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4. Kubernetes
5. Kubernetes Agent Configuration

Configuring the Honeycomb Kubernetes Agent

Applications in Kubernetes tend to use different logging formats. In our opinion, your own applications should use a structured, self-describing log format such as JSON. But Kubernetes system components use the glog format, reverse proxies and ingress controllers may use a combined log format, and so on.

You might also want to aggregate events only from specific services, rather than from everything that might be running in a cluster. Or you might want to send logs from different services to different datasets.

To accommodate these real-world use cases, you can customize the Honeycomb Kubernetes Agent’s behavior with a YAML configuration file. Ordinarily, you will create this file as a Kubernetes ConfigMap that will be mounted inside the agent container.

How the Honeycomb Kubernetes Agent Works 

First, a bit of background. The Honeycomb Kubernetes Agent runs as a DaemonSet. That is, one copy of the agent runs on each node in the cluster.

Metrics for resources running on the node are collected by communicating with the local node’s kubelet directly.

Logs from containers' stdout and stderr are written by the Docker daemon to the local node filesystem. The Honeycomb Kubernetes Agent reads these logs, augments them with metadata from the Kubernetes API, and ships them to Honeycomb so that you can see what is going on.

The Honeycomb Kubernetes Agent’s configuration file describes which pods' logs to process, and how to handle them, as well as which resource types to collect metrics from.

Metadata 

What metadata does the agent add to these logs?

• pod.labels
• pod.name
• pod.namespace
• pod.resourceVersion
• pod.UID
• pod.nodeName
• pod.nodeSelector
• pod.serviceAccountName
• pod.subdomain
• pod.annotations
• container.args
• container.command
• container.name
• container.env
• container.image
• container.ports
• container.VolumeMounts
• container.workingDir
• container.resources

The above metadata is added by default. Node metadata can be added by specifying includeNodeLabels: true within the agent’s metrics configuration.

Metrics Collection Configuration 

Metrics collection can be configured using the metrics configuration property.

metrics:
  enabled: true
  dataset: kubernetes-metrics
  clusterName: MyCluster
  metricGroups:
    - node
    - pod

A clusterName should be specified for each cluster. By default, only node and pod metrics will be collected.

The following table describes all properties for metrics configuration:

Example Metrics Configuration 

This configuration will collect metrics from the node, pods, containers, and volumes, every 10 seconds. The auto generated controller-revision-hash label will be omitted, and additional fields for region and az will be added.

metrics:
  enabled: true
  dataset: kubernetes-metrics
  clusterName: k8s-cluster
  interval: 10s
  metricGroups:
    - node
    - pod
    - container
    - volume
  omitLabels:
    - controller-revision-hash
  additionalFields:
    region: us-east
    az: us-east-1a

Log Watchers Configuration 

Logs parsing and collection can be configured using the watchers configuration property.

watchers:
- labelSelector: "app=nginx"
  parser: nginx
  dataset: kubernetes-nginx

- labelSelector: "app=frontend"
  parser: json
  dataset: kubernetes-frontend

Each block in the watchers list describes a set of pods whose logs you want to handle in a specific way, and has the following keys:

“Glob-style” means:

• * matches any sequence of non-path-separators
• /**/ matches zero or more directories
• ? matches any single non-path-separator character

Validating a Configuration File 

To check a configuration file without needing to deploy it into the cluster, you can run the Honeycomb Kubernetes Agent container locally with the --validate flag:

docker run -v /FULL/PATH/TO/YOUR/config.yaml:/etc/honeycomb/config.yaml honeycombio/honeycomb-kubernetes-agent:head --validate

Uploading a Configuration File to a Cluster 

To make a configuration file visible to the Honeycomb Kubernetes Agent inside a Kubernetes cluster, you will need to create a Kubernetes ConfigMap from it.

To create a brand-new ConfigMap from a local file config.yaml, run:

kubectl create configmap honeycomb-agent-config --from-file=config.yaml

To replace an existing ConfigMap, you can run:

kubectl create configmap honeycomb-agent-config \
    --from-file=config.yaml --output=yaml \
    --dry-run | kubectl replace --filename=-

Then restart running agent pods:

kubectl delete pod --selector k8s-app=honeycomb-agent

Parsers 

Currently, the following parsers are supported:

Nop 

Does no parsing on logs, and submits an event with the entire contents of the log line in a "log" field, plus the aforementioned kubernetes metadata. Use this if you just want the “raw” log line, or if your log line structure does not match one of the parsers below. You can still query datasets with raw log lines to some degree using string filters and derived columns, but structuring your logs is strongly encouraged.

JSON 

JSON is a great format for structured logs. With the JSON parser, we map JSON key/value pairs to event fields.

NGINX 

Parses NGINX access logs.

If you are using a custom NGINX log format, you can specify the format using the following configuration:

watchers:
- labelSelector: "io.kompose.service=nginx"
  parser:
    name: nginx
    dataset: nginx-inner
    options:
      log_format: '$remote_addr - $remote_user [$time_local] $host "$request" $status $bytes_sent $body_bytes_sent $request_time "$http_referer" "$http_user_agent" $request_length "$http_authorization" "$http_x_forwarded_proto" "$http_x_forwarded_for" $server_name'

Glog 

Parses logs produced by glog, which look like this:

I0719 23:09:54.422170       1 kube.go:118] Node controller sync successful

This format is commonly used by Kubernetes system components, such as the API server.

Redis 

Parses logs produced by redis 3.0+, which look like this:

1:M 08 Aug 22:59:58.739 * Background saving started by pid 43

Thanks to MacRae Linton for contributing the Redis parser.

Keyval 

Parses logs in key=value format, such as:

time=2022-05-15T05:43:19Z msg="server response - time 12ms code: 401 - request: GET /hello ..."

Key-value formatted logs often have a special prefix, such as a log level.

INFO: time=2022-05-15T05:43:19Z msg="server response - time 12ms code: 401 - request: GET /hello ..."

For parsing lines that have additional fields without an equal sign, and to ensure fields are extracted properly into fields in the Honeycomb UI, specify a regular expression to parse that prefix in the configuration.

watchers:
- labelSelector: "com.myco.logging.keyvalformat=true"
  parser:
    name: keyval
    options:
      prefixRegex: "(?P<loglevel>[A-Z]+): (?P<timestamp>time=[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}Z )"

If you would like to see support for additional log formats, please open an issue!

Processors 

Processors transform events after they are parsed. Currently, the following processors are supported:

additional_fields 

The additional_fields processor accepts a static map of field names and values and appends those to every event it processes. These values will overwrite existing fields of the same name, if they exist.

For example, with the following configuration:

processors:
  - additional_fields:
      environment: production
      owner: me@example.com

The field’s environment and owner will be added to the event.

sample 

The sample processor will only send a subset of events to Honeycomb. Honeycomb natively supports sampled event streams, allowing you to send a representative subset of events while still getting high-fidelity query results.

Options:

drop_field 

The drop_field processor will remove the specified field from all events before sending them to Honeycomb. This is useful for removing sensitive information from events.

Options:

request_shape 

The request_shape processor will take a field representing an HTTP request, such as GET /api/v1/users?id=22 HTTP/1.1, and unpack it into its constituent parts.

Options:

For example, with the following configuration:

processors:
- request_shape:
    field: request
    patterns:
    - /api/:version/:resource
    queryKeys:
    - id

the request_shape processor will expand the event

{"request": "GET /api/v1/users?id=22 HTTP/1.1", ...}

into

{
    "request": "GET /api/v1/users?id=22 HTTP/1.1",
    "request_method": "GET",
    "request_protocol_version": "HTTP/1.1",
    "request_uri": "/api/v1/users?id=22",
    "request_path": "/api/v1/users",
    "request_query": "id=22",
    "request_shape": "/api/:version/:resource?id=?",
    "request_path_version": "v1",
    "request_path_resource": "users",
    "request_pathshape": "/api/:version/:resource",
    "request_queryshape": "id=?",
    "request_query_id": "22",
    ...
}

timefield 

The timefield processor will replace the default timestamp in an event with one extracted from a specific field in the event.

Options:

Note: This processor is not generally necessary when collecting pod logs. The Honeycomb Kubernetes Agent will automatically use the timestamp recorded by the Docker json-log driver. It is useful when parsing logs that live at a particular path on the node filesystem, such as Kubernetes audit logs.

Sample Configurations 

Here are some example Kubernetes Honeycomb Agent configurations.

Parse logs from pods labelled with app: nginx:

---
writekey: "YOUR_API_KEY"
watchers:
  - labelSelector: app=nginx
    parser: nginx
    dataset: nginx-kubernetes

    processors:
    - request_shape:
        field: request

Send logs from different services to different datasets:

---
writekey: "YOUR_API_KEY"
watchers:
  - labelSelector: "app=nginx"
    parser: nginx
    dataset: nginx-kubernetes

  - labelSelector: "app=frontend-web"
    parser: json
    dataset: frontend

Sample events from a frontend-web deployment: only send one in 20 events from the prod namespace, and one in 10 events from the staging namespace.

---
writekey: "YOUR_API_KEY"
watchers:
  - labelSelector: "app=frontend-web"
    namespace: prod
    parser: json
    dataset: frontend

    processors:
      - sample:
          type: static
          rate: 20
      - drop_field:
        field: user_email

  - labelSelector: "app=frontend-web"
    namespace: staging
    parser: json
    dataset: frontend

    processors:
      - sample:
          type: static
          rate: 10

Get logs from a multi-container pod, but only from the sidecar container:

---
writekey: "YOUR_API_KEY"
watchers:
  - labelSelector: "app=frontend-web"
    containerName: sidecar
    parser: json
    dataset: frontend

Getting Help 

Have questions? Encountering difficulties? Missing features? Join our Pollinators Community Slack to ask questions and learn more.

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