log.js

const util = require('util');

module.exports = {
  /**
  Creates a json (newline delimited) logger.

  @param {Object} details fields sent in every log call.
  */
  createLogger(details) {
    return function(type, values) {
      let logObject = { type: type };
      Object.assign(logObject, details);
      if (typeof values === 'object') {
        Object.assign(logObject, values);
      } else {
        logObject.value = values;
      }
      process.stdout.write(JSON.stringify(logObject) + '\n');
    };
  },

  fmtLog() {
    let args = Array.prototype.slice.call(arguments);
    let ts = new Date().toISOString().replace('T', ' ');
    return '[taskcluster ' + ts + '] ' + util.format.apply(this, args) + '\n';
  },

  fmtErrorLog() {
    let args = Array.prototype.slice.call(arguments);
    // always include a newline before this string, so that it is at the beginning of the line
    // where treeherder expects it, even if the last output was not newline-terminated
    return '\n[taskcluster:error] ' + util.format.apply(this, args) + '\n';
  },
};