x-pack/filebeat/input/cel: make http functions always available (#40912)

HTTP functions were previously conditional on the resource URL being an
HTTP/HTTPS URL. In hindsight, this offers no benefits and can result in
confusing errors when the end user enters an invalid URL for an HTTP-based
integration. Instead of a URL-related or HTTP-related error, the user is
given a compilation error indicating that the HTTP-related function that
are being called (and they may not be aware of in any way) are not valid
references. So let's just always make them available.

CHANGELOG.next.asciidoc

@@ -303,6 +303,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Allow attribute selection in the Active Directory entity analytics provider. {issue}40482[40482] {pull}40662[40662]
 - Improve error quality when CEL program does not correctly return an events array. {pull}40580[40580]
 - Add `use_kubeadm` config option for filebeat (both filbeat.input and autodiscovery) in order to toggle kubeadm-config api requests {pull}40301[40301]
+- Make HTTP library function inclusion non-conditional in CEL input. {pull}40912[40912]
 
 *Auditbeat*
 

x-pack/filebeat/input/cel/config.go

@@ -81,15 +81,11 @@ func (c config) Validate() error {
  return fmt.Errorf("failed to check regular expressions: %w", err)
  }
  // TODO: Consider just building the program here to avoid this wasted work.
- var client *http.Client
- if wantClient(c) {
- client = &http.Client{}
- }
  var patterns map[string]*regexp.Regexp
  if len(c.Regexps) != 0 {
  patterns = map[string]*regexp.Regexp{".": nil}
  }
- _, _, err = newProgram(context.Background(), c.Program, root, client, nil, nil, patterns, c.XSDs, logp.L().Named("input.cel"), nil)
+ _, _, err = newProgram(context.Background(), c.Program, root, &http.Client{}, nil, nil, patterns, c.XSDs, logp.L().Named("input.cel"), nil)
  if err != nil {
  return fmt.Errorf("failed to check program: %w", err)
  }

x-pack/filebeat/input/cel/input.go

@@ -727,9 +727,6 @@ func getLimit(which string, rateLimit map[string]interface{}, log *logp.Logger)
 const lumberjackTimestamp = "[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]T[0-9][0-9]-[0-9][0-9]-[0-9][0-9].[0-9][0-9][0-9]"
 
 func newClient(ctx context.Context, cfg config, log *logp.Logger, reg *monitoring.Registry) (*http.Client, *httplog.LoggingRoundTripper, error) {
- if !wantClient(cfg) {
- return nil, nil, nil
- }
  c, err := cfg.Resource.Transport.Client(clientOptions(cfg.Resource.URL.URL, cfg.Resource.KeepAlive.settings())...)
  if err != nil {
  return nil, nil, err
@@ -1012,14 +1009,12 @@ func newProgram(ctx context.Context, src, root string, client *http.Client, limi
  lib.Debug(debug(log, trace)),
  lib.File(mimetypes),
  lib.MIME(mimetypes),
+ lib.HTTPWithContext(ctx, client, limiter, auth),
  lib.Limit(limitPolicies),
  lib.Globals(map[string]interface{}{
  "useragent": userAgent,
  }),
  }
- if client != nil {
- opts = append(opts, lib.HTTPWithContext(ctx, client, limiter, auth))
- }
  if len(patterns) != 0 {
  opts = append(opts, lib.Regexp(patterns))
  }