github.com/danp/terraform@v0.9.5-0.20170426144147-39d740081351/builtin/providers/template/datasource_template_file.go (about)

     1  package template
     2  
     3  import (
     4  	"crypto/sha256"
     5  	"encoding/hex"
     6  	"fmt"
     7  	"os"
     8  	"path/filepath"
     9  	"strings"
    10  
    11  	"github.com/hashicorp/hil"
    12  	"github.com/hashicorp/hil/ast"
    13  	"github.com/hashicorp/terraform/config"
    14  	"github.com/hashicorp/terraform/helper/pathorcontents"
    15  	"github.com/hashicorp/terraform/helper/schema"
    16  )
    17  
    18  func dataSourceFile() *schema.Resource {
    19  	return &schema.Resource{
    20  		Read: dataSourceFileRead,
    21  
    22  		Schema: map[string]*schema.Schema{
    23  			"template": &schema.Schema{
    24  				Type:          schema.TypeString,
    25  				Optional:      true,
    26  				Description:   "Contents of the template",
    27  				ConflictsWith: []string{"filename"},
    28  			},
    29  			"filename": &schema.Schema{
    30  				Type:        schema.TypeString,
    31  				Optional:    true,
    32  				Description: "file to read template from",
    33  				// Make a "best effort" attempt to relativize the file path.
    34  				StateFunc: func(v interface{}) string {
    35  					if v == nil || v.(string) == "" {
    36  						return ""
    37  					}
    38  					pwd, err := os.Getwd()
    39  					if err != nil {
    40  						return v.(string)
    41  					}
    42  					rel, err := filepath.Rel(pwd, v.(string))
    43  					if err != nil {
    44  						return v.(string)
    45  					}
    46  					return rel
    47  				},
    48  				Deprecated:    "Use the 'template' attribute instead.",
    49  				ConflictsWith: []string{"template"},
    50  			},
    51  			"vars": &schema.Schema{
    52  				Type:         schema.TypeMap,
    53  				Optional:     true,
    54  				Default:      make(map[string]interface{}),
    55  				Description:  "variables to substitute",
    56  				ValidateFunc: validateVarsAttribute,
    57  			},
    58  			"rendered": &schema.Schema{
    59  				Type:        schema.TypeString,
    60  				Computed:    true,
    61  				Description: "rendered template",
    62  			},
    63  		},
    64  	}
    65  }
    66  
    67  func dataSourceFileRead(d *schema.ResourceData, meta interface{}) error {
    68  	rendered, err := renderFile(d)
    69  	if err != nil {
    70  		return err
    71  	}
    72  	d.Set("rendered", rendered)
    73  	d.SetId(hash(rendered))
    74  	return nil
    75  }
    76  
    77  type templateRenderError error
    78  
    79  func renderFile(d *schema.ResourceData) (string, error) {
    80  	template := d.Get("template").(string)
    81  	filename := d.Get("filename").(string)
    82  	vars := d.Get("vars").(map[string]interface{})
    83  
    84  	contents := template
    85  	if template == "" && filename != "" {
    86  		data, _, err := pathorcontents.Read(filename)
    87  		if err != nil {
    88  			return "", err
    89  		}
    90  
    91  		contents = data
    92  	}
    93  
    94  	rendered, err := execute(contents, vars)
    95  	if err != nil {
    96  		return "", templateRenderError(
    97  			fmt.Errorf("failed to render %v: %v", filename, err),
    98  		)
    99  	}
   100  
   101  	return rendered, nil
   102  }
   103  
   104  // execute parses and executes a template using vars.
   105  func execute(s string, vars map[string]interface{}) (string, error) {
   106  	root, err := hil.Parse(s)
   107  	if err != nil {
   108  		return "", err
   109  	}
   110  
   111  	varmap := make(map[string]ast.Variable)
   112  	for k, v := range vars {
   113  		// As far as I can tell, v is always a string.
   114  		// If it's not, tell the user gracefully.
   115  		s, ok := v.(string)
   116  		if !ok {
   117  			return "", fmt.Errorf("unexpected type for variable %q: %T", k, v)
   118  		}
   119  		varmap[k] = ast.Variable{
   120  			Value: s,
   121  			Type:  ast.TypeString,
   122  		}
   123  	}
   124  
   125  	cfg := hil.EvalConfig{
   126  		GlobalScope: &ast.BasicScope{
   127  			VarMap:  varmap,
   128  			FuncMap: config.Funcs(),
   129  		},
   130  	}
   131  
   132  	result, err := hil.Eval(root, &cfg)
   133  	if err != nil {
   134  		return "", err
   135  	}
   136  	if result.Type != hil.TypeString {
   137  		return "", fmt.Errorf("unexpected output hil.Type: %v", result.Type)
   138  	}
   139  
   140  	return result.Value.(string), nil
   141  }
   142  
   143  func hash(s string) string {
   144  	sha := sha256.Sum256([]byte(s))
   145  	return hex.EncodeToString(sha[:])
   146  }
   147  
   148  func validateVarsAttribute(v interface{}, key string) (ws []string, es []error) {
   149  	// vars can only be primitives right now
   150  	var badVars []string
   151  	for k, v := range v.(map[string]interface{}) {
   152  		switch v.(type) {
   153  		case []interface{}:
   154  			badVars = append(badVars, fmt.Sprintf("%s (list)", k))
   155  		case map[string]interface{}:
   156  			badVars = append(badVars, fmt.Sprintf("%s (map)", k))
   157  		}
   158  	}
   159  	if len(badVars) > 0 {
   160  		es = append(es, fmt.Errorf(
   161  			"%s: cannot contain non-primitives; bad keys: %s",
   162  			key, strings.Join(badVars, ", ")))
   163  	}
   164  	return
   165  }