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Ioto is controlled via several JSON/5 configuration files that are that are read at startup by Ioto.

The configuration files are:

File Description
auth.json5 Authentication configuration for the web server. Includes defined roles, users and passwords.
config.json5 Primary Ioto configuration file. Configures enabled services, logging and log file ingestion
provision.json5 Device and cloud provisioning configuration.
shadow.json5 Local copy of the AWS IoT shadow state.
web.json5 Web server configuration file.


Ioto uses a human-readable JSON/5 for configuration. JSON/5 an extension of JSON that makes it easier to create, read and maintain configuration files in JSON.

JSON/5 adds the following JavaScript features to JSON.

  • Object keys may be JavaScript identifiers without quotes.
  • Objects or arrays may have a trailing comma.
  • Strings may be single quoted.
  • Strings may span multiple lines (single, double or back-tick quotes).
  • Numbers may have a leading or trailing decimal point, can be hexadecimal, and may begin with a plus.
  • Values may be regular expressions.
  • Undefined is a valid value.
  • Single and multiline comments are allowed and preserved.
    // single-comment
        Multi-line comment
    unquotedKey: 42,
    singleQuoteString: 'The "lazy brown fox" jumped...',
    multiLine: "Line one
        line two
    hex: 0x42,
    trailingComma: {
        one: 1,
        two: 2,

Some Ioto configuration properties accept numeric values as human-readable string with unit suffixes. In this case, the value must be string. The limits and timeouts properties in the web.json5 file support the suffixes: unlimited, infinite, kb, k, mb, m, gb, g, byte, bytes, infinite, never, sec, secs, seconds, min, mins, minute, minutes, hr, hrs, hour, hours, day, days, week, weeks, month, months, year and years.


The primary Ioto configuration file is called config.json.

Here is a sample config.json:

    services: {
        cloud: {
            keys: true,
            logs: false,
            provision: true,
            serialize: 'auto',
            shadow: false,
            sync: true,
        database: true,
        mqtt: true,
        url: true,
        web: false,
    logs: {
        files: [
            {path: '/var/log/sys*log', group: 'ioto', stream: '{hostname}' }
    limits: {
        stack: '16k',
    trace: {
        path: 'aws',
        format: '%D %H %A[%P] %T %S %M',
        types: 'error,info',
        sources: 'all',

The configuration file defines the following items:

  • The services to enable.
  • The log files to capture and send to CloudWatch logs.
  • The Ioto execution limits that defines the default stack size
  • The Ioto trace log configuration.

The configuration properties are defined in the Configuration Properties.