i am getting the error 503 Service Temporarily Unavailable many times in my application
and i want to detect why this error occurs, how ? if there's a log file or something like that, since i am not familiar with apache.
second thing is that, is it possible to handle this error, that when it occurs apache is restarted ?
There is of course some apache log files. Search in your apache configuration files for 'Log' keyword, you'll certainly find plenty of them. Depending on your OS and installation places may vary (in a Typical Linux server it would be /var/log/apache2/[access|error].log).
Having a 503 error in Apache usually means the proxied page/service is not available. I assume you're using tomcat and that means tomcat is either not responding to apache (timeout?) or not even available (down? crashed?). So chances are that it's a configuration error in the way to connect apache and tomcat or an application inside tomcat that is not even sending a response for apache.
Sometimes, in production servers, it can as well be that you get too much traffic for the tomcat server, apache handle more request than the proxyied service (tomcat) can accept so the backend became unavailable.
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Doesn't have to be Apache, but that's just the only HTTP server I know of (Actually could you guys recommend alternatives that I could look into as well?)
Anyways, so I have been messing around with Amazon Web Services and I created an EC2 server instance with an Amazon Linux Image. On that, (Following guides and examples) I installed Apache and now when I make a GET request to my public IP, it returns to me the HTML files I created on my server.
My question is, what if I never installed Apache, and then made an HTTP request to my public IP? For no reason really, the question just came up in my head and I'm curious. I'd rather not figure out how to uninstall Apache or create a new instance to figure it out, so I was wondering if somebody could weigh in as well as tell me a little more about what it is exactly apache does on a server. My understanding is that it is a layer you can install on your server OS that will create a socket listener to port 80 (HTTP), and when a request is made on that port, Apache will return web pages? Also I think I read somewhere you could configure Apache to forward a port to something like a python server script?
Thanks in advance for your time!
could you guys recommend alternatives that I could look into as well?)
nginx is a popular alternative to apache. It's much more efficient.
what if I never installed Apache, and then made an HTTP request to my public IP?
Your browser would get a "connection reset" because there is nothing on port 80. Your browser would display a message (Chrome says "This webpage is not available"). You would NOT get a "404" because that requires an HTTP server to send HTTP codes.
If your server was firewalled instead, you'd bet a busy wait for a while, then a message about the server not responding.
Also I think I read somewhere you could configure Apache to forward a port to something like a python server script?
Yes, that is called "reverse proxy" mode. It's essential to any application website if you want to scale. The web server(s) can distribute traffic to one or more backends running the application. The web server is useful for filtering bad requests (since your backend in Ruby/Python will be 1000's of times slower than the reverse proxy.)
Well, if you want to test what will happen if Apache isn't installed, you can always just stop the Apache service by typing:
sudo service apache2 stop
or
sudo service httpd stop
depending on your version. Then if you visit your site's webpage you'll get a 404 error or something similar.
There are ways to use python scripts to run simple servers, but in general it's easier to just let Apache handle that and use a framework like Ruby on Rails or Django to control the display and creation of content for your server.
For well over a year and a half I have been running Apache (using HTTPD, naturally) through WAMP without issue, or at least no issues like this. On this system, we host around 8 or so different web sites and a few applications that use the MySQL database.
Recently I had a full system crash and when I rebuilt the system on the same operating system with the same versions of Apache, MySQL, and PHP and near-identical configuration files.
The issue I am having is this: On startup our web services initially seem to work fine, and this can hold over for an hour or so, sometimes less, sometimes more. However after some period of time, all web sites suddenly become entirely unavailable, to include the localhost landing on the web server itself or any local browsing for that matter. Apache identifies as still running, remains listening on port 80, and has no abnormal access or error logs (to include in debug mode).
I've gone over this quite a few times, reinstalled WAMP and have interchanged different versions of Apache. Additionally I've vetted the configuration files compared to the old system and have ensured that the modules, extensions, and so on are the same as our previous version.
I would really appreciate any insight as I continue to rack my head over what might be causing this erroneous issue.
--
Some additional details and notes that might prove insightful.
I've ensured the firewall isn't an issue, plus that wouldn't explain the sudden downtime or downtime at the localhost.
A restart of just the Apache service tends to fix the issue, but only for a little while.
Because we host multiple web sites, we do use virtual hosts. They work fine when the system is up and I don't believe they are of issue.
The issue tends to result in indefinite "Waiting for host (site.com, localhost, etc.)".
When I reset Apache during that indefinite error, it then errors out with "The connection to site.com was interrupted.", so something is still running.
During these downtimes, httpd -d DUMP_VHOSTS is able to return the active virtual hosts.
Using ab -n 1000 site.com when the site is 'down', the following result occurs:
Benchmarking site.com (be patient)
Completed 100 requests
Completed 200 requests
apr_pollset_poll: The timeout specified has expired (70007)
Total of 216 requests completed
Add this into httpd.conf
EnableMMAP off
EnableSendfile off
AcceptFilter http none
AcceptFilter https none
This will disable Apache from using some of the more advanced functions for networking that the OS provides.
These functions can get broken with 3rd-party software installs.
Sometimes reinstalling TCP/IP (winsock) can remove the 3rd-party filters/drivers attached to the network layer.
netsh winsock reset
I am running an install of Coldfusion10 on my local Windows7 machine. I now want to configure it to serve the site on apache web server (primarily I want to use the apache mod_rewrite functionality to rewrite urls).
However, once I have configured Coldfusion to use Apache (via the web server configuration tool) my apache service is stopped and I cannot restart it.
On restarting I get this error:
Syntax error on line 2 of C:/apache/apache2/conf/mod_jk.conf:
cannot load C:/coldfusion10/config/wsconfig/1/mod_jk.so into server: The specified procedure could not be found.
I have tried re-downloading the mod_jk.so file that should work with my version of apache, and whilst that stops the above error being shown, me apache server still doesn start.
Anyone experienced this or have any suggestions?
Cheers
I use mod_spdy to realize SPDY on apache. But I met some problems.
I did every step on ubuntu according to Google's document of installing mod_spdy.And I realized https on Apache. When I checked if mod_spdy has worked, I sent https request to the server, but I donot see server's domain listed in the "SPDY session" table that means the mod_spdy don't work. I also checked Apache server logs, and I didn't find any error message from mod_spdy.
I hope somebody can help me to deal with this problem.
Recently our Software Analytic provider (NETTRACKER) sent us a plugin in order to be able to capture visitors in a better way. This plugin is for Apache 1.x and Apache 2.x. They said and I quote
that since Apache Tomcat is built on Apache HTTP server the configuration of the plugin should be the same.
I have looked for a httpd.conf in our tomcat deployment but we cannot find one, the only configuration that is similar to that one is the server.xml under the /conf directory.
If someone has better information regarding these two incredible products (Apache HTTP server and Apache Tomcat) I will greatly appreciate to draw the differences.
EDIT:
In case you are curious we know that Apache Web Server and Tomcat can work together using the mod_jk option and other proxys. But this will be too complex for our deployment.
Apache Tomcat and Apache HTTP are completely different server technologies. It is impossible to use a plugin for Apache HTTP server with Tomcat.
Apache HTTP server is developed in C and so are the plug-ins. On the contrary Tomcat is now completely developed in Java. Tomcat doesn't only serve static content, but it can also serve JSP pages and servlets.
Tomcat is used for hosting Java Web Applications. It can sure serve static content - you can host a web application using only Tomcat. Secure connections are supported and the performance is also very good (comparable with the performance of HTTP server).
A plain installation of Apache serves static content. Using the appropriate plug-ins, HTTP requests can be redirected to an application server (Tomcat, JBoss, Glassfish) or a script language interpreter (PHP). With this way dynamic content can be generated. The big advantages of Apache are the numerous plug-ins available, which allows administrators to configure and monitor web sites any way they want and that is the most widespread server available. This makes it the most secure solution, since it is thoroughly tested and any discovered flaw is corrected very quickly.
The best solution would be to use Tomcat proxied by an Apache server. It isn't so difficult to set up. If you can't do this, then you can't take advantage of Apache's plug-ins.
You see this confusion all the time. Many people think that Apache is a web server where in reality it is the name of an organization that has a web server project called "The Apache HTTP Server Project". In short the web server is called HTTPD (D as in daemon or Unix process).
Tomcat is another Apache project. This project implements a Java servlet engine to serve JSP pages and servlets. Tomcat and HTTPD have nothing to do with each other. However, you can set up HTTPD and Tomcat so that they work together. This way you can have HTTPD serve all static content, do URL rewriting and much more fancy stuff that the built in Tomcat web server can't do (or can't do very well). Whenever a JSP page is requested, HTTPD will pass the request on to Tomcat. Tomcat will process the request and will hand the output back to HTTPD which in turn will send it to the client.
Apache has many interesting projects. E.g. there is also a project called Geronimo which is a Java Enterprise server (J2EE). You can e.g. choose to embed Tomcat inside Geronimo to handle requests for JSP's and servlets where Geronimo does the more enterprisy stuff (LDAP, Messaging etc.). And you guessed it probably already, you can use HTTPD as a static content server for Geronimo as well.
totally bogus. Apache httpd plugins are written in C, Tomcat is pure Java.
Tomcat is a Java servlet engine. It can be hosted under Apache or IIS or quite a number of other external facing web servers. It sounds like you may be currently running your Tomcat instance standalone...
If you serve the JSP/servlets off of port 8080 and have it do things standalone, on the same host machine that Apache is running on, this can allow you to have them loosely coupled. Having multiple web servers fielding independent requests is not recommended, especially if you want to use server-based authentication along with Apache. Typically, you have one outside facing server that shepherds everything through it... Apache does this quite well, and the plugin you mention probably relies on this type of setup (everything gets wired through Apache) for its features/capabilities, based on your brief description of it.
If you would like to serve up your Tomcat servlets under Apache, you could configure apache to forward a class of URIs to your tomcat server instances. you could achieve this type of forwarding through mod_rewrite. this is a slower option performance-wise, as it adds slight overhead on everything you server up. You could also proxy incoming requests via a CGI mechanism similarly, from Apache to Tomcat.
mod_jk will simplify deployment and increase performance for placing Tomcat into an Apache server config. It is pretty painless to configure if you follow the docs, so I am not sure what you mean by "too complex" for your deployment -- if you want Apache and have Tomcat already, it would seem only a matter of slight config changes to get mod_jk downloaded and installed.