Docker swarm secret not working correctly in node.js api (mongoDB) - node.js

Question

I am trying to get my mongo_username and mongo_password in a swarm secret, but for some reason they are converted? I get this error in the container log
/usr/src/app/node_modules/saslprep/index.js:99
throw new Error(
^
Error: Prohibited character, see https://tools.ietf.org/html/rfc4013#section-2.3
at saslprep (/usr/src/app/node_modules/saslprep/index.js:99:11)
at continueScramConversation (/usr/src/app/node_modules/mongodb/lib/core/auth/scram.js:126:36)
at /usr/src/app/node_modules/mongodb/lib/core/auth/scram.js:111:5
at MessageStream.messageHandler (/usr/src/app/node_modules/mongodb/lib/cmap/connection.js:277:5)
at MessageStream.emit (events.js:315:20)
at processIncomingData (/usr/src/app/node_modules/mongodb/lib/cmap/message_stream.js:144:12)
at MessageStream._write (/usr/src/app/node_modules/mongodb/lib/cmap/message_stream.js:42:5)
at writeOrBuffer (_stream_writable.js:353:12)
at MessageStream.Writable.write (_stream_writable.js:303:12)
at Socket.ondata (_stream_readable.js:713:22)
at Socket.emit (events.js:315:20)
at addChunk (_stream_readable.js:302:12)
at readableAddChunk (_stream_readable.js:278:9)
at Socket.Readable.push (_stream_readable.js:217:10)
at TCP.onStreamRead (internal/stream_base_commons.js:186:23)
I added the secret like this
echo admin | docker secret create mongo_username -
echo totallySecurePassword23456789 | docker secret create mongo_password -
and when i log those two secrets in my DB connect function like this:
const mongoose = require("mongoose"); // For connection to DB
const {
MONGO_USERNAME,
MONGO_PASSWORD,
MONGO_HOSTNAME,
MONGO_PORT,
MONGO_DATABASE_NAME,
} = process.env;
console.log(MONGO_USERNAME);
console.log(MONGO_PASSWORD);
console.log(MONGO_HOSTNAME);
console.log(MONGO_PORT);
console.log(MONGO_DATABASE_NAME);
const url = `mongodb://${MONGO_USERNAME}:${MONGO_PASSWORD}#${MONGO_HOSTNAME}:${MONGO_PORT}/${MONGO_DATABASE_NAME}?retryWrites=true$w=majority`;
console.log(url);
const connectDB = async () => {
const conn = await mongoose.connect(url, {
useNewUrlParser: true,
useCreateIndex: true,
useFindAndModify: false,
useUnifiedTopology: true,
});
console.log(`MongoDB Connected: ${conn.connection.host}`.cyan.underline.bold);
};
module.exports = connectDB;
They show up correctly as:
admin
totallySecurePassword23456789
host.docker.internal
27020
mainDB
and yet the url which is made which is supposed to look like mongodb://admin:totallySecurePassword23456789#host.docker.internal:27020/mainDB?retryWrites=true$w=majority
shows up as #host.docker.internal:27020/mainDB?retryWrites=true$w=majority
And this ofcourse makes the connection fail
the hostname, port and database_name work fine because these are defined as normal environment variables
Any help would be really appreciated, and if more info is needed please let me know!
Edit 1:
Here is the docker-compose file i use to run docker stack:
version: "3.8"
services:
main:
image: main:5.0.0
environment:
- MONGO_USERNAME_FILE=/run/secrets/mongo_username
- MONGO_PASSWORD_FILE=/run/secrets/mongo_password
- MONGO_HOSTNAME=host.docker.internal
- MONGO_PORT=27020
- MONGO_DATABASE_NAME=mainDB
secrets:
- mongo_username
- mongo_password
networks:
- main-net
ports:
- "80:3001"
deploy:
replicas: 1
restart_policy:
condition: on-failure
delay: 10s
window: 60s
networks:
main-net:
driver: overlay
secrets:
mongo_username:
external: true
mongo_password:
external: true
Edit 2:
Fixed the compose file missing the _FILE behind the username and password

Answer 1

After lots of investigating i found out i was having this problem https://github.com/aspnet/Configuration/issues/701, with no good fix found i settled on editing the entrypoint i was using (https://github.com/BretFisher/node-docker-good-defaults/blob/main/docker-entrypoint.sh) so it removed the end of line stuff before setting it as a environment variable by using
export "$var"="${val//[$'\t\r\n ']}"

Answer 2

I assume you use gnu bash. If you use echo shell builtin without -n option, it automatically adds new line to provided string.
Try these:
echo -n admin | docker secret create mongo_username -
echo -n totallySecurePassword23456789 | docker secret create mongo_password -
If you want to check your secret value whether includes new line, execute the following command on the machine where your docker cli resides:
docker container exec <your_container_name or id> cat -e /run/secrets/<your_secret_name>
If this command returns your value followed by $ symbol then we can conclude that new line character was appended while you were creating secret.
Note: I presume your container is a linux container. Also, be sure your container is in running state and its PATH environment variable must include the directory path where cat binary reside.