Fix SmartOS build #1017

[dfredell]

This is a fix for issue #1017
@discordianfish You reviewed my previous SmartOS PR #762 Can you take a look again?

I apologize if I created a pile of notifications trying to get my commit username correct.

[discordianfish]

I have actually 0 experience with smartos and last time I touched solaris was 10 years ago.. Are you sure this doesn't break other solarises? I don't know why these lines were added before.

[dfredell]

I'm not sure if it breaks others, it fixes it for me though. I can now run the exporter and get the metrics.

[root@smartos-fun ~]# go/bin/node_exporter 
INFO[0000] Starting node_exporter (version=, branch=, revision=)  source="node_exporter.go:82"
INFO[0000] Build context (go=go1.10, user=, date=)       source="node_exporter.go:83"
INFO[0000] Enabled collectors:                           source="node_exporter.go:90"
INFO[0000]  - loadavg                                    source="node_exporter.go:97"
INFO[0000]  - textfile                                   source="node_exporter.go:97"
INFO[0000]  - time                                       source="node_exporter.go:97"
INFO[0000] Listening on :9100                            source="node_exporter.go:111"
[root@smartos-fun ~]# bg
[1]+ go/bin/node_exporter &
[root@smartos-fun ~]# curl localhost:9100/metrics
# HELP go_gc_duration_seconds A summary of the GC invocation durations.
# TYPE go_gc_duration_seconds summary
go_gc_duration_seconds{quantile="0"} 0
go_gc_duration_seconds{quantile="0.25"} 0
...
# HELP node_load1 1m load average.
# TYPE node_load1 gauge
node_load1 0.37890625
# HELP node_load15 15m load average.
# TYPE node_load15 gauge
node_load15 0.4453125
# HELP node_load5 5m load average.
# TYPE node_load5 gauge
node_load5 0.46875

My little research points to golang/go#23749 which is a security change in golang the prevents unknown gcc flags.

[discordianfish]

@kpettijohn You've added this collector. Can you confirm that removing this doesn't break other solarises?

[mamash]

These cgo flags might have been required for a specific GCC compiler provided with a specific SunOS platform. They should not be hardcoded here, because A) -fno-stack-protector is a compiler flag and not on the linker flag whitelist in golang (recent security measures made to tackle golang/go#23672); and B) only compilers should set these if requested at compile time, as SunOS platforms, compilers and user security preferences may differ.

[kpettijohn]

@mamash thanks for the additional information! When making the original PR I was using SmartOS (joyent_20150820T062742Z) and it "seemed" required to add the flags for a successful build.

@discordianfish sorry for not jumping in sooner but based on @mamash comments it sounds like dropping the -fno-stack-protector is the correct action and might actually help support more SunOS platforms. Unfortunately I no longer have an environment for testing these changes.

[discordianfish]

Ok, thanks for the feedback. That sounds reasonable, so LGTM.

@SuperQ wdyt?

[SuperQ]

LGTM