How to Run Crow C++ with Apache

📦 Dependencies

First, of course, you need to have Crow C++ installed on your system. To do this, install the dependencies:

On Windows

See here: How to Install Crow C++ on Windows. It’s more interesting to run it without Apache, using Crow’s built-in server by running the binary directly!

On Ubuntu:

sudo apt install git build-essential cmake make libasio-dev g++

On Arch:

sudo pacman -S git base-devel cmake asio

Now clone, compile, and install Crow C++:

git clone https://github.com/CrowCpp/Crow
cd Crow
cmake . -B build -DCROW_BUILD_EXAMPLES=OFF -DCROW_BUILD_TESTS=OFF
sudo cmake --install build

If you want, you can now remove the cloned repository: cd .. && rm -rf CrowCpp

⚙️ Running with Apache

Make sure you have Apache installed with the correct read and write permissions.

On Ubuntu:

sudo apt install apache2
sudo chown -R $USER:$USER /var/www/html/

On Arch:

sudo pacman -S apache
sudo chown -R $USER:$USER /srv/http

01. Create a folder in your Apache root directory and enter it, for example:

# Ubuntu  
mkdir -p /var/www/html/crow  
cd /var/www/html/crow  

# Arch  
mkdir -p /srv/http/crow  
cd /srv/http/crow

02. Create a simple example code for testing:

main.cpp

#include <crow.h> // On Windows, use double quotes  

int main(){  
    crow::SimpleApp app;  

    CROW_ROUTE(app, "/")([](){  
        return "Hello world";  
    });  

    app.port(18080).multithreaded().run();  
}

Compile: g++ main.cpp -o app and test: ./app. Then access it in your browser at: http://localhost:18080.

🏃 Running Directly with Apache Without Manually Running the Binary

Use similar paths and commands on Arch.

01. Create a `systemd` file:

sudo vim /etc/systemd/system/crow-app.service (or use your preferred editor).

Paste this inside:

On Arch, replace all instances of /var/www/html with /srv/http, and instead of www-data, use just http for both User and Group.

[Unit]  
Description=Crow C++ Web Application  
After=network.target  

[Service]  
Type=simple  
User=www-data  
Group=www-data  
WorkingDirectory=/var/www/html/crow  
ExecStart=/var/www/html/crow/app  
Restart=always  
RestartSec=10  

[Install]  
WantedBy=multi-user.target

Save and exit.

02. Enable and start the service:

sudo systemctl daemon-reload  
sudo systemctl enable crow-app  
sudo systemctl start crow-app  
sudo systemctl status crow-app  # to check if it's running

You should see something like this:

Crow Apache

03. Configure Apache as a Reverse Proxy

Enable the necessary modules:

On Ubuntu:

sudo a2enmod proxy  
sudo a2enmod proxy_http  
sudo a2enmod proxy_balancer  
sudo a2enmod lbmethod_byrequests

On Arch:
Edit the file: sudo vim /etc/httpd/conf/httpd.conf and uncomment (or add, if missing) the following lines:

LoadModule proxy_module modules/mod_proxy.so  
LoadModule proxy_http_module modules/mod_proxy_http.so  
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so  
LoadModule lbmethod_byrequests_module modules/mod_lbmethod_byrequests.so  
LoadModule rewrite_module modules/mod_rewrite.so

Also, find (or add) the following line:

If it’s commented out (with a #), remove the # to uncomment it.

Include conf/extra/httpd-vhosts.conf

04. Add this configuration to your Apache VirtualHost

Ubuntu: sudo vim /etc/apache2/sites-available/000-default.conf
Arch: sudo vim /etc/httpd/conf/extra/httpd-vhosts.conf

Delete everything inside and paste this:

On Arch, change /var/www/html to /srv/http and replace ${APACHE_LOG_DIR} with /var/log/httpd.

<VirtualHost *:80>  
    ServerAdmin webmaster@localhost  
    DocumentRoot /var/www/html  

    # Simple reverse proxy that removes the prefix  
    ProxyRequests Off  
    ProxyPreserveHost On  

    # Proxy for port 18080  
    ProxyPass /crow/ http://127.0.0.1:18080/  
    ProxyPassReverse /crow/ http://127.0.0.1:18080/  

    # Rewrite URLs to remove the /crow/ prefix  
    RewriteEngine On  
    RewriteRule ^/crow/(.*)$ http://127.0.0.1:18080/$1 [P,L]  
    RewriteRule ^/crow/?$ http://127.0.0.1:18080/ [P,L]  

    ErrorLog ${APACHE_LOG_DIR}/error.log  
    CustomLog ${APACHE_LOG_DIR}/access.log combined  
</VirtualHost>

Enable rewrite mode, restart Apache, and test by accessing the URL:

On Arch, just restart with: sudo systemctl restart httpd.

sudo pkill -f app  # Optional if you haven't modified the binary  
sudo a2enmod rewrite  
sudo systemctl restart apache2  
xdg-open http://localhost/crow/

Done! Now you can develop your applications with Crow!

Remember that whenever you modify the binary, you need to restart it using pkill:

sudo pkill -f app

On Arch, prefer using these two commands instead:

sudo systemctl daemon-reexec  # or daemon-reload if you didn’t modify the systemd binary  
sudo systemctl enable --now crow-app.service

To check the status: sudo systemctl status crow-app.service

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