VARIABLE::CONFIG 1g 2024-06-04 laplante@plcb.ca GOWEB/variable

title: “GoWeb VARIABLE::CONFIG Function” author: “Pierre Laplante” date: 2025-08-30 version: “1.0.2” section: “1g”

module: “Goweb/Variable”

Name

variable::config return all configuration parameters

Synopsis

variable::config() or simply config()

Description

The config() function returns variable definitions found in the config.toml file.
The exact information returned depends on the file content.

By default, the system searches for the configuration file in the following locations, in order:

1. $HOME/.config/goweb
2. /www
3. . (current directory)

Examples

Example 1: Using goweb.toml with goweb --config config.toml

When invoked, the file is searched in the current directory.
Here is an example configuration file (config.toml):

project = "extengo"
version = "0.0.0"
plugin = [ "example" ]
timeout = "10s"
load = "filename"
preload = "function"
redirect = "redirect"
error = "filename"
index_name = ["index", "index.html"]
exec_dir = [ "/extengo/table/secure/api", "/extengo/ide/" ]
pidfile = "/run/pidfile"
404 = "404.html"
routes = "route file"

[http_server]
port = ":8081"
docroot = "/home/laplante/go/src/goweb/cmd/goweb/www/"
htmldir = "html"
logdir = "log"
readtimeout = "10s"
writetimeout = "10s"
url = "https://goweb.pierrelaplante.ca"

[default_db]
source_name = "goweb:goweb@tcp(127.0.0.1:3306)/goweb"
driver_name = "mysql"

[lg]
# for Linux : fr = "fr_CA.utf8"
fr = "fr_CA.UTF-8"
en = "en_CA.utf8"

[handlers]
show_tables = "/show_tables"

[example]
file = "/usr/local/lib/example.so"
init = "Register_function"

• source_name follows the format:
  username:password@tcp(ip:port)/database_name

• exec_dir specifies which directories can be executed by goweb.
  Paths are relative to docroot. All other paths are served statically.

• If the URL points to a directory, index_name values are appended in order to locate the file.

• 404 specifies the file returned when a resource is not found.

Example call

config()

Result:

{
    "description.plugin":["example"],
    "description.version":"0.0.0",
    "description.timeout":"10s",
    "example.file":"/usr/local/lib/example.so",
    "example.init":"Register_function",
    "http_server.docroot":"/home/laplante/go/src/goweb/cmd/goweb/www/",
    "http_server.driver_name":"mysql",
    "http_server.htmldir":"html",
    "http_server.logdir":"log",
    "http_server.port":":8081",
    "http_server.readtimeout":"10s",
    "http_server.source_name":"xxx:---@tcp(127.0.0.1:3306)/xxx",
    "http_server.url":"https://goweb.pierrelaplante.ca",
    "http_server.writetimeout":"10s",
    "lg.en":"en_CA.utf8",
    "lg.fr":"fr_CA.UTF-8"
}

Example 2: load and preload

• load specifies a filename to be loaded into memory, typically containing functions.
  
• One of these functions, named preload, can be specified to run before each request.

The preload function must return one of the following values:

• preload::CONT (0) — Continue processing the request.
  
• preload::REWRITE (1) — Output the function result and exit.
  
• preload::RETURN (3) — Immediately return a status (often used with status functions).
  

Example:

func preload() {
    r := request();
    errorf("Executing preload on %!s(MISSING)\n", r.path);

    if r.path == "/tests/http1/test-009" {
        "rewrite to r.path="; r.path;
        return preload::REWRITE;
    }
    return preload::CONT;
}

Example 3: Redirect

Redirects are defined in the load file.

Example:

func redirect() {
    r := request();
    if r.path == "/redirect" {
        redirect("/index.html");
        return preload::REWRITE;
    }
    return preload::CONT;
}

Browser response:

HTTP/1.0 303 See Other
Content-Type: text/html; charset=utf-8
Location: /index.html
X-Goweb: 0.0.17
Date: Mon, 18 Mar 2024 16:44:34 GMT
Content-Length: 39

<a href="/index.html">See Other</a>.

Example 4: Handlers

Handlers allow execution of in-memory functions.

[handlers]
show_tables = "/show_tables"

Accessing /show_tables executes the show_tables function.
If the function is modified, the goweb server must be restarted.

Example 5: Routes

The routes parameter specifies a file with routing rules, for example:

GET /album/(.*) : file /album/list getMatch() to extract regex values
PUT /album/(.*) : func f to process request

• The file is relative to docroot.
  
• The handler function must be defined in the preload file and return PRELOAD::ROUTE.

Example:

func preload() {
    r := request();
    errorf("preload " + r.path);
    return preload::CONT;
}

func redirect() {
    r := request();
    errorf("Redirect " + r.path);
    
    if r.path == "/redirect" {
        redirect("/index.html");
        return preload::REWRITE;
    }
    
    return preload::CONT;
}

func testFuncRoute() {
    "In test func route\n";
    "match = "; getMatch();
    return preload::ROUTE;
}

To update the route file without restarting the server:

kill -USR1 <goweb_pid>

Example 6: Error Handling

If a filename is specified for the error parameter, that file will be executed whenever an error occurs.
Additionally:

• The variable errmsg is set with the error message.
  
• All variables from the source file remain available.
  

Author

Pierre Laplante laplante@plcb.ca

See Also

• Variable functions
  
• Index

Version

• 1.0.2 (2024-06-04) — Added flag to configuration file.
  
• 1.0.1 (2024-03-17) — Added handlers.
  
• 1.0 (2023-07-11) — Initial version.