1/*
 2 *
 3 * Copyright 2018 gRPC authors.
 4 *
 5 * Licensed under the Apache License, Version 2.0 (the "License");
 6 * you may not use this file except in compliance with the License.
 7 * You may obtain a copy of the License at
 8 *
 9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19// Package envconfig contains grpc settings configured by environment variables.
20package envconfig
21
22import (
23	"os"
24	"strconv"
25	"strings"
26)
27
28var (
29	// TXTErrIgnore is set if TXT errors should be ignored ("GRPC_GO_IGNORE_TXT_ERRORS" is not "false").
30	TXTErrIgnore = boolFromEnv("GRPC_GO_IGNORE_TXT_ERRORS", true)
31	// RingHashCap indicates the maximum ring size which defaults to 4096
32	// entries but may be overridden by setting the environment variable
33	// "GRPC_RING_HASH_CAP".  This does not override the default bounds
34	// checking which NACKs configs specifying ring sizes > 8*1024*1024 (~8M).
35	RingHashCap = uint64FromEnv("GRPC_RING_HASH_CAP", 4096, 1, 8*1024*1024)
36	// LeastRequestLB is set if we should support the least_request_experimental
37	// LB policy, which can be enabled by setting the environment variable
38	// "GRPC_EXPERIMENTAL_ENABLE_LEAST_REQUEST" to "true".
39	LeastRequestLB = boolFromEnv("GRPC_EXPERIMENTAL_ENABLE_LEAST_REQUEST", false)
40	// ALTSMaxConcurrentHandshakes is the maximum number of concurrent ALTS
41	// handshakes that can be performed.
42	ALTSMaxConcurrentHandshakes = uint64FromEnv("GRPC_ALTS_MAX_CONCURRENT_HANDSHAKES", 100, 1, 100)
43	// EnforceALPNEnabled is set if TLS connections to servers with ALPN disabled
44	// should be rejected. The HTTP/2 protocol requires ALPN to be enabled, this
45	// option is present for backward compatibility. This option may be overridden
46	// by setting the environment variable "GRPC_ENFORCE_ALPN_ENABLED" to "true"
47	// or "false".
48	EnforceALPNEnabled = boolFromEnv("GRPC_ENFORCE_ALPN_ENABLED", true)
49	// XDSFallbackSupport is the env variable that controls whether support for
50	// xDS fallback is turned on. If this is unset or is false, only the first
51	// xDS server in the list of server configs will be used.
52	XDSFallbackSupport = boolFromEnv("GRPC_EXPERIMENTAL_XDS_FALLBACK", true)
53	// NewPickFirstEnabled is set if the new pickfirst leaf policy is to be used
54	// instead of the exiting pickfirst implementation. This can be enabled by
55	// setting the environment variable "GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST"
56	// to "true".
57	NewPickFirstEnabled = boolFromEnv("GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST", false)
58)
59
60func boolFromEnv(envVar string, def bool) bool {
61	if def {
62		// The default is true; return true unless the variable is "false".
63		return !strings.EqualFold(os.Getenv(envVar), "false")
64	}
65	// The default is false; return false unless the variable is "true".
66	return strings.EqualFold(os.Getenv(envVar), "true")
67}
68
69func uint64FromEnv(envVar string, def, min, max uint64) uint64 {
70	v, err := strconv.ParseUint(os.Getenv(envVar), 10, 64)
71	if err != nil {
72		return def
73	}
74	if v < min {
75		return min
76	}
77	if v > max {
78		return max
79	}
80	return v
81}