limit concurrent command execution

Author: Pytal

package.json

@@ -14,7 +14,8 @@
     "terse": "ts-node scripts/terse.ts lib/"
   },
   "dependencies": {
-    "env-cmd": "^10.1.0"
+    "env-cmd": "^10.1.0",
+    "p-limit": "^3.0.1"
   },
   "devDependencies": {
     "@types/node": "^14.0.19",

src/helpers/helpers.ts

@@ -1,8 +1,11 @@
 import { access } from 'fs/promises'
 import { exec as execCallback } from 'child_process'
+import pLimit = require('p-limit')
 
 export const exists = (path: string) => access(path).then(_ => true).catch(_ => false)
 
 export const exec = (cmd: string): Promise<string> => new Promise( (res,rej) =>
   execCallback( cmd, (_,stdout,stderr) => res(stdout + stderr) )
 )
+
+export const limit = pLimit(8)

src/utils/vercel-env.ts

@@ -1,4 +1,4 @@
-import { exec } from '../helpers/helpers'
+import { exec, limit } from '../helpers/helpers'
 import { printStdout } from '../helpers/print'
 import { getEnvVarMap } from './get-env'
 import type { DeploymentEnv, EnvVarMap } from '../types/types'
@@ -7,7 +7,7 @@ const removeEnv = async (deploymentEnv: DeploymentEnv, envVarMap: EnvVarMap) =>
   const stdoutList: Promise<void>[] = []
   for (const varName in envVarMap) {
     stdoutList.push(
-      exec( `vercel env rm ${varName} ${deploymentEnv} -y` ).then(printStdout)
+      limit(() => exec( `vercel env rm ${varName} ${deploymentEnv} -y` ).then(printStdout))
     )
   }
 
@@ -19,7 +19,7 @@ const addEnv = async (deploymentEnv: DeploymentEnv, envVarMap: EnvVarMap) => {
   for (const varName in envVarMap) {
     const varValue = envVarMap[varName]
     stdoutList.push(
-      exec( `echo -n ${varValue} | vercel env add ${varName} ${deploymentEnv}` ).then(printStdout)
+      limit(() => exec( `echo -n ${varValue} | vercel env add ${varName} ${deploymentEnv}` ).then(printStdout))
     )
   }