fix: Put back build-agent customisation

cmd/build.go

@@ -22,6 +22,7 @@ func newLocalExecuteCommand(config *settings.Config) *cobra.Command {
 	}
 
 	local.AddFlagsForDocumentation(buildCommand.Flags())
+	buildCommand.Flags().String("build-agent-version", "", `The version of the build agent image you want to use. This can be configured by writing in $HOME/.circleci/build_agent_settings.json: '{"LatestSha256":"<version-of-build-agent>"}'`)
 	buildCommand.Flags().StringP("org-slug", "o", "", "organization slug (for example: github/example-org), used when a config depends on private orbs belonging to that org")
 	buildCommand.Flags().String("org-id", "", "organization id, used when a config depends on private orbs belonging to that org")
 

local/local.go

@@ -1,11 +1,12 @@
 package local
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
-	"regexp"
+	"path"
 	"strings"
 	"syscall"
 
@@ -71,7 +72,8 @@ func Execute(flags *pflag.FlagSet, cfg *settings.Config, args []string) error {
 		return err
 	}
 
-	image, err := picardImage(os.Stdout)
+	picardVersion, _ := flags.GetString("build-agent-version")
+	image, err := picardImage(os.Stdout, picardVersion)
 	if err != nil {
 		return errors.Wrap(err, "Could not find picard image")
 	}
@@ -130,7 +132,7 @@ func buildAgentArguments(flags *pflag.FlagSet) ([]string, string) {
 
 	// build a list of all supplied flags, that we will pass on to build-agent
 	flags.Visit(func(flag *pflag.Flag) {
-		if flag.Name != "org-slug" && flag.Name != "config" && flag.Name != "debug" && flag.Name != "org-id" && flag.Name != "docker-socket-path" {
+		if flag.Name != "build-agent-version" && flag.Name != "org-slug" && flag.Name != "config" && flag.Name != "debug" && flag.Name != "org-id" && flag.Name != "docker-socket-path" {
 			result = append(result, unparseFlag(flags, flag)...)
 		}
 	})
@@ -141,10 +143,10 @@ func buildAgentArguments(flags *pflag.FlagSet) ([]string, string) {
 	return result, configPath
 }
 
-func picardImage(output io.Writer) (string, error) {
+func picardImage(output io.Writer, picardVersion string) (string, error) {
 	fmt.Fprintf(output, "Fetching latest build environment...\n")
 
-	sha, err := findLatestPicardSha()
+	sha, err := getPicardSha(output, picardVersion)
 	if err != nil {
 		return "", err
 	}
@@ -153,47 +155,44 @@ func picardImage(output io.Writer) (string, error) {
 	return fmt.Sprintf("%s@%s", picardRepo, sha), nil
 }
 
-func ensureDockerIsAvailable() (string, error) {
-
-	dockerPath, err := exec.LookPath("docker")
-
-	if err != nil {
-		return "", errors.New("could not find `docker` on the PATH; please ensure that docker is installed")
+func getPicardSha(output io.Writer, picardVersion string) (string, error) {
+	// If the version was passed as argument, we take it
+	if picardVersion != "" {
+		return picardVersion, nil
 	}
 
-	dockerRunning := exec.Command(dockerPath, "version").Run() == nil // #nosec
+	var sha string
+	var err error
 
-	if !dockerRunning {
-		return "", errors.New("failed to connect to docker; please ensure that docker is running, and that `docker version` succeeds")
+	sha, err = loadBuildAgentShaFromConfig()
+	if sha != "" && err == nil {
+		return sha, nil
+	}
+	if err != nil && !os.IsNotExist(err) {
+		fmt.Fprintf(output, "Unable to parse JSON file %s because: %s\n", buildAgentSettingsPath(), err)
+		fmt.Fprintf(output, "Falling back to latest build-agent version\n")
 	}
 
-	return dockerPath, nil
+	// We are freezing build-agent cli as we would like to deprecate this path
+	fixedSha := "sha256:008ba7f4223f1e26c11df9575283491b620074fa96da6961e0dcde47fb757014"
+	return fixedSha, nil
 }
 
-// Still depends on a function in cmd/build.go
-func findLatestPicardSha() (string, error) {
-	if _, err := ensureDockerIsAvailable(); err != nil {
-		return "", err
-	}
+func ensureDockerIsAvailable() (string, error) {
 
-	// We are freezing build-agent cli as we would like to deprecate this path
-	// this is frozen to build-agent branch https://github.com/circleci/build-agent/tree/frozen-circleci-cli
-	imageName := fmt.Sprintf("%s:1.0.183556-5a2aabb6", picardRepo)
-	outputBytes, err := exec.Command("docker", "pull", imageName).CombinedOutput() // #nosec
+	dockerPath, err := exec.LookPath("docker")
 
 	if err != nil {
-		return "", errors.Wrap(err, "failed to pull latest docker image")
+		return "", errors.New("could not find `docker` on the PATH; please ensure that docker is installed")
 	}
 
-	output := string(outputBytes)
-	sha256 := regexp.MustCompile("(?m)sha256:[0-9a-f]+")
-	latest := sha256.FindString(output)
+	dockerRunning := exec.Command(dockerPath, "version").Run() == nil // #nosec
 
-	if latest == "" {
-		return "", fmt.Errorf("failed to parse sha256 from docker pull output")
+	if !dockerRunning {
+		return "", errors.New("failed to connect to docker; please ensure that docker is running, and that `docker version` succeeds")
 	}
 
-	return latest, nil
+	return dockerPath, nil
 }
 
 // Write data to a temp file, and return the path to that file.
@@ -247,3 +246,37 @@ func unparseFlag(flags *pflag.FlagSet, flag *pflag.Flag) []string {
 	}
 	return result
 }
+
+type buildAgentSettings struct {
+	LatestSha256 string
+}
+
+func loadBuildAgentShaFromConfig() (string, error) {
+	if _, err := os.Stat(buildAgentSettingsPath()); os.IsNotExist(err) {
+		// Settings file does not exist.
+		return "", nil
+	}
+
+	file, err := os.Open(buildAgentSettingsPath())
+	if err != nil {
+		return "", errors.Wrap(err, "Could not open build settings config")
+	}
+	defer file.Close()
+
+	var settings buildAgentSettings
+
+	buf, err := io.ReadAll(file)
+	if err != nil {
+		return "", errors.Wrap(err, "Couldn't read from build settings file")
+	}
+
+	if err = json.Unmarshal(buf, &settings); err != nil {
+		return "", errors.Wrap(err, "Could not parse build settings config")
+	}
+
+	return settings.LatestSha256, nil
+}
+
+func buildAgentSettingsPath() string {
+	return path.Join(settings.SettingsPath(), "build_agent_settings.json")
+}