feat: Added discovery of Python peer from executors dir

Author: beneboy

src/serve.ts

@@ -21,30 +21,38 @@ replaceHandlers(data =>
   })
 )
 
-// Discover other executors registered on this machine
-// In the future this may attempt to discover remote executors as well
-const manifests = discoverStdio()
-if (manifests.length === 0) {
-  log.warn(
-    'No peer executors discovered on this machine. Executor will have limited capabilities.'
-  )
-}
+async function main() {
+  // Discover other executors registered on this machine
+  // In the future this may attempt to discover remote executors as well
+  const manifests = await discoverStdio()
+  if (manifests.length === 0) {
+    log.warn(
+      'No peer executors discovered on this machine. Executor will have limited capabilities.'
+    )
+  }
 
-// Create a list of client types that can be used by executor
-const clientTypes: ClientType[] = [StdioClient as ClientType]
+  // Create a list of client types that can be used by executor
+  const clientTypes: ClientType[] = [StdioClient as ClientType]
 
-// Create executor that will served by servers
-const executor = new Executor(manifests, clientTypes)
+  // Create executor that will served by servers
+  const executor = new Executor(manifests, clientTypes)
 
-// Add server classes based on supplied options
-const servers: Server[] = []
-if (options.tcp !== undefined) {
-  servers.push(new TcpServer(executor, options.tcp))
-}
-if (servers.length === 0) {
-  log.warn(
-    'No servers specified in options (e.g. --tcp --stdio). Executor will not be accessible.'
-  )
+  // Add server classes based on supplied options
+  const servers: Server[] = []
+  if (options.tcp !== undefined) {
+    servers.push(new TcpServer(executor, options.tcp))
+  }
+  if (servers.length === 0) {
+    log.warn(
+      'No servers specified in options (e.g. --tcp --stdio). Executor will not be accessible.'
+    )
+  }
+
+  executor.start(servers)
 }
 
-executor.start(servers)
+main()
+  .then(() => {})
+  .catch(err => {
+    log.error(err)
+  })

src/stdio/discover.ts

@@ -1,46 +1,89 @@
 import { Manifest } from '../base/Executor'
 import { Transport } from '../base/Transports'
+import * as path from 'path'
+import * as os from 'os'
+import * as fs from 'fs'
+import * as util from 'util'
+import { getLogger } from '@stencila/logga'
 
-export default function discover(): Manifest[] {
+const glob = util.promisify(require('glob'))
+
+const log = getLogger('executa:serve')
+
+const EXECUTORS_DIR_NAME = 'executors'
+
+export default async function discover(): Promise<Manifest[]> {
   // TODO: implement discovery of manifest files from ~/.stencila/executors/ (or similar)
   // Should be able to mostly copy and paste from
   //   https://github.com/stencila/node/blob/24c30d1c89b5f6b6719a0beeda7a55d19401c294/lib/host/Host.js#L654-L666
   // See https://github.com/stencila/executa/issues/2
-  return [python, js]
-}
 
-// These are just stubs to be replaced by JSON read in from manifest.json files...
+  let stencilaHome: string
 
-const python: Manifest = {
-  capabilities: {
-    execute: {
-      type: 'object',
-      required: ['node'],
-      properties: {
-        node: {
-          type: 'object',
-          required: ['type', 'programmingLanguage'],
-          properties: {
-            type: {
-              enum: ['CodeChunk', 'CodeExpression']
-            },
-            programmingLanguage: {
-              enum: ['python']
-            }
-          }
-        }
-      }
+  switch (os.platform()) {
+    case 'darwin':
+      stencilaHome = path.join(
+        process.env.HOME !== undefined ? process.env.HOME : '',
+        'Library',
+        'Application Support',
+        'Stencila'
+      )
+      break
+    case 'linux':
+      stencilaHome = path.join(
+        process.env.HOME !== undefined ? process.env.HOME : '',
+        '.stencila'
+      )
+      break
+    case 'win32': // is 'win32' even on 64 bit windows systems
+      stencilaHome = path.join(
+        process.env.APPDATA !== undefined ? process.env.APPDATA : '',
+        'Stencila'
+      )
+      break
+    default:
+      stencilaHome = path.join(
+        process.env.HOME !== undefined ? process.env.HOME : '',
+        'stencila'
+      )
+  }
+  const executorsDir = path.join(stencilaHome, EXECUTORS_DIR_NAME)
+
+  const manifests: Manifest[] = []
+
+  const discoverDir = async (dir: string): Promise<Manifest | undefined> => {
+    // Check the folder exists (they may not e.g. if no packages have been registered)
+    try {
+      fs.accessSync(dir, fs.constants.R_OK)
+    } catch (error) {
+      return
     }
-  },
-  addresses: {
-    stdio: {
-      type: Transport.stdio,
-      command: 'python3',
-      args: ['-m', 'stencila.schema', 'listen']
+    // For each host in the directory
+    for (const file of await glob(path.join(dir, '*.json'))) {
+      let json
+      try {
+        json = fs.readFileSync(file, { encoding: 'utf8' })
+      } catch (error) {
+        log.warn(`Warning: error reading file "${file}": ${error.message}`)
+        continue
+      }
+
+      try {
+        manifests.push(JSON.parse(json) as Manifest)
+      } catch (error) {
+        log.warn(`Warning: error parsing file "${file}": ${error.message}`)
+      }
     }
   }
+
+  await discoverDir(executorsDir)
+
+  manifests.push(js)
+  return manifests
 }
 
+// These are just stubs to be replaced by JSON read in from manifest.json files...
+
 const js: Manifest = {
   capabilities: {
     execute: {