index.js

var util = require('util'),
  request = require('request'),
  Writable = require('stream').Writable;

util.inherits(LogStream, Writable);

function LogStream(db, opts) {
  this.db = db;
  this.opts = opts || {};

  this._createdDb = false;

  Writable.call(this, { objectMode: true });
}

LogStream.prototype._write = function(chunk, encoding, callback) {
  request.post(
    {
      url: this.db,
      auth: this.opts.auth,
      json: chunk
    },
    function(err, resp, body) {
      if (err) return callback(err);
      if (resp.statusCode >= 400) {
        if (
          !this._createdDb &&
          resp.statusCode === 404 &&
          body &&
          (body.reason === 'no_db_file' ||
            body.reason.includes('Database does not exist'))
        ) {
          // try to create DB
          request.put(
            {
              url: this.db,
              auth: this.opts.auth,
              json: true
            },
            function(err, resp, body) {
              this._createdDb = true;
              if (err) return callback(err);
              if (resp.statusCode >= 400) {
                return callback(
                  new Error(
                    'Could not create db.' +
                      (body ? ' ' + (body.reason || body.error) : '')
                  )
                );
              }

              this._write(chunk, encoding, callback);
            }.bind(this)
          );
        } else {
          callback(new Error(body ? body.reason : 'could not POST to CouchDB'));
        }
      } else {
        callback(null);
      }
    }.bind(this)
  );
};

module.exports = LogStream;