TLDR: just looking for the code? Skip to the end.
Download Docker Desktop here.
Make sure Docker is running.
The following command will pull an image of mongo if one doesn't exist, then create a container for it.
docker run --name some-mongo -p 27017:27017 -d mongo:4.4
If containerization was successful, you should see the container when you run docker ps -a from your terminal.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1b5dea6eb2f0 mongo:4.4 "docker-entrypoint.s…" 12 seconds ago Up 10 seconds 0.0.0.0:27017->27017/tcp some-mongo
Explanation of the flags above
--name: container name. In the example above,some-mongois the name of your container. We typically only need one database container, but if you want your containers to be project based, consider something likegroceries-db-p: port mapping<host_port>:<container_port>. Mongo runs on port27017inside the container, i.e. port27017on your localhost doesn't automatically connect to the database. If you want your local port27017to point to the container's port27017, you need to specify it.
At this point you will have a running container with Mongo running inside of it. You can connect to the database from your local node application. If you don't know how, the next sections detail how to connect to your container as well as to your database.
Assume the same some-mongo container name as before. Note that you can also open the CLI from Docker Desktop.
docker exec -it some-mongo bash
With the container's CLI running, you can login to your Mongo database.
MacBook-Pro:~ ericdo$ docker exec -it some-mongo bash
root@1b5dea6eb2f0:/# mongo
MongoDB shell version v4.4.15
MongoDB server version: 4.4.15
Welcome to the MongoDB shell.
> show dbs
admin 0.000GB
config 0.000GB
fetcher 0.000GB
local 0.000GB
You should now also be able to connect directly to the containerized database from your node application.
You can put this code wherever you connect your database, e.g. in database/index.js.
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/fetcher'); // change "fetcher" to your DB name
If the connection is successful, no error will be thrown.
Your data will be saved even when you stop your containers.
The only thing you do need to worry about is when you remove your containers, e.g. rm -rf <container id>. This is the equivalent of uninstalling the database, so data may not persist then.
You shouldn't need to remove your database container unless you're upgrading/downgrading database versions or specifically want to delete the database instance. Persisting data across such scenarios is done with volumes, which are outside of scope of this installation guide for now.
Example error message when using Mongoose:
UnhandledPromiseRejectionWarning: MongoNetworkError: failed to connect to server [localhost:27017] on first connect [Error: connect ECONNREFUSED 127.0.0.1:27017
Your container may have stopped.
- Confirm container statuses with:
docker ps -a - Restart the relevant container if it has status
Exitedwith:docker start <CONTAINER ID>
$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1b5dea6eb2f0 mongo:4.4 "docker-entrypoint.s…" 7 days ago Exited (0) 2 minutes ago some-mongo
$ docker start 1b5dea6eb2f0
1b5dea6eb2f0
If you have a local installation (not installed with Docker) of your database, it may be running on the same port 27017.
- Confirm services running on port
27017:lsof -i tcp:27017 killunneeded services:kill <PID>- Restart our Dockerized container:
docker restart <CONTAINER ID>
$ lsof -i tcp:27017
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
com.docke 16558 ericdo 128u IPv6 0xf8014bcbf1ced6b7 0t0 TCP *:27017 (LISTEN)
mongod 45795 ericdo 9u IPv4 0xf8014bda59f55517 0t0 TCP localhost:27017 (LISTEN)
$ kill 45795
$ docker restart 1b5dea6eb2f0
Note in the example above, mongod is running. We only want our Dockerized instance of the database running, so kill the mongod process then restart the Dockerized container.
If this is your first time reading this document, do not go directly to this section unless you just want to get lost, break things, and learn the hard way.
- Install Docker
docker run --name some-mongo -p 27017:27017 -d mongo:4.4- Connect your application
docker ps -a
docker start <CONTAINER ID>
docker restart <CONTAINER ID>
docker stop <CONTAINER ID>
docker rm -rf <CONTAINER ID>
You can remove a container anytime as long as you've stopped it. You should not remove a container unless you want to delete that database instance or want to upgrade/downgrade database versions.
docker exec -it <CONTAINER NAME> bash
mongo
@eric-do Slight concern when we want to persist data and students happen to stop running containers. Perhaps a branch of instructions to include this bit using volumes, especially because we are doing this on sprints heavy on data persistence.