Executable MVP

Magefile.go

@@ -7,7 +7,7 @@ import (
 )
 
 func Build() error {
-    return sh.RunV("go", "build", "-o", "build/verit", "cmd/verit.go")
+    return sh.RunV("go", "build", "-o", "build/verit", "main.go")
 }
 
 func Test() error {

README.md

@@ -1,22 +1,30 @@
-
-
 # VerIt
 
 **work in progress**
 
 ## Usage
+```
+verit <current-version> <pattern>
+
+<current-version>: SemVer denoting the current version of your artifact
+<pattern>: SemVer denoting the next version of your artifact. One of <major>.<minor>.<patch> may be set to "x" to increment from current-version.
+```
+
+## Examples
+```
+verit 1.0.0 1.x.0 # prints 1.1.0
+```
+```
+verit 0.9.0 1.x.0 # prints 1.0.0
+```
+
+## CI/CD Example
 
+If your artifact should have major version `0`, but you also want to bump the minor version with each build:
 ```
-$ git init && echo "hello" > README.md && git add . && git commit -m "initial commit"
-$ verit 0.x.0
-0.1.0
-# end of (successful) build
-$ git push --tags
-$ verit 0.x.0
-0.2.0
-# manually bump major version 0 -> 1, don't move the x for doing just that!
-$ verit 1.x.0
-1.0.0
-$ verit 1.x.0
-1.1.0
+currentVersion=$(git describe --abbrev=0)
+nextVersion=$(verit "$currentVersion" 0.x.0)
+git tag "$nextVersion"
+git push --tags
+# ... use $version, e.g. to tag a docker image.
 ```

main.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+    "fmt"
+    "os"
+    "verit/pkg/version"
+)
+
+const usage = `Usage: verit <current-version> <pattern>
+
+Example: verit 1.0.0 1.x.0 # prints 1.1.0
+
+<current-version>: SemVer denoting the current version of your artifact
+<pattern>: SemVer denoting the next version of your artifact. One of <major>.<minor>.<patch> may be set to "x" to increment from current-version.
+`
+
+func main() {
+    args := os.Args[1:]
+    if len(args) != 2 {
+        exitWithMessage(usage)
+    }
+    next, err := version.Next(args[0], args[1])
+    if err != nil {
+        exitWithMessage(usage)
+    }
+    fmt.Println(next)
+}
+
+func exitWithMessage(message string) {
+    _, _ = os.Stderr.WriteString(message)
+    os.Exit(1)
+}