FastCGI is an optimized CGI protocol implementation used by web servers to execute scripts or other programs.

Well, it's NOT only for web servers. Yes, you've read that right ;-)

This package is a Processor for the Go-Guerrilla default Backend interface implementation. Typical use for this package is if you would like to add the ability to deliver emails to your FastCGI backend, using Go-Guerrilla's built-in gateway backend.

Just like a web server would hand over the HTTP request to a FastCGI backend, this plugin allows you to hand over the processing of an email to your FastCGI backend, such as php-fpm.

The reason why you would do this is because perhaps your codebase is in a scripting language such as PHP, so there's no need to learn Go, becoming easier for you to maintain, no need to re-compile to change, use your favourite framework / library / IDE, etc.

Also, there's no overhead of a web server - it goes straight to your script.

Import "github.com/flashmob/fastcgi-processor" to your Go-guerrilla project.
Assuming you have imported the go-guerrilla package already, and all dependencies.

Then, when using go-guerrilla as a package, use something like this

cfg := &AppConfig{
    LogFile:      "stderr",
    AllowedHosts: []string{"example.com"},
    BackendConfig: backends.BackendConfig{
        "save_process" : "HeadersParser|Debugger|FastCGI",
        "validate_process" : "FastCGI",
        "fcgi_script_filename_save" : "/home/path/to/save.php",
        "fcgi_script_filename_validate" : "/home/path/to/validate.php",
        "fcgi_connection_type" : "unix",
        "fcgi_connection_address" : "/tmp/php-fpm.sock"
    },
}
d := Daemon{Config: cfg}
d.AddProcessor("FastCGI", fastcgi_processor.Processor)

d.Start()

// .. keep the server busy..

This will let Go-Guerrilla know about your FastCGI processor. Note that here we've added FastCGI to the end of the save_process config option, then used the d.AddProcessor api call to register it. Then configured other settings.

See the configuration section for how to configure.

The following values are required in your backend_config section

{
  "fcgi_script_filename_save" : "/home/path/to/save.php",
  "fcgi_script_filename_validate" : "/home/path/to/validate.php",
  "fcgi_connection_type" : "unix",
  "fcgi_connection_address" : "/tmp/php-fpm.sock"
}           

fcgi_connection_type type can be unix or tcp. fcgi_connection_address is a path to a unix socket descriptor, or IP address with tcp port eg. "127.0.0.1:8000"

If fcgi_connection_address using the unix socket descriptor, make sure your program has permissions for writing to it. The permissions will be tested during initialization.

Don't forget to add FastCGI to the end of your save_process config option, eg:

"save_process": "HeadersParser|Debugger|Hasher|Header|FastCGI",

also, add FastCGI to the end of your validate_process config option if you want to use the validate script, eg:

"validate_process": "FastCGI",

A single parameter comes to to your recipient validating script via HTTP GET.

• rcpt_to - the email address that we want to validate

Output:

Please echo the string PASS and nothing else if validation passed. Otherwise return anything you wish.

The parameters comes to to your saving script via a HTTP POST.

The following parameters will be sent:

• remote_ip - remote ip address of the client that we got the email from (not the sender)
• subject - the subject of the email (if available)
• tls_on - boolean, represented as string "true" or "false", was the connection a TLS connection?
• helo - hello sent by the client when connecting to us
• mail_from - string of the From email address, could be blank to indicate a bounce
• body - the raw email body, along with the headers. Please make sure your Fast CGI gateway can handle large enough POST

Output:

Please echo the string SAVED if successful.

See MailDiranasaurus - it uses this package as an example, https://github.com/flashmob/MailDiranasaurus

This package depends on Shen Sheng's Go Fastcgi client package.

go get github.com/sloonz/go-maildir

Your FastCGI script should timeout well before 30 seconds, preferably finish under 1 second.