Kubernetes and Clickhouse Integration

Input and output integration overview

This plugin captures metrics for Kubernetes pods and containers by communicating with the Kubelet API.

Telegraf’s SQL output plugin sends collected metrics to an SQL database using a straightforward table schema and dynamic column generation. When configured for ClickHouse, it adjusts DSN formatting and type conversion settings to ensure seamless data integration.

Integration details

Kubernetes

The Kubernetes input plugin interfaces with the Kubelet API to gather metrics for running pods and containers on a single host, ideally as part of a daemonset in a Kubernetes installation. By operating on each node within the cluster, it collects metrics from the locally running kubelet, ensuring that the data reflects the real-time state of the environment. Being a rapidly evolving project, Kubernetes sees frequent updates, and this plugin adheres to the major cloud providers’ supported versions, maintaining compatibility across multiple releases within a limited time span. Significant consideration is given to the potential high series cardinality, which can burden the database; thus, users are advised to implement filtering techniques and retention policies to manage this load effectively. Configuration options provide flexible customization of the plugin’s behavior to integrate seamlessly into different setups, enhancing its utility in monitoring Kubernetes environments.

Clickhouse

The SQL output plugin is designed to store Telegraf metrics in an SQL database using a simple, hard-coded schema. Each metric type gets its own table, and columns are generated for every tag and field, with an optional timestamp column. For ClickHouse, the plugin leverages a specialized DSN format as defined by clickhouse-go v1.5.4 and customizes metric type conversion to align with ClickHouse data types. This ensures that integers, texts, timestamps, booleans, and real numbers are mapped to ClickHouse’s native types such as Int64, String, DateTime, UInt8, and Float64 respectively.

Configuration

Kubernetes

[[inputs.kubernetes]]
  ## URL for the kubelet, if empty read metrics from all nodes in the cluster
  url = "http://127.0.0.1:10255"

  ## Use bearer token for authorization. ('bearer_token' takes priority)
  ## If both of these are empty, we'll use the default serviceaccount:
  ## at: /var/run/secrets/kubernetes.io/serviceaccount/token
  ##
  ## To re-read the token at each interval, please use a file with the
  ## bearer_token option. If given a string, Telegraf will always use that
  ## token.
  # bearer_token = "/var/run/secrets/kubernetes.io/serviceaccount/token"
  ## OR
  # bearer_token_string = "abc_123"

  ## Kubernetes Node Metric Name
  ## The default Kubernetes node metric name (i.e. kubernetes_node) is the same
  ## for the kubernetes and kube_inventory plugins. To avoid conflicts, set this
  ## option to a different value.
  # node_metric_name = "kubernetes_node"

  ## Pod labels to be added as tags.  An empty array for both include and
  ## exclude will include all labels.
  # label_include = []
  # label_exclude = ["*"]

  ## Set response_timeout (default 5 seconds)
  # response_timeout = "5s"

  ## Optional TLS Config
  # tls_ca = /path/to/cafile
  # tls_cert = /path/to/certfile
  # tls_key = /path/to/keyfile
  ## Use TLS but skip chain & host verification
  # insecure_skip_verify = false

Clickhouse

[[outputs.sql]]
  ## Database driver
  ## Valid options include mssql, mysql, pgx, sqlite, snowflake, clickhouse
  driver = "clickhouse"

  ## Data source name
  ## For ClickHouse, the DSN follows the clickhouse-go v1.5.4 format.
  ## Example DSN: "tcp://localhost:9000?debug=true"
  data_source_name = "tcp://localhost:9000?debug=true"

  ## Timestamp column name
  timestamp_column = "timestamp"

  ## Table creation template
  ## Available template variables:
  ##  {TABLE}        - table name as a quoted identifier
  ##  {TABLELITERAL} - table name as a quoted string literal
  ##  {COLUMNS}      - column definitions (list of quoted identifiers and types)
  table_template = "CREATE TABLE {TABLE} ({COLUMNS})"

  ## Table existence check template
  ## Available template variables:
  ##  {TABLE} - table name as a quoted identifier
  table_exists_template = "SELECT 1 FROM {TABLE} LIMIT 1"

  ## Initialization SQL (optional)
  init_sql = ""

  ## Maximum amount of time a connection may be idle. "0s" means connections are never closed due to idle time.
  connection_max_idle_time = "0s"

  ## Maximum amount of time a connection may be reused. "0s" means connections are never closed due to age.
  connection_max_lifetime = "0s"

  ## Maximum number of connections in the idle connection pool. 0 means unlimited.
  connection_max_idle = 2

  ## Maximum number of open connections to the database. 0 means unlimited.
  connection_max_open = 0

  ## Metric type to SQL type conversion for ClickHouse.
  ## The conversion maps Telegraf metric types to ClickHouse native data types.
  [outputs.sql.convert]
    conversion_style = "literal"
    integer          = "Int64"
    text             = "String"
    timestamp        = "DateTime"
    defaultvalue     = "String"
    unsigned         = "UInt64"
    bool             = "UInt8"
    real             = "Float64"

Input and output integration examples

Kubernetes

1. Dynamic Resource Allocation Monitoring: By utilizing the Kubernetes plugin, teams can set up alerts for resource usage patterns across various pods and containers. This proactive monitoring approach enables automatic scaling of resources in response to specific thresholds—helping to optimize performance while minimizing costs during peak usage.

2. Multi-tenancy Resource Isolation Analysis: Organizations using Kubernetes can leverage this plugin to track resource consumption per namespace. In a multi-tenant scenario, understanding the resource allocations and usages across different teams becomes critical for ensuring fair access and performance guarantees, leading to better resource management strategies.

3. Real-time Health Dashboards: Integrate the data captured by the Kubernetes plugin into visualization tools like Grafana to create real-time dashboards. These dashboards provide insights into the overall health and performance of the Kubernetes environment, allowing teams to quickly identify and rectify issues across clusters, pods, and containers.

4. Automated Incident Response Workflows: By combining the Kubernetes plugin with alert management systems, teams can automate incident response procedures based on real-time metrics. If a pod’s resource usage exceeds predefined limits, an automated workflow can trigger remediation actions, such as restarting the pod or reallocating resources—all of which can help improve system resilience.

Clickhouse

1. Basic ClickHouse Integration: Configure the plugin by setting the driver to ‘clickhouse’ and providing the appropriate DSN format as required by clickhouse-go v1.5.4. This ensures that Telegraf can connect and write metrics to your ClickHouse database.

2. Customized Table Schemas: Leverage the table creation and existence check templates to tailor the database schema. This allows you to predefine column types and even disable automatic table creation if you prefer manual schema management.

3. Advanced Type Conversion: Utilize the ClickHouse-specific conversion settings to map Telegraf metric types directly to ClickHouse data types (e.g., mapping integers to Int64 and timestamps to DateTime). This ensures data is stored with the correct precision and format.

4. Initialization and Connection Tuning: Use the init_sql setting to run custom SQL commands upon connection, and adjust connection pool settings (like connection_max_idle_time and connection_max_open) to optimize performance for high-throughput environments.

Feedback

Thank you for being part of our community! If you have any general feedback or found any bugs on these pages, we welcome and encourage your input. Please submit your feedback in the InfluxDB community Slack.