data-source/external: Make Read function context aware

Reference: #14
Reference: #22

This will enable the data source to exit immediately when receiving an interupt signal from Terraform. This also prepares the data source for future enhancements, such as including Terraform Plugin SDK context with logging messages and including additional information in return diagnostics.

internal/provider/data_source.go

@@ -2,11 +2,12 @@ package provider
 
 import (
  "bytes"
+ "context"
  "encoding/json"
- "fmt"
  "log"
  "os/exec"
 
+ "github.com/hashicorp/terraform-plugin-sdk/v2/diag"
  "github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 )
 
@@ -27,7 +28,7 @@ func dataSource() *schema.Resource {
  "or external programs beyond standard shell utilities, so it is not recommended to use this data source " +
  "within configurations that are applied within Terraform Enterprise.",
 
- Read: dataSourceRead,
+ ReadContext: dataSourceRead,
 
  Schema: map[string]*schema.Schema{
  "program": {
@@ -72,7 +73,7 @@ func dataSource() *schema.Resource {
  }
 }
 
-func dataSourceRead(d *schema.ResourceData, meta interface{}) error {
+func dataSourceRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
 
  programI := d.Get("program").([]interface{})
  workingDir := d.Get("working_dir").(string)
@@ -81,23 +82,23 @@ func dataSourceRead(d *schema.ResourceData, meta interface{}) error {
  // This would be a ValidateFunc if helper/schema allowed these
  // to be applied to lists.
  if err := validateProgramAttr(programI); err != nil {
- return err
+ return diag.FromErr(err)
  }
 
  program := make([]string, len(programI))
  for i, vI := range programI {
  program[i] = vI.(string)
  }
 
- cmd := exec.Command(program[0], program[1:]...)
+ cmd := exec.CommandContext(ctx, program[0], program[1:]...)
 
  cmd.Dir = workingDir
 
  queryJson, err := json.Marshal(query)
  if err != nil {
  // Should never happen, since we know query will always be a map
  // from string to string, as guaranteed by d.Get and our schema.
- return err
+ return diag.FromErr(err)
  }
 
  cmd.Stdin = bytes.NewReader(queryJson)
@@ -107,18 +108,18 @@ func dataSourceRead(d *schema.ResourceData, meta interface{}) error {
  if err != nil {
  if exitErr, ok := err.(*exec.ExitError); ok {
  if exitErr.Stderr != nil && len(exitErr.Stderr) > 0 {
- return fmt.Errorf("failed to execute %q: %s", program[0], string(exitErr.Stderr))
+ return diag.Errorf("failed to execute %q: %s", program[0], string(exitErr.Stderr))
  }
- return fmt.Errorf("command %q failed with no error message", program[0])
+ return diag.Errorf("command %q failed with no error message", program[0])
  } else {
- return fmt.Errorf("failed to execute %q: %s", program[0], err)
+ return diag.Errorf("failed to execute %q: %s", program[0], err)
  }
  }
 
  result := map[string]string{}
  err = json.Unmarshal(resultJson, &result)
  if err != nil {
- return fmt.Errorf("command %q produced invalid JSON: %s", program[0], err)
+ return diag.Errorf("command %q produced invalid JSON: %s", program[0], err)
  }
 
  d.Set("result", result)