version": "v1",
      "sources": [
        {
          "name": "SOURCE_NAME",
          "category": "SOURCE_CATEGORY",
          "automaticDateParsing": true,
          "contentType": "Graphite",
          "timeZone": "UTC",
          "encoding": "UTF-8",
          "protocol": "TCP",
          "port": 2003,
          "sourceType": "Graphite"
        }
      ]
    }

Kubernetes service

apiVersion: v1
kind: Service
metadata:
  name: sumo-graphite
spec:
  ports:
    - port: 2003
  selector:
    app: sumo-graphite

Kubernetes deployment

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  labels:
    app: sumo-graphite
  name: sumo-graphite
spec:
  replicas: 1
  template:
    metadata:
      labels:
        name: sumo-graphite
        app:sumo-graphite
      volumes:
      - name: sumo-sources
        configMap:
          name: "sumo-sources"
          items:
          - key: sources.json
            path: sources.json
      containers:
      - name: sumo-graphite
        image: sumologic/collector:latest
        ports:
        - containerPort: 2003
        volumeMounts:
        - mountPath: /sumo
          name: sumo-sources
        env:
        - name: SUMO_ACCESS_ID
          value: <ACCESS_ID>
        - name: SUMO_ACCESS_KEY
          value: <ACCESS_KEY>
        - name: SUMO_SOURCES_JSON
          value: /sumo/sources.json

Log data

After performing the configuration described above, your logs should start streaming to Sumoin json or text format with the appropriate metadata. If you are using json format you can auto extract fields, for example:

_sourceCategory=some/app | json auto.

Docker

docker.png

Kubelet

kubelet.png

Containers
container.png

Taints and Tolerations

By default, the Fluentd pods will schedule on, and therefore collect logs from, any worker nodes that do not have a taint and any master node that does not have a taint beyond the default master taint. If you would like to schedule pods on all nodes, regardless of taints, uncomment the following line from fluentd.yaml before applying it.

tolerations:
           #- operator: "Exists"