Re^2: Change cgi script to PSGI app

Toby, just keep writing more of those “ramblings” of yours, anytime! But I do find myself with a couple of questions / points for clarification, if you would, please.

Ordinarily, I do use PSGI, by means of Plack. (N-O-T to ignite any religious wars here, I do not use mod_perl.) If everything is going to be done on a single computer, I simply let Apache own the child processes, e.g. using mod_fastcgi. My only use for plackup is as a command-line tool which allows me to run the scripts and connect to them on localhost for development purposes only; it is never put into any “shebang” lines. Therefore, I am quite puzzled by your other suggested use for it. I don’t quite understand you on that point ...

Although I have never had need to use Plack’s adapter for CGI-scripts, its docs seem sensible. Quite frankly, I just design apps to run under Plack.

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Re^3: Change cgi script to PSGI app by tobyink (Canon) on Sep 12, 2014 at 09:00 UTC
"Therefore, I am quite puzzled by your other suggested use for it. I don’t quite understand you on that point" The use of `plackup` in a shebang line for CGI scripts is documented in Plack::Handler::CGI. If you're interested in how/why it works, read on. `plackup`'s normal behaviour is to run a server which listens on a TCP port, and handles multiple HTTP requests, and keeps going until it gets killed. You can observe this behaviour by running: `plackup -e'sub { [200,[],[q/ok/]] }'` [download] It will print out a URL; you can paste that into your browser, and it will serve up a small text file containing the word "ok". And you can hit "reload" and it will do it again and again. Awesome. But, of course, not what you want from a CGI script! So how is `plackup` any good in a shebang line? Hit Ctrl+C to kill plackup, and then set the following environment variables: `GATEWAY_INTERFACE=1 SERVER_NAME=localhost SERVER_PORT=8080 REQUEST_METHOD=GET SCRIPT_NAME=-e` [download] Now run this again: `plackup -e'sub { [200,[],[q/ok/]] }'` [download] And you'll see that instead of spawning an HTTP server and printing out its address for you, `plackup` now behaves like a CGI script, printing out the response headers and body to STDOUT. `plackup` (or rather the `guess` sub defined in Plack::Loader) detects that it's running in a CGI environment and behaves appropriately. toby döt ink	[reply] [d/l] [select]

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Re^3: Change cgi script to PSGI app
by tobyink (Canon) on Sep 12, 2014 at 09:00 UTC

"Therefore, I am quite puzzled by your other suggested use for it. I don’t quite understand you on that point"

The use of plackup in a shebang line for CGI scripts is documented in Plack::Handler::CGI. If you're interested in how/why it works, read on.

plackup's normal behaviour is to run a server which listens on a TCP port, and handles multiple HTTP requests, and keeps going until it gets killed. You can observe this behaviour by running:

plackup -e'sub { [200,[],[q/ok/]] }'
[download]

It will print out a URL; you can paste that into your browser, and it will serve up a small text file containing the word "ok". And you can hit "reload" and it will do it again and again. Awesome. But, of course, not what you want from a CGI script! So how is plackup any good in a shebang line?

Hit Ctrl+C to kill plackup, and then set the following environment variables:

GATEWAY_INTERFACE=1
SERVER_NAME=localhost
SERVER_PORT=8080
REQUEST_METHOD=GET
SCRIPT_NAME=-e
[download]

Now run this again:

plackup -e'sub { [200,[],[q/ok/]] }'
[download]

And you'll see that instead of spawning an HTTP server and printing out its address for you, plackup now behaves like a CGI script, printing out the response headers and body to STDOUT.

plackup (or rather the guess sub defined in Plack::Loader) detects that it's running in a CGI environment and behaves appropriately.

toby döt ink

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