Use CI environment variables to figure out tag

internal/pipe/changelog/changelog.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"regexp"
 	"sort"
@@ -189,6 +190,10 @@ func gitLog(refs ...string) (string, error) {
 }
 
 func previous(tag string) (result string, err error) {
+	if tag := os.Getenv("GORELEASER_PREVIOUS_TAG"); tag != "" {
+		return tag, nil
+	}
+
 	result, err = git.Clean(git.Run("describe", "--tags", "--abbrev=0", fmt.Sprintf("tags/%s^", tag)))
 	if err != nil {
 		result, err = git.Clean(git.Run("rev-list", "--max-parents=0", "HEAD"))

internal/pipe/changelog/changelog_test.go

@@ -109,6 +109,30 @@ func TestChangelog(t *testing.T) {
 	require.NotEmpty(t, string(bts))
 }
 
+func TestChangelogPreviousTagEnv(t *testing.T) {
+	folder, back := testlib.Mktmp(t)
+	defer back()
+	testlib.GitInit(t)
+	testlib.GitCommit(t, "first")
+	testlib.GitTag(t, "v0.0.1")
+	testlib.GitCommit(t, "second")
+	testlib.GitTag(t, "v0.0.2")
+	testlib.GitCommit(t, "third")
+	testlib.GitTag(t, "v0.0.3")
+	var ctx = context.New(config.Project{
+		Dist:      folder,
+		Changelog: config.Changelog{Filters: config.Filters{}},
+	})
+	ctx.Git.CurrentTag = "v0.0.3"
+	require.NoError(t, os.Setenv("GORELEASER_PREVIOUS_TAG", "v0.0.1"))
+	require.NoError(t, Pipe{}.Run(ctx))
+	require.NoError(t, os.Setenv("GORELEASER_PREVIOUS_TAG", ""))
+	require.Contains(t, ctx.ReleaseNotes, "## Changelog")
+	require.NotContains(t, ctx.ReleaseNotes, "first")
+	require.Contains(t, ctx.ReleaseNotes, "second")
+	require.Contains(t, ctx.ReleaseNotes, "third")
+}
+
 func TestChangelogForGitlab(t *testing.T) {
 	folder, back := testlib.Mktmp(t)
 	defer back()

internal/pipe/git/git.go

@@ -1,14 +1,16 @@
 package git
 
 import (
+	"os"
 	"os/exec"
 	"strings"
 
 	"github.com/apex/log"
+	"github.com/pkg/errors"
+
 	"github.com/goreleaser/goreleaser/internal/git"
 	"github.com/goreleaser/goreleaser/internal/pipe"
 	"github.com/goreleaser/goreleaser/pkg/context"
-	"github.com/pkg/errors"
 )
 
 // Pipe that sets up git state
@@ -122,6 +124,10 @@ func getFullCommit() (string, error) {
 }
 
 func getTag() (string, error) {
+	if tag := os.Getenv("GORELEASER_CURRENT_TAG"); tag != "" {
+		return tag, nil
+	}
+
 	return git.Clean(git.Run("describe", "--tags", "--abbrev=0"))
 }
 

internal/pipe/git/git_test.go

@@ -6,10 +6,12 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
 	"github.com/goreleaser/goreleaser/internal/testlib"
 	"github.com/goreleaser/goreleaser/pkg/config"
 	"github.com/goreleaser/goreleaser/pkg/context"
-	"github.com/stretchr/testify/assert"
 )
 
 func TestDescription(t *testing.T) {
@@ -189,3 +191,41 @@ func TestGitNotInPath(t *testing.T) {
 	assert.NoError(t, os.Setenv("PATH", ""))
 	assert.EqualError(t, Pipe{}.Run(context.New(config.Project{})), ErrNoGit.Error())
 }
+
+func TestTagFromCI(t *testing.T) {
+	_, back := testlib.Mktmp(t)
+	defer back()
+	testlib.GitInit(t)
+	testlib.GitRemoteAdd(t, "git@github.com:foo/bar.git")
+	testlib.GitCommit(t, "commit1")
+	testlib.GitTag(t, "v0.0.1")
+	testlib.GitTag(t, "v0.0.2")
+
+	for _, tc := range []struct {
+		envs     map[string]string
+		expected string
+	}{
+		// It is not possible to concisely figure out the tag if a commit has more than one tags. Git always
+		// returns the tags in lexicographical order (ASC), which implies that we expect v0.0.1 here.
+		// More details: https://github.com/goreleaser/goreleaser/issues/1163
+		{expected: "v0.0.1"},
+		{
+			envs:     map[string]string{"GORELEASER_CURRENT_TAG": "v0.0.2"},
+			expected: "v0.0.2",
+		},
+	} {
+		for name, value := range tc.envs {
+			require.NoError(t, os.Setenv(name, value))
+		}
+
+		var ctx = &context.Context{
+			Config: config.Project{},
+		}
+		assert.NoError(t, Pipe{}.Run(ctx))
+		assert.Equal(t, tc.expected, ctx.Git.CurrentTag)
+
+		for name := range tc.envs {
+			require.NoError(t, os.Setenv(name, ""))
+		}
+	}
+}

www/content/build.md

@@ -149,3 +149,9 @@ GOVERSION=$(go version) goreleaser
  ```
 
  [hook]: /hooks
+
+## Define Build Tag
+
+Goreleaser uses `git describe` to get the build tag. You can set
+a different build tag using the environment variable `GORELEASER_CURRENT_TAG`.
+This is useful in scenarios where two tags point to the same commit.

www/content/release.md

@@ -137,6 +137,12 @@ changelog:
       - (?i)foo
 ```
 
+### Define Previos Tag
+
+Goreleaser uses `git describe` to get the previous tag used for generating the Changelog.
+. You can set a different build tag using the environment variable `GORELEASER_PREVIOUS_TAG`.
+This is useful in scenarios where two tags point to the same commit.
+
 ## Custom release notes
 
 You can specify a file containing your custom release notes, and