feat(cli): cdk8s init template for java (#245)

Signed-off-by: campionfellin <campionfellin@gmail.com>

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: campionfellin

packages/cdk8s-cli/bin/cmds/init.ts

@@ -2,6 +2,7 @@ import * as yargs from 'yargs';
 import * as fs from 'fs-extra';
 import * as path from 'path';
 import { sscaff } from 'sscaff';
+const constructsVersion = require('../../package.json').dependencies.constructs;
 
 const templatesDir = path.join(__dirname, '..', '..', 'templates');
 const availableTemplates = fs.readdirSync(templatesDir).filter(x => !x.startsWith('.'));
@@ -41,7 +42,8 @@ async function determineDeps(version: string, dist?: string): Promise<Deps> {
     const ret = {
       'npm_cdk8s': path.resolve(dist, 'js', `cdk8s@${version}.jsii.tgz`),
       'npm_cdk8s_cli': path.resolve(dist, 'js', `cdk8s-cli-${version}.tgz`),
-      'pypi_cdk8s': path.resolve(dist, 'python', `cdk8s-${version.replace(/-/g, '_')}-py3-none-any.whl`)
+      'pypi_cdk8s': path.resolve(dist, 'python', `cdk8s-${version.replace(/-/g, '_')}-py3-none-any.whl`),
+      'mvn_cdk8s': path.resolve(dist, 'java', `org/cdk8s/cdk8s/${version}/cdk8s-${version}.jar`),
     };
 
     for (const file of Object.values(ret)) {
@@ -50,7 +52,15 @@ async function determineDeps(version: string, dist?: string): Promise<Deps> {
       }
     }
 
-    return ret;
+    const versions = {
+      'cdk8s_version': version,
+      'constructs_version': constructsVersion,
+    }
+
+    return {
+      ...ret,
+      ...versions,
+    };
   }
 
   if (version === '0.0.0') {
@@ -67,13 +77,19 @@ async function determineDeps(version: string, dist?: string): Promise<Deps> {
     'npm_cdk8s': `cdk8s@${ver}`,
     'npm_cdk8s_cli': `cdk8s-cli@${ver}`,
     'pypi_cdk8s': `cdk8s~=${version}`, // no support for pre-release
+    'mvn_cdk8s': version,
+    'cdk8s_version': version,
+    'constructs_version': constructsVersion,
   };
 }
 
 interface Deps {
   npm_cdk8s: string;
   npm_cdk8s_cli: string;
   pypi_cdk8s: string;
+  mvn_cdk8s: string;
+  cdk8s_version: string;
+  constructs_version: string;
 }
 
 module.exports = new Command();

packages/cdk8s-cli/templates/java-app/.hooks.sscaff.js

@@ -0,0 +1,34 @@
+const { execSync } = require('child_process');
+const { readFileSync } = require('fs');
+
+const cli = require.resolve('../../bin/cdk8s');
+
+exports.pre = (variables) => {
+  try {
+    execSync('which mvn');
+  } catch {
+    console.error(`Unable to find "mvn". Install from https://maven.apache.org/install.html`);
+    process.exit(1);
+  }
+  variables.constructs_version = variables.constructs_version.replace('^', '').replace('~', '');
+};
+
+exports.post = options => {
+  const { mvn_cdk8s, cdk8s_version } = options;
+  if (!mvn_cdk8s) {
+    throw new Error(`missing context "mvn_cdk8s"`);
+  }
+
+  // This is used for installing artifacts that are local (not from Maven)
+  // https://maven.apache.org/plugins/maven-install-plugin/usage.html
+  if (mvn_cdk8s.endsWith('.jar')) {
+    execSync(`mvn install:install-file -Dfile=${mvn_cdk8s} -DgroupId=org.cdk8s -DartifactId=cdk8s -Dversion=${cdk8s_version} -Dpackaging=jar`)
+  }
+
+  execSync(`mvn install`);
+  execSync(`${cli} import k8s -l java`);
+  execSync(`mvn compile`);
+  execSync(`mvn exec:java -Dexec.mainClass="com.mycompany.app.Main"`);
+
+  console.log(readFileSync('./help', 'utf-8'));
+};

packages/cdk8s-cli/templates/java-app/cdk8s.yaml

@@ -0,0 +1,4 @@
+language: java
+app:  mvn exec:java -Dexec.mainClass="com.mycompany.app.HelloKube"
+imports:
+  - k8s

packages/cdk8s-cli/templates/java-app/help

@@ -0,0 +1,13 @@
+========================================================================================================
+
+ Your cdk8s Java project is ready!
+
+   cat help      Prints this message  
+   cdk8s synth   Synthesize k8s manifests to dist/
+   cdk8s import  Imports k8s API objects to "src/main/java/imports/"
+   mvn compile   Compiles your java packages
+
+  Deploy:
+   kubectl apply -f dist/*.k8s.yaml
+
+========================================================================================================

packages/cdk8s-cli/templates/java-app/pom.xml

@@ -0,0 +1,35 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.mycompany.app</groupId>
+  <artifactId>my-app</artifactId>
+  <packaging>jar</packaging>
+  <version>1.0-SNAPSHOT</version>
+  <name>my-app</name>
+  <url>http://maven.apache.org</url>
+  <dependencies>
+    <dependency>
+      <groupId>org.cdk8s</groupId>
+      <artifactId>cdk8s</artifactId>
+      <version>{{ cdk8s_version }}</version>
+    </dependency>
+    <dependency>
+      <groupId>software.constructs</groupId>
+      <artifactId>constructs</artifactId>
+      <version>{{ constructs_version }}</version>
+    </dependency>
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>29.0-jre</version>
+    </dependency>  
+  </dependencies>
+  <properties>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
+  </properties>
+  <build>
+    <sourceDirectory>src/main/java</sourceDirectory>
+    <testSourceDirectory>src/test/java</testSourceDirectory>
+  </build>
+</project>

packages/cdk8s-cli/templates/java-app/src/main/java/com/mycompany/app/Main.java

@@ -0,0 +1,27 @@
+package com.mycompany.app;
+
+import software.constructs.Construct;
+
+import org.cdk8s.App;
+import org.cdk8s.Chart;
+import org.cdk8s.ChartOptions;
+
+public class Main extends Chart 
+{
+
+    public Main(final Construct scope, final String id) {
+        this(scope, id, null);
+    }
+
+    public Main(final Construct scope, final String id, final ChartOptions options) {
+        super(scope, id, options);
+
+        // define resources here
+    }
+
+    public static void main(String[] args) {
+        final App app = new App();
+        new Main(app, "{{ $base }}");
+        app.synth();
+    }
+}