sync: periodically retry if on-demand fails inline, closes #281

sync: don't return error on sync signatures, just skip them, closes #375
sync: sync signatures on demand
sync on demand: in case of parallel requests pull image just once, closes #344

Signed-off-by: Petu Eusebiu <peusebiu@cisco.com>

examples/README.md

@@ -386,8 +386,10 @@ Configure each registry sync:
 				"urls": ["https://registry1:5000"],
 				"onDemand": false,                  # pull any image which the local registry doesn't have
 				"pollInterval": "6h",               # polling interval, if not set then periodically polling will not run
-				"tlsVerify": true,                  # whether or not to verify tls
+				"tlsVerify": true,                  # whether or not to verify tls (default is true)
 				"certDir": "/home/user/certs",      # use certificates at certDir path, if not specified then use the default certs dir
+        "maxRetries": 5,                    # mandatory option! maxRetries in case of temporary errors
+				"retryDelay": "10m",                # mandatory option! delay between retries, retry options are applied for both on demand and periodically sync.
 				"content":[                         # which content to periodically pull, also it's used for filtering ondemand images, if not set then periodically polling will not run
 					{
 						"prefix":"/repo1/repo",         # pull image repo1/repo
@@ -409,6 +411,8 @@ Configure each registry sync:
 				"pollInterval": "12h",
 				"tlsVerify": false,
 				"onDemand": false,
+        "maxRetries": 5,
+				"retryDelay": "10m",
 				"content":[
 					{
 						"prefix":"/repo2",
@@ -420,8 +424,10 @@ Configure each registry sync:
 			},
 			{
 				"urls": ["https://docker.io/library"],
-				"onDemand": true,                   # doesn't have content, don't periodically pull, pull just on demand.
-				"tlsVerify": true
+				"onDemand": true,                     # doesn't have content, don't periodically pull, pull just on demand.
+				"tlsVerify": true,
+        "maxRetries": 3,                      
+        "retryDelay": "15m"
 			}
 		]
 		}

examples/config-sync.json

@@ -19,6 +19,8 @@
 				"pollInterval": "6h",
 				"tlsVerify": true,
 				"certDir": "/home/user/certs",
+				"maxRetries": 3,
+				"retryDelay": "5m",
 				"content":[
 					{
 						"prefix":"/repo1/repo",
@@ -37,6 +39,8 @@
 				"pollInterval": "12h",
 				"tlsVerify": false,
 				"onDemand": false,
+				"maxRetries": 5,
+				"retryDelay": "10m",
 				"content":[
 					{
 						"prefix":"/repo2",
@@ -49,7 +53,9 @@
 			{
 				"urls": ["https://docker.io/library"],
 				"onDemand": true,
-				"tlsVerify": true
+				"tlsVerify": true,
+				"maxRetries": 6,
+				"retryDelay": "5m"
 			}
 		]
 		}