Fixes: #4222
# Data Filtering
This PR will implement filtering for the following endpoints:
## Supported HTTP Endpoints
- `/agent/checks`
- `/agent/services`
- `/catalog/nodes`
- `/catalog/service/:service`
- `/catalog/connect/:service`
- `/catalog/node/:node`
- `/health/node/:node`
- `/health/checks/:service`
- `/health/service/:service`
- `/health/connect/:service`
- `/health/state/:state`
- `/internal/ui/nodes`
- `/internal/ui/services`
More can be added going forward and any endpoint which is used to list some data is a good candidate.
## Usage
When using the HTTP API a `filter` query parameter can be used to pass a filter expression to Consul. Filter Expressions take the general form of:
```
<selector> == <value>
<selector> != <value>
<value> in <selector>
<value> not in <selector>
<selector> contains <value>
<selector> not contains <value>
<selector> is empty
<selector> is not empty
not <other expression>
<expression 1> and <expression 2>
<expression 1> or <expression 2>
```
Normal boolean logic and precedence is supported. All of the actual filtering and evaluation logic is coming from the [go-bexpr](https://github.com/hashicorp/go-bexpr) library
## Other changes
Adding the `Internal.ServiceDump` RPC endpoint. This will allow the UI to filter services better.
* Add cache types for catalog/services and health/services and basic test that caching works
* Support non-blocking cache types with Cache-Control semantics.
* Update API docs to include caching info for every endpoint.
* Comment updates per PR feedback.
* Add note on caching to the 10,000 foot view on the architecture page to make the new data path more clear.
* Document prepared query staleness quirk and force all background requests to AllowStale so we can spread service discovery load across servers.
By default, the Consul agent listens on the local interface
at port 8500 for API requests. This change makes the API examples
using `curl` copy-pasteable for this default configuration.
* Updates the API client to support the current `ScriptArgs` parameter
for checks.
* Updates docs for checks to explain the `ScriptArgs` parameter issue.
* Adds mappings for "args" and "script-args" to give th API parity
with config.
* Adds checks on return codes.
* Removes debug logging that shows empty when args are used.
* agent: consolidate http method not allowed checks
This patch uses the error handling of the http handlers to handle HTTP
method not allowed errors across all available endpoints. It also adds a
test for testing whether the endpoints respond with the correct status
code.
* agent: do not panic on metrics tests
* agent: drop other tests for MethodNotAllowed
* agent: align /agent/join with reality
/agent/join uses PUT instead of GET as documented.
* agent: align /agent/check/{fail,warn,pass} with reality
/agent/check/{fail,warn,pass} uses PUT instead of GET as documented.
* fix some tests
* Drop more tests for method not allowed
* Align TestAgent_RegisterService_InvalidAddress with reality
* Changes API client join to use PUT instead of GET.
* Fixes agent endpoint verbs and removes obsolete tests.
* Updates the change log.
Matt Keeler