4. Create a self signed SSL certificate

Slate uses a local Express server to serve your assets locally. It's a good idea to create a trusted, self-signed SSL certificate on your device so the assets, served via https, are never blocked.

1. Run the following commands to install mkcert. See the installation docs for more details.

brew install mkcert

2. Copy and paste the bash function into your terminal (or into your .bashrc file if you want to have it available in the future):

function ssl-check() {
    f=~/.localhost_ssl;
    ssl_crt=$f/server.crt
    ssl_key=$f/server.key
    b=$(tput bold)
    c=$(tput sgr0)
    
    local_ip=$(ipconfig getifaddr $(route get default | grep interface | awk '{print $2}'))
    # local_ip=999.999.999 # (uncomment for testing)
    
    domains=(
        "localhost"
        "$local_ip"
    )
    
    if [[ ! -f $ssl_crt ]]; then
        echo -e "\n🛑  ${b}Couldn't find a Slate SSL certificate:${c}"
        make_key=true
    elif [[ ! $(openssl x509 -noout -text -in $ssl_crt | grep $local_ip) ]]; then
        echo -e "\n🛑  ${b}Your IP Address has changed:${c}"
        make_key=true
    else
        echo -e "\n✅  ${b}Your IP address is still the same.${c}"
    fi
    
    if [[ $make_key == true ]]; then
        echo -e "Generating a new Slate SSL certificate...\n"
        count=$(( ${#domains[@]} - 1))
        mkcert ${domains[@]}
    
        # Create Slate's default certificate directory, if it doesn't exist
        test ! -d $f && mkdir $f
    
        # It appears mkcert bases its filenames off the number of domains passed after the first one.
        # This script predicts that filename, so it can copy it to Slate's default location.
        if [[ $count = 0 ]]; then
            mv ./localhost.pem $ssl_crt
            mv ./localhost-key.pem $ssl_key
        else
            mv ./localhost+$count.pem $ssl_crt
            mv ./localhost+$count-key.pem $ssl_key
        fi
    fi
}

3. Run the function you just declared in step 2:

ssl-check

4. You now have successfully created a local, self-signed SSL certificate for developing with Slate!

Common mistakes

Even after performing the above steps, you might encounter the following errors and warnings when developing with Slate:

An example of https requests to your local asset server being blocked

An example of Chrome warning you of an untrusted https certificate

This is most likely because your local IP has changed and the self-signed SSL certificate you created is no longer valid. To remove these warnings and errors, simply repeat steps 2 and 3 above to regenerate a new self-signed certificate.

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Next: Start developing