tPSGI

NAME

TPSGI - Abstraction layer around starman to become a general purpose HTTP server & static renderer.

VERSION

version 0.001

SYNOPSIS

A router module, which routers in ~/.tpsgi.ini names:

package My::Routes;

our @routes = (
    '/hello' => {
        method    => 'GET',
        callbacks => { 'text/html' => \&hello },
    },
);

sub hello {
    my ( $tpsgi, $query ) = @_;
    return [ 200, [ 'Content-Type' => 'text/html' ], ['Hello world'] ];
}

DESCRIPTION

Start it with the Starman options you want, from the directory of the application, with tarbaby on the PATH:

tpsgi ... [starman args]

A PSGI server built to migrate old mod_perl/apache stacks onto psgi, and that powers tCMS.

Will execute any executable file (chmod +x) in www/ as CGI, and otherwise host any static file therein.

The idea here is as a bridge between old and new which allows you to modernize at your own pace, gradually turning CGIs into routes.

The other idea is that we don't want to add any extra abstraction if we don't have to, while gently guiding into better practices. Shops used to having full control over the HTTP response should continue to do so, rather than being locked into one framework or another. This allows them to continue doing whatever funky thing they have been doing, like COMET, et cetera. The best way to do that is to expect raw PSGI to be output.

request_id($regenerate) = STRING

The UUID of the request being answered, which every log line carries. A true $regenerate makes a new one, which app() does as each request comes in.

log() = Log::Dispatch

The process's Log::Dispatch, made by build_log() the first time it is asked for.

build_log() = Log::Dispatch

A new Log::Dispatch from the options: the rotated file at log_name, the screen, and each class that loggers names, which is loaded by name. log() keeps the first one this makes.

DEBUG, INFO, NOTE, WARN, ERROR, CRIT, ALERT, EMERG, FATAL($message)

Log $message at that level, stamped with the time, the worker, the request and the user. FATAL logs at the emergency level and then dies with the line.

new(%options)

Load the routers and build the routing table. It dies unless it runs as user, and http_user and tpsgi_dir are set. get_config() returns the options, and among them are:

custom_log
verbose
routers
loggers
auth

indices() = ARRAYREF

The directory index files, in the order they are tried: the indices option, then index.html, index.htm and index.cgi.

routes() = ARRAYREF

The routing table: each route's pattern, then its definition, for every router in the order they were loaded.

serve($fullpath, $path, $start, $streaming, $ranges, $last_fetch, $deflate)

Serve a file, with options to stream and cache the output.

serve_ranges($fh, $ranges, %args) = PSGI response

Answer a Range request from $fh with a 206, or a 416 when a range is outside the file. $ranges is what parse_ranges() returns, and %args is size, the size of the file, headers, a HASH reference of the response headers so far, and fullpath, the URL for the log. More than one range is answered as multipart/byteranges.

redirect, redirect_permanent, see_also

Redirects to the provided page.

ok

Return a generic HTTP 200 OK

notfound, forbidden, badrequest, toolong, error, unavailable

If you need to return these HTTP errors, return these within a route:

sub route {
    my ($self, $query) = @_;
    ...
    return $self->notfound($query);
}

app($env) = PSGI response

The PSGI application: respond() to the request, or answer it with error() when that dies.

cannot_start($error, $env, %options) = ARRAYREF

What to answer with when new() died, so there is no object to answer with. Usually a router that would not load: a missing module, a syntax error.

The error goes to psgi.errors, and to the log by way of a stand-in built from the same options, so it lands in the same places a request's own errors do. If building the log is what failed -- a logger that will not load -- psgi.errors is all there is, and the answer is still a 500 rather than a second exception.

The answer is a page of our own, not the router's error page: the router is what failed. With TPSGI_DEBUG set it carries the error itself, trace and all, for the same reason the error pages add one; without, it says nothing a visitor could use to map the installation.

The worker retires once it has answered, on a server that offers psgix.harakiri, which Starman does. A router that died while it compiled leaves its file in %INC as a failure, and every later require of it in this process says only "Attempt to reload ... aborted" -- so a load that failed once, to a race or a lock, would otherwise fail for every request the worker ever serves. A fresh worker tries again from nothing.

respond($env) = PSGI response

Answer one request: from a route when one matches, by running a CGI when the file under www/ is executable, and otherwise by serving the file.

mangle_filename($path) = STRING

$path, lowercased on the systems whose filesystems ignore case.

parse_ranges($env) = LIST

The byte ranges of the request's Range header, as ARRAY references of start and end. An end that the header leaves out is undef. If-Range without Range asks for the whole file.

appears_executable($path) = BOOL

Whether $path is a CGI to run rather than a file to serve: it is executable, and it has no extension or one of cgi, sh, exe, pl, php and py.

route($route, $env, %request) = PSGI response

Run the callback of $route that answers the request's content type, with the query that extract_query() builds. respond() calls it, with %request holding fullpath, path, start, last_fetch, deflate, domain and port.

extract_query($path, $route, $env) = HASHREF

The query a route's callback is given: the query string, then the POST body, then the route's captures and its data, each over the last. When the route names parameters, a parameter that fails its validator, or one it does not name, gets a badrequest() instead.

cgi($env, $fullpath, $file_actual, $last_fetch) = PSGI response

Run $file_actual as a CGI. Read until we are done with headers, then pass off the filehandle to PSGI for streaming.

stream_raw_cgi($cgi)

Run the perl file $cgi in this process, as a CGI: its STDIN is the request body, and what it prints goes to the client. The worker exits when it is done.

Use when you just have a .cgi file you want to run without pipe-open. XXX this is extraordinarily unsafe, inefficient and kills workers. But sometimes you have to bite the bullet and do this to migrate stuff effectively.

stream_raw_psgi($response, $query)

Write the PSGI $response straight to the client's socket, close it, then run the callbacks that add_post_close_callback() queued. route() does this when there are any. The worker exits when it is done.

stream_raw_http($query, $last_fetch, $to_fork, $callback, $error_handler)

Answer with a 200 whose headers and body a forked child prints: $to_fork runs in the child with the client's socket selected, and then $error_handler, when there is one. Once the child exits and the socket is closed, $callback runs. The worker exits when it is done.

extract_headers($fh, $last_fetch)

Extract the headers from a filehandle. Set the 'Last Modified' header appropriately based on the output of `stat` on the filehandle.

Returns a code and parsed headers hash. Code will be 304 if the file hasn't changed since $last_fetch, otherwise will be the code in the parsed headers.

static($fullpath, $path, $start, $streaming, $last_fetch) = PSGI response

Answer with the static render of $path that save_render() made, headers and all, or forbidden() when there is none.

get_config() = HASH

TPSGI::Startup::get_config(): ~/.tpsgi.ini, over the defaults.

checkpoint($query, $name)

Mark the time as $name, for the Server-Timing header that build_server_timing() makes.

build_server_timing($query) = STRING

A Server-Timing header value: how long each checkpoint() took after the one before it, and the total since the request started.

add_post_close_callback()

Add a thing to do after closing stdout; useful for housekeeping that doesn't need to hold up pageload.

signal_restart_parent()

Instruct tPSGI to reload after closing stdout.

save_render($path, $extension, $body)

Save a static render of the page. Good to queue after closing stdout.

Passed file extension slapped on the end of the path. You can then serve them as statics with an appropriately done try_files block in nginx.

invalidate_render($path, $extension)

Remove an existing static render of a path.

invalidate_renders($extension)

Remove all existing static renders with the provided extension. Useful when it's not easy to figure out what to re-render due to including templates in other templates, etc.

watch_for_changes(@dirs)

TPSGI::Startup::watch_for_changes(), which watches the .pm files under @dirs for autoreload. A function, not a method.

add_watch($path, $callback, %options)

Add an arbitrary file or directory to the inotify watchlist, along with a callback to run when it changes. Returns the inotify watch descriptor.

The callback is invoked as:

$callback->( $tpsgi, $change );

...where $change is a HASH reference describing what happened:

path    => full path of the thing which changed
watched => the path the watch was registered against
events  => ARRAY reference of event names, e.g. [ 'MODIFY' ]
name    => entry within a watched directory, if the watch was on a directory
wd      => inotify watch descriptor
mask    => raw inotify event mask

Which makes the common case - blowing away a static render because the thing it was generated from changed - look like:

$tpsgi->add_watch( "data/posts.json", sub {
    my ( $tpsgi, $change ) = @_;
    $tpsgi->invalidate_renders('html');
});

%options are passed through to TPSGI::Startup::add_watch, so you may also pass 'events' (defaults to CREATE, MODIFY, DELETE and MOVE) and 'key' (an explicit dedupe key for the callback).

Some caveats worth knowing about:

• Watches live in the inotify instance tarbaby sets up before forking, and are therefore shared by every worker. Whichever worker notices a change first consumes it for all of them, so register the same callbacks in every worker (declare them in your router module, which every worker loads) and make sure they're safe to run in any worker.
• Changes are only noticed when a request comes in, since nothing is sitting in a select loop over the inotify FD. Renders are invalidated promptly in practice, but not instantly.
• Watching a directory rather than a single file is more robust, as watching a file which is later replaced wholesale (the usual write-tempfile-then- rename dance) only survives because we re-establish the watch afterwards. If the file is deleted and not immediately recreated, the watch is gone for good.

remove_watch($path)

Drop a path, and any callbacks registered against it, from the watchlist.

handle_changes

Drain the inotify queue, running the callbacks registered for whatever changed, and restart tPSGI if any of the relevant libdir files changed (assuming autoreload is on). Powers both the autorestart feature and app-registered watches.

restart_if_changes

Deprecated alias for handle_changes().

CONFIGURATION

Obeys ~/.tpsgi.ini -- this is what will control all the custom aspects mentioned below:

verbose     : Whether to print all log messages or not
custom_log  : Custom location for default (rotated) log
routers     : Router module(s), separate with comma.  Relative to TPSGI install dir.
indices     : Dirindex files.  In addition to index.html, index.htm, index.cgi
loggers     : Logger module(s), separate with comma.  Each is a Log::Dispatch::Output class.  tPSGI loads it by name, so it can live beside a router
auth        : Authentication module
domain      : Domain name of the application, used by things like service files
basedir     : Directory you want to chdir into on startup. Relative to TPSGI install dir.  Default '.'
user        : Who to run as
http_user   : Who's proxying this application (used for statics)
autoreload  : Whether or not to automatically reload the application when library files change. Default 0.

You can run bin/tpsgi-config to get any config value needed by scripts.

We wrap starman with a custom script, bin/tarbaby that implements Plack::Loader::Reload far less dangerously. It only reloads the code relevant to tPSGI and your application itself. All the CPAN deps should be updated out-of-band and the service manually restarted, as this is far more fraught.

CUSTOM ROUTING

All passed routing modules will be required, and combined to form a routing table so you have an analogue to rewrite rules.

Routing Modules look like so:

our @routes = (
    '/foo/(\w+)/save' => {
        method    => 'GET',
        callbacks => { # Run these subroutines to execute the appropriate handler given the content-type.  Expects normal PSGI output.
            'text/html'        => \&render,
            'application/json' => \&dump,
        },
        noindex   => 0, # Explicitly exclude this in robots.txt
        nomap     => 0, # Don't put this in the sitemap
        acls      => ['admin'], # Route requires both authentication by auth handler and the auth'd user to have the provided ACLs.
        data      => { baz => 'throb' }, # Arbitrary data to inject into the GET/POST data hashref
        captures  => ['name','parameter'], # Name parameters of the capture groups in the route key.  Suppose we want /foo/don/keys here.
        static    => 1, # Whether we can save a static render of this
        invalidates => ['/foo/(\w+)'], # Static renders which are invalidated by this route returning a successful response code.
    },
    ...
);

Note that this is an array, as we want this to preserve order. Fat commas are used to hint that this is in fact a tuple.

Router callbacks are passed the TPSGI object and the raw query, which means you can do:

sub route {
    my ($self, $query) = @_;
    $self->INFO("whatever");
    $self->ERROR("eeee");
    $self->DEBUG("blah");

    # Either from the GET or POST data, POST is preferred when both are present.
    my $param = $query->{param};

    my %headers = ...;

    return [200, \%headers, ["Hello world"]]
}

WATCHING FILES FOR CHANGES

tPSGI already watches your library directories with inotify so that it can reload itself when your code changes. Your application can put arbitrary files and directories onto that same watchlist, along with a callback to run when they change. The usual reason to want this is throwing away a static render because the thing it was generated from changed underneath it.

Routing modules declare these the same way they declare routes:

our %watches = (
    # A bare coderef is the common case: run this when the path changes.
    'data/posts.json' => sub {
        my ($tpsgi, $change) = @_;
        $tpsgi->invalidate_renders('html');
    },

    # Or spell it out if you want to be picky about which events you care about.
    'www/assets' => {
        callback => \&asset_changed,
        events   => [qw{CREATE MOVE}],
    },
);

...or register them at runtime with $tpsgi->add_watch($path, $callback, %options), and drop them again with $tpsgi->remove_watch($path).

Callbacks are passed the TPSGI object and a hashref describing what happened:

sub asset_changed {
    my ($tpsgi, $change) = @_;

    $change->{path};    # full path of the thing which changed
    $change->{watched}; # the path the watch was registered against
    $change->{events};  # arrayref of event names, e.g. ['MODIFY']

    $tpsgi->invalidate_render($change->{path}, 'html');
}

A few things worth knowing:

• Watches are shared by every worker, so whichever worker notices a change first consumes it for all of them. Declare your watches in your routing module (which every worker loads) rather than from inside a single route, and make the callbacks safe to run in any worker.
• Nothing sits in a select loop over the inotify descriptor, so changes are noticed when the next request comes in. Prompt, but not instant.
• Watching the containing directory is more robust than watching a single file. Watches on files which get replaced wholesale (write a tempfile, rename over the target) are re-established afterwards, but a file which is deleted and not recreated takes its watch with it.

CUSTOM AUTHENTICATION HANDLING

The (optional) Authentication handler can be passed, and look like so:

package Auth::Handler;

# Is user who they say they are
sub authenticate {
    my (%auth_payload) = @_;
    ...
    return ($session_cookie);
}

# is the user authorized to do $thing
sub authorized {
    my ($user, $priv) = @_;
    ...
    return 1 || 0;
}

# Available ACLs
sub acls {
    ...
    return %acls;
}

# Dump acls for user
sub acls_for_user {
    my $user = shift;
    ...
    return %acls;
}

# What is the user for this session token
sub user_for_session {
    my $session = shift;
    ...
    return $user;
}

In the event that auth or route handlers are found, these events will be noted in the startup log.

LOGGING

By default we have two log handlers...which you can augment with your own, based on Log::Dispatch.

The first default is to print ERROR and worse to the STDOUT of the PSGI server. The other is to emit INFO or better to logs/tpsgi.log

Pass your own dispatch subclasses and watch it go whir.

SERVICE CONFIGURATION

Proper operation of this as a production service requires some things:

1. You have a user which has this repository as their home directory.
2. You run the shell script, tpsgi.sh in service/ to run this as a service.
3. You set the username and the domain name of the service in .tpsgi.ini
4. You set your PATH appropriately to pick up on things like custom perls in a .bashrc
5. You set the group of your reverse proxy application in .tpsgi.ini (the http_user variable)

run service/tpsgi.sh as root and you should be set supposing the above is true.

In general the operation is like so:

1. nginx (or whatever) looks for a sock file owned $USER:$WEB_GROUP, and reverse proxies to this
2. tpsgi is actively listening on this sock file.

Generally you'll just run bin/build_service and then systemctl start $domain. It's configured to start as root, then drop privs thanks to Net::Server's capabilities inherited in starman.

Secrets the application needs

An application often needs a key or a password that has no business living in its own checkout, where it would go into every backup alongside whatever it protects. bin/build_service makes one and puts it in systemd's credential store; the unit imports it and service/tpsgi.sh hands it on.

You do not have to do anything for this. build_service writes /etc/credstore.encrypted/tpsgi-vault if it is not there already, encrypted with systemd-creds --with-key=auto: sealed to the TPM when the machine has a usable one, and to the host key when it does not. It says which you got, since that is the difference between a stolen disk being useless and a stolen disk being a stolen key. An existing key is left alone.

systemd decrypts it into a ramdisk at /run/credentials/$service that only this service can read. Nothing breaks if it is not there: ImportCredential= is quiet about a credential that does not exist, so an installation whose application wants no secrets starts normally.

The workers are chrooted into the application directory and that ramdisk is outside it, so service/tpsgi.sh reads the credential before the chroot happens and exports it -- tpsgi-vault becomes TPSGI_VAULT_KEY. An application taking one is expected to read it out of its environment as it starts and delete it there and then, so that nothing it forks afterwards inherits it.

It is named for tPSGI rather than for whatever is being served, because this is tPSGI's unit and one service is one application in one directory.

The key is not backed up and cannot be recovered. That is deliberate: it lives and dies with the machine, so that it is never sitting in the same backup as the data it protects. Rebuilding the host means whatever was sealed under it is gone and gets stored again.

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/Troglodyne-Internet-Widgets/tPSGI/issues

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHORS

Current Maintainers:

• George S. Baugh george@troglodyne.net

CONTRIBUTORS

• Andy Baugh andy@troglodyne.net
• troglodyne-bot morpheus@troglodyne.net

COPYRIGHT AND LICENSE

Copyright (c) 2026 Troglodyne LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.