Ecosystem File

Ecosystem File

PM2 empowers your process management workflow. It allows you to fine-tune the behavior, options, environment variables, logs files of each application via a process file. It’s particularly useful for micro-service based applications.

Configuration format supported are Javascript, JSON and YAML.

Generate configuration

To generate a sample process file you can type this command:

pm2 ecosystem

This will generate a sample ecosystem.config.js:

module.exports = {
  apps : [{
    name: "app",
    script: "./app.js",
    env: {
      NODE_ENV: "development",
    },
    env_production: {
      NODE_ENV: "production",
    }
  }]
}

Once edited at your convenience you can start/restart/stop/delete this file via CLI:

$ pm2 [start|restart|stop|delete] ecosystem.config.js

Checkout the section about acting with CLI on ecosystem.config.js to know more.

Javascript format

You can declare multiple application easily and specify different options for each of them:

module.exports = {
  apps : [{
    name        : "worker",
    script      : "./worker.js",
    watch       : true,
    env: {
      "NODE_ENV": "development",
    },
    env_production : {
       "NODE_ENV": "production"
    }
  },{
    name       : "api-app",
    script     : "./api.js",
    instances  : 4,
    exec_mode  : "cluster"
  }]
}

Note that using a Javascript configuration file requires to end the file name with .config.js

YAML format

You can also create a Ecosystem file in YAML format. Example:

apps:
  - script   : ./api.js
    name     : 'api-app'
    instances: 4
    exec_mode: cluster
  - script : ./worker.js
    name   : 'worker'
    watch  : true
    env    :
      NODE_ENV: development
    env_production:
      NODE_ENV: production

CLI

Then you can run and manage your processes easily:

# Start all applications
pm2 start ecosystem.config.js

# Start only the app named worker-app
pm2 start ecosystem.config.js --only worker-app

# Stop all
pm2 stop ecosystem.config.js

# Restart all
pm2 start   ecosystem.config.js
## Or
pm2 restart ecosystem.config.js

# Reload all
pm2 reload ecosystem.config.js

# Delete all
pm2 delete ecosystem.config.js

Act on a specific process

You can also act on a particular application by using its name and the option --only <app_name>:

pm2 start   ecosystem.config.js --only api-app
pm2 restart ecosystem.config.js --only api-app
pm2 reload  ecosystem.config.js --only api-app
pm2 delete  ecosystem.config.js --only api-app

Switching environments

You may have noticed that you can declare environment-specific variables with the attribute env_* (e.g. env_production, env_staging…). They can be switched easily. You just need to specify the --env <environment_name> when acting on the application declaration.

Example:

# Inject what is declared in env_production
pm2 start process.json --env production

# Inject what is declared in env_staging
pm2 restart process.json --env staging

Attributes available

Application behavior and configuration can be fine-tuned with the following attributes:

General

Advanced features

Log files

Control flow

Deployment

Considerations

All command line options passed when using the JSON app declaration will be dropped i.e.

Multiple JSON

You can start as many JSON application declarations as you want.

$ cat node-app-1.json
{
  "name" : "node-app-1",
  "script" : "app.js",
  "cwd" : "/srv/node-app-1/current"
}

$ cat node-app-2.json
{
  "name" : "node-app-2",
  "script" : "app2.js",
  "cwd" : "/srv/node-app-2/current"
}

pm2 start node-app-1.json
pm2 start node-app-2.json

Will result in two apps launched:

ps aux | grep node-app
root  14735  5.8  1.1  752476  83932 ? Sl 00:08 0:00 pm2: node-app-1
root  24271  0.0  0.3  696428  24208 ? Sl 17:36 0:00 pm2: node-app-2

CWD

cwd: your JSON declaration does not need to reside with your script. If you wish to maintain the JSON(s) in a location other than your script (say, /etc/pm2/conf.d/node-app.json) you will need to use the cwd feature (Note, this can be really helpful for capistrano style directory structures that uses symlinks). Files can be either relative to the cwd directory, or absolute (see example below).

CLI/JSON options

All the keys can be used in a JSON configured file, but will remain almost the same on the command line e.g.:

exec_mode         -> --execute-command
max_restarts      -> --max-restarts
force             -> --force

Using quotes to make an ESC, e.g.:

$pm2 start test.js --node-args "port=3001 sitename='first pm2 app'"

The nodeArgs argument will be parsed as

[
  "port=3001",
  "sitename=first pm2 app"
]

but not

[
  "port=3001",
  "sitename='first",
  "pm2",
  "app'"
]

Disabling logs

You can pass /dev/null to error_file or out_file to disable logs saving. Note: starting PM2 2.4.0, /dev/null or NULL disable logs independently of the platform.

Logs suffix

You can disable automatic ID suffixs on logs (e.g. app-name-ID.log) by passing enabling the option merge_logs: true

Environment definition

You’ll need to use --env <envname> to tell pm2 to use specific environment defined inside a process file :

{
  "apps" : [{
    "name"        : "worker",
    "script"      : "./worker.js",
    "watch"       : true,
    "env": {
      "NODE_ENV": "development"
    },
    "env_production" : {
       "NODE_ENV": "production"
    }
  },{
    "name"       : "api-app",
    "script"     : "./api.js",
    "instances"  : 4,
    "exec_mode"  : "cluster"
  }]
}

In this example, you will run pm2 start ecosystem.json and it will start your application with the default environment (in development so). Then you use pm2 start ecosystem.json --env production and it will use the attribute env_<name> where name is production here, so it will start your app with NODE_ENV=production.

Special ext_type

• min_uptime Value of min_uptime can be:
  • Number e.g. "min_uptime": 3000 means 3000 milliseconds.
  • String Therefore, we are making it short and easy to configure: h, m and s, e.g.: "min_uptime": "1h" means one hour, "min_uptime": "5m" means five minutes and "min_uptime": "10s" means ten seconds (those will be transformed into milliseconds).
• max_memory_restart Value of max_memory_restart can be:
  • Number e.g. "max_memory_restart": 1024 means 1024 bytes (NOT BITS).
  • String Therefore, we are making it short and easy to configure: G, M and K, e.g.: "max_memory_restart": "1G" means one gigabyte, "max_memory_restart": "5M" means five megabytes and "max_memory_restart": "10K" means ten kilobytes (those will be transformed into byte(s)).

• Optional values For example exec_mode can take cluster (cluster_mode) or fork (fork_mode) as possible values.

• Things to know
  • "instances": 0 means that PM2 will launch the maximum processes possible according to the numbers of CPUs (cluster mode)
  • array args, node_args and ignore_watch could be type of Array (e.g.: "args": ["--toto=heya coco", "-d", "1"]) or string (e.g.: "args": "--to='heya coco' -d 1")