From 69cbb964e1ce12ea4cba270859c3064093383675 Mon Sep 17 00:00:00 2001
From: Danielle Lancashire <dani@hashicorp.com>
Date: Tue, 11 Feb 2020 14:30:34 +0100
Subject: [PATCH] client: Pass an RPC Client to AllocRunners

As part of introducing support for CSI, AllocRunner hooks need to be
able to communicate with Nomad Servers for validation of and interaction
with storage volumes. Here we create a small RPCer interface and pass
the client (rpc client) to the AR in preparation for making these RPCs.
---
 client/allocrunner/alloc_runner.go       | 10 ++++++++++
 client/allocrunner/alloc_runner_hooks.go |  2 +-
 client/allocrunner/config.go             |  4 ++++
 client/allocrunner/csi_hook.go           | 12 +++++++-----
 client/client.go                         |  2 ++
 5 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/client/allocrunner/alloc_runner.go b/client/allocrunner/alloc_runner.go
index 4cdf4ee00..cd43318c1 100644
--- a/client/allocrunner/alloc_runner.go
+++ b/client/allocrunner/alloc_runner.go
@@ -158,6 +158,15 @@ type allocRunner struct {
 	serversContactedCh chan struct{}
 
 	taskHookCoordinator *taskHookCoordinator
+
+	// rpcClient is the RPC Client that should be used by the allocrunner and its
+	// hooks to communicate with Nomad Servers.
+	rpcClient RPCer
+}
+
+// RPCer is the interface needed by hooks to make RPC calls.
+type RPCer interface {
+	RPC(method string, args interface{}, reply interface{}) error
 }
 
 // NewAllocRunner returns a new allocation runner.
@@ -193,6 +202,7 @@ func NewAllocRunner(config *Config) (*allocRunner, error) {
 		devicemanager:            config.DeviceManager,
 		driverManager:            config.DriverManager,
 		serversContactedCh:       config.ServersContactedCh,
+		rpcClient:                config.RPCClient,
 	}
 
 	// Create the logger based on the allocation ID
diff --git a/client/allocrunner/alloc_runner_hooks.go b/client/allocrunner/alloc_runner_hooks.go
index 793ec530b..d37dd1dff 100644
--- a/client/allocrunner/alloc_runner_hooks.go
+++ b/client/allocrunner/alloc_runner_hooks.go
@@ -134,7 +134,7 @@ func (ar *allocRunner) initRunnerHooks(config *clientconfig.Config) error {
 			logger:         hookLogger,
 		}),
 		newConsulSockHook(hookLogger, alloc, ar.allocDir, config.ConsulConfig),
-		newCSIHook(hookLogger, alloc),
+		newCSIHook(hookLogger, alloc, ar.rpcClient),
 	}
 
 	return nil
diff --git a/client/allocrunner/config.go b/client/allocrunner/config.go
index 257d8db69..8eb013ede 100644
--- a/client/allocrunner/config.go
+++ b/client/allocrunner/config.go
@@ -68,4 +68,8 @@ type Config struct {
 	// ServersContactedCh is closed when the first GetClientAllocs call to
 	// servers succeeds and allocs are synced.
 	ServersContactedCh chan struct{}
+
+	// RPCClient is the RPC Client that should be used by the allocrunner and its
+	// hooks to communicate with Nomad Servers.
+	RPCClient RPCer
 }
diff --git a/client/allocrunner/csi_hook.go b/client/allocrunner/csi_hook.go
index cccd66397..edb427398 100644
--- a/client/allocrunner/csi_hook.go
+++ b/client/allocrunner/csi_hook.go
@@ -10,8 +10,9 @@ import (
 //
 // It is a noop for allocs that do not depend on CSI Volumes.
 type csiHook struct {
-	alloc  *structs.Allocation
-	logger hclog.Logger
+	alloc     *structs.Allocation
+	logger    hclog.Logger
+	rpcClient RPCer
 }
 
 func (c *csiHook) Name() string {
@@ -27,10 +28,11 @@ func (c *csiHook) Prerun() error {
 	return nil
 }
 
-func newCSIHook(logger hclog.Logger, alloc *structs.Allocation) *csiHook {
+func newCSIHook(logger hclog.Logger, alloc *structs.Allocation, rpcClient RPCer) *csiHook {
 	return &csiHook{
-		alloc:  alloc,
-		logger: logger.Named("csi_hook"),
+		alloc:     alloc,
+		logger:    logger.Named("csi_hook"),
+		rpcClient: rpcClient,
 	}
 }
 
diff --git a/client/client.go b/client/client.go
index fae2b2928..05ce5dd6a 100644
--- a/client/client.go
+++ b/client/client.go
@@ -1088,6 +1088,7 @@ func (c *Client) restoreState() error {
 			DeviceManager:       c.devicemanager,
 			DriverManager:       c.drivermanager,
 			ServersContactedCh:  c.serversContactedCh,
+			RPCClient:           c,
 		}
 		c.configLock.RUnlock()
 
@@ -2351,6 +2352,7 @@ func (c *Client) addAlloc(alloc *structs.Allocation, migrateToken string) error
 		CSIManager:          c.csimanager,
 		DeviceManager:       c.devicemanager,
 		DriverManager:       c.drivermanager,
+		RPCClient:           c,
 	}
 	c.configLock.RUnlock()