Error while using persistent datasource using mongodb ini hyperledger composer - mongodb

Question

I am trying to use persistent datasource using mongoDB in hyperledger composer on a UBUNTU droplet
but after starting the rest server and den after issuing a command docker logs -f rest i am getting the following error(i have provided a link to the image)
webuser#ubuntu16:~$ docker logs -f rest
[2018-08-29T12:38:31.278Z] PM2 log: Launching in no daemon mode
[2018-08-29T12:38:31.351Z] PM2 log: Starting execution sequence in -fork mode- for app name:composer-rest-server id:0
[2018-08-29T12:38:31.359Z] PM2 log: App name:composer-rest-server id:0 online
WARNING: NODE_APP_INSTANCE value of '0' did not match any instance config file names.
WARNING: See https://github.com/lorenwest/node-config/wiki/Strict-Mode
Discovering types from business network definition ...
(node:15) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
Connection fails: Error: Error trying to ping. Error: Failed to connect before the deadline
It will be retried for the next request.
Exception: Error: Error trying to ping. Error: Failed to connect before the deadline
Error: Error trying to ping. Error: Failed to connect before the deadline
at _checkRuntimeVersions.then.catch (/home/composer/.npm-global/lib/node_modules/composer-rest-server/node_modules/composer-connector-hlfv1/lib/hlfconnection.js:806:34)
at <anonymous>
[2018-08-29T12:38:41.021Z] PM2 log: App [composer-rest-server] with id [0] and pid [15], exited with code [1] via signal [SIGINT]
[2018-08-29T12:38:41.024Z] PM2 log: Starting execution sequence in -fork mode- for app name:composer-rest-server id:0
[2018-08-29T12:38:41.028Z] PM2 log: App name:composer-rest-server id:0 online
WARNING: NODE_APP_INSTANCE value of '0' did not match any instance config file names.
WARNING: See https://github.com/lorenwest/node-config/wiki/Strict-Mode
Discovering types from business network definition ...
(node:40) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
Connection fails: Error: Error trying to ping. Error: Failed to connect before the deadline
It will be retried for the next request.
I don't understand what is the problem and what wrong I am doing because I have followed all the steps in the hyperledger composer document with success....
Is it because I am using it on ubuntu droplet....?? anyone help
EDIT
I followed all the steps mentioned in this tutorial
but instead of using google authentication i am using github authentication.
Also i have changed my local host to the ip of my ubuntu droplet in connection.json file and also in this command
sed -e 's/localhost:7051/peer0.org1.example.com:7051/' -e 's/localhost:7053/peer0.org1.example.com:7053/' -e 's/localhost:7054/ca.org1.example.com:7054/' -e 's/localhost:7050/orderer.example.com:7050/' < $HOME/.composer/cards/restadmin#trade-network/connection.json > /tmp/connection.json && cp -p /tmp/connection.json $HOME/.composer/cards/restadmin#trade-network/
bt yet with no success! i get the following error now.....
webuser#ubuntu16:~$ docker logs rest
[2018-08-30T05:03:02.916Z] PM2 log: Launching in no daemon mode
[2018-08-30T05:03:02.989Z] PM2 log: Starting execution sequence in -fork mode- for app name:composer-rest-server id:0
[2018-08-30T05:03:02.997Z] PM2 log: App name:composer-rest-server id:0 online
WARNING: NODE_APP_INSTANCE value of '0' did not match any instance config file names.
WARNING: See https://github.com/lorenwest/node-config/wiki/Strict-Mode
Discovering types from business network definition ...
(node:15) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
Discovering the Returning Transactions..
Discovered types from business network definition
Generating schemas for all types in business network definition ...
Generated schemas for all types in business network definition
Adding schemas for all types to Loopback ...
Added schemas for all types to Loopback
SyntaxError: Unexpected string in JSON at position 92
at JSON.parse ()
at Promise.then (/home/composer/.npm-global/lib/node_modules/composer-rest-server/server/server.js:141:34)
at
at process._tickDomainCallback (internal/process/next_tick.js:228:7)
[2018-08-30T05:03:09.942Z] PM2 log: App [composer-rest-server] with id [0] and pid [15], exited with code 1 via signal [SIGINT]

Answer 1

This error Error trying to ping. Error: Failed to connect before the deadline means that the composer-rest-server in the container cannot see/connect to the underlying Fabric at the URLs in the connection.json of the card that you are using to start the REST server.
There are a number of reasons why:
The Fabric is not started
You are using a Business Network Card that has localhost in the URLs of the connection.json, and localhost just re-directs back into the rest container.
Your rest container is started on a different Docker network bridge to your Fabric containers and cannot connect to the Fabric.
Have you followed this tutorial in the Composer documentation? If followed completely it will avoid the 3 problems mentioned above.