poundctl.tmpl - templates for poundctl.

Copyright © 2023-2025 Sergey Poznyakoff License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. pound January 2, 2025 POUNDCTL.TMPL(5)

The syntax of poundctl templates is modelled after and mostly conforming to the specifications of the golang template module (https://pkg.go.dev/text/template). Templates are executed by applying them to a JSON object. Annotations in a template refer to attributes of the object to control execution and derive values to be displayed. Execution of the template walks the structure and sets the cursor, represented by a period (called dot), to the value at the current location in the object as execution proceeds. The input text for a template is as ASCII text is arbitrary format. Actions -- data evaluations or control structures -- are delimited by {{ and }}; all text outside actions is copied to the output verbatim. To aid in formatting template source code, if {{ is followed immediately by a minus sign and white space, all trailing white space is trimmed from the immediately preceding text. Similarly, if }} is preceded by white space and a minus sign, all leading white space is trimmed from the immediately following text. Notice that the presence of the whitespace in these trim markers is mandatory: "{{- 3}}" trims the immediately preceding text and outputs "3", while "{{-3}}" parses as an action containing the number -3. Actions Here is the list of actions. Arguments and pipelines are evaluations of data, defined in detail in the corresponding sections that follow. {{}} Empty action is discarded. It may be useful to trim the preceding or following whitespace, as in {{--}}.{{/*acomment*/}} Comments are discarded. They may span multiple lines of text. Comments do not nest and must start immediately after the opening delimiter (with optional dash and whitespace in between). A comment may be followed by any action described below. Comments may be used to control trailing and leading whitespace as well: {{-acommenttrimmingthesurroundingwhitespace-}}{{pipeline}}Pipeline is evaluated, and the default textual representation of its value is copied to the output. {{ifpipeline}}T1{{end}} If the value of the pipeline is empty, no output is generated; otherwise, T1 is executed. The empty values are null, false, numeric 0, empty string (""), array ([]), or object ({}). Dot is unaffected. {{ifpipeline}}T1{{else}}T0{{end}} If the value of the pipeline is empty, T0 is executed; otherwise, T1 is executed. Dot is unaffected. {{ifpipeline}}T1{{elseifpipeline}}T2{{else}}T0{{end}} A shortcut to simplify writing the if-else chains. Equivalent to (newlines added for readability): {{if pipeline }} T1 {{else -}} {{if pipeline }} T2 {{else}} T0 {{end}} {{end}} {{rangepipeline}}T1{{end}} The value of pipeline must be an object or array. If it is of length zero, nothing is output. Otherwise, dot is set to the successive elements of the array or object and T1 is executed. For objects, the elements will be visited in sorted key order. {{rangepipeline}}T1{{else}}T0{{end}} Same as above, except that if the value of the pipeline is of length zero, T0 is executed with dot unaffected. Within the {{range}} action, the following two keywords may appear: {{break}} The innermost {{rangepipeline}} loop is ended early, stopping the current iteration and bypassing all remaining iterations. {{continue}} The current iteration of the innermost {{rangepipeline}} loop is stopped, and the loop starts the next iteration. {{define"name"}}text{{end}} The text is collected and stored for the further use as template with the given name. It can be invoked using the {{template}} action (see below). {{template"name"}} The template with the specified name (see the {{define}}above)isexecutedwithdotsettonull. {{template"name"value}} The template with the specified name (see the {{define}}above)isexecutedwithdotsettovalue. {{block"name"pipeline}}T1{{end}} A block is shorthand for defining a template {{define "name"}} T1 {{end}} and then executing it in place {{template "name" pipeline}} {{withpipeline}}T1{{end}} If the value of the pipeline is empty, no output is generated; otherwise, dot is set to the value of the pipeline and T1 is executed. {{withpipeline}}T1{{else}}T0{{end}} Same as above, but if the value of the pipeline is empty, T0 is executed with dot unchanged. Arguments An argument is a simple value, i.e. any of the following: Numeric value (integer or floating point) Boolean value: true or false. Quoted string. A dot (.) This represents the cursor value. Attribute: .Attr This is the value of the attribute Attr in the current value (dot). Attribute references can be nested, as in .Attr.Xattr.Yattr. A variable reference: $var. Here, var is the name of the variable defined in the range action. See the subsection Variables, below. Function call in parentheses, for grouping. Pipelines A pipeline is a series of one or more commands delimited by pipe sign (|). Each command is either an argument or a functioncall, in form: func arg1 arg2... where func is the name of one of the built-in functions discussed below. Pipelines are executed from left to right, with the result of the previous command implicitly added to the list of arguments of each subsequent command. For example, the pipeline .attr | eq $x is equivalent to eq $x .attr i.e. it calls the built-in function eq with two arguments: the value of the variable x and attribute attr of the cursor value. The following built-in functions are defined: andA1A2 Evaluates to true if pipelines A1 and A2 both evaluate to true. Notice, that there is no boolean shortcut evaluation: both pipelines are evaluated prior to calling and. orA1A2 Evaluates to true if at least one of the pipelines A1 and A2 evaluates to true. Notice, that there is no boolean shortcut evaluation: both pipelines are evaluated prior to calling or. indexA1A2... Returns the result of indexing its first argument by the following arguments. Thus, if . is an array, then: index . 5 evaluates to its fifth element (.[5]). lenA1 Returns the integer length of its argument. notA1 Returns true if its argument evaluates to false. eqA1A2 Returns true if both its arguments are equal. This applies only if both A1 and A2 are numeric or if they both are strings. neA1A2 Returns true if its arguments (both must be numeric or strings) are not equal. ltA1A2 Returns true if A1 is numerically less than A2. leA1A2 Returns true if A1 is numerically less than or equal to A2. gtA1A2 Returns true if A1 is numerically greater than A2. geA1A2 Returns true if A1 is numerically greater than or equal to A2. evenA1 Returns true if A1, which must evaluate to an integer value, is divisible by 2. printfFMTA1... Implements the printf(3) function. FMT must evaluate to a string. Rest of arguments is interpreted according to the conversion specifications in FMT. The result is a formatted string. In addition to the standard conversion specifications described in printf(3), the "%v" specifier is implemented: it formats its argument in the best way, depending on its actual type. typeofA1 Evaluates to the type of its argument, one of: null, bool, number, integer, string, array, object. existsA1A2A1 must evaluate to an object and A2 to string. The function evaluates to true if the attribute A2 is present in A1. addA1A2... Returns the sum of its arguments. subA1A2 Returns the difference A1 - A2. mulA1A2 Multiplies A1 by A2. divA1A2 Divides A1 by A2. Variables Variables (referred to as $name) can be defined in range and with actions. For range, the syntax is: {{range$index,$element=pipeline}}T1{{end}} where index and element are arbitrary variable names. When executing this action, during each iteration $index and $element are set to the index (attribute name) and value of each successive element. Dot remains unaffected. For with, the syntax is: {{with$var=pipeline}}T1{{end}}Pipeline is evaluated, its result is assigned to $var and the T1 block is executed with dot unchanged. A variable's scope extends to the end action of the control structure (with or range) in which it is declared. This includes any nested statements that may appear in between.

Depending on the request issued by poundctl, the invoked template can receive as its argument (dot) an object of the following types: full listing, listener, service, or backend. Since there is no explicit indication of the object type being passed, templates normally use heuristics based on the presence or absence of certain attribute to deduce the object type in question. The recommended approach is described in the following pseudo-code fragment: {{if exists . "listeners" }} {{/* This is a full listing, as requested by poundctllist. */}} ... {{else if exists . "services"}} {{/* Single listener, as requested by poundctllist/L. Notice that this attribute is present in the full listing as well, so presence of "listeners" should be checked first. */}} ... {{else if exists . "backends"}} {{/* Single service, as requested by poundctllist/L/S. */}} ... {{else}} {{/* Backend listing (poundctllist/L/S/B) */}} ... {{end}} Structures of each object are discussed in subsections that follow. Fulllisting A full listing contains the following attributes: listeners An array of listener objects. See below for a description. services An array of service objects, representing services defined in the global scope of the pound configuration file. pid PID of the running pound daemon. versionPound version number (string). workers Workers statistics. This is a JSON object with the following attributes: active Number of active threads. count Number of threads currently running. max Maximum number of threads. min Minimum number of threads. timeout Thread idle timeout. queue_len Number of incoming HTTP requests in the queue (integer). timestamp Current time on the server, formatted as ISO 8601 date-time with microsecond precision, e.g.: "2023-01-05T22:43:18.071559". Listener A listener object represents a single HTTP or HTTPS listener in pound configuration. It has the following attributes: addressString. Address of this listener. A string formatted as "IP:PORT" for IPv4 and IPv6 addresses or containing socket file name, for UNIX sockets. protocolString. Protocol used: either http or https. services Array of service objects representing services defined in this listener. See below for the definition of a service object. enabledBoolean. Whether this listener is enabled or not. nohttps11Integer. Value of the NoHTTPS11 configuration statement for this listener. One of: 0, 1, 2. Service A service object describes a single service. nameString. Symbolic name of this service. enabledBoolean. Whether this service is enabled or not. session_typeString. Name of the session handling algorithm for this service. One of: IP, BASIC, URL, PARM, COOKIE, HEADER. sessions List of active sessions in this service. Each session is represented as object with the following attributes: keyString. Session key. backendInteger. Number of the backend assigned to handle requests with this session. expireTimestamp. Expiration time of this session, with microsecond precision. backends List of backends defined for this service. emergency Emergency backend object, or null if no such backend is defined. Backend The following attributes are always present in each backend object: aliveBoolean. Whether or not this backend is alive. conn_toInteger. Connection timeout for this backend (seconds). enabledBoolean. Whether or not this backend is enabled. io_toInteger. I/O timeout for this backend (seconds). priorityInteger in range 0-9. Priority value assigned to this backend. protocolString. Protocol used by this backend: either http or https. typeString. Backend type. One of: acme, backend, control, redirect. ws_toInteger Websocket timeout (seconds). Depending on the backend type, the following attributes may be present: acmepathString. Directory where ACME challenges are stored. backendaddressString. Backend address. redirecturlString. URL to redirect to. codeInteger. HTTP code for redirection responses. One of: 301, 302, 307. redir_reqBoolean. Whether to append the original request path to the resulting location. If backend statistics is enabled (see BackendStats in pound(8)), the stats object will be present, with the following attributes: request_count Total number of requests processed by this backend. request_time_avg Average time per request, in nanoseconds. request_time_stddev Standard deviation of the above.

poundctl.tmpl - templates for poundctl.

Report bugs to <gray@gnu.org>. You may also use github issue tracker at https://github.com/graygnuorg/pound/issues.

pound(8), poundctl(8).