#!/bin/bash
#
# lib/apache
# Functions to control configuration and operation of apache web server

# Dependencies:
#
# - ``functions`` file
# - ``STACK_USER`` must be defined
#
# lib/apache exports the following functions:
#
# - install_apache_wsgi
# - apache_site_config_for
# - enable_apache_site
# - disable_apache_site
# - start_apache_server
# - stop_apache_server
# - restart_apache_server

# Save trace setting
_XTRACE_LIB_APACHE=$(set +o | grep xtrace)
set +o xtrace

# Allow overriding the default Apache user and group, default to
# current user and his default group.
APACHE_USER=${APACHE_USER:-$STACK_USER}
APACHE_GROUP=${APACHE_GROUP:-$(id -gn $APACHE_USER)}


# Set up apache name and configuration directory
# Note that APACHE_CONF_DIR is really more accurately apache's vhost
# configuration dir but we can't just change this because public interfaces.
if is_ubuntu; then
    APACHE_NAME=apache2
    APACHE_CONF_DIR=${APACHE_CONF_DIR:-/etc/$APACHE_NAME/sites-available}
    APACHE_SETTINGS_DIR=${APACHE_SETTINGS_DIR:-/etc/$APACHE_NAME/conf-enabled}
elif is_fedora; then
    APACHE_NAME=httpd
    APACHE_CONF_DIR=${APACHE_CONF_DIR:-/etc/$APACHE_NAME/conf.d}
    APACHE_SETTINGS_DIR=${APACHE_SETTINGS_DIR:-/etc/$APACHE_NAME/conf.d}
elif is_suse; then
    APACHE_NAME=apache2
    APACHE_CONF_DIR=${APACHE_CONF_DIR:-/etc/$APACHE_NAME/vhosts.d}
    APACHE_SETTINGS_DIR=${APACHE_SETTINGS_DIR:-/etc/$APACHE_NAME/conf.d}
fi
APACHE_LOG_DIR="/var/log/${APACHE_NAME}"

# Functions
# ---------

# Enable apache mod and restart apache if it isn't already enabled.
function enable_apache_mod {
    local mod=$1
    # Apache installation, because we mark it NOPRIME
    if is_ubuntu; then
        # Skip mod_version as it is not a valid mod to enable
        # on debuntu, instead it is built in.
        if [[ "$mod" != "version" ]] && ! a2query -m $mod ; then
            sudo a2enmod $mod
            restart_apache_server
        fi
    elif is_suse; then
        if ! a2enmod -q $mod ; then
            sudo a2enmod $mod
            restart_apache_server
        fi
    elif is_fedora; then
        # pass
        true
    else
        exit_distro_not_supported "apache enable mod"
    fi
}

# NOTE(sdague): Install uwsgi including apache module, we need to get
# to 2.0.6+ to get a working mod_proxy_uwsgi. We can probably build a
# check for that and do it differently for different platforms.
function install_apache_uwsgi {
    local apxs="apxs2"
    if is_fedora; then
        apxs="apxs"
    fi

    # This varies based on packaged/installed.  If we've
    # pip_installed, then the pip setup will only build a "python"
    # module that will be either python2 or python3 depending on what
    # it was built with.
    #
    # For package installs, the distro ships both plugins and you need
    # to select the right one ... it will not be autodetected.
    UWSGI_PYTHON_PLUGIN=python3

    if is_ubuntu; then
        local pkg_list="uwsgi uwsgi-plugin-python3 libapache2-mod-proxy-uwsgi"
        if [[ "$DISTRO" == 'bionic' ]]; then
            pkg_list="${pkg_list} uwsgi-plugin-python"
        fi
        install_package ${pkg_list}
    elif is_fedora; then
        # Note httpd comes with mod_proxy_uwsgi and it is loaded by
        # default; the mod_proxy_uwsgi package actually conflicts now.
        # See:
        #  https://bugzilla.redhat.com/show_bug.cgi?id=1574335
        #
        # Thus there is nothing else to do after this install
        install_package uwsgi \
                        uwsgi-plugin-python3
    elif [[ $os_VENDOR =~ openSUSE ]]; then
        install_package uwsgi \
                        uwsgi-python3 \
                        apache2-mod_uwsgi
    else
        # Compile uwsgi from source.
        local dir
        dir=$(mktemp -d)
        pushd $dir
        pip_install uwsgi
        pip download uwsgi -c $REQUIREMENTS_DIR/upper-constraints.txt
        local uwsgi
        uwsgi=$(ls uwsgi*)
        tar xvf $uwsgi
        cd uwsgi*/apache2
        sudo $apxs -i -c mod_proxy_uwsgi.c
        popd
        # delete the temp directory
        sudo rm -rf $dir
        UWSGI_PYTHON_PLUGIN=python
    fi

    if is_ubuntu || is_suse ; then
        # we've got to enable proxy and proxy_uwsgi for this to work
        sudo a2enmod proxy
        sudo a2enmod proxy_uwsgi
    elif is_fedora; then
        # redhat is missing a nice way to turn on/off modules
        echo "LoadModule proxy_uwsgi_module modules/mod_proxy_uwsgi.so" \
            | sudo tee /etc/httpd/conf.modules.d/02-proxy-uwsgi.conf
    fi
    restart_apache_server
}

# install_apache_wsgi() - Install Apache server and wsgi module
function install_apache_wsgi {
    # Apache installation, because we mark it NOPRIME
    if is_ubuntu; then
        # Install apache2, which is NOPRIME'd
        install_package apache2
        if is_package_installed libapache2-mod-wsgi; then
            uninstall_package libapache2-mod-wsgi
        fi
        install_package libapache2-mod-wsgi-py3
    elif is_fedora; then
        sudo rm -f /etc/httpd/conf.d/000-*
        install_package httpd python3-mod_wsgi
        # For consistency with Ubuntu, switch to the worker mpm, as
        # the default is event
        sudo sed -i '/mod_mpm_prefork.so/s/^/#/g' /etc/httpd/conf.modules.d/00-mpm.conf
        sudo sed -i '/mod_mpm_event.so/s/^/#/g' /etc/httpd/conf.modules.d/00-mpm.conf
        sudo sed -i '/mod_mpm_worker.so/s/^#//g' /etc/httpd/conf.modules.d/00-mpm.conf
    elif is_suse; then
        install_package apache2 apache2-mod_wsgi
    else
        exit_distro_not_supported "apache wsgi installation"
    fi
    # WSGI isn't enabled by default, enable it
    enable_apache_mod wsgi
}

# apache_site_config_for() - The filename of the site's configuration file.
# This function uses the global variables APACHE_NAME and APACHE_CONF_DIR.
#
# On Ubuntu 14.04+, the site configuration file must have a .conf suffix for a2ensite and a2dissite to
# recognise it. a2ensite and a2dissite ignore the .conf suffix used as parameter. The default sites'
# files are 000-default.conf and default-ssl.conf.
#
# On Fedora and openSUSE, any file in /etc/httpd/conf.d/ whose name ends with .conf is enabled.
#
# On RHEL and CentOS, things should hopefully work as in Fedora.
#
# The table below summarizes what should happen on each distribution:
# +----------------------+--------------------+--------------------------+--------------------------+
# | Distribution         | File name          | Site enabling command    | Site disabling command   |
# +----------------------+--------------------+--------------------------+--------------------------+
# | Ubuntu 14.04         | site.conf          | a2ensite site            | a2dissite site           |
# | Fedora, RHEL, CentOS | site.conf.disabled | mv site.conf{.disabled,} | mv site.conf{,.disabled} |
# +----------------------+--------------------+--------------------------+--------------------------+
function apache_site_config_for {
    local site=$@
    if is_ubuntu; then
        # Ubuntu 14.04 - Apache 2.4
        echo $APACHE_CONF_DIR/${site}.conf
    elif is_fedora || is_suse; then
        # fedora conf.d is only imported if it ends with .conf so this is approx the same
        local enabled_site_file="$APACHE_CONF_DIR/${site}.conf"
        if [ -f $enabled_site_file ]; then
            echo ${enabled_site_file}
        else
            echo ${enabled_site_file}.disabled
        fi
    fi
}

# enable_apache_site() - Enable a particular apache site
function enable_apache_site {
    local site=$@
    # Many of our sites use mod version. Just enable it.
    enable_apache_mod version
    if is_ubuntu; then
        sudo a2ensite ${site}
    elif is_fedora || is_suse; then
        local enabled_site_file="$APACHE_CONF_DIR/${site}.conf"
        # Do nothing if site already enabled or no site config exists
        if [[ -f ${enabled_site_file}.disabled ]] && [[ ! -f ${enabled_site_file} ]]; then
            sudo mv ${enabled_site_file}.disabled ${enabled_site_file}
        fi
    fi
}

# disable_apache_site() - Disable a particular apache site
function disable_apache_site {
    local site=$@
    if is_ubuntu; then
        sudo a2dissite ${site} || true
    elif is_fedora || is_suse; then
        local enabled_site_file="$APACHE_CONF_DIR/${site}.conf"
        # Do nothing if no site config exists
        if [[ -f ${enabled_site_file} ]]; then
            sudo mv ${enabled_site_file} ${enabled_site_file}.disabled
        fi
    fi
}

# start_apache_server() - Start running apache server
function start_apache_server {
    start_service $APACHE_NAME
}

# stop_apache_server() - Stop running apache server
function stop_apache_server {
    if [ -n "$APACHE_NAME" ]; then
        stop_service $APACHE_NAME
    else
        exit_distro_not_supported "apache configuration"
    fi
}

# restart_apache_server
function restart_apache_server {
    # Apache can be slow to stop, doing an explicit stop, sleep, start helps
    # to mitigate issues where apache will claim a port it's listening on is
    # still in use and fail to start.
    restart_service $APACHE_NAME
}

function write_uwsgi_config {
    local file=$1
    local wsgi=$2
    local url=$3
    local http=$4
    local name=""
    name=$(basename $wsgi)

    # create a home for the sockets; note don't use /tmp -- apache has
    # a private view of it on some platforms.
    local socket_dir='/var/run/uwsgi'

    # /var/run will be empty on ubuntu after reboot, so we can use systemd-temptiles
    # to automatically create $socket_dir.
    sudo mkdir -p /etc/tmpfiles.d/
    echo "d $socket_dir 0755 $STACK_USER root" | sudo tee /etc/tmpfiles.d/uwsgi.conf
    sudo systemd-tmpfiles --create /etc/tmpfiles.d/uwsgi.conf

    local socket="$socket_dir/${name}.socket"

    # always cleanup given that we are using iniset here
    rm -rf $file
    iniset "$file" uwsgi wsgi-file "$wsgi"
    iniset "$file" uwsgi processes $API_WORKERS
    # This is running standalone
    iniset "$file" uwsgi master true
    # Set die-on-term & exit-on-reload so that uwsgi shuts down
    iniset "$file" uwsgi die-on-term true
    iniset "$file" uwsgi exit-on-reload false
    # Set worker-reload-mercy so that worker will not exit till the time
    # configured after graceful shutdown
    iniset "$file" uwsgi worker-reload-mercy $WORKER_TIMEOUT
    iniset "$file" uwsgi enable-threads true
    iniset "$file" uwsgi plugins http,${UWSGI_PYTHON_PLUGIN}
    # uwsgi recommends this to prevent thundering herd on accept.
    iniset "$file" uwsgi thunder-lock true
    # Set hook to trigger graceful shutdown on SIGTERM
    iniset "$file" uwsgi hook-master-start "unix_signal:15 gracefully_kill_them_all"
    # Override the default size for headers from the 4k default.
    iniset "$file" uwsgi buffer-size 65535
    # Make sure the client doesn't try to re-use the connection.
    iniset "$file" uwsgi add-header "Connection: close"
    # This ensures that file descriptors aren't shared between processes.
    iniset "$file" uwsgi lazy-apps true

    # If we said bind directly to http, then do that and don't start the apache proxy
    if [[ -n "$http" ]]; then
        iniset "$file" uwsgi http $http
    else
        local apache_conf=""
        apache_conf=$(apache_site_config_for $name)
        iniset "$file" uwsgi socket "$socket"
        iniset "$file" uwsgi chmod-socket 666
        echo "ProxyPass \"${url}\" \"unix:${socket}|uwsgi://uwsgi-uds-${name}/\" retry=0 " | sudo tee -a $apache_conf
        enable_apache_site $name
        restart_apache_server
    fi
}

# For services using chunked encoding, the only services known to use this
# currently are Glance and Swift, we need to use an http proxy instead of
# mod_proxy_uwsgi because the chunked encoding gets dropped. See:
# https://github.com/unbit/uwsgi/issues/1540 You can workaround this on python2
# but that involves having apache buffer the request before sending it to
# uwsgi.
function write_local_uwsgi_http_config {
    local file=$1
    local wsgi=$2
    local url=$3
    name=$(basename $wsgi)

    # create a home for the sockets; note don't use /tmp -- apache has
    # a private view of it on some platforms.

    # always cleanup given that we are using iniset here
    rm -rf $file
    iniset "$file" uwsgi wsgi-file "$wsgi"
    port=$(get_random_port)
    iniset "$file" uwsgi http-socket "127.0.0.1:$port"
    iniset "$file" uwsgi processes $API_WORKERS
    # This is running standalone
    iniset "$file" uwsgi master true
    # Set die-on-term & exit-on-reload so that uwsgi shuts down
    iniset "$file" uwsgi die-on-term true
    iniset "$file" uwsgi exit-on-reload false
    iniset "$file" uwsgi enable-threads true
    iniset "$file" uwsgi plugins http,${UWSGI_PYTHON_PLUGIN}
    # uwsgi recommends this to prevent thundering herd on accept.
    iniset "$file" uwsgi thunder-lock true
    # Set hook to trigger graceful shutdown on SIGTERM
    iniset "$file" uwsgi hook-master-start "unix_signal:15 gracefully_kill_them_all"
    # Set worker-reload-mercy so that worker will not exit till the time
    # configured after graceful shutdown
    iniset "$file" uwsgi worker-reload-mercy $WORKER_TIMEOUT
    # Override the default size for headers from the 4k default.
    iniset "$file" uwsgi buffer-size 65535
    # Make sure the client doesn't try to re-use the connection.
    iniset "$file" uwsgi add-header "Connection: close"
    # This ensures that file descriptors aren't shared between processes.
    iniset "$file" uwsgi lazy-apps true
    iniset "$file" uwsgi chmod-socket 666
    iniset "$file" uwsgi http-raw-body true
    iniset "$file" uwsgi http-chunked-input true
    iniset "$file" uwsgi http-auto-chunked true
    iniset "$file" uwsgi http-keepalive false
    # Increase socket timeout for slow chunked uploads
    iniset "$file" uwsgi socket-timeout 30

    enable_apache_mod proxy
    enable_apache_mod proxy_http
    local apache_conf=""
    apache_conf=$(apache_site_config_for $name)
    echo "KeepAlive Off" | sudo tee $apache_conf
    echo "SetEnv proxy-sendchunked 1" | sudo tee -a $apache_conf
    echo "ProxyPass \"${url}\" \"http://127.0.0.1:$port\" retry=0 " | sudo tee -a $apache_conf
    enable_apache_site $name
    restart_apache_server
}

# Write a straight-through proxy for a service that runs locally and just needs
# to be reachable via the main http proxy at $loc
function write_local_proxy_http_config {
    local name=$1
    local url=$2
    local loc=$3
    local apache_conf
    apache_conf=$(apache_site_config_for $name)

    enable_apache_mod proxy
    enable_apache_mod proxy_http

    echo "KeepAlive Off" | sudo tee $apache_conf
    echo "SetEnv proxy-sendchunked 1" | sudo tee -a $apache_conf
    echo "ProxyPass \"${loc}\" \"$url\" retry=0 " | sudo tee -a $apache_conf
    enable_apache_site $name
    restart_apache_server
}

function remove_uwsgi_config {
    local file=$1
    local wsgi=$2
    local name=""
    name=$(basename $wsgi)

    rm -rf $file
    disable_apache_site $name
}

# Restore xtrace
$_XTRACE_LIB_APACHE

# Tell emacs to use shell-script-mode
## Local variables:
## mode: shell-script
## End: