The rewrite rule specified with the -r flag must be a string of the form:

	pattern -> replacement

Both pattern and replacement must be valid Go expressions.
In the pattern, single-character lowercase identifiers serve as
wildcards matching arbitrary sub-expressions; those expressions
will be substituted for the same identifiers in the replacement.

When gofmt reads from standard input, it accepts either a full Go program

}

// generatePatterns generates all possible patterns using a representative
// sample of parts.
func generatePatterns() []*pattern {
	var pats []*pattern

	collect := func(s string) {
		// Replace duplicate wildcards with unique ones.
		var b strings.Builder
		wc := 0
		for {
			i := strings.Index(s, "{x}")
			if i < 0 {
				b.WriteString(s)
				break
			}
			b.WriteString(s[:i])
			fmt.Fprintf(&b, "{x%d}", wc)

		}

		if url != "" && strings.ContainsRune(url[:len(url)-1], '*') {
			allErrs = append(allErrs, field.Invalid(fldPath.Index(i), url, "non-resource URL wildcards '*' must be the final character of the rule"))
		}
	}
	return allErrs
}

func validateResources(groupResources []audit.GroupResources, fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList

To achieve this, the backend must have a list of "allowed origins".

In this case, it would have to include `http://localhost:8080` for the frontend to work correctly.

## Wildcards

It's also possible to declare the list as `"*"` (a "wildcard") to say that all are allowed.

		{
			host.Names{"b", "a", "aa"},
			host.Names{"aa", "a", "b"},
		},
		{
			host.Names{"foo.com", "bar.com", "foo.bar.com"},
			host.Names{"foo.bar.com", "bar.com", "foo.com"},
		},
		// We sort wildcards last, always
		{
			host.Names{"a", "*", "z"},
			host.Names{"a", "z", "*"},
		},
		{
			host.Names{"foo.com", "bar.com", "*.com"},
			host.Names{"bar.com", "foo.com", "*.com"},
		},
		{

---
#The following example demonstrates the use of wildcards in the hosts for
#external services. If the connection has to be routed to the IP address
#requested by the application (i.e. application resolves DNS and attempts
#to connect to a specific IP), the discovery mode must be set to `NONE`.
apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: external-svc-wildcard-example
  namespace: seexamples
spec:

! stdout 'example.com/version'

# 'go list -m' with wildcards should fail. Wildcards match modules in the
# build list, so they aren't meaningful outside a module.
! go list -m ...

        then:
        project.tasks.openIdea != null
    }

    def "configures idea project"() {
        when:
        applyPluginToProjects()

        then:
        project.idea.project.wildcards == ['!?*.java', '!?*.groovy', '!?*.class', '!?*.scala'] as Set
        project.idea.project.languageLevel.level ==  new IdeaLanguageLevel(JavaVersion.VERSION_1_6).level
    }

					},
				},
			},
			expected: map[string]int{
				"a": 0, "b": 1,
				"a.test.com": 0, "b.test.com": 1,
				"test.com": 0,
			},
		},
		{
			// wildcards
			certs: []namedtestCertSpec{
				{
					testCertSpec: testCertSpec{
						host:  "a",
						names: []string{"a.test.com", "test.com"},
					},
					explicitNames: []string{"*.test.com", "test.com"},

			return nil, fmt.Errorf("bad label/annotation selection %s, must have format key=value", ss)
		}
		if strings.Contains(kv[0], "*") {
			return nil, fmt.Errorf("bad label/annotation selection %s, key cannot have '*' wildcards", ss)
		}
		out[kv[0]] = kv[1]
	}
	return out, nil
}

func (s *SelectionSpec) UnmarshalJSON(b []byte) error {
	ft := []ResourceType{Namespace, Deployment, Pod, Label, Annotation, Container}