github.com/vtorhonen/terraform@v0.9.0-beta2.0.20170307220345-5d894e4ffda7/builtin/providers/external/util.go (about)

     1  package external
     2  
     3  import (
     4  	"fmt"
     5  	"os/exec"
     6  )
     7  
     8  // validateProgramAttr is a validation function for the "program" attribute we
     9  // accept as input on our resources.
    10  //
    11  // The attribute is assumed to be specified in schema as a list of strings.
    12  func validateProgramAttr(v interface{}) error {
    13  	args := v.([]interface{})
    14  	if len(args) < 1 {
    15  		return fmt.Errorf("'program' list must contain at least one element")
    16  	}
    17  
    18  	for i, vI := range args {
    19  		if _, ok := vI.(string); !ok {
    20  			return fmt.Errorf(
    21  				"'program' element %d is %T; a string is required",
    22  				i, vI,
    23  			)
    24  		}
    25  	}
    26  
    27  	// first element is assumed to be an executable command, possibly found
    28  	// using the PATH environment variable.
    29  	_, err := exec.LookPath(args[0].(string))
    30  	if err != nil {
    31  		return fmt.Errorf("can't find external program %q", args[0])
    32  	}
    33  
    34  	return nil
    35  }