[mesos] 06/17: Windows: Add comment about V2S2 Docker image Manifest.

[qi...@apache.org]

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qianzhang pushed a commit to branch 1.7.x
in repository https://gitbox.apache.org/repos/asf/mesos.git

commit 88936159fd4700bd064d89165f192fb222361491
Author: Liangyu Zhao <t-...@microsoft.com>
AuthorDate: Wed Aug 29 13:52:18 2018 -0700

    Windows: Add comment about V2S2 Docker image Manifest.
    
    Review: https://reviews.apache.org/r/68562/
---
 src/uri/fetchers/docker.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/uri/fetchers/docker.cpp b/src/uri/fetchers/docker.cpp
index c1012cb..a87d7f0 100644
--- a/src/uri/fetchers/docker.cpp
+++ b/src/uri/fetchers/docker.cpp
@@ -749,6 +749,11 @@ Future<Nothing> DockerFetcherPluginProcess::__fetch(
   // https://docs.docker.com/registry/spec/manifest-v2-2/
   //
   // If fetch is failed, program continues without schema 2 manifest.
+  //
+  // Schema 2 manifest may have foreign URLs to fetch blobs from servers
+  // other than Docker Hub. Some file layers, for example, Windows OS
+  // layers are only stored on Microsoft servers, so only with schema 2
+  // manifest, such layers can be successfully fetched.
   http::Headers s2ManifestHeaders = {
     {"Accept", "application/vnd.docker.distribution.manifest.v2+json"}
   };