Script command capture_local does not stop execution

This patch modifies script command capture_local to avoid crashing
the script execution upon error. This fix captures the command error
and writes it in the file and contines the script execution.

Signed-off-by: Vladimir Vivien <[email protected]>

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.7.0
 	github.com/spf13/cobra v1.1.1
-	github.com/vladimirvivien/gexe v0.1.0
+	github.com/vladimirvivien/gexe v0.1.1
 	go.starlark.net v0.0.0-20201006213952-227f4aabceb5
 	golang.org/x/crypto v0.0.0-20201012173705-84dcc777aaee
 	golang.org/x/oauth2 v0.0.0-20200902213428-5d25da1a8d43 // indirect

go.sum

@@ -318,8 +318,8 @@ github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/subosito/gotenv v1.2.0/go.mod h1:N0PQaV/YGNqwC0u51sEeR/aUtSLEXKX9iv69rRypqCw=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20190109142713-0ad062ec5ee5/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
-github.com/vladimirvivien/gexe v0.1.0 h1:Dge3QyscrV/yhmZkWDO6SXhrpyz+C6HnH8e+LVjhUus=
-github.com/vladimirvivien/gexe v0.1.0/go.mod h1:LHQL00w/7gDUKIak24n801ABp8C+ni6eBht9vGVst8w=
+github.com/vladimirvivien/gexe v0.1.1 h1:2A0SBaOSKH+cwLVdt6H+KkHZotZWRNLlWygANGw5DxE=
+github.com/vladimirvivien/gexe v0.1.1/go.mod h1:LHQL00w/7gDUKIak24n801ABp8C+ni6eBht9vGVst8w=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=

starlark/capture_local.go

@@ -7,14 +7,15 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/vladimirvivien/gexe"
 	"go.starlark.net/starlark"
 )
 
 // captureLocalFunc is a built-in starlark function that runs a provided command on the local machine.
 // The output of the command is stored in a file at a specified location under the workdir directory.
-// Starlark format: run_local(cmd=<command> [,workdir=path][,file_name=name][,desc=description][,append=append])
+// Starlark format: capture_local(cmd=<command> [,workdir=path][,file_name=name][,desc=description][,append=append])
 func captureLocalFunc(thread *starlark.Thread, b *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
 	var cmdStr, workdir, fileName, desc string
 	var append bool
@@ -42,16 +43,24 @@ func captureLocalFunc(thread *starlark.Thread, b *starlark.Builtin, args starlar
 
 	filePath := filepath.Join(workdir, fileName)
 	if err := os.MkdirAll(workdir, 0744); err != nil && !os.IsExist(err) {
-		return starlark.None, fmt.Errorf("%s: %s", identifiers.captureLocal, err)
+		msg := fmt.Sprintf("%s error: %s", identifiers.captureLocal, err)
+		return starlark.String(msg), nil
 	}
 
 	p := gexe.StartProc(cmdStr)
+	// upon error, write error in file, return filepath
 	if p.Err() != nil {
-		return starlark.None, fmt.Errorf("%s: %s", identifiers.captureLocal, p.Err())
+		msg := fmt.Sprintf("%s error: %s: %s", identifiers.captureLocal, p.Err(), p.Result())
+		if err := captureOutput(strings.NewReader(msg), filePath, desc, append); err != nil {
+			msg := fmt.Sprintf("%s error: %s", identifiers.captureLocal, err)
+			return starlark.String(msg), nil
+		}
+		return starlark.String(filePath), nil
 	}
 
 	if err := captureOutput(p.Out(), filePath, desc, append); err != nil {
-		return starlark.None, fmt.Errorf("%s: %s", identifiers.captureLocal, err)
+		msg := fmt.Sprintf("%s error: %s", identifiers.captureLocal, err)
+		return starlark.String(msg), nil
 	}
 
 	return starlark.String(filePath), nil

starlark/capture_local_test.go

@@ -123,6 +123,42 @@ func TestCaptureLocalFunc(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "capture with error",
+			args: func(t *testing.T) []starlark.Tuple {
+				return []starlark.Tuple{{starlark.String("cmd"), starlark.String("nacho 'Hello World!'")}}
+			},
+			eval: func(t *testing.T, kwargs []starlark.Tuple) {
+				val, err := captureLocalFunc(newTestThreadLocal(t), nil, nil, kwargs)
+				if err != nil {
+					t.Fatal(err)
+				}
+				result := ""
+				if r, ok := val.(starlark.String); ok {
+					result = string(r)
+				}
+				defer func() {
+					os.RemoveAll(result)
+					os.RemoveAll(defaults.workdir)
+				}()
+
+				file, err := os.Open(result)
+				if err != nil {
+					t.Fatal(err)
+				}
+				buf := new(bytes.Buffer)
+				if _, err := io.Copy(buf, file); err != nil {
+					t.Fatal(err)
+				}
+				expected := strings.TrimSpace(buf.String())
+				if !strings.Contains(expected, "not found") {
+					t.Errorf("unexpected content captured: %s", expected)
+				}
+				if err := file.Close(); err != nil {
+					t.Error(err)
+				}
+			},
+		},
 	}
 
 	for _, test := range tests {