go-gitver/README.md

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# git-version.go
Use git tags to add semver to your go package.
```txt
Goal: Either use an exact version like v1.0.0
or translate the git version like v1.0.0-4-g0000000
to a semver like v1.0.1-pre4+g0000000
Fail gracefully when git repo isn't available.
```
# Demo
Generate an `xversion.go` file:
```bash
go run git.rootprojects.org/root/go-gitver
cat xversion.go
```
<small>**Note**: The file is named `xversion.go` by default so that the
generated file's `init()` will come later, and thus take priority, over
most other files.</small>
See `go-gitver`s self-generated version:
```bash
go run git.rootprojects.org/root/go-gitver version
```
# QuickStart
Add this to the top of your main file:
```go
//go:generate go run -mod=vendor git.rootprojects.org/root/go-gitver
```
Add a file that imports go-gitver (for versioning)
```go
// +build tools
package example
import _ "git.rootprojects.org/root/go-gitver"
```
Change you build instructions to be something like this:
```bash
go mod vendor
go generate -mod=vendor ./...
go build -mod=vendor -o example cmd/example/*.go
```
You don't have to use `mod vendor`, but I highly recommend it.
# Options
```txt
version print version and exit
--fail exit with non-zero status code on failure
--package <name> will set the package name
--outfile <name> will replace `xversion.go` with the given file path
```
ENVs
```bash
# Alias for --fail
GITVER_FAIL=true
```
For example:
```go
//go:generate go run -mod=vendor git.rootprojects.org/root/go-gitver --fail
```
```bash
go run -mod=vendor git.rootprojects.org/root/go-gitver version
```
# Usage
See `examples/basic`
1. Create a `tools` package in your project
2. Guard it against regular builds with `// +build tools`
3. Include `_ "git.rootprojects.org/root/go-gitver"` in the imports
4. Declare `var GitRev, GitVersion, GitTimestamp string` in your `package main`
5. Include `//go:generate go run -mod=vendor git.rootprojects.org/root/go-gitver` as well
`tools/tools.go`:
```go
// +build tools
// This is a dummy package for build tooling
package tools
import (
_ "git.rootprojects.org/root/go-gitver"
)
```
`main.go`:
```go
//go:generate go run git.rootprojects.org/root/go-gitver --fail
package main
import "fmt"
var (
GitRev = "0000000"
GitVersion = "v0.0.0-pre0+0000000"
GitTimestamp = "0000-00-00T00:00:00+0000"
)
func main() {
fmt.Println(GitRev)
fmt.Println(GitVersion)
fmt.Println(GitTimestamp)
}
```
If you're using `go mod vendor` (which I highly recommend that you do),
you'd modify the `go:generate` ever so slightly:
```go
//go:generate go run -mod=vendor git.rootprojects.org/root/go-gitver --fail
```
The only reason I didn't do that in the example is that I'd be included
the repository in itself and that would be... weird.
# Why a tools package?
> import "git.rootprojects.org/root/go-gitver" is a program, not an importable package
Having a tools package with a build tag that you don't use is a nice way to add exact
versions of a command package used for tooling to your `go.mod` with `go mod tidy`,
without getting the error above.
# git: behind the curtain
These are the commands that are used under the hood to produce the versions.
Shows the git tag + description. Assumes that you're using the semver format `v1.0.0` for your base tags.
```bash
git describe --tags --dirty --always
# v1.0.0
# v1.0.0-1-g0000000
# v1.0.0-dirty
```
Show the commit date (when the commit made it into the current tree).
Internally we use the current date when the working tree is dirty.
```bash
git show v1.0.0-1-g0000000 --format=%cd --date=format:%Y-%m-%dT%H:%M:%SZ%z --no-patch
# 2010-01-01T20:30:00Z-0600
# fatal: ambiguous argument 'v1.0.0-1-g0000000-dirty': unknown revision or path not in the working tree.
```
Shows the most recent commit.
```bash
git rev-parse HEAD
# 0000000000000000000000000000000000000000
```