Local build fails - can't find sd-journal.h

[steveww]

Describe the bug
github.com/grafana/loki/vendor/github.com/coreos/go-systemd/sdjournal
vendor/github.com/coreos/go-systemd/sdjournal/journal.go:27:11: fatal error: systemd/sd-journal.h: No such file or directory
// #include <systemd/sd-journal.h>
^~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

To Reproduce
git pull
go build cmd/promtail

Expected behavior
Successful compile of Promtail

Environment:
Ubuntu 18.04.2
Linux server1 4.15.0-54-generic #58-Ubuntu SMP Mon Jun 24 10:55:24 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
go version go1.12.4 linux/amd64

Screenshots, promtail config, or terminal output
If applicable, add any output to help explain your problem.

[rfratto]

Since #730 was merged promtail requires the systemd headers to be installed on linux (apt install libsystemd-dev). If you don't want to do that you can build promtail with CGO disabled which should also fix the problem for you: CGO_ENABLED=0 go build cmd/promtail.

We should probably update the build instructions to include this or disable journal support by default through a custom build tag.

[steveww]

New build instructions look good. Thanks.