diff options
| author | Sami Hiltunen <shiltunen@gitlab.com> | 2021-03-17 14:11:31 +0300 |
|---|---|---|
| committer | Sami Hiltunen <shiltunen@gitlab.com> | 2021-03-29 14:32:55 +0300 |
| commit | 0aa12d0e309cd7eccb95b2a228078c4c4fc9b7a8 (patch) | |
| tree | 8fa69088f999ef787a29e82e1b9fd9bae253b723 /go.sum | |
| parent | dec655a6dbf2a93b09ba738f94f74132e5bdcc7f (diff) | |
add backchannel package for bidirectional gRPC invocations
When Gitaly needs to cast a vote for a reference transaction, it
currently relies on Praefect to provide address information and tokens
needed to dial to the Praefect for voting. This can be problematic as
Praefect's listening socket may not be reachable by the Gitaly. Configuring
TLS provides additional challenges, as Gitaly would need to have the certificates
to identify the Praefect.
Praefect already establishes a connection to Gitaly, so we can avoid these problems
by piggybacking Gitaly's votes through that same connection. This piggybacking could
be implemented as persistent bidi stream that Praefect calls Gitaly with. However, this
leaves a lot of the complexities managed by gRPC up to us, such as request routing,
concurrency handling, cancellations and request packing.
In order to leverage gRPC for the above, we can instead multiplex the network
connection established by Praefect in order to run multiple gRPC/HTTP2 sessions in it.
This allows for dialing from Gitaly to a gRPC server running on Praefect's end of the
established connection. This allows us to rely on simply using gRPC in the usual fashion
to communicate with the transaction service running in Praefect.
The implementation has components in the client and the server.
The client implements a function, a ServerFactory, that returns a server that should
serve on the client's end of the connection. It implements a ClientHanshake which multiplexes
the connection and starts the backchannel server on it. The gRPC ClientConn itself looks like
normal ClientConn to the rest of the code.
The server implements most of the functionality in gRPC's ServerHandshake. When a connection
is established, the server peeks the stream to see if the client has indicated it supports
multiplexing. Client indicates this by sending magic bytes to the server after establishing
the connection. If the client is not multiplexing aware, the server handles the connection
as it does usually. If the client is multiplexing aware, the server establishes a multiplexing
session, dials the client's backchannel server and starts serving the connection as usual.
The ServerHandshake injects an identifier which can be accessed through the RPC handler's
context. The ID can be used to retrieve the peer's backchannel connection when it is needed,
namely when the votes need to be cast. Connections are uniquely identified by an incrementing
counter, so no ID can ever refer to the wrong peer.
Diffstat (limited to 'go.sum')
| -rw-r--r-- | go.sum | 8 |
1 files changed, 2 insertions, 6 deletions
@@ -196,6 +196,8 @@ github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ github.com/hashicorp/golang-lru v0.5.4 h1:YDjusn29QI/Das2iO9M0BHnIbxPeyuCHsjMW+lJfyTc= github.com/hashicorp/golang-lru v0.5.4/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4= github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ= +github.com/hashicorp/yamux v0.0.0-20210316155119-a95892c5f864 h1:Y4V+SFe7d3iH+9pJCoeWIOS5/xBJIFsltS7E+KJSsJY= +github.com/hashicorp/yamux v0.0.0-20210316155119-a95892c5f864/go.mod h1:CtWFDAQgb7dxtzFs4tWbplKIe2jSi3+5vKbgIO0SLnQ= github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI= github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU= github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc= @@ -304,14 +306,10 @@ github.com/opentracing/opentracing-go v1.2.0 h1:uEJPy/1a5RIPAJ0Ov+OIO8OxWu77jEv+ github.com/opentracing/opentracing-go v1.2.0/go.mod h1:GxEUsuufX4nBwe+T+Wl9TAgYrxe9dPLANfrWvHYVTgc= github.com/otiai10/copy v1.0.1 h1:gtBjD8aq4nychvRZ2CyJvFWAw0aja+VHazDdruZKGZA= github.com/otiai10/copy v1.0.1/go.mod h1:8bMCJrAqOtN/d9oyh5HR7HhLQMvcGMpGdwRDYsfOCHc= -github.com/otiai10/copy v1.0.1/go.mod h1:8bMCJrAqOtN/d9oyh5HR7HhLQMvcGMpGdwRDYsfOCHc= -github.com/otiai10/copy v1.0.1/go.mod h1:8bMCJrAqOtN/d9oyh5HR7HhLQMvcGMpGdwRDYsfOCHc= github.com/otiai10/curr v0.0.0-20150429015615-9b4961190c95/go.mod h1:9qAhocn7zKJG+0mI8eUu6xqkFDYS2kb2saOteoSB3cE= github.com/otiai10/curr v1.0.0 h1:TJIWdbX0B+kpNagQrjgq8bCMrbhiuX73M2XwgtDMoOI= github.com/otiai10/curr v1.0.0/go.mod h1:LskTG5wDwr8Rs+nNQ+1LlxRjAtTZZjtJW4rMXl6j4vs= github.com/otiai10/mint v1.2.3/go.mod h1:YnfyPNhBvnY8bW4SGQHCs/aAFhkgySlMZbrF5U0bOVw= -github.com/otiai10/mint v1.2.3/go.mod h1:YnfyPNhBvnY8bW4SGQHCs/aAFhkgySlMZbrF5U0bOVw= -github.com/otiai10/mint v1.2.3/go.mod h1:YnfyPNhBvnY8bW4SGQHCs/aAFhkgySlMZbrF5U0bOVw= github.com/otiai10/mint v1.3.0 h1:Ady6MKVezQwHBkGzLFbrsywyp09Ah7rkmfjV3Bcr5uc= github.com/otiai10/mint v1.3.0/go.mod h1:F5AjcsTsWUqX+Na9fpHb52P8pcRX2CI6A3ctIT91xUo= github.com/pborman/getopt v0.0.0-20170112200414-7148bc3a4c30/go.mod h1:85jBQOZwpVEaDAr341tbn15RS4fCAsIst0qp7i8ex1o= @@ -360,7 +358,6 @@ github.com/sebest/xff v0.0.0-20160910043805-6c115e0ffa35/go.mod h1:wozgYq9WEBQBa github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo= github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc= github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo= -github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo= github.com/sirupsen/logrus v1.3.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo= github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE= github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88= @@ -423,7 +420,6 @@ gitlab.com/gitlab-org/gitaly v1.68.0/go.mod h1:/pCsB918Zu5wFchZ9hLYin9WkJ2yQqdVN gitlab.com/gitlab-org/gitlab-shell v1.9.8-0.20201117050822-3f9890ef73dc h1:ENBJqb2gK3cZFHe8dbEM/TPXCwkAxDuxGK255ux4XPg= gitlab.com/gitlab-org/gitlab-shell v1.9.8-0.20201117050822-3f9890ef73dc/go.mod h1:5QSTbpAHY2v0iIH5uHh2KA9w7sPUqPmnLjDApI/sv1U= gitlab.com/gitlab-org/labkit v0.0.0-20190221122536-0c3fc7cdd57c/go.mod h1:rYhLgfrbEcyfinG+R3EvKu6bZSsmwQqcXzLfHWSfUKM= -gitlab.com/gitlab-org/labkit v0.0.0-20190221122536-0c3fc7cdd57c/go.mod h1:rYhLgfrbEcyfinG+R3EvKu6bZSsmwQqcXzLfHWSfUKM= gitlab.com/gitlab-org/labkit v0.0.0-20200908084045-45895e129029/go.mod h1:SNfxkfUwVNECgtmluVayv0GWFgEjjBs5AzgsowPQuo0= gitlab.com/gitlab-org/labkit v1.0.0 h1:t2Wr8ygtvHfXAMlCkoEdk5pdb5Gy1IYdr41H7t4kAYw= gitlab.com/gitlab-org/labkit v1.0.0/go.mod h1:nohrYTSLDnZix0ebXZrbZJjymRar8HeV2roWL5/jw2U= |