Add google_storage_object_signed_url documentation.

builtin/providers/google/data_source_storage_object_signed_url.go

@@ -176,7 +176,7 @@ func loadJwtConfig(d *schema.ResourceData, meta interface{}) (*jwt.Config, error
 		return cfg, nil
 	}
 
-	return nil, fmt.Errorf("Credentials not provided in resource or provider configuration or GOOGLE_APPLICATION_CREDENTIALS environment variable.")
+	return nil, fmt.Errorf("Credentials not found in datasource, provider configuration or GOOGLE_APPLICATION_CREDENTIALS environment variable.")
 }
 
 func guessUnixHomeDir() string {
@@ -281,6 +281,7 @@ func (u *UrlData) BuildUrl() string {
 }
 
 func SignString(toSign []byte, cfg *jwt.Config) ([]byte, error) {
+	// Parse private key
 	pk, err := parsePrivateKey(cfg.PrivateKey)
 	if err != nil {
 		return nil, fmt.Errorf("could not parse key: %v\nKey:%s", err, string(cfg.PrivateKey))
@@ -290,9 +291,10 @@ func SignString(toSign []byte, cfg *jwt.Config) ([]byte, error) {
 	hasher := sha256.New()
 	hasher.Write(toSign)
 
+	// Sign string
 	signed, err := rsa.SignPKCS1v15(rand.Reader, pk, crypto.SHA256, hasher.Sum(nil))
 	if err != nil {
-		return nil, fmt.Errorf("Error from signing: %s\n", err)
+		return nil, fmt.Errorf("error signing string: %s\n", err)
 	}
 
 	return signed, nil

website/source/docs/providers/google/d/signed_url.html.markdown

@@ -0,0 +1,54 @@
+---
+layout: "google"
+page_title: "Google: google_storage_object_signed_url"
+sidebar_current: "docs-google-datasource-signed_url"
+description: |-
+    Provides signed URL to Google Cloud Storage object.
+---
+
+# google\_storage\_object\_signed_url
+
+The Google Cloud storage signed URL data source generates a signed URL for a given storage object. Signed URLs provide a way to give time-limited read or write access to anyone in possession of the URL, regardless of whether they have a Google account.
+
+For more info about signed URL's is available [here](https://cloud.google.com/storage/docs/access-control/signed-urls).
+
+## Example Usage
+
+```
+data "google_storage_object_signed_url" "artifact" {
+  bucket = "install_binaries"
+  path   = "path/to/install_file.bin"
+
+}
+
+resource "google_compute_instance" "vm" {
+    name = "vm"
+    ...
+    
+    provisioner "remote-exec" {
+        inline = [
+                "wget ${data.google_storage_object_signed_url.artifact.signed_url}",
+                "chmod +x install_file.bin",
+                "./install_file.bin"
+                ]
+     }
+}
+```
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `bucket` - (Required) The name of the bucket to read the object from
+* `path` - (Required) The full path to the object inside the bucket
+* `http_method` - (Optional) What HTTP Method will the signed URL allow (defaults to `GET`)
+* `duration` - (Optional) For how long shall the signed URL be valid (defaults to 1 hour `1h`). See [here](https://golang.org/pkg/time/#ParseDuration) for info on valid duration formats.
+* `credentials` - (Optional) What Google service account credentials json should be used to sign the URL. This data source checks the following locations for credentials, in order of preference: data source `credentials` attribute, provider `credentials` attribute and finally the GOOGLE_APPLICATION_CREDENTIALS environment variable.
+    
+> **NOTE** the default google credentials configured by `gcloud` sdk or the service account associated with a compute instance cannot be used, because these do not include the private key required to sign the URL. A valid `json` service account credentials key file must be used, as generated via Google cloud console. 
+
+## Attributes Reference
+
+The following attributes are exported:
+
+* `signed_url` - The signed URL that can be used to access the storage object without authentication.

website/source/layouts/google.erb

@@ -10,6 +10,15 @@
 		<a href="/docs/providers/google/index.html">Google Provider</a>
 		</li>
 
+        <li<%= sidebar_current(/^docs-google-datasource/) %>>
+        <a href="#">Data Sources</a>
+            <ul class="nav nav-visible">
+                <li<%= sidebar_current("docs-google-datasource-signed_url") %>>
+                    <a href="/docs/providers/google/d/signed_url.html">google_storage_object_signed_url</a>
+                </li>
+            </ul>
+        </li>
+
 		<li<%= sidebar_current(/^docs-google-compute/) %>>
 		<a href="#">Google Compute Engine Resources</a>
 		<ul class="nav nav-visible">