Add experimental javascript hooks

Author: tsmetana

README.md

@@ -20,6 +20,8 @@ It follows the same release cycle as other containers, so the latest release is
 You will need to setup the environment variable `CSI_ENDPOINT` for the mock driver to know where to create the unix
 domain socket.
 
+For more complicated test-cases see [how to use JavaScript hooks from the driver](hooks-howto.md).
+
 ## For CSI Driver Tests
 
 To test drivers please take a look at [pkg/sanity](https://github.com/kubernetes-csi/csi-test/tree/master/pkg/sanity).

cmd/mock-driver/main.go

@@ -18,6 +18,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"net"
 	"os"
 	"os/signal"
@@ -26,17 +27,20 @@ import (
 
 	"github.com/kubernetes-csi/csi-test/v3/driver"
 	"github.com/kubernetes-csi/csi-test/v3/mock/service"
+	"gopkg.in/yaml.v2"
 )
 
 func main() {
 	var config service.Config
+	var hooksFile string = ""
 	flag.BoolVar(&config.DisableAttach, "disable-attach", false, "Disables RPC_PUBLISH_UNPUBLISH_VOLUME capability.")
 	flag.StringVar(&config.DriverName, "name", service.Name, "CSI driver name.")
 	flag.Int64Var(&config.AttachLimit, "attach-limit", 2, "number of attachable volumes on a node")
 	flag.BoolVar(&config.NodeExpansionRequired, "node-expand-required", false, "Enables NodeServiceCapability_RPC_EXPAND_VOLUME capacity.")
 	flag.BoolVar(&config.DisableControllerExpansion, "disable-controller-expansion", false, "Disables ControllerServiceCapability_RPC_EXPAND_VOLUME capability.")
 	flag.BoolVar(&config.DisableOnlineExpansion, "disable-online-expansion", false, "Disables online volume expansion capability.")
 	flag.BoolVar(&config.PermissiveTargetPath, "permissive-target-path", false, "Allows the CO to create PublishVolumeRequest.TargetPath, which violates the CSI spec.")
+	flag.StringVar(&hooksFile, "hooks-file", "", "YAML file with hook scripts.")
 	flag.Parse()
 
 	endpoint := os.Getenv("CSI_ENDPOINT")
@@ -46,6 +50,15 @@ func main() {
 		controllerEndpoint = endpoint
 	}
 
+	if hooksFile != "" {
+		execHooks, err := parseHooksFile(hooksFile)
+		if err == nil {
+			config.ExecHooks = execHooks
+		} else {
+			fmt.Printf("Failed to load hooks file %s: %v", hooksFile, err)
+		}
+	}
+
 	// Create mock driver
 	s := service.New(config)
 
@@ -198,3 +211,20 @@ func listen(endpoint string) (net.Listener, func(), error) {
 	l, err := net.Listen(proto, addr)
 	return l, cleanup, err
 }
+
+func parseHooksFile(file string) (*service.Hooks, error) {
+	var hooks service.Hooks
+
+	fr, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer fr.Close()
+	bytes, _ := ioutil.ReadAll(fr)
+	err = yaml.UnmarshalStrict([]byte(bytes), &hooks)
+	if err != nil {
+		return nil, err
+	}
+	fmt.Printf("Hooks file %s loaded\n", file)
+	return &hooks, err
+}

go.mod

@@ -10,11 +10,13 @@ require (
 	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
 	github.com/onsi/ginkgo v1.10.3
 	github.com/onsi/gomega v1.7.1
+	github.com/robertkrimen/otto v0.0.0-20191219234010-c382bd3c16ff
 	github.com/sirupsen/logrus v1.4.2
 	golang.org/x/net v0.0.0-20191112182307-2180aed22343
 	golang.org/x/sys v0.0.0-20191113165036-4c7a9d0fe056 // indirect
 	golang.org/x/text v0.3.2 // indirect
 	google.golang.org/genproto v0.0.0-20191114150713-6bbd007550de // indirect
 	google.golang.org/grpc v1.25.1
+	gopkg.in/sourcemap.v1 v1.0.5 // indirect
 	gopkg.in/yaml.v2 v2.2.5
 )

go.sum

@@ -34,6 +34,8 @@ github.com/onsi/gomega v1.7.1/go.mod h1:XdKZgCCFLUoM/7CFJVPcG8C1xQ1AJ0vpAezJrB7J
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/robertkrimen/otto v0.0.0-20191219234010-c382bd3c16ff h1:+6NUiITWwE5q1KO6SAfUX918c+Tab0+tGAM/mtdlUyA=
+github.com/robertkrimen/otto v0.0.0-20191219234010-c382bd3c16ff/go.mod h1:xvqspoSXJTIpemEonrMDFq6XzwHYYgToXWj5eRX1OtY=
 github.com/sirupsen/logrus v1.4.2 h1:SPIRibHv4MatM3XXNO2BJeFLZwZ2LvZgfQ5+UNI2im4=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -86,6 +88,8 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/fsnotify.v1 v1.4.7 h1:xOHLXZwVvI9hhs+cLKq5+I5onOuwQLhQwiu63xxlHs4=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
+gopkg.in/sourcemap.v1 v1.0.5 h1:inv58fC9f9J3TK2Y2R1NPntXEn3/wjWHkonhIUODNTI=
+gopkg.in/sourcemap.v1 v1.0.5/go.mod h1:2RlvNNSMglmRrcvhfuzp4hQHwOtjxlbjX7UPY/GXb78=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

hooks-howto.md

@@ -0,0 +1,72 @@
+# JavaScript Hooks in the CSI Mock Driver
+The CSI mock driver can call JavaScript hooks during the execution of the CSI
+method calls. These hooks can be configured in an external YAML file that can be
+passed to the mock driver sidecar container as a `ConfigMap` volume.
+
+## Example
+Here's an usage example of the feature. First, prepare a YAML file defining
+some JavaScript hooks. Let's call it `hooks.yaml`:
+
+```javascript
+globals: |
+  count = 0;
+  console.log("Globals loaded, count set to " + count);
+createVolumeStart: |
+  count = count + 1;
+  console.log("CreateVolumeStart: The value of count is " + count);
+  if (count > 2) { OK; } else { DEADLINEEXCEEDED; };
+createVolumeEnd: |
+  console.log("CreateVolumeEnd");
+```
+
+Create a `ConfigMap` from the YAML:
+
+```sh
+kubectl create configmap hooks-config --from-file hooks.yaml
+```
+Configure the CSI mock driver to use it -- these are the relevant parts of the
+sidecar definition YAMLs:
+
+```yaml
+...
+containers:
+  ...
+  - name: csi-mock-plugin
+    ...
+    args:
+      - --hooks-file=/etc/hooks/hooks.yaml
+    ...
+    volumeMounts:
+      ...
+      - name: hooks-volume
+        mountPath: /etc/hooks
+...
+volumes:
+  - name: hooks-volume
+    configMap:
+      name: hooks-config
+...
+```
+
+Now the driver finds the hooks definitions file and creates a JavaScript VM.
+Just one instance of the VM exists through the life of the driver. It executes
+the pieces of code as per the YAML file. One special case is the `globals` hook
+that is executed right after loading the file and it's intended for variable
+initialization, common function definitions, etc.
+
+Each code snippet is executed at given place in the code: in this example
+`createVolumeStart` at the beginning of the `CreateVolume` method in the driver.
+The result of the hook snipped is evaluated: it would be the value of the last
+expression executed. If the result is an integer value it gets interpreted as
+gRPC code and in case it's non-zero (not `OK`), the CSI driver method would
+return this as its response error. The complete list of the gRPC constants is
+defined in the [hooks-const.go](./mock/service/hooks-const.go) file.
+
+In the example: The variable `count` was initialized to zero in the `globals`
+hook. Each time the `CreateVolume` method is called the hook is executed so
+`count` is increased by one (it's always the same variable) and for the first
+two calls the last expression of the code snipped is `DEADLINEEXCEEDED` which
+causes the `CreateVolume` method to fail with the given code. Subsequent calls
+would return `0` so things would work normally. Also -- the `console.out()`
+allows for logging to stdout so the messages from the hooks appear among the
+output from the driver itself.