97 lines
3.8 KiB
Markdown
97 lines
3.8 KiB
Markdown
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---
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title: Logging
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section: 7
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description: Why, What & How We Log
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---
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### Description
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The `npm` CLI has various mechanisms for showing different levels of information back to end-users for certain commands, configurations & environments.
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### Setting Log File Location
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All logs are written to a debug log, with the path to that file printed if the execution of a command fails.
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The default location of the logs directory is a directory named `_logs` inside the npm cache. This can be changed with the `logs-dir` config option.
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For example, if you wanted to write all your logs to the current working directory, you could run: `npm install --logs-dir=.`. This is especially helpful in debugging a specific `npm` issue as you can run
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a command multiple times with different config values and then diff all the log files.
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Log files will be removed from the `logs-dir` when the number of log files exceeds `logs-max`, with the oldest logs being deleted first.
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To turn off logs completely set `--logs-max=0`.
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### Setting Log Levels
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#### `loglevel`
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`loglevel` is a global argument/config that can be set to determine the type of information to be displayed.
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The default value of `loglevel` is `"notice"` but there are several levels/types of logs available, including:
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- `"silent"`
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- `"error"`
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- `"warn"`
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- `"notice"`
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- `"http"`
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- `"info"`
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- `"verbose"`
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- `"silly"`
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All logs pertaining to a level proceeding the current setting will be shown.
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##### Aliases
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The log levels listed above have various corresponding aliases, including:
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- `-d`: `--loglevel info`
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- `--dd`: `--loglevel verbose`
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- `--verbose`: `--loglevel verbose`
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- `--ddd`: `--loglevel silly`
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- `-q`: `--loglevel warn`
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- `--quiet`: `--loglevel warn`
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- `-s`: `--loglevel silent`
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- `--silent`: `--loglevel silent`
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#### `foreground-scripts`
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The `npm` CLI began hiding the output of lifecycle scripts for `npm install` as of `v7`. Notably, this means you will not see logs/output from packages that may be using "install scripts" to display information back to you or from your own project's scripts defined in `package.json`. If you'd like to change this behavior & log this output you can set `foreground-scripts` to `true`.
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### Timing Information
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The [`--timing` config](/using-npm/config#timing) can be set which does a few
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things:
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1. Always shows the full path to the debug log regardless of command exit status
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1. Write timing information to a process specific timing file in the cache or `logs-dir`
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1. Output timing information to the terminal
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This file contains a `timers` object where the keys are an identifier for the
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portion of the process being timed and the value is the number of milliseconds it took to complete.
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Sometimes it is helpful to get timing information without outputting anything to the terminal. For
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example, the performance might be affected by writing to the terminal. In this case you can use
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`--timing --silent` which will still write the timing file, but not output anything to the terminal
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while running.
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### Registry Response Headers
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#### `npm-notice`
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The `npm` CLI reads from & logs any `npm-notice` headers that are returned from the configured registry. This mechanism can be used by third-party registries to provide useful information when network-dependent requests occur.
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This header is not cached, and will not be logged if the request is served from the cache.
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### Logs and Sensitive Information
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The `npm` CLI makes a best effort to redact the following from terminal output and log files:
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- Passwords inside basic auth URLs
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- npm tokens
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However, this behavior should not be relied on to keep all possible sensitive information redacted. If you are concerned about secrets in your log file or terminal output, you can use `--loglevel=silent` and `--logs-max=0` to ensure no logs are written to your terminal or filesystem.
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### See also
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* [config](/using-npm/config)
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