Module: KubernetesMetadata::WatchPods

Includes:
Common
Included in:
Fluent::Plugin::KubernetesMetadataFilter
Defined in:
lib/fluent/plugin/kubernetes_metadata_watch_pods.rb

Overview

rubocop:disable Metrics/ModuleLength

Instance Method Summary collapse

Methods included from Common

#match_annotations, #parse_namespace_metadata, #parse_pod_metadata, #syms_to_strs

Instance Method Details

#get_pods_and_start_watcher ⇒ Object

List all pods, record the resourceVersion and return a watcher starting from that resourceVersion.



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# File 'lib/fluent/plugin/kubernetes_metadata_watch_pods.rb', line 128

def get_pods_and_start_watcher # rubocop:disable Metrics/AbcSize, Metrics/MethodLength, Naming/AccessorMethodName
  options = {
    resource_version: '0' # Fetch from API server cache instead of etcd quorum read
  }
  options[:field_selector] = "spec.nodeName=#{ENV['K8S_NODE_NAME']}" if ENV['K8S_NODE_NAME']
  if @last_seen_resource_version
    options[:resource_version] = @last_seen_resource_version
  else
    pods = @client.get_pods(**options)
    pods[:items].each do |pod|
      cache_key = pod[:metadata][:uid]
      @cache[cache_key] = parse_pod_metadata(pod)
      @stats.bump(:pod_cache_host_updates)
    end

    # continue watching from most recent resourceVersion
    options[:resource_version] = pods[:metadata][:resourceVersion]
  end

  watcher = @client.watch_pods(**options)
  reset_pod_watch_retry_stats
  watcher
end

#process_pod_watcher_notices(watcher) ⇒ Object

Process a watcher notice and potentially raise an exception.



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# File 'lib/fluent/plugin/kubernetes_metadata_watch_pods.rb', line 160

def process_pod_watcher_notices(watcher) # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity
  watcher.each do |notice| # rubocop:disable Metrics/BlockLength
    # store version we processed to not reprocess it ... do not unset when there is no version in response
    version = # TODO: replace with &.dig once we are on ruby 2.5+
      notice[:object] && notice[:object][:metadata] && notice[:object][:metadata][:resourceVersion]

    @last_seen_resource_version = version if version

    case notice[:type]
    when 'MODIFIED'
      reset_pod_watch_retry_stats
      cache_key = notice.dig(:object, :metadata, :uid)
      cached = @cache[cache_key]
      if cached
        @cache[cache_key] = parse_pod_metadata(notice[:object])
        @stats.bump(:pod_cache_watch_updates)
      elsif ENV['K8S_NODE_NAME'] == notice[:object][:spec][:nodeName]
        @cache[cache_key] = parse_pod_metadata(notice[:object])
        @stats.bump(:pod_cache_host_updates)
      else
        @stats.bump(:pod_cache_watch_misses)
      end
    when 'DELETED'
      reset_pod_watch_retry_stats
      # ignore and let age out for cases where pods
      # deleted but still processing logs
      @stats.bump(:pod_cache_watch_delete_ignored)
    when 'ERROR'
      if notice[:object] && notice[:object][:code] == 410
        @last_seen_resource_version = nil # requested resourceVersion was too old, need to reset
        @stats.bump(:pod_watch_gone_notices)
        raise GoneError
      else
        @stats.bump(:pod_watch_error_type_notices)
        message = notice[:object][:message] if notice[:object] && notice[:object][:message]
        raise "Error while watching pods: #{message}"
      end
    else
      reset_pod_watch_retry_stats
      # Don't pay attention to creations, since the created pod may not
      # end up on this node.
      @stats.bump(:pod_cache_watch_ignored)
    end
  end
end

#reset_pod_watch_retry_stats ⇒ Object

Reset pod watch retry count and backoff interval as there is a successful watch notice.



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# File 'lib/fluent/plugin/kubernetes_metadata_watch_pods.rb', line 154

def reset_pod_watch_retry_stats
  Thread.current[:pod_watch_retry_count] = 0
  Thread.current[:pod_watch_retry_backoff_interval] = @watch_retry_interval
end

#set_up_pod_thread ⇒ Object

rubocop:disable Metrics/AbcSize, Metrics/MethodLength, Metrics/PerceivedComplexity



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# File 'lib/fluent/plugin/kubernetes_metadata_watch_pods.rb', line 29

def set_up_pod_thread # rubocop:disable Metrics/AbcSize, Metrics/MethodLength, Metrics/PerceivedComplexity
  # Any failures / exceptions in the initial setup should raise
  # Fluent:ConfigError, so that users can inspect potential errors in
  # the configuration.
  pod_watcher = start_pod_watch

  Thread.current[:pod_watch_retry_backoff_interval] = @watch_retry_interval
  Thread.current[:pod_watch_retry_count] = 0

  # Any failures / exceptions in the followup watcher notice
  # processing will be swallowed and retried. These failures /
  # exceptions could be caused by Kubernetes API being temporarily
  # down. We assume the configuration is correct at this point.
  loop do # rubocop:disable Metrics/BlockLength
    pod_watcher ||= get_pods_and_start_watcher
    process_pod_watcher_notices(pod_watcher)
  rescue GoneError => e
    # Expected error. Quietly go back through the loop in order to
    # start watching from the latest resource versions
    @stats.bump(:pod_watch_gone_errors)
    log.info('410 Gone encountered. Restarting pod watch to reset resource versions.', e)
    pod_watcher = nil
  rescue KubeException => e
    if e.error_code == 401
      # recreate client to refresh token
      log.info("Encountered '401 Unauthorized' exception in watch, recreating client to refresh token")
      create_client
      pod_watcher = nil
    else
      # treat all other errors the same as StandardError, log, swallow and reset
      @stats.bump(:pod_watch_failures)
      if Thread.current[:pod_watch_retry_count] < @watch_retry_max_times
        # Instead of raising exceptions and crashing Fluentd, swallow
        # the exception and reset the watcher.
        log.info(
          'Exception encountered parsing pod watch event. The ' \
          'connection might have been closed. Sleeping for ' \
          "#{Thread.current[:pod_watch_retry_backoff_interval]} " \
          'seconds and resetting the pod watcher.',
          e
        )
        sleep(Thread.current[:pod_watch_retry_backoff_interval])
        Thread.current[:pod_watch_retry_count] += 1
        Thread.current[:pod_watch_retry_backoff_interval] *= @watch_retry_exponential_backoff_base
        pod_watcher = nil
      else
        # Since retries failed for many times, log as errors instead
        # of info and raise exceptions and trigger Fluentd to restart.
        message =
          'Exception encountered parsing pod watch event. The ' \
          'connection might have been closed. Retried ' \
          "#{@watch_retry_max_times} times yet still failing. Restarting."
        log.error(message, e)
        raise Fluent::UnrecoverableError, message
      end
    end
  rescue StandardError => e
    @stats.bump(:pod_watch_failures)
    if Thread.current[:pod_watch_retry_count] < @watch_retry_max_times
      # Instead of raising exceptions and crashing Fluentd, swallow
      # the exception and reset the watcher.
      log.info(
        'Exception encountered parsing pod watch event. The ' \
        'connection might have been closed. Sleeping for ' \
        "#{Thread.current[:pod_watch_retry_backoff_interval]} " \
        'seconds and resetting the pod watcher.',
        e
      )
      sleep(Thread.current[:pod_watch_retry_backoff_interval])
      Thread.current[:pod_watch_retry_count] += 1
      Thread.current[:pod_watch_retry_backoff_interval] *= @watch_retry_exponential_backoff_base
      pod_watcher = nil
    else
      # Since retries failed for many times, log as errors instead
      # of info and raise exceptions and trigger Fluentd to restart.
      message =
        'Exception encountered parsing pod watch event. The ' \
        'connection might have been closed. Retried ' \
        "#{@watch_retry_max_times} times yet still failing. Restarting."
      log.error(message, e)
      raise Fluent::UnrecoverableError, message
    end
  end
end

#start_pod_watch ⇒ Object 



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# File 'lib/fluent/plugin/kubernetes_metadata_watch_pods.rb', line 114

def start_pod_watch
  get_pods_and_start_watcher
rescue StandardError => e
  message = 'start_pod_watch: Exception encountered setting up pod watch ' \
            "from Kubernetes API #{@apiVersion} endpoint " \
            "#{@kubernetes_url}: #{e.message}"
  message += " (#{e.response})" if e.respond_to?(:response)
  log.debug(message)

  raise Fluent::ConfigError, message
end