Rule Based Routing

Rule based routing

Experimental, not fully tested. Everything, including syntax, may change until it is considered complete and stable.

Fields

Rule has the following fields:

• name - rule name (optional)
• on - trigger condition (required, except name=default)
• do - actions (required)

Behaviors

• When no rule matches, default rule (if defined) will be executed
• When no rule matches and default rule is not defined, request will be passed to reverse proxy
• When do is set to pass, request will be passed through to reverse proxy

Syntax

Like in linux shell, values that contains spaces and quotes should be quoted or escaped, i.e.

header Some-Header "foo bar"     # foo bar
header Some-Header 'foo bar'     # foo bar
header Some-Header foo\ bar      # foo bar
header Some-Header 'foo \"bar\"' # foo "bar"

Supported escape sequences:

• \n - new line
• \t - tab
• \r - return
• \\ - backslash
• \" - double quote
• \' - single quote
• \ - space

On

Conditions seperated by:

• | will be considered as OR
• lines will be considered as AND

<condition> <args> [ | <condition> <args>...]

Conditions:

Condition	Arguments	Description
header	<name> <value>	match when request header <name> equals <value>
header	<name>	match on any request header <name>
query	<name> <value>	match when query parameter <name> equals <value>
query	<name>	match on any query parameter <name>
cookie	<name> <value>	match when cookie name equals <value>
cookie	<name>	match on any cookie <name>
form	<name> <value>	match when form value <name> equals <value>
form	<name>	match on any form value <name>
postform	<name> <value>	match when form value <name> equals <value>
postform	<name>	match on any form value <name>
method	<method>	match when request method equals <method>
path	<path>	match when request path matches glob <path>
remote	<ip | cidr>	match when client IP matches <ip> or <cidr>
basic_auth	<username> <hashed_password>	match when request basic auth username equals <username> and password equals <hashed_password>, <hashed_password> is bcrypt hashed value

postform vs form

They both returns the first value for the named component of

• postform has the precedence order:

  1. application/x-www-form-urlencoded form body (POST, PUT, PATCH only)
  2. query parameters (always)
  3. multipart/form-data form body (always)
  • form: the POST, PUT, or PATCH request body

Basic auth

<hashed_password> can be generated with htpasswd -nbB '' some-password | cut -c 2-

Example basic auth rule:

services:
  app:
    container_name: app
    ...
    labels:
      proxy.app.rules: |
        - name: default
          do: require_basic_auth any
        - name: auth
          on: basic_auth user1 "$2y$0..." | basic_auth user2 "$2y$0..."
          do: pass

on.path glob syntax

Compile creates Glob for given pattern and strings (if any present after pattern) as separators.
The pattern syntax is:

   pattern:
       { term }

   term:
       `*`         matches any sequence of non-separator characters
       `**`        matches any sequence of characters
       `?`         matches any single non-separator character
       `[` [ `!` ] { character-range } `]`
                   character class (must be non-empty)
       `{` pattern-list `}`
                   pattern alternatives
       c           matches character c (c != `*`, `**`, `?`, `\`, `[`, `{`, `}`)
       `\` c       matches character c

   character-range:
       c           matches character c (c != `\\`, `-`, `]`)
       `\` c       matches character c
       lo `-` hi   matches character c for lo <= c <= hi

   pattern-list:
       pattern { `,` pattern }
                   comma-separated (without spaces) patterns

Do

• Actions are executed in order
• Actions that returns afterwards must be the last action, e.g.:

  # invalid
  on: method GET
  do: |
    serve /static/index.html
    serve /static/404.html
  # invalid
  on: method GET
  do: |
    redirect /foo/bar
    serve /static/index.html
  # valid
  on: method GET
  do: |
    rewrite / /index.html
    serve /static

Actions:

Action	Arguments	Returns	Description
rewrite	<from> <to>	false	rewrite request path from <from> to <to>
serve	<path>	true	serve static files / directory from <path>
proxy	<target>	true	proxy request to <target>
redirect	<url | path>	true	redirect request to absolute <url> or relative <path>
error	<status> <msg>	true	respond with status code <status> and <msg>
require_basic_auth	<realm>	true	require basic auth with realm <realm>
set	<field> <key> <value>	false	set <field> <key> to <value>
add	<field> <key> <value>	false	add <value> to <field> <key>
remove	<field> <key>	false	remove <key> from <field>
pass		true	pass request to reverse proxy

Set/Add/Remove fields

• headers
• query
• cookies

Examples

# docker compose
services:
  app:
    container_name: goaccess
    ...
    labels:
      proxy.goaccess.rules: |
        - name: block POST and PUT requests
          on: method POST | method PUT
          do: error 403 "Not allowed"
        - name: websocket
          on: |
            header Connection Upgrade
            header Upgrade websocket
          do: pass
        - name: default
          do: |
            rewrite / /report.html
            serve /tmp/access

# Route file
goaccess:
  rules:
    - name: websocket
      on: |
        header Connection Upgrade
        header Upgrade websocket
      do: pass
    - name: default
      do: |
        rewrite / /report.html
        serve /tmp/access

# config.yml
# same as above, under `entrypoint` section
entrypoint:
  rules:
    ...