v0.4.0

Changelog

97437a2 Update CHANGELOG for 0.4.0.
d214032 Test drone with golang:1.12.
e9edb61 Add go version to go.mod.
2451596 Move code to internal.
b30fa9b Pin dependencies versions to tags.
044c3e8 Welcome 2019.
90b1b9c Drop travis.
e3db533 Use drone ci, drop coveralls and golangci.
10aaf7e Add initial drone config.
3df8ff9 Run install step in travis.
08553d9 Enable GO111MODULE in travis build.

Docker images

• docker pull jbub/pgbouncer_exporter:latest
• docker pull jbub/pgbouncer_exporter:v0.4.0