Docker mongodb + node js。 如何build立工作形象？

我怎样才能build立这个形象？

在运行图像我得到

npm info it worked if it ends with ok npm info using npm@2.15.5 npm info using node@v4.4.5 npm info prestart koaapp@1.0.0 npm info start koaapp@1.0.0 > koaapp@1.0.0 start /home/pwrchrd/Projects/KOAapp/test > node server.js connection error: { [MongoError: getaddrinfo ENOTFOUND db_1 db_1:27017] name: 'MongoError', message: 'getaddrinfo ENOTFOUND db_1 db_1:27017' }