mkdir -p /etc/apt/apt.conf.d

tee /etc/apt/apt.conf.d/95proxies <<-'EOF'
Acquire {
    HTTP::proxy "http://127.0.0.1:7890";
    HTTPS::proxy "http://127.0.0.1:7890";
    FTP::proxy "http://127.0.0.1:7890";
}
EOF