Add basic config command (#33)

* add basic config command

* Add a success message

* Grammar

* Remove extra spaces

Readme.md

@@ -56,9 +56,13 @@ produce the [pkg](https://github.com/zeit/pkg) binaries.
 
 ## Setup
 
-Configuration of one or more providers via `login` command is necessary. If no logins are active and `now`
+Configuration of one or more providers via `login` command is necessary.
 
-Global configuration is stored as `~/.now/config.json`. Your default provider will be the first one you log in to.
+Global configuration is stored as `~/.now/config.json`. Your default provider will be the first one you log in to. If you are logged into multiple providers and want to set default provider, run:
+
+```
+now config set defaultProvider gcp
+```
 
 ### Now.sh
 
@@ -85,7 +89,7 @@ to synchronize your credentials.
 Serverless deployments are provisioned by using:
 
 - Lambda functions λ
-	- A proxy is automatically used to bridge the API between 
+	- A proxy is automatically used to bridge the API between
 	  HTTP and lambda functions and retain a consistent interface
 - Certificate Manager
 - API Gateway
@@ -136,7 +140,7 @@ The v1 release of `now.json` includes the following specification:
 - `env` (optional). One of
   - `Object` a dictionary mapping the name of the environmental variable
     to expose to the deployment and its value.
-    If the value begins with `@`, it's considered a 
+    If the value begins with `@`, it's considered a
   - `Array` a list of suggested environmental variables that the project
     _might_ require to be deployed and function correctly
 - `regions` - `Array` of `String`
@@ -234,13 +238,13 @@ or framework are present, attempt to provide sane defaults.
 
 Examples of this is the presence of `Dockerfile` or `package.json`. When
 publishing a project it's recommended that the [`type`](#type) is strictly
-configured in [`now.json`](#now-json) to avoid 
+configured in [`now.json`](#now-json) to avoid
 
 ## Contributions and Roadmap
 
 #### Community
 
-All feedback and suggestions are welcome! 
+All feedback and suggestions are welcome!
 
 - 💬 Chat: Join us on [zeit.chat](https://zeit.chat) `#now-client`.
 - 📣 Stay up to date on new features and announcments on [@zeithq](https://twitter.com/zeithq).
@@ -284,4 +288,3 @@ npm run build
 
 Now is licensed under the Apache License, Version 2.0.
 See LICENSE for the full license text.
-

src/config/help.js

@@ -0,0 +1,25 @@
+const { bold } = require('chalk')
+const cmd = require('../util/output/cmd')
+const li = require('../util/output/list-item')
+const link = require('../util/output/link')
+
+// prettier-disable
+const help = () =>
+  console.log(
+    `
+  ${bold('now config [subcommand]')}: manage global configuration.
+
+  Subcommands:
+
+    ${li('set <name> <value>')}
+    ${li('help')}
+
+  For example, to set default provider to AWS Lambda, run:
+
+    ${cmd('now config set defaultProvider aws')}
+
+  For more information: ${link('https://github.com/zeit/now')}.
+`
+  )
+
+module.exports = help

src/config/index.js

@@ -0,0 +1,11 @@
+module.exports = {
+  subcommands: new Set(['help', 'set']),
+
+  get help() {
+    return require('./help')
+  },
+
+  get set() {
+    return require('./set')
+  }
+}

src/config/set.js

@@ -0,0 +1,38 @@
+const debug = require('debug')('now:config:set')
+const error = require('../util/output/error')
+const success = require('../util/output/success')
+const param = require('../util/output/param')
+const hp = require('../util/humanize-path')
+const { writeToConfigFile, getConfigFilePath } = require('../util/config-files')
+
+const CONFIGS = new Map([
+  [
+    'defaultProvider',
+    value => {
+      const providers = require('../providers')
+      return providers.hasOwnProperty(value)
+    }
+  ]
+])
+
+module.exports = function set(ctx) {
+  const [name, value] = ctx.argv.slice(4)
+
+  debug('setting config %s to %s', name, value)
+
+  if (!CONFIGS.has(name)) {
+    console.error(error(`Unexpected config name: ${name}`))
+    return 1
+  }
+
+  const validate = CONFIGS.get(name)
+  if (!validate(value)) {
+    console.error(error(`Unexpected config value for ${name}: ${value}`))
+    return 1
+  }
+
+  ctx.config[name] = value
+  writeToConfigFile(ctx.config)
+
+  console.log(success(`Config saved in ${param(hp(getConfigFilePath()))}`))
+}

src/now.js

@@ -245,6 +245,31 @@ const main = async (argv_): Promise<number> => {
     )
   }
 
+  // the context object to supply to the providers or the commands
+  const ctx = {
+    config,
+    authConfig,
+    argv: argv_
+  }
+
+  if (targetOrSubcommand === 'config') {
+    const _config = require('./config')
+    const subcommand = _config.subcommands.has(argv._[3]) ? argv._[3] : 'help'
+
+    debug(`executing config %s`, subcommand)
+
+    try {
+      return _config[subcommand](ctx)
+    } catch (err) {
+      console.error(
+        error(
+          `An unexpected error occurred in config ${subcommand}: ${err.stack}`
+        )
+      )
+      return 1
+    }
+  }
+
   let suppliedProvider = null
 
   // if the target is something like `aws`
@@ -304,13 +329,6 @@ const main = async (argv_): Promise<number> => {
 
   const provider: Object = providers[suppliedProvider || defaultProvider]
 
-  // the context object to supply to the providers
-  const ctx = {
-    config,
-    authConfig,
-    argv: argv_
-  }
-
   let subcommand
 
   // we check if we are deploying something