Add dependency check (fix #22) (#27)

index.js

@@ -2,6 +2,7 @@
 const yargs       = require('yargs');
 const { version } = require('./package.json');
 
+const { check } = require('./lib/dependencies');
 const env = require('./lib/env');
 
 // Environment reset/sanity check
@@ -12,6 +13,7 @@ const env = require('./lib/env');
     await env.setup();
 
     yargs
+        .middleware(check)
         .commandDir('./lib/commands')
         .version()
         .epilog(version ? `Version: ${version}`: '')

lib/args.js

@@ -2,7 +2,7 @@ const providers = Object.keys(require('./providers'));
 
 const providerArg = {
     alias: 'p',
-    choices: providers,
+    choices: ['hyperkit', 'kvm', 'virtualbox'],
     default: defaultProvider(),
     description: 'the vm provider to use',
     type: 'string'

lib/dependencies.js

@@ -0,0 +1,42 @@
+const hasbin = require('hasbin');
+
+const providers = Object.keys(require('./providers'));
+
+const { error } = require('./logger');
+
+const depMap = {
+    'build': [
+        () => mustBin('cpio'),
+        () => mustBin('docker'),
+        () => mustBin('gzip'),
+        () => mustBin('mkisofs'),
+    ],
+    'delete': [],
+    'images': [],
+    'run': [],
+    'vms': []
+}
+
+const mustBin = bin => {
+    if (!hasbin.sync(bin)) throw `You must have ${bin} installed to build a microkernel`;
+}
+
+exports.check = argv => {
+    let cmd = argv._[0];
+
+    try {
+        if (providers.length === 0) {
+            throw 'You don\'t have any providers installed! Please see the docs for a list of supported providers';
+        }
+
+        let { provider } = argv;
+        if (provider && providers.indexOf(provider) === -1) {
+            throw `Provider ${provider} is not installed! Please see the docs for a list of supported providers`;
+        }
+
+        depMap[cmd].forEach(d => d(argv));
+    } catch (e) {
+        error(e);
+        process.exit(1);
+    }
+};

lib/providers.js

@@ -1,12 +1,9 @@
 const hasbin = require('hasbin');
 
 // TODO add hyperkit
-const kvm = require('./providers/kvm');
-const vbox = require('./providers/virtualbox');
-
 const providers = {};
 
-if (hasbin.sync('virsh')) providers['kvm'] = kvm;
-if (hasbin.sync('vboxmanage')) providers['virtualbox'] = vbox;
+if (hasbin.sync('virsh')) providers['kvm'] = require('./providers/kvm');
+if (hasbin.sync('vboxmanage')) providers['virtualbox'] = require('./providers/virtualbox');
 
 module.exports = providers;