update.config¶
The update.config file controls how Traffic Server performs a scheduled update of specific local cache content. The file contains a list of URLs specifying objects that you want to schedule for update.
A scheduled update performs a local HTTP GET on the objects at the specific time or interval. You can control the following parameters for each specified object:
- The URL
- URL-specific request headers, which overrides the default
- The update time and interval
- The recursion depth
After you modify the update.config file, run the traffic_line -x command to apply changes. When you apply changes to one node in a cluster, Traffic Server automatically applies the changes to all other nodes in the cluster.
Supported Tag/Attribute Pairs¶
Scheduled update supports the following tag/attribute pairs when performing recursive URL updates:
- <a href=" ">
- <img src=" ">
- <img href=" ">
- <body background=" ">
- <frame src=" ">
- <iframe src=" ">
- <fig src=" ">
- <overlay src=" ">
- <applet code=" ">
- <script src=" ">
- <embed src=" ">
- <bgsound src=" ">
- <area href=" ">
- <base href=" ">
- <meta content=" ">
Scheduled update is designed to operate on URL sets consisting of hundreds of input URLs (expanded to thousands when recursive URLs are included); it is not intended to operate on extremely large URL sets, such as those used by Internet crawlers.
Format¶
Each line in the update.config file uses the following format:
URL\request_headers\offset_hour\interval\recursion_depth\
The following list describes each field.
- ``URL`` {#URL}
- HTTP-based URLs.
- ``request_headers`` {#request_headers}
- Optional. A list of headers, separated by semicolons, passed in each GET request. You can define any request header that conforms to the HTTP specification; the default is no request header.
- ``offset_hour`` {#offset_hour}
- The base hour used to derive the update periods. The range is 00-23 hours.
- ``interval`` {#interval}
- The interval (in seconds) at which updates should occur, starting at the offset hour.
- ``recursion_depth`` {#recursion_depth}
- The depth to which referenced URLs are recursively updated, starting at the given URL. This field applies only to HTTP.
Examples¶
An example HTTP scheduled update is provided below:
http://www.company.com\User-Agent: noname user agent\13\3600\5\
The example specifies the URL and request headers, an offset hour of 13 (1 pm), an interval of one hour, and a recursion depth of 5. This would result in updates at 13:00, 14:00, 15:00, and so on. To schedule an update that occurs only once a day, use an interval value 86400 (i.e., 24 hours x 60 minutes x 60 seconds = 86400).
Specifying URL Regular Expressions (url_regex)¶
This section describes how to specify a url_regex. Entries of type url_regex within the configuration files use regular expressions to perform a match.
The following list provides examples to show how to create a valid url_regex.
- x
- Matches the character x
- .
- Match any character
- ^
- Specifies beginning of line
- $
- Specifies end of line
- [xyz]
- A character class. In this case, the pattern matches either x, y, orz
- [abj-oZ]
- A character class with a range. This pattern matches a, b, any letter from j through o, or Z
- [^A-Z]
- A negated character class. For example, this pattern matches any character except those in the class.
- r*
- Zero or more r, where r is any regular expression.
- r+
- One or more r, where r is any regular expression.
- r?
- Zero or one r, where r is any regular expression.
- r{2,5}
- From two to five r, where r is any regular expression.
- r{2,}
- Two or more r, where r is any regular expression.
- r{4}
- Exactly four r, where r is any regular expression.
- "[xyz]\"images"
- The literal string [xyz]"images"
- \X
- If X is a, b, f, n, r, t, or v, then the ANSI-C interpretation of \x; otherwise, a literal X. This is used to escape operators such as *
- \0
- A NULL character
- \123
- The character with octal value 123
- \x2a
- The character with hexadecimal value 2a
- (r)
- Matches an r, where r is any regular expression. You can use parentheses to override precedence.
- rs
- The regular expression r, followed by the regular expression s
- r|s
- Either an r or an s
- #<n>#
- Inserts an end node, which causes regular expression matching to stop when reached. The value n is returned.
You can specify dest_domain=mydomain.com to match any host in mydomain.com. Likewise, you can specify dest_domain=. to match any request.
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