* reorganize for clarity and update for value syntax
* fix quotes around value
* Apply suggestions from code review
Co-authored-by: Blake Covarrubias <blake@covarrubi.as>
* Apply suggestions from code review
Co-authored-by: Freddy <freddygv@users.noreply.github.com>
Co-authored-by: Blake Covarrubias <blake@covarrubi.as>
Co-authored-by: Freddy <freddygv@users.noreply.github.com>
To create a filter expression, you will write one or more expressions using matching operators, selectors, and values.
Filtering is executed on the Consul server, before data is returned, reducing the network load. To pass a
filter expression to Consul, use the `filter` query parameter when sending requests to HTTP API endpoints that support it.
## Expression Syntax
## Creating Expressions
Expressions are written in plain text format. Boolean logic and parenthesization are
A single expression is a matching operator with a selector and value. They are written in plain text format, boolean logic and parenthesization are
supported. In general whitespace is ignored, except within literal
strings.
### Expressions
There are several methods for connecting expressions, including
- logical `or`
- logical `and`
- logical `not`
- grouping with parenthesis
- matching expressions
```text
// Logical Or - evaluates to true if either sub-expression does
<Expression 1> or <Expression 2>
// Logical And - evaluates to true if both sub-expressions do
<Expression 1 > and <Expression 2>
// Logical Not - evaluates to true if the sub-expression does not
not <Expression 1>
// Grouping - Overrides normal precedence rules
( <Expression 1> )
// Inspects data to check for a match
<Matching Expression 1>
```
Standard operator precedence can be expected for the various forms. For
example, the following two expressions would be equivalent.
```text
<Expression 1> and not <Expression 2> or <Expression 3>
( <Expression 1> and (not <Expression 2> )) or <Expression 3>
```
### Matching Operators
Matching operators are used to create an expression. All matching operators use a selector or value to choose what data should be
All matching operators use a selector or value to choose what data should be
matched. Each endpoint that supports filtering accepts a potentially
different list of selectors and is detailed in the API documentation for
those endpoints.
```text
// Equality & Inequality checks
<Selector> == <Value>
<Selector> != <Value>
<Selector> == "<Value>"
<Selector> != "<Value>"
// Emptiness checks
<Selector> is empty
<Selector> is not empty
// Contains checks or Substring Matching
<Value> in <Selector>
<Value> not in <Selector>
<Selector> contains <Value>
<Selector> not contains <Value>
"<Value>" in <Selector>
"<Value>" not in <Selector>
<Selector> contains "<Value>"
<Selector> not contains "<Value>"
// Regular Expression Matching
<Selector> matches <Value>
<Selector> not matches <Value>
<Selector> matches "<Value>"
<Selector> not matches "<Value>"
```
### Selectors
@ -108,12 +73,51 @@ ServiceMeta["foo"]
### Values
Values are used by matching operators to create an expression. Values can be any valid selector, a number, or a quoted string. For numbers any
base 10 integers and floating point numbers are possible. For quoted strings,
Values are used by matching operators to create an expression. Values can be any valid selector, a number, or a string. It is best practice to quote values.
Numbers can be base 10 integers or floating point numbers.
When quoting strings,
they may either be enclosed in double quotes or backticks. When enclosed in
backticks they are treated as raw strings and escape sequences such as `\n`
will not be expanded.
## Connecting Expressions
There are several methods for connecting expressions, including
- logical `or`
- logical `and`
- logical `not`
- grouping with parenthesis
- matching expressions
```text
// Logical Or - evaluates to true if either sub-expression does
<Expression 1> or <Expression 2>
// Logical And - evaluates to true if both sub-expressions do
<Expression 1 > and <Expression 2>
// Logical Not - evaluates to true if the sub-expression does not
not <Expression 1>
// Grouping - Overrides normal precedence rules
( <Expression 1> )
// Inspects data to check for a match
<Matching Expression 1>
```
Standard operator precedence can be expected for the various forms. For
example, the following two expressions would be equivalent.
```text
<Expression 1> and not <Expression 2> or <Expression 3>
( <Expression 1> and (not <Expression 2> )) or <Expression 3>
```
## Filter Utilization
Generally, only the main object is filtered. When filtering for
@ -195,7 +199,7 @@ curl -X GET localhost:8500/v1/agent/services
kaitlincarter-hc
4 years ago
committed by