#!/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

    # Ubuntu xenial is back level on uwsgi so the proxy doesn't
    # actually work. Hence we have to build from source for now.
    #
    # Centos 7 actually has the module in epel, but there was a big
    # push to disable epel by default. As such, compile from source
    # there as well.

    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

    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 python3_enabled; then
            if is_package_installed libapache2-mod-wsgi; then
                uninstall_package libapache2-mod-wsgi
            fi
            install_package libapache2-mod-wsgi-py3
        else
            install_package libapache2-mod-wsgi
        fi
    elif is_fedora; then
        sudo rm -f /etc/httpd/conf.d/000-*
        install_package httpd mod_wsgi
    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 socket "$socket"
    iniset "$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 true
    iniset "$file" uwsgi enable-threads true
    iniset "$file" uwsgi plugins python
    # uwsgi recommends this to prevent thundering herd on accept.
    iniset "$file" uwsgi thunder-lock true
    # Override the default size for headers from the 4k default.
    iniset "$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

    # 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 $name)
        echo "ProxyPass \"${url}\" \"unix:${socket}|uwsgi://uwsgi-uds-${name}/\" retry=0 " | sudo tee $apache_conf
        enable_apache_site $name
        restart_apache_server
    fi
}

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

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