enable Cache-Control headers on S3 caches

cache/s3/README.md

@@ -4,7 +4,7 @@ s3cache is an abstraction on top of Amazon Web Services (AWS) Simple Storage Ser
 
 ```toml
 [cache]
-type="s3"   
+type="s3"
 bucket="tegola-test-data"
 ```
 
@@ -19,6 +19,8 @@ The s3cache config supports the following properties:
 - `max_zoom` (int): [Optional] the max zoom the cache should cache to. After this zoom, Set() calls will return before doing work.
 - `endpoint` (string): the endpoint where the S3 compliant backend is located. only necessary for non-AWS deployments. defaults to ''.
 - `access_control_list` (string): the S3 access control to set on the file when putting the file. defaults to ''.
+- `cache_control` (string): the HTTP cache control header to set on the file when putting the file. defaults to ''.
+
 
 ## Credential chain
 If the `aws_access_key_id` and `aws_secret_access_key` are not set, then the [credential provider chain](http://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/configuring-sdk.html) will be used. The provider chain supports multiple methods for passing credentials, one of which is setting environment variables. For example:

cache/s3/s3.go

@@ -35,6 +35,7 @@ const (
 	ConfigKeyAWSAccessKeyID = "aws_access_key_id"
 	ConfigKeyAWSSecretKey   = "aws_secret_access_key"
 	ConfigKeyACL            = "access_control_list" //	defaults to ""
+	ConfigKeyCacheControl   = "cache_control" //	defaults to ""
 )
 
 const (
@@ -62,6 +63,7 @@ func init() {
 // 		max_zoom (int): max zoom to use the cache. beyond this zoom cache Set() calls will be ignored
 // 		endpoint (string): the endpoint where the S3 compliant backend is located. only necessary for non-AWS deployments. defaults to ''
 //  	access_control_list (string): the S3 access control to set on the file when putting the file. defaults to ''.
+//  	cache_control (string): the http cache-control header to set on the file when putting the file. defaults to ''.
 
 func New(config dict.Dicter) (cache.Interface, error) {
 	var err error
@@ -155,6 +157,14 @@ func New(config dict.Dicter) (cache.Interface, error) {
 	}
 	s3cache.ACL = acl
 
+	// check for control_access_list env var
+	cachecontrol := os.Getenv("AWS_CacheControl")
+	cachecontrol, err = config.String(ConfigKeyCacheControl, &cachecontrol)
+	if err != nil {
+		return nil, err
+	}
+	s3cache.CacheControl = cachecontrol
+
 	// in order to confirm we have the correct permissions on the bucket create a small file
 	// and test a PUT, GET and DELETE to the bucket
 	key := cache.Key{
@@ -220,6 +230,9 @@ type Cache struct {
 
 	// ACL is the aws ACL, if the not set it will use the default value for aws.
 	ACL string
+
+	// CacheControl is the http Cache Control header, if the not set it will use the default value for aws.
+	CacheControl string
 }
 
 func (s3c *Cache) Set(key *cache.Key, val []byte) error {
@@ -241,6 +254,9 @@ func (s3c *Cache) Set(key *cache.Key, val []byte) error {
 	if s3c.ACL != "" {
 		input.ACL = aws.String(s3c.ACL)
 	}
+	if s3c.CacheControl != "" {
+		input.CacheControl = aws.String(s3c.CacheControl)
+	}
 
 	_, err = s3c.Client.PutObject(&input)
 	if err != nil {