async pullImage() {
    const stream = await this.docker.pull(this.image);
    return new Promise((resolve, reject) => {
      const onFinished = (err) => {
        if (err) {
          reject(err);
          return;
        }
        resolve(this.image);
      };
      const slog = require('single-line-log').stdout;
      const statuses = {};
      const onProgress = (event) => {
        let status = event.status;
        if (event.progress) {
          status = `${event.status} ${event.progress}`;
        }
        if (event.id) {
          statuses[event.id] = status;
        }
        // Print
        let output = '';
        const keys = Object.keys(statuses);
        for (const key of keys) {
          output += key + ': ' + statuses[key] + '\n';
        }
        if (!event.id) {
          output += event.status;
        }
        slog(output);
      };
      this.docker.modem.followProgress(stream, onFinished, onProgress);
    });
  }
Pull the container image from the registry.

@return {Promise<Void>}