https://github.com/mmcshane/salp

USDT probes in Golang on Linux
https://github.com/mmcshane/salp

cgo ebpf go golang usdt

Last synced: 2 months ago
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USDT probes in Golang on Linux

• Host: GitHub
• URL: https://github.com/mmcshane/salp
• Owner: mmcshane
• License: mit
• Created: 2017-11-23T08:20:57.000Z (about 7 years ago)
• Default Branch: main
• Last Pushed: 2023-08-10T20:05:52.000Z (over 1 year ago)
• Last Synced: 2024-06-20T03:28:48.588Z (7 months ago)
• Topics: cgo, ebpf, go, golang, usdt
• Language: Go
• Homepage:
• Size: 30.3 KB
• Stars: 31
• Watchers: 1
• Forks: 3
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Salp

Salp is a library that enables Go programs to create and fire USDT probes at

runtime. Such probes allow API-stable (i.e. not dependent on function names) 

tracing of executables written in Go - especially important since function

tracing of Go code requires some unappealing (though not unimpressive)

[hacks](http://www.brendangregg.com/blog/2017-01-31/golang-bcc-bpf-function-tracing.html).

Salp uses the [libstapsdt](https://github.com/sthima/libstapsdt) library to create

and fire these probes.

[![GoDoc](https://godoc.org/github.com/mmcshane/salp?status.svg)](https://godoc.org/github.com/mmcshane/salp)

## Build

### Dependencies

Salp depends on `libstapsdt` which in turn depends on `libelf` and `libdl`.

`libstapsdt` can be built from source or (for debian based distros) installed

via an Ubuntu PPA. Full instructions are available in the [docs for

libstapsdt](http://libstapsdt.readthedocs.io/en/latest/getting-started/getting-started.html)

### Build and Test

If `libstdapsdt` is installed globally (e.g. from the PPA above or via `make

install`), you should be able to simply `go build` or `go test`. However if you

have built `libstapsdt` from source then you will need to tell the `cgo` tool

how to find the headers and .so files for `libstapsdt` using the `CGO_CFLAGS`,

`CGO_LDFLAGS`, and `LD_LIBRARY_PATH` environment variables.

```bash

export CGO_CFLAGS="-I/path/to/libstapsdt/src"

export CGO_LDFLAGS="-L/path/to/libstapsdt/out"

export LD_LIBRARY_PATH="/path/to/libstapsdt/out"

```

## Demo

This repository contains a demo executable that will fire two different probes

every second. The demo can be observed using the `trace` and `tplist` tools from

the [bcc](https://github.com/iovisor/bcc) project. Use two terminals to run the

demo - one to execute the tracable salpdemo go program and one to run the bcc

tools and see their output. In the first window run

```bash

go run internal/salpdemo.go

```

This program will print out how to monitor itself but then won't print out

anything after that. In the second window run the bcc trace program on the

`salpdemo` process, monitoring probes `p1` and `p2`.

```bash

sudo trace -p "$(pgrep -n salpdemo)"                    \

    'u::p1 "i=%d err='%s' date='%s'", arg1, arg2, arg3' \

    'u::p2 "j=%d flag=%d", arg1, arg2'

```

or alternatively the same thing with `bpftrace`

```bash

sudo bpftrace -p "$(pgrep -n salpdemo)" /dev/stdin <