mirror of https://github.com/istio/istio.io.git
73 lines
3.6 KiB
Markdown
73 lines
3.6 KiB
Markdown
---
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title: Component Logging
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description: Describes how to use component-level logging to get insights into a running component's behavior.
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weight: 70
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keywords: [ops]
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aliases:
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- /help/ops/component-logging
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- /docs/ops/troubleshooting/component-logging
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owner: istio/wg-user-experience-maintainers
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test: no
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---
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Istio components are built with a flexible logging framework which provides a number of features and controls to
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help operate these components and facilitate diagnostics. You control these logging features by passing
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command-line options when starting the components.
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## Logging scopes
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Logging messages output by a component are categorized by *scopes*. A scope represents a set of related log messages which
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you can control as a whole. Different components have different scopes, depending on the features the component
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provides. All components have the `default` scope, which is used for non-categorized log messages.
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As an example, as of this writing, `istioctl` has 25 scopes, representing different functional areas within the command:
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- `ads`, `adsc`, `all`, `analysis`, `authn`, `authorization`, `ca`, `cache`, `cli`, `default`, `installer`, `klog`, `mcp`, `model`, `patch`, `processing`, `resource`, `source`, `spiffe`, `tpath`, `translator`, `util`, `validation`, `validationController`, `wle`
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Pilot-Agent, Pilot-Discovery, and the Istio Operator have their own scopes which you can discover by looking at their [reference documentation](/docs/reference/commands/).
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Each scope has a unique output level which is one of:
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1. none
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1. error
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1. warning
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1. info
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1. debug
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where `none` produces no output for the scope, and `debug` produces the maximum amount of output. The default level for all scopes
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is `info` which is intended to provide the right amount of logging information for operating Istio in normal conditions.
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To control the output level, you use the `--log_output_level` command-line option. For example:
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{{< text bash >}}
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$ istioctl analyze --log_output_level klog:none,cli:info
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{{< /text >}}
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In addition to controlling the output level from the command-line, you can also control the output level of a running component
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by using its [ControlZ](/docs/ops/diagnostic-tools/controlz) interface.
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## Controlling output
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Log messages are normally sent to a component's standard output stream. The `--log_target` option lets you direct the output to
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any number of different locations. You give the option a comma-separated list of file system paths, along with the special
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values `stdout` and `stderr` to indicate the standard output and standard error streams respectively.
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Log messages are normally output in a human-friendly format. The `--log_as_json` option can be used to force the output into JSON,
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which can be easier for tools to process.
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## Log rotation
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Istio control plane components can automatically manage log rotation, which make it simple to break up large logs into smaller log files.
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The `--log_rotate` option lets you specify the base file name to use for rotation. Derived names will be used for individual
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log files.
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The `--log_rotate_max_age` option lets you specify the maximum number of days before file rotation takes place, while the `--log_rotate_max_size` option
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let you specify the maximum size in megabytes before file rotation takes place. Finally, the `--log_rotate_max_backups` option lets you control
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the maximum number of rotated files to keep, older files will be automatically deleted.
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## Component debugging
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The `--log_caller` and `--log_stacktrace_level` options let you control whether log information includes
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programmer-level information. This is useful when trying to track down bugs in a component but is not
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normally used in day-to-day operation.
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