mirror of https://github.com/docker/cli.git
62 lines
2.8 KiB
Markdown
62 lines
2.8 KiB
Markdown
# procfs
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This package provides functions to retrieve system, kernel, and process
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metrics from the pseudo-filesystems /proc and /sys.
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*WARNING*: This package is a work in progress. Its API may still break in
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backwards-incompatible ways without warnings. Use it at your own risk.
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[](https://pkg.go.dev/github.com/prometheus/procfs)
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[](https://circleci.com/gh/prometheus/procfs/tree/master)
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[](https://goreportcard.com/report/github.com/prometheus/procfs)
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## Usage
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The procfs library is organized by packages based on whether the gathered data is coming from
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/proc, /sys, or both. Each package contains an `FS` type which represents the path to either /proc,
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/sys, or both. For example, cpu statistics are gathered from
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`/proc/stat` and are available via the root procfs package. First, the proc filesystem mount
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point is initialized, and then the stat information is read.
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```go
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fs, err := procfs.NewFS("/proc")
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stats, err := fs.Stat()
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```
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Some sub-packages such as `blockdevice`, require access to both the proc and sys filesystems.
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```go
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fs, err := blockdevice.NewFS("/proc", "/sys")
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stats, err := fs.ProcDiskstats()
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```
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## Package Organization
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The packages in this project are organized according to (1) whether the data comes from the `/proc` or
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`/sys` filesystem and (2) the type of information being retrieved. For example, most process information
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can be gathered from the functions in the root `procfs` package. Information about block devices such as disk drives
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is available in the `blockdevices` sub-package.
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## Building and Testing
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The procfs library is intended to be built as part of another application, so there are no distributable binaries.
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However, most of the API includes unit tests which can be run with `make test`.
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### Updating Test Fixtures
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The procfs library includes a set of test fixtures which include many example files from
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the `/proc` and `/sys` filesystems. These fixtures are included as a [ttar](https://github.com/ideaship/ttar) file
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which is extracted automatically during testing. To add/update the test fixtures, first
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ensure the `fixtures` directory is up to date by removing the existing directory and then
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extracting the ttar file using `make fixtures/.unpacked` or just `make test`.
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```bash
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rm -rf testdata/fixtures
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make test
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```
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Next, make the required changes to the extracted files in the `fixtures` directory. When
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the changes are complete, run `make update_fixtures` to create a new `fixtures.ttar` file
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based on the updated `fixtures` directory. And finally, verify the changes using
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`git diff testdata/fixtures.ttar`.
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