I have a Go 1.5 application that binds with a C library (GEOS, FWIW) using cgo. What I need to do is vendor it so that it can ultimately be deployed through our continuous integration system. The problem is that I don't know how to convince the linker to link with the library once it is vendored. After running godep, the file with the cgo directive is .../vendor/.../geos.go. I created a lib directory there, added in the five .so files from GEOS, and changed the preamble to the following:
/*
#cgo LDFLAGS: -L${SRCDIR}/lib -lgeos_c
#include "geos.h"
*/
import "C"
This only works to a point - when I run go build it finds the first library but not any of the successive libraries.
/usr/bin/ld: warning: libgeos-3.4.2.so, needed by vendor/github.com/paulsmith/gogeos/geos/lib/libgeos_c.so, not found (try using -rpath or -rpath-link)
How do I get the entire thing to link properly?
I got the following feedback offline:
The low-level C dependencies, like the cgo binding mentioned in the stack overflow are super tricky, and are difficult to vendor as you can imagine. This is why in the past I've simply either bypassed the vendoring requirement by building my go binary (linux target) on a local or CI box and pushing using the binary buildpack or I've built a Docker image with my application's binary in it.
In other words, don't do what I was suggesting. Just build it the old fashioned way.