forked from hashicorp/consul
/
config_gce.go
159 lines (135 loc) · 4.6 KB
/
config_gce.go
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package agent
import (
"context"
"fmt"
"io/ioutil"
"log"
"net/http"
"strings"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
compute "google.golang.org/api/compute/v1"
)
// discoverGCEHosts searches a Google Compute Engine region, returning a list
// of instance ips that match the tags given in GCETags.
func (c *Config) discoverGCEHosts(logger *log.Logger) ([]string, error) {
config := c.RetryJoinGCE
ctx := oauth2.NoContext
var client *http.Client
var err error
logger.Printf("[INFO] agent: Initializing GCE client")
if config.CredentialsFile != "" {
logger.Printf("[INFO] agent: Loading credentials from %s", config.CredentialsFile)
key, err := ioutil.ReadFile(config.CredentialsFile)
if err != nil {
return nil, err
}
jwtConfig, err := google.JWTConfigFromJSON(key, compute.ComputeScope)
if err != nil {
return nil, err
}
client = jwtConfig.Client(ctx)
} else {
logger.Printf("[INFO] agent: Using default credential chain")
client, err = google.DefaultClient(ctx, compute.ComputeScope)
if err != nil {
return nil, err
}
}
computeService, err := compute.New(client)
if err != nil {
return nil, err
}
if config.ProjectName == "" {
logger.Printf("[INFO] agent: No GCE project provided, will discover from metadata.")
config.ProjectName, err = gceProjectIDFromMetadata(logger)
if err != nil {
return nil, err
}
} else {
logger.Printf("[INFO] agent: Using pre-defined GCE project name: %s", config.ProjectName)
}
zones, err := gceDiscoverZones(ctx, logger, computeService, config.ProjectName, config.ZonePattern)
if err != nil {
return nil, err
}
logger.Printf("[INFO] agent: Discovering GCE hosts with tag %s in zones: %s", config.TagValue, strings.Join(zones, ", "))
var servers []string
for _, zone := range zones {
addresses, err := gceInstancesAddressesForZone(ctx, logger, computeService, config.ProjectName, zone, config.TagValue)
if err != nil {
return nil, err
}
if len(addresses) > 0 {
logger.Printf("[INFO] agent: Discovered %d instances in %s/%s: %v", len(addresses), config.ProjectName, zone, addresses)
}
servers = append(servers, addresses...)
}
return servers, nil
}
// gceProjectIDFromMetadata queries the metadata service on GCE to get the
// project ID (name) of an instance.
func gceProjectIDFromMetadata(logger *log.Logger) (string, error) {
logger.Printf("[INFO] agent: Attempting to discover GCE project from metadata.")
client := &http.Client{}
req, err := http.NewRequest("GET", "http://metadata.google.internal/computeMetadata/v1/project/project-id", nil)
if err != nil {
return "", err
}
req.Header.Add("Metadata-Flavor", "Google")
resp, err := client.Do(req)
if err != nil {
return "", err
}
defer resp.Body.Close()
project, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", err
}
logger.Printf("[INFO] agent: GCE project discovered as: %s", project)
return string(project), nil
}
// gceDiscoverZones discovers a list of zones from a supplied zone pattern, or
// all of the zones available to a project.
func gceDiscoverZones(ctx context.Context, logger *log.Logger, computeService *compute.Service, project, pattern string) ([]string, error) {
var zones []string
if pattern != "" {
logger.Printf("[INFO] agent: Discovering zones for project %s matching pattern: %s", project, pattern)
} else {
logger.Printf("[INFO] agent: Discovering all zones available to project: %s", project)
}
call := computeService.Zones.List(project)
if pattern != "" {
call = call.Filter(fmt.Sprintf("name eq %s", pattern))
}
if err := call.Pages(ctx, func(page *compute.ZoneList) error {
for _, v := range page.Items {
zones = append(zones, v.Name)
}
return nil
}); err != nil {
return zones, err
}
logger.Printf("[INFO] agent: Discovered GCE zones: %s", strings.Join(zones, ", "))
return zones, nil
}
// gceInstancesAddressesForZone locates all instances within a specific project
// and zone, matching the supplied tag. Only the private IP addresses are
// returned, but ID is also logged.
func gceInstancesAddressesForZone(ctx context.Context, logger *log.Logger, computeService *compute.Service, project, zone, tag string) ([]string, error) {
var addresses []string
call := computeService.Instances.List(project, zone)
if err := call.Pages(ctx, func(page *compute.InstanceList) error {
for _, v := range page.Items {
for _, t := range v.Tags.Items {
if t == tag && len(v.NetworkInterfaces) > 0 && v.NetworkInterfaces[0].NetworkIP != "" {
addresses = append(addresses, v.NetworkInterfaces[0].NetworkIP)
}
}
}
return nil
}); err != nil {
return addresses, err
}
return addresses, nil
}