Add support for build arg files in yaml format.

README.md

@@ -80,16 +80,29 @@ _(As a convention in the list below, all task parameters are specified with a
 * `$BUILD_ARG_*`: params prefixed with `BUILD_ARG_` will be provided as build
   args. For example `BUILD_ARG_foo=bar`, will set the `foo` build arg as `bar`.
 
-* `$BUILD_ARGS_FILE` (default empty): path to a file containing build args in
-  the form `foo=bar`, one per line. Empty lines are skipped.
+* `$BUILD_ARGS_FILE` (default empty): path to a file containing build args. By
+    default the task will assume each line is in the form `foo=bar`, one per
+    line. Empty lines are skipped. If the file ends in `yml` or `yaml` it will
+    be parsed as a YAML file. The YAML file can only contain string keys and
+    values.
 
-  Example file contents:
+  Example simple file contents:
 
   ```
-  EMAIL=me@yopmail.com
+  EMAIL=me@example.com
   HOW_MANY_THINGS=1
   DO_THING=false
   ```
+  Example YAML file contents:
+
+  ```yaml
+  EMAIL: [email protected]
+  HOW_MANY_THINGS: "1"
+  DO_THING: "false"
+  MULTI_LINE_ARG: |
+    thing1
+    thing2
+  ```
 
 * `$BUILDKIT_SECRET_*`: files with extra secrets which are made available via
   `--mount=type=secret,id=...`. See [New Docker Build secret information](https://docs.docker.com/develop/develop-images/build_enhancements/#new-docker-build-secret-information) for more information on build secrets.

go.mod

@@ -38,5 +38,5 @@ require (
 	golang.org/x/sync v0.8.0 // indirect
 	golang.org/x/sys v0.26.0 // indirect
 	golang.org/x/term v0.25.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1
 )

task.go

@@ -3,6 +3,7 @@ package task
 import (
 	"encoding/json"
 	"fmt"
+	"gopkg.in/yaml.v3"
 	"io"
 	"os"
 	"os/exec"
@@ -373,13 +374,24 @@ func sanitize(cfg *Config) error {
 			return errors.Wrap(err, "read build args file")
 		}
 
-		for _, arg := range strings.Split(string(buildArgs), "\n") {
-			if len(arg) == 0 {
-				// skip blank lines
-				continue
+		if strings.HasSuffix(cfg.BuildArgsFile, ".yml") || strings.HasSuffix(cfg.BuildArgsFile, ".yaml") {
+			var buildArgsData map[string]string
+			err = yaml.Unmarshal(buildArgs, &buildArgsData)
+			if err != nil {
+				return errors.Wrap(err, "read build args yaml file")
 			}
+			for key, arg := range buildArgsData {
+				cfg.BuildArgs = append(cfg.BuildArgs, key + "=" + arg)
+			}
+		} else {
+			for _, arg := range strings.Split(string(buildArgs), "\n") {
+				if len(arg) == 0 {
+					// skip blank lines
+					continue
+				}
 
-			cfg.BuildArgs = append(cfg.BuildArgs, arg)
+				cfg.BuildArgs = append(cfg.BuildArgs, arg)
+			}
 		}
 	}
 

task_test.go

@@ -152,6 +152,15 @@ func (s *TaskSuite) TestBuildArgsFile() {
 	s.NoError(err)
 }
 
+func (s *TaskSuite) TestBuildArgsYamlFile() {
+	s.req.Config.ContextDir = "testdata/build-args"
+	s.req.Config.BuildArgsFile = "testdata/build-args/build_args_file.yaml"
+
+	// the Dockerfile itself asserts that the arg has been received
+	_, err := s.build()
+	s.NoError(err)
+}
+
 func (s *TaskSuite) TestBuildArgsStaticAndFile() {
 	s.req.Config.ContextDir = "testdata/build-args"
 	s.req.Config.BuildArgs = []string{"some_arg=some_value"}

testdata/build-args/build_args_file.yaml

@@ -0,0 +1,2 @@
+some_arg: some_value
+some_other_arg: some_other_value