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.
20 package envconfig
21 22 import (
23 "os"
24 "strconv"
25 "strings"
26 )
27 28 var (
29 // EnableTXTServiceConfig is set if the DNS resolver should perform TXT
30 // lookups for service config ("GRPC_ENABLE_TXT_SERVICE_CONFIG" is not
31 // "false").
32 EnableTXTServiceConfig = boolFromEnv("GRPC_ENABLE_TXT_SERVICE_CONFIG", true)
33 34 // TXTErrIgnore is set if TXT errors should be ignored
35 // ("GRPC_GO_IGNORE_TXT_ERRORS" is not "false").
36 TXTErrIgnore = boolFromEnv("GRPC_GO_IGNORE_TXT_ERRORS", true)
37 38 // RingHashCap indicates the maximum ring size which defaults to 4096
39 // entries but may be overridden by setting the environment variable
40 // "GRPC_RING_HASH_CAP". This does not override the default bounds
41 // checking which NACKs configs specifying ring sizes > 8*1024*1024 (~8M).
42 RingHashCap = uint64FromEnv("GRPC_RING_HASH_CAP", 4096, 1, 8*1024*1024)
43 44 // ALTSMaxConcurrentHandshakes is the maximum number of concurrent ALTS
45 // handshakes that can be performed.
46 ALTSMaxConcurrentHandshakes = uint64FromEnv("GRPC_ALTS_MAX_CONCURRENT_HANDSHAKES", 100, 1, 100)
47 48 // EnforceALPNEnabled is set if TLS connections to servers with ALPN disabled
49 // should be rejected. The HTTP/2 protocol requires ALPN to be enabled, this
50 // option is present for backward compatibility. This option may be overridden
51 // by setting the environment variable "GRPC_ENFORCE_ALPN_ENABLED" to "true"
52 // or "false".
53 EnforceALPNEnabled = boolFromEnv("GRPC_ENFORCE_ALPN_ENABLED", true)
54 55 // XDSEndpointHashKeyBackwardCompat controls the parsing of the endpoint hash
56 // key from EDS LbEndpoint metadata. Endpoint hash keys can be disabled by
57 // setting "GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT" to "true". When the
58 // implementation of A76 is stable, we will flip the default value to false
59 // in a subsequent release. A final release will remove this environment
60 // variable, enabling the new behavior unconditionally.
61 XDSEndpointHashKeyBackwardCompat = boolFromEnv("GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT", true)
62 63 // RingHashSetRequestHashKey is set if the ring hash balancer can get the
64 // request hash header by setting the "requestHashHeader" field, according
65 // to gRFC A76. It can be enabled by setting the environment variable
66 // "GRPC_EXPERIMENTAL_RING_HASH_SET_REQUEST_HASH_KEY" to "true".
67 RingHashSetRequestHashKey = boolFromEnv("GRPC_EXPERIMENTAL_RING_HASH_SET_REQUEST_HASH_KEY", false)
68 69 // ALTSHandshakerKeepaliveParams is set if we should add the
70 // KeepaliveParams when dial the ALTS handshaker service.
71 ALTSHandshakerKeepaliveParams = boolFromEnv("GRPC_EXPERIMENTAL_ALTS_HANDSHAKER_KEEPALIVE_PARAMS", false)
72 73 // EnableDefaultPortForProxyTarget controls whether the resolver adds a default port 443
74 // to a target address that lacks one. This flag only has an effect when all of
75 // the following conditions are met:
76 // - A connect proxy is being used.
77 // - Target resolution is disabled.
78 // - The DNS resolver is being used.
79 EnableDefaultPortForProxyTarget = boolFromEnv("GRPC_EXPERIMENTAL_ENABLE_DEFAULT_PORT_FOR_PROXY_TARGET", true)
80 81 // XDSAuthorityRewrite indicates whether xDS authority rewriting is enabled.
82 // This feature is defined in gRFC A81 and is enabled by setting the
83 // environment variable GRPC_EXPERIMENTAL_XDS_AUTHORITY_REWRITE to "true".
84 XDSAuthorityRewrite = boolFromEnv("GRPC_EXPERIMENTAL_XDS_AUTHORITY_REWRITE", false)
85 )
86 87 func boolFromEnv(envVar string, def bool) bool {
88 if def {
89 // The default is true; return true unless the variable is "false".
90 return !strings.EqualFold(os.Getenv(envVar), "false")
91 }
92 // The default is false; return false unless the variable is "true".
93 return strings.EqualFold(os.Getenv(envVar), "true")
94 }
95 96 func uint64FromEnv(envVar string, def, min, max uint64) uint64 {
97 v, err := strconv.ParseUint(os.Getenv(envVar), 10, 64)
98 if err != nil {
99 return def
100 }
101 if v < min {
102 return min
103 }
104 if v > max {
105 return max
106 }
107 return v
108 }
109