cppweb

Using Docker

# create docker container
docker build -t cppbox .

# use a volume with the container
docker run -v <host directory>:<container directory> -ti <image> bash

# run container and map ports
docker run -v <host directory>:<container directory> -p <host port>:<container port> -e PORT=8081 <image> <app to run>

To run our server from a Docker container and access it from the host, we need to open a port, by defalut they're closed. For that we use -p to open a port and map it to the host machine and -e to create an environmental variable, we use it to tell the server which port it should use.

Then, you should create an image with the compiled files.

docker docker cp . <running container id>:/usr/src/cppweb
docker cp . <running container id>:/usr/src/cppweb
docker commit 176ec05f4c05 hello_crow:latest

<running container id> is the container where you have the compiled application. Your image will be named hello_crow:latest.

Using Heroku

First, you need to have an account in heroku and have heroku-cli. Then, you can login from the terminal.

heroku login
heroku container:login
heroku create

After these commands, you will see your application name (<app name given by heroku>).

Then, you create a container and push your image. For this, you need to create a Dockerfile that launch your application. We will use the image that we created that has the application and its dependencies compiled. Create a file like this:

FROM hello_crow
WORKDIR /usr/src/cppweb/hello_crow/build
CMD ["./hello_crow"]

Now, you build it.

docker build -t hello_crow -f Dockerfile .

Finally, you can release it to heroku.

heroku container:push web -a <app name given by heroku>
heroku container:release web -a <app name given by heroku>
heroku open -a <app name given by heroku>

After this, you will be able to access the <app name given by heroku>.heroku.com (or something like that) to see your application.

Databases with MongoDB Atlas - Load JSON

• Use MongoDB Atlas.

  • Create a Cluster. Note that the name cannot be changed later.
  • Setup which IPs can access the cluster (for this example all of them)
  • Configure an user and a password. Provide Atlas Admin privileges.
  • Connect to the cluster using mongodb shell. Follow instructions in Atlas site.

• Install mongodb in your host machine.

brew update
brew install mongodb
# this may also be required for mongoimport
brew install mongodb/brew/mongodb-database-tools

• You can import a JSON to your database in MongoDB Atlas.

I couldn't make the mongoimport --host command work, and the uri version was not working either. To make this work I created the collection and the database maually using the Atlas interface. Then, I needed the uri, I found it on the connection section of the cluster. I noticed that the string for the host was different from the uri because the uri one needed to have my user and password embedded on the string. After that this command worked.

mongoimport --uri "mongodb+srv://<user>:<password>@<cluster>/<database>"  -c <collection> --drop --file <file>.json --jsonArray

To connect to your database you need the mongodb cpp driver

Build the bbox container to build mongodb-c-driver and mongodb-cpp-driver.

cd hello_crow/bbox
docker build --rm --squash --no-cache -t bbox:latest .

After this step you'll have a new image, bbox:latest, that has the mongodb drivers required.

Now you need to update the hello_crow/Dockerfile to use this new image. Re-build that image too.

cd hello_crow
docker build --rm --squash --no-cache -t hello_crow:latest .

We will add to hello_crow/main.cpp functionality to use the <database> that we loaded in the last section. The CMakeList and Dockerfile were modified as a result of this.

Then, we build that image (this will compile our application and link it with mongodb-cpp-driver libraries) and launch the app.

docker build --rm --squash --no-cache -t hello_crow:latest .
docker run -p 8080:8080 -e PORT=8080 -e MONGODB_URI="mongodb+srv://<user>:<password>@<cluster>/<database>" hello_crow:latest

Go to heroku's container, on the Settings tab click on Config Vars. There you will add this MONGODB_URI="mongodb+srv://<user>:<password>@<cluster>/<database>".

Resources

• This content was done following Linkedin Learning course Web Servers and APIs using C++
• MongoDB Atlas mongoimport issues cannot decode array into a D
• Load File with mongoimport