Kernel and SQLite Integration

Input and output integration overview

The Kernel plugin collects various statistics about the Linux kernel, including context switches, page usage, and entropy availability.

Telegraf’s SQL output plugin stores metrics in an SQL database by creating tables dynamically for each metric type. When configured for SQLite, it utilizes a file-based DSN and a minimal SQL schema tailored for lightweight, embedded database usage.

Integration details

Kernel

The Kernel plugin is designed exclusively for Linux systems and gathers essential kernel statistics that are not covered by other plugins. It primarily focuses on the metrics available in /proc/stat, as well as the entropy available from /proc/sys/kernel/random/entropy_avail. Additional functionalities include the capture of Kernel Samepage Merging (KSM) data and Pressure Stall Information (PSI), requiring Linux kernel version 4.20 or later. This plugin provides a comprehensive look into system behaviors, enabling better understanding and optimization of resource management and usage. The metrics it collects are critical for monitoring system health and performance.

SQLite

The SQL output plugin writes Telegraf metrics to an SQL database using a dynamic schema where each metric type corresponds to a table. For SQLite, the plugin uses the modernc.org/sqlite driver and requires a DSN in the format of a file URI (e.g., ‘file:/path/to/telegraf.db?cache=shared’). This configuration leverages standard ANSI SQL for table creation and data insertion, ensuring compatibility with SQLite’s capabilities.

Configuration

Kernel

[[inputs.kernel]]
  ## Additional gather options
  ## Possible options include:
  ## * ksm - kernel same-page merging
  ## * psi - pressure stall information
  # collect = []

SQLite

[[outputs.sql]]
  ## Database driver
  ## Valid options: mssql (Microsoft SQL Server), mysql (MySQL), pgx (Postgres),
  ## sqlite (SQLite3), snowflake (snowflake.com), clickhouse (ClickHouse)
  driver = "sqlite"

  ## Data source name
  ## For SQLite, the DSN is a filename or URL with the scheme "file:".
  ## Example: "file:/path/to/telegraf.db?cache=shared"
  data_source_name = "file:/path/to/telegraf.db?cache=shared"

  ## 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
  ## The values on the left are the data types Telegraf has and the values on the right are the SQL types used when writing to SQLite.
  #[outputs.sql.convert]
  #  integer       = "INT"
  #  real          = "DOUBLE"
  #  text          = "TEXT"
  #  timestamp     = "TIMESTAMP"
  #  defaultvalue  = "TEXT"
  #  unsigned      = "UNSIGNED"
  #  bool          = "BOOL"

Input and output integration examples

Kernel

1. Memory Optimization through KSM: Utilize the KSM capabilities of this plugin to monitor memory usage patterns in your applications and dynamically adjust the memory allocation strategy based on shared page usage metrics. By analyzing the data collected, you can identify opportunities for consolidating memory and optimizing performance without manual intervention.

2. Real-time System Health Monitoring: Integrate the metrics collected by the Kernel plugin into a real-time dashboard that visualizes key kernel statistics including context switches, interrupts, and entropy availability. This setup allows system administrators to proactively respond to performance issues before they escalate into critical failures, ensuring smooth operation of Linux servers.

3. Enhanced Anomaly Detection: Combine the data from this plugin with machine learning models to predict and detect anomalies in kernel behavior. By continuously monitoring metrics like process forking rates and entropy levels, you can implement an adaptive alerting system that triggers on performance anomalies, allowing for quick responses to potential issues.

4. Resource Usage Patterns Analysis: Use the Pressure Stall Information collected by the plugin to analyze resource usage patterns over time and identify potential bottlenecks under load conditions. By adjusting application performance based on the PSI metrics, you can improve overall resource management and maintain service reliability under varying workloads.

SQLite

1. Local Monitoring Storage: Configure the plugin to write metrics to a local SQLite database file. This is ideal for lightweight deployments where setting up a full-scale database server is not required.
2. Embedded Applications: Use SQLite as the backend for applications embedded in edge devices, benefiting from its file-based architecture and minimal resource requirements.
3. Quick Setup for Testing: Leverage SQLite’s ease of use to quickly set up a testing environment for Telegraf metrics collection without the need for external database services.
4. Custom Schema Management: Adjust the table creation templates to predefine your schema if you require specific column types or indexes, ensuring compatibility with your application’s needs.

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.