Nginx: unknown directive "ngx.flush(true)"

Question

I'm having some trouble by using the nginx devel (ndk) and lua-module. I compiled nginx-rpm using the following configuration:

./configure \
        --prefix=%{_sysconfdir}/nginx/ \
        --sbin-path=%{_sbindir}/nginx \
        --conf-path=%{_sysconfdir}/nginx/nginx.conf \
        --error-log-path=%{_localstatedir}/log/nginx/error.log \
        --http-log-path=%{_localstatedir}/log/nginx/access.log \
        --pid-path=%{_localstatedir}/run/nginx.pid \
        --lock-path=%{_localstatedir}/run/nginx.lock \
        --http-client-body-temp-path=%{_localstatedir}/cache/nginx/client_temp \
        --http-proxy-temp-path=%{_localstatedir}/cache/nginx/proxy_temp \
        --http-fastcgi-temp-path=%{_localstatedir}/cache/nginx/fastcgi_temp \
        --http-uwsgi-temp-path=%{_localstatedir}/cache/nginx/uwsgi_temp \
        --http-scgi-temp-path=%{_localstatedir}/cache/nginx/scgi_temp \
        --user=%{nginx_user} \
        --group=%{nginx_group} \
        --with-http_ssl_module \
        --with-http_realip_module \
        --with-http_addition_module \
        --with-http_sub_module \
        --with-http_dav_module \
        --with-http_flv_module \
        --with-http_mp4_module \
        --with-http_gzip_static_module \
        --with-http_random_index_module \
        --with-http_secure_link_module \
        --with-http_stub_status_module \
        --with-mail \
        --with-mail_ssl_module \
        --with-file-aio \
        --with-ipv6 \
        --with-cc-opt="%{optflags} $(pcre-config --cflags)" \
        --add-module=%{_builddir}/nginx-%{version}/mods/upload_progress \
    --add-module=%{_builddir}/nginx-%{version}/mods/ngx_devel_kit \
    --add-module=%{_builddir}/nginx-%{version}/mods/lua-nginx-module \

Calling nginx -V after the installation also shows that ngx and lua seems to be installed/activated. But... when I do the following:

location /abc/ {
    # For demonstration purposes only...
    ngx.flush(true);
    expires 30d;
}

I always get the following error:

nginx: [emerg] unknown directive "ngx.flush(true)" in /etc/nginx/conf.d/default.conf:53
nginx: configuration file /etc/nginx/nginx.conf test failed

What's wrong with my configuration? Is there anything I need to activate to use ngx-directives in the conf-file?

Thanks in advance for any suggestion!

Lukas · Accepted Answer · 2013-03-14T20:32:05.113

ngx.flush() is one of NginxLuaModule's Lua functions, not an nginx configuration directive.
To achieve the behaviour you seem to be desiring (just flush the content), do this:

location /abc/ {
    content_by_lua '
        ngx.flush(true);
    ';
    expires 30d;
}

You have to wrap Lua code into one of the *_by_lua directives, or load the code from a file using one of the *_by_lua_file directives in your nginx config.
Lua code can be executed in different contexts, e.g. to set a variable (set_by_lua), at rewrite state (rewrite_by_lua), to serve content (content_by_lua), or others.

You should have a look at the nginx wiki page.

Note, that every context of executing Lua code is designed to perform different tasks and runs at different times while processing and serving a request.
This makes it practically impossible to explain code behaviour, code requirements, or available functions in a generic way

Nginx: unknown directive "ngx.flush(true)"

1 Answers1