Update Provisioner example with ability to trigger dynamic provider change (#513)

* Add a user-settable changeToken property to ConnectionArgs that can be used to detect changes to scripts.

* Add the changeToken property to the input args of the provisioner and the componentresources.

Author: praneetloke

aws-ts-ec2-provisioners/.gitignore

@@ -1,3 +1,5 @@
 rsa
 rsa.pub
 node_modules/
+yarn.lock
+package-lock.json

aws-ts-ec2-provisioners/index.ts

@@ -3,6 +3,7 @@
 import * as aws from "@pulumi/aws";
 import * as pulumi from "@pulumi/pulumi";
 import * as provisioners from "./provisioners";
+import { getFileHash } from "./util";
 
 // Get the config ready to go.
 const config = new pulumi.Config();
@@ -54,22 +55,25 @@ const server = new aws.ec2.Instance("server", {
     keyName: keyName,
     vpcSecurityGroupIds: [ secgrp.id ],
 });
-const conn = {
+const conn: provisioners.ConnectionArgs = {
     host: server.publicIp,
     username: "ec2-user",
     privateKey,
     privateKeyPassphrase,
 };
 
+const changeToken = getFileHash("myapp.conf");
 // Copy a config file to our server.
 const cpConfig = new provisioners.CopyFile("config", {
+    changeToken,
     conn,
     src: "myapp.conf",
     dest: "myapp.conf",
 }, { dependsOn: server });
 
 // Execute a basic command on our server.
 const catConfig = new provisioners.RemoteExec("cat-config", {
+    changeToken,
     conn,
     command: "cat myapp.conf",
 }, { dependsOn: cpConfig });

aws-ts-ec2-provisioners/provisioners/index.ts

@@ -129,14 +129,22 @@ export class CopyFile extends pulumi.ComponentResource {
             `${name}-provisioner`,
             {
                 dep: args.conn,
+                changeToken: args.changeToken,
                 onCreate: (conn) => copyFile(conn, args.src, args.dest),
             },
             { parent: this },
         );
     }
 }
 
-export interface CopyFileArgs {
+interface ChangeTrackingProvisioner {
+    // changeToken allows you to specify a value that controls the replacement of the dependent dynamic resources.
+    // Specifing a value that changes with the content of the file(s) allows the provisioner resources to be
+    // replaced every time the content(s) change.
+    changeToken?: string;
+}
+
+export interface CopyFileArgs extends ChangeTrackingProvisioner {
     // conn contains information on how to connect to the destination, in addition to dependency information.
     conn: pulumi.Input<ConnectionArgs>;
     // src is the source of the file or directory to copy. It can be specified as relative to the current
@@ -175,6 +183,7 @@ export class RemoteExec extends pulumi.ComponentResource {
                     }
                     return results;
                 },
+                changeToken: args.changeToken,
             },
             { parent: this },
         );
@@ -184,7 +193,7 @@ export class RemoteExec extends pulumi.ComponentResource {
     }
 }
 
-export interface RemoteExecArgs {
+export interface RemoteExecArgs extends ChangeTrackingProvisioner {
     // The connection to use for the remote command execution.
     conn: ConnectionArgs;
     // The command to execute.  Exactly one of 'command' and 'commands' is required.

aws-ts-ec2-provisioners/provisioners/provisioner.ts

@@ -11,10 +11,23 @@ export class Provisioner<T, U> extends pulumi.dynamic.Resource {
     constructor(name: string, props: ProvisionerProperties<T, U>, opts?: pulumi.CustomResourceOptions) {
         const provider: pulumi.dynamic.ResourceProvider = {
             diff: async (id: pulumi.ID, olds: State<T, U>, news: State<T, U>) => {
-                const replace = JSON.stringify(olds.dep) !== JSON.stringify(news.dep);
+                let replace = false;
+                let replacementProperties = [];
+                if (JSON.stringify(olds.dep) !== JSON.stringify(news.dep)) {
+                    replace = true;
+                    replacementProperties.push("dep");
+                }
+                // Only trigger replacement due to the `changeToken` property, IFF
+                // the changeToken still has a value in the new inputs, and it doesn't
+                // match with the old value. If, say, the user decides to no longer specify
+                // the changeToken in the new inputs, then we don't trigger a replacement.
+                if (news.changeToken && olds.changeToken !== news.changeToken) {
+                    replace = true;
+                    replacementProperties.push("changeToken");
+                }
                 return {
                     changes: replace,
-                    replaces: replace ? ["dep"] : undefined,
+                    replaces: replace ? replacementProperties : undefined,
                     deleteBeforeReplace: true,
                 };
             },
@@ -32,10 +45,12 @@ export class Provisioner<T, U> extends pulumi.dynamic.Resource {
 
 export interface ProvisionerProperties<T, U> {
     dep: pulumi.Input<T>;
+    changeToken: pulumi.Input<string>;
     onCreate: (dep: pulumi.Unwrap<T>) => Promise<pulumi.Unwrap<U>>;
 }
 
 interface State<T, U> {
     dep: pulumi.Unwrap<T>;
+    changeToken: pulumi.Unwrap<string>;
     result: pulumi.Unwrap<U>;
 }

aws-ts-ec2-provisioners/util.ts

@@ -0,0 +1,12 @@
+// Copyright 2016-2020, Pulumi Corporation.  All rights reserved.
+
+import * as crypto from "crypto";
+import * as fs from "fs";
+import * as path from "path";
+
+// getFileHash calculates a hash for all of the files under the scripts directory.
+export function getFileHash(filename: string): string {
+    const data = fs.readFileSync(path.join(__dirname, filename), {encoding: "utf8"});
+    const hash = crypto.createHash("md5").update(data, "utf8");
+    return hash.digest("hex");
+}