Instead of a nice super-minimal production docker image, create one based on alpine with sql clients installed (`mariadb-client`, `postgresql-client`, and `sqlite`).
* Increases docker image size from 10 MB to 56 MB 👎
* Allows people to run `dbmate dump` command with our docker image (fixes#114) 👍
* I'm not sure what compatibility is like between `mysqldump` from `mariadb-client` versus `mysql-client`, but starting here since mariadb is included with alpine, and the version I built using mysql and ubuntu weighed in at 165 MB. 🤔
Prior to this commit, we released two linux binaries:
* `dbmate-linux-amd64` (built with cgo, dynamically linked)
* `dbmate-linux-musl-amd64` (built without cgo, statically linked, no sqlite support)
The statically linked binary is desirable for alpine linux users (or anyone else using musl libc or minimal docker images). The original reason for having two separate binaries was that the easiest method to create a static binary for go is to set `CGO_ENABLED=0`, but unfortunately this also prevented us from building sqlite (which requires cgo).
With this commit, all linux and windows binaries are explicitly statically linked while leaving cgo enabled. Hat tip to https://www.arp242.net/static-go.html which explained the necessary flags to enable this.
As an added bonus, the `dbmate` docker image now now uses a `scratch` base rather than `gcr.io/distroless/base`, reducing the image size from 26.7 MB to 9.8 MB.
Adds `dbmate dump` command to write the database schema to a file.
The intent is for this file to be checked in to the codebase, similar to Rails' `schema.rb` (or `structure.sql`) file. This allows developers to share a single file documenting the database schema, and makes it considerably easier to review PRs which add (or change) migrations.
The existing `up`, `migrate`, and `rollback` commands will automatically trigger a schema dump, unless `--no-dump-schema` is passed.
Closes https://github.com/amacneil/dbmate/issues/5
