| // Copyright 2022 Google LLC |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package internal |
| |
| import ( |
| "io/ioutil" |
| "net" |
| "net/http" |
| "os" |
| "strings" |
| "time" |
| |
| "cloud.google.com/go/compute/metadata" |
| ) |
| |
| // ResourceAttributesGetter abstracts environment lookup methods to query for environment variables, metadata attributes and file content. |
| type ResourceAttributesGetter interface { |
| EnvVar(name string) string |
| Metadata(path string) string |
| ReadAll(path string) string |
| } |
| |
| var getter ResourceAttributesGetter = &defaultResourceGetter{ |
| metaClient: metadata.NewClient(&http.Client{ |
| Transport: &http.Transport{ |
| Dial: (&net.Dialer{ |
| Timeout: 1 * time.Second, |
| KeepAlive: 10 * time.Second, |
| }).Dial, |
| }, |
| })} |
| |
| // ResourceAttributes provides read-only access to the ResourceAtttributesGetter interface implementation. |
| func ResourceAttributes() ResourceAttributesGetter { |
| return getter |
| } |
| |
| type defaultResourceGetter struct { |
| metaClient *metadata.Client |
| } |
| |
| // EnvVar uses os.LookupEnv() to lookup for environment variable by name. |
| func (g *defaultResourceGetter) EnvVar(name string) string { |
| return os.Getenv(name) |
| } |
| |
| // Metadata uses metadata package Client.Get() to lookup for metadata attributes by path. |
| func (g *defaultResourceGetter) Metadata(path string) string { |
| val, err := g.metaClient.Get(path) |
| if err != nil { |
| return "" |
| } |
| return strings.TrimSpace(val) |
| } |
| |
| // ReadAll reads all content of the file as a string. |
| func (g *defaultResourceGetter) ReadAll(path string) string { |
| bytes, err := ioutil.ReadFile(path) |
| if err != nil { |
| return "" |
| } |
| return string(bytes) |
| } |