[SOLVED] Running MongoDB shell commands from within shell script connection refused

Issue

I have the following shell script which I am running in UserData section of a CloudFormation template:

#!/bin/sh
wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | apt-key add -
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | tee /etc/apt/sources.list.d/mongodb-org-4.4.list
apt-get update
apt-get install -y mongodb-org
apt install mongodb-clients
systemctl start mongod
systemctl status mongod
systemctl enable mongod
echo "ABOUT TO ENTER WHILE LOOP"
while :
do
    echo "waiting to RUN MONGO COMMANDS"
    echo "$(systemctl show -p ActiveState --value mongod)"
    if [ "$(systemctl show -p ActiveState --value mongod)" = "active" ]
    then
        echo "RUNNING MONGO COMMANDS"
        mongo crawler --eval "db.websites.insertOne({ customerId: '1', url: 'https://dootli.com' })"
        mongo crawler --eval "db.createUser({ user: 'username', pwd: 'password', roles: 'clusterAdmin' })"
        break
    fi
done

As far I can tell the script is valid, how I'm getting the this output (and error) when it is run during the initialization of the EC2 instance:

Reading package lists...
Building dependency tree...
Reading state information...
The following package was automatically installed and is no longer required:
  mongodb-database-tools
Use 'apt autoremove' to remove it.
The following additional packages will be installed:
  libboost-filesystem1.71.0 libboost-iostreams1.71.0
  libboost-program-options1.71.0 libgoogle-perftools4 libpcrecpp0v5
  libsnappy1v5 libtcmalloc-minimal4 libyaml-cpp0.6 mongo-tools
The following packages will be REMOVED:
  mongodb-org mongodb-org-database-tools-extra mongodb-org-mongos
  mongodb-org-server mongodb-org-shell mongodb-org-tools
The following NEW packages will be installed:
  libboost-filesystem1.71.0 libboost-iostreams1.71.0
  libboost-program-options1.71.0 libgoogle-perftools4 libpcrecpp0v5
  libsnappy1v5 libtcmalloc-minimal4 libyaml-cpp0.6 mongo-tools mongodb-clients
0 upgraded, 10 newly installed, 6 to remove and 87 not upgraded.
Need to get 35.2 MB of archives.
After this operation, 44.4 MB disk space will be freed.
Do you want to continue? [Y/n] Abort.
● mongod.service - MongoDB Database Server
     Loaded: loaded (/lib/systemd/system/mongod.service; disabled; vendor preset: enabled)
     Active: active (running) since Sat 2021-02-06 20:38:12 UTC; 15ms ago
       Docs: https://docs.mongodb.org/manual
   Main PID: 2738 (mongod)
     Memory: 288.0K
     CGroup: /system.slice/mongod.service
             └─2738 /usr/bin/mongod --config /etc/mongod.conf

Feb 06 20:38:12 ip-172-31-64-168 systemd[1]: Started MongoDB Database Server.
Created symlink /etc/systemd/system/multi-user.target.wants/mongod.service → /lib/systemd/system/mongod.service.
ABOUT TO ENTER WHILE LOOP
waiting to RUN MONGO COMMANDS
RUNNING MONGO COMMANDS
MongoDB shell version v4.4.3
connecting to: mongodb://127.0.0.1:27017/crawler?compressors=disabled&gssapiServiceName=mongodb
Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:374:17
@(connect):2:6
exception: connect failed
exiting with code 1
MongoDB shell version v4.4.3
connecting to: mongodb://127.0.0.1:27017/crawler?compressors=disabled&gssapiServiceName=mongodb
Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:374:17
@(connect):2:6
exception: connect failed
exiting with code 1
Cloud-init v. 20.3-2-g371b392c-0ubuntu1~20.04.1 running 'modules:final' at Sat, 06 Feb 2021 20:37:42 +0000. Up 27.35 seconds.
ci-info: no authorized SSH keys fingerprints found for user ubuntu.
Cloud-init v. 20.3-2-g371b392c-0ubuntu1~20.04.1 finished at Sat, 06 Feb 2021 20:38:12 +0000. Datasource DataSourceEc2Local.  Up 56.97 seconds

Solution

I modified the code to work. I identified that the main issue is mongodb-clients which causes failures of monogdb. Also your command db.createUser is invalid and will lead to failure as well. I did not fix that, as its not related to your issue about connection refused. You can make new question why your db.createUser is incorrect (I don't know how to fix that, its mongodb specific).

#!/bin/sh
wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | apt-key add -
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | tee /etc/apt/sources.list.d/mongodb-org-4.4.list

apt update
apt install -y  mongodb-org

systemctl enable mongod
systemctl start mongod

echo "ABOUT TO ENTER WHILE LOOP"
while :
do
    echo "waiting to RUN MONGO COMMANDS"

    sleep 5

    echo "$(systemctl show -p ActiveState --value mongod)"

    if [ "$(systemctl show -p ActiveState --value mongod)" = "active" ]
    then
        echo "RUNNING MONGO COMMANDS"
        mongo crawler --eval "db.websites.insertOne({ customerId: '1', url: 'https://dootli.com' })"

        [ $? != 0 ] && continue

        echo "db.websites.insertOne command successful"

        break
    fi

done

Answered By - Marcin