/
fake_metadata.go
72 lines (60 loc) · 1.91 KB
/
fake_metadata.go
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package cmd
import (
"fmt"
"net/http"
"net/http/httptest"
"os"
"strings"
"cloud.google.com/go/compute/metadata"
)
const metadataHostEnv = "GCE_METADATA_HOST"
// Instance struct for supported fake values for metadata server.
type Instance struct {
ProjectID string
ProjectNumber string
InstanceID string
InstanceName string
Zone string
}
// MetadataServer provides fake implementation for the GCE metadata server.
type MetadataServer struct {
server *httptest.Server
oldMetadataHostEnv string
responses map[string]string
}
// NewMetadataServer starts and hooks up a Server, serving env.
// data is the mock Instance data the metadata server will respond with.
func NewMetadataServer(data Instance) (*MetadataServer, error) {
resp := map[string]string{}
resp["project/project-id"] = data.ProjectID
resp["project/numeric-project-id"] = data.ProjectNumber
resp["instance/id"] = data.InstanceID
resp["instance/zone"] = data.Zone
resp["instance/name"] = data.InstanceName
handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
path := "/computeMetadata/v1/"
uri := strings.TrimPrefix(r.URL.Path, path)
if uri != "" {
res, found := resp[uri]
if found {
w.Write([]byte(res))
return
}
}
http.Error(w, http.StatusText(http.StatusNotImplemented), http.StatusNotImplemented)
})
httpServer := httptest.NewServer(handler)
old := os.Getenv(metadataHostEnv)
s := &MetadataServer{oldMetadataHostEnv: old, server: httpServer, responses: resp}
os.Setenv(metadataHostEnv, strings.TrimPrefix(s.server.URL, "http://"))
if !metadata.OnGCE() {
s.Stop()
return nil, fmt.Errorf("gcpmocks.NewMetadataServer: failed to fake being on a GCE instance")
}
return s, nil
}
// Stop shuts down the server and restores original metadataHostEnv env var.
func (s *MetadataServer) Stop() {
os.Setenv(metadataHostEnv, s.oldMetadataHostEnv)
s.server.Close()
}