Add Listen Address resolver

config/listenaddress/listenaddress.go

@@ -0,0 +1,100 @@
+// Copyright (c) 2018 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package listenaddress provides a configuration struct for resolving
+// a listen address from YAML.
+package listenaddress
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+)
+
+// Resolver is a type of port resolver
+type Resolver string
+
+const (
+	// ConfigResolver resolves port using a value provided in config
+	ConfigResolver Resolver = "config"
+	// EnvironmentResolver resolves port using an environment variable
+	// of which the name is provided in config
+	EnvironmentResolver Resolver = "environment"
+)
+
+// Configuration is the configuration for resolving a listen address.
+type Configuration struct {
+	// Hostname is the hostname to use
+	Hostname string `yaml:"hostname" validate:"nonzero"`
+
+	// Port specifies the port to listen on
+	Port *Port `yaml:"port" validate:"nonzero"`
+}
+
+// Port specifies the port to use
+type Port struct {
+	// PortType is the port type for the port
+	PortType Resolver `yaml:"portType" validate:"nonzero"`
+
+	// Value is the config specified port if using config port type.
+	Value *int `yaml:"value"`
+
+	// EnvVarName is the environment specified port if using environment port type.
+	EnvVarName *string `yaml:"envVarName"`
+}
+
+// Resolve returns the resolved listen address given the configuration.
+func (c Configuration) Resolve() (string, error) {
+	if c.Port == nil {
+		return "", errors.New("missing port config")
+	}
+	p := c.Port
+
+	var port int
+	switch p.PortType {
+	case ConfigResolver:
+		if p.Value == nil {
+			err := fmt.Errorf("missing port type using: resolver=%s",
+				string(p.PortType))
+			return "", err
+		}
+		port = *p.Value
+	case EnvironmentResolver:
+		if p.EnvVarName == nil {
+			err := fmt.Errorf("missing port env var name using: resolver=%s",
+				string(p.PortType))
+			return "", err
+		}
+		portStr := os.Getenv(*p.EnvVarName)
+		var err error
+		port, err = strconv.Atoi(portStr)
+		if err != nil {
+			err := fmt.Errorf("invalid port env var value using: resolver=%s, name=%s",
+				string(p.PortType), *p.EnvVarName)
+			return "", err
+		}
+	default:
+		return "", fmt.Errorf("unknown port type: resolver=%s",
+			string(p.PortType))
+	}
+
+	return fmt.Sprintf("%s:%d", c.Hostname, port), nil
+}

config/listenaddress/listenaddress_test.go

@@ -0,0 +1,138 @@
+// Copyright (c) 2018 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package listenaddress provides a configuration struct for resolving
+// a listen address from YAML.
+package listenaddress
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	port     = 9000
+	hostname = "0.0.0.0"
+)
+
+func TestListenAddressResolver(t *testing.T) {
+	cfg := Configuration{
+		Hostname: hostname,
+		Port: &Port{
+			PortType: ConfigResolver,
+			Value:    &port,
+		},
+	}
+
+	value, err := cfg.Resolve()
+	require.NoError(t, err)
+
+	assert.Equal(t, "0.0.0.0:9000", value)
+}
+
+func TestConfigResolverErrorWhenMissing(t *testing.T) {
+	cfg := Configuration{
+		Hostname: hostname,
+	}
+
+	_, err := cfg.Resolve()
+	require.Error(t, err)
+}
+
+func TestEnvironmentVariableResolver(t *testing.T) {
+	varName := "PORT_ENV_NAME"
+	expected := "9000"
+
+	require.NoError(t, os.Setenv(varName, expected))
+
+	cfg := Configuration{
+		Hostname: hostname,
+		Port: &Port{
+			PortType:   EnvironmentResolver,
+			EnvVarName: &varName,
+		},
+	}
+
+	value, err := cfg.Resolve()
+	require.NoError(t, err)
+
+	assert.Equal(t, "0.0.0.0:9000", value)
+}
+
+func TestInvalidEnvironmentVariableResolver(t *testing.T) {
+	varName := "PORT_ENV_NAME"
+	expected := "foo"
+
+	require.NoError(t, os.Setenv(varName, expected))
+
+	cfg := Configuration{
+		Hostname: hostname,
+		Port: &Port{
+			PortType:   EnvironmentResolver,
+			EnvVarName: &varName,
+		},
+	}
+
+	_, err := cfg.Resolve()
+	require.Error(t, err)
+}
+
+func TestEnvironmentResolverErrorWhenNameMissing(t *testing.T) {
+	cfg := Configuration{
+		Hostname: hostname,
+		Port: &Port{
+			PortType: EnvironmentResolver,
+		},
+	}
+
+	_, err := cfg.Resolve()
+	require.Error(t, err)
+}
+
+func TestEnvironmentResolverErrorWhenValueMissing(t *testing.T) {
+	varName := "PORT_ENV_NAME_OTHER"
+
+	cfg := Configuration{
+		Hostname: hostname,
+		Port: &Port{
+			PortType:   EnvironmentResolver,
+			EnvVarName: &varName,
+		},
+	}
+
+	_, err := cfg.Resolve()
+	require.Error(t, err)
+}
+
+func TestUnknownResolverError(t *testing.T) {
+	cfg := Configuration{
+		Hostname: hostname,
+		Port: &Port{
+			PortType: "some-unknown-resolver",
+			Value:    &port,
+		},
+	}
+
+	_, err := cfg.Resolve()
+	require.Error(t, err)
+}