PostgreSQL Workload Analyzer User Interface


You can run the POWA User Interface in various ways : as Perl webservice (Morbo), as a CGI with Apache or with Nginx (as a reverse proxy in front of Hypnotoad).

But first let’s talk about safety:


You need to be careful about the security of your PostgreSQL server when installing POWA

We designed POWA so that the user interface will only communicate with PostgreSQL via prepared statements. This will prevent the risk of SQL injection.

However to connect to the POWA User Interface, you will use the login and password of a postgeSQL superuser. See the main documentation for more details. If you don’t protect your communications, an attacker placed between the GUI and PostgreSQL, or between you and the GUI, could gain superuser rights to your database server.

Therefore we strongly recommend the following precautions :

  • Read the Great PostgreSQL Documentation
  • Check your pg_hba.conf file
  • Do not allow users to access POWA from the Internet
  • Do not allow users to access PostgreSQL from the Internet
  • Run POWA on a HTTPS server and disable HTTP access
  • Use SSL to protect the connection between the GUI and PostgreSQL
  • Reject unprotected connections between the GUI and PostgreSQL (hostnossl .... reject)
  • Check your pg_hba.conf file again


The versions showed have been tested, it may work with older versions

  • Perl 5.10
  • Mojolicious 4.75 and later
  • Perl DBI and DBD-Pg modules
  • PostgreSQL 9.3
  • A CGI/Perl webserver

Browser compatibility

PoWA is designed to respect standards and should work on most standard compliant browser.

If you are using an old version of Microsoft Internet Explorer, you might not see some graphs. We recommend that you either :

  • upgrade to a version (at least IE9)
  • or switch to Mozilla Firefox.


Install powa extension and configure it as seen it main file.

Install other prerequisites: Mojolicious is available on CPAN and sometimes packages, for example the package in Debian is libmojolicious-perl

If the needed version is not available anymore on your distribution, you can download Mojolicious 4.75 here.

As you are then not using a package, you may not want to install Mojolicious globally on your system. So here is how to install it locally (let’s say you installed powa in /path/to/powa):

perl Makefile.PL PREFIX=/path/to/powa/mojo make install

Check that make tells you the files have been copied to /path/to/powa/mojo.

Now, you’ll just have to tell perl that there is an extension in /path/to/powa/mojo (we’ll see that with the morbo command below).

Copy powa.conf-dist to powa.conf and edit it.

If you have multiple PostgreSQL servers with PoWA installed, you can configure them in the powa.conf file, in the servers section. Each entry is of the form “name”: { info... }, and must be coma separated.

For instance, if you have a production server listening on, port 5432 and a development server listening on, port 5433, the servers section should look like :

"servers" : {
    "production" : {
        "dbname"   : "powa",
        "host"     : "",
        "port"     : "5432"
    "development" : {
        "dbname"   : "powa",
        "host"     : "",
        "port"     : "5433"

You can also optionally configure a user and a password for each server. If credentials are found in the config file for the selected server, they will override what a user could provide on the login page, and of course the fields will become optionnal on the login page.

For instance, if you have a “test” server with must use the username “dba” and the password “testing”, the powa.conf file will look like :

"servers" : {
    "test" : {
    "development" : {
        "dbname"   : "powa",
        "host"     : "",
        "port"     : "5433",
        "username" : "dba",
        "password" : "testing"

CAREFUL: If you use this feature, it’s strongly advised to rely on an external security method, such as what is built-in on most of the http servers.

CAREFUL: If upgrading from PoWA 1.1 or PoWA 1.2, you need to change the format of the database section. See in PoWA main directory for more details.

Run With Morbo

To quickly run the UI, do not activate rewrite in the config (this is Apache rewrite rules when run as a CGI) and start the morbo webserver inside the source directory:

morbo script/powa

If you have installed Mojolicious locally, you’ll have to do this command instead (the paths may vary depending on where you run this command from):

PERL5LIB=/path/to/powa/mojo/share/perl5/site_perl mojo/bin/site_perl/morbo ui/script/powa

Of course, putting PERL5LIB and PATH in your .bashrc file wouldn’t be a bad idea...

It will output what is printed to STDOUT/STDOUT in the code in the term. The web pages are available on http://localhost:3000/

Run With Apache

To run the UI with Apache, here is an example using CGI:

<VirtualHost *:80>
    DocumentRoot /var/www/powa/public/

    <Directory /var/www/powa/public/>
        AllowOverride None
        Order allow,deny
        allow from all
        IndexIgnore *

        RewriteEngine On
        RewriteBase /
        RewriteRule ^$ powa.cgi [L]
        RewriteCond %{REQUEST_FILENAME} !-f
        RewriteCond %{REQUEST_FILENAME} !-d
        RewriteRule ^(.*)$ powa.cgi/$1 [L]

    ScriptAlias /powa.cgi /var/www/powa/script/powa
    <Directory /var/www/powa/script/>
        AddHandler cgi-script .cgi
        Options +ExecCGI
        AllowOverride None
        Order allow,deny
        allow from all
        SetEnv MOJO_MODE production
        SetEnv MOJO_MAX_MESSAGE_SIZE 4294967296

    ErrorLog ${APACHE_LOG_DIR}/powa.log
    # Possible values include: debug, info, notice, warn, error, crit,
    # alert, emerg.
    LogLevel warn

    CustomLog ${APACHE_LOG_DIR}/powa.log combined

Run with Nginx

If you want ot use Nginx, the best solution is probably to run Hypnotoad behind a reverse proxy:

More details here :