metadata

Documentation

Overview

Package metadata provides access to Google Compute Engine (GCE) metadata and API service accounts.

This package is a wrapper around the GCE metadata service, as documented at https://developers.google.com/compute/docs/metadata.

Index

• func ExternalIP() (string, error)
• func Get(suffix string) (string, error)
• func Hostname() (string, error)
• func InstanceAttributeValue(attr string) (string, error)
• func InstanceAttributes() ([]string, error)
• func InstanceID() (string, error)
• func InstanceName() (string, error)
• func InstanceTags() ([]string, error)
• func InternalIP() (string, error)
• func NumericProjectID() (string, error)
• func OnGCE() bool
• func ProjectAttributeValue(attr string) (string, error)
• func ProjectAttributes() ([]string, error)
• func ProjectID() (string, error)
• func Scopes(serviceAccount string) ([]string, error)
• func Subscribe(suffix string, fn func(v string, ok bool) error) error
• func Zone() (string, error)
• type Client
  • func NewClient(c *http.Client) *Client
  • func (c *Client) ExternalIP() (string, error)
  • func (c *Client) Get(suffix string) (string, error)
  • func (c *Client) Hostname() (string, error)
  • func (c *Client) InstanceAttributeValue(attr string) (string, error)
  • func (c *Client) InstanceAttributes() ([]string, error)
  • func (c *Client) InstanceID() (string, error)
  • func (c *Client) InstanceName() (string, error)
  • func (c *Client) InstanceTags() ([]string, error)
  • func (c *Client) InternalIP() (string, error)
  • func (c *Client) NumericProjectID() (string, error)
  • func (c *Client) ProjectAttributeValue(attr string) (string, error)
  • func (c *Client) ProjectAttributes() ([]string, error)
  • func (c *Client) ProjectID() (string, error)
  • func (c *Client) Scopes(serviceAccount string) ([]string, error)
  • func (c *Client) Subscribe(suffix string, fn func(v string, ok bool) error) error
  • func (c *Client) Zone() (string, error)
• type NotDefinedError
  • func (suffix NotDefinedError) Error() string

Examples

• NewClient

Functions

func ExternalIP

func ExternalIP() (string, error)

ExternalIP returns the instance's primary external (public) IP address.

func Get

func Get(suffix string) (string, error)

Get calls Client.Get on the default client.

func Hostname

func Hostname() (string, error)

Hostname returns the instance's hostname. This will be of the form "<instanceID>.c.<projID>.internal".

func InstanceAttributeValue

func InstanceAttributeValue(attr string) (string, error)

InstanceAttributeValue calls Client.InstanceAttributeValue on the default client.

func InstanceAttributes

func InstanceAttributes() ([]string, error)

InstanceAttributes calls Client.InstanceAttributes on the default client.

func InstanceID

func InstanceID() (string, error)

InstanceID returns the current VM's numeric instance ID.

func InstanceName

func InstanceName() (string, error)

InstanceName returns the current VM's instance ID string.

func InstanceTags

func InstanceTags() ([]string, error)

InstanceTags returns the list of user-defined instance tags, assigned when initially creating a GCE instance.

func InternalIP

func InternalIP() (string, error)

InternalIP returns the instance's primary internal IP address.

func NumericProjectID

func NumericProjectID() (string, error)

NumericProjectID returns the current instance's numeric project ID.

func OnGCE

func OnGCE() bool

OnGCE reports whether this process is running on Google Compute Engine.

func ProjectAttributeValue

func ProjectAttributeValue(attr string) (string, error)

ProjectAttributeValue calls Client.ProjectAttributeValue on the default client.

func ProjectAttributes

func ProjectAttributes() ([]string, error)

ProjectAttributes calls Client.ProjectAttributes on the default client.

func ProjectID

func ProjectID() (string, error)

ProjectID returns the current instance's project ID string.

func Scopes

func Scopes(serviceAccount string) ([]string, error)

Scopes calls Client.Scopes on the default client.

func Subscribe

func Subscribe(suffix string, fn func(v string, ok bool) error) error

Subscribe calls Client.Subscribe on a client designed for subscribing (one with no ResponseHeaderTimeout).

func Zone

func Zone() (string, error)

Zone returns the current VM's zone, such as "us-central1-b".

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

A Client provides metadata.

func NewClient

func NewClient(c *http.Client) *Client

NewClient returns a Client that can be used to fetch metadata. All HTTP requests will use the given http.Client instead of the default client.

Example

This example demonstrates how to use your own transport when using this package.

package main

import (
	"net/http"

	"cloud.google.com/go/compute/metadata"
)

// This example demonstrates how to use your own transport when using this package.
func main() {
	c := metadata.NewClient(&http.Client{Transport: userAgentTransport{
		userAgent: "my-user-agent",
		base:      http.DefaultTransport,
	}})
	p, err := c.ProjectID()
	if err != nil {
		// TODO: Handle error.
	}
	_ = p // TODO: Use p.
}

// userAgentTransport sets the User-Agent header before calling base.
type userAgentTransport struct {
	userAgent string
	base      http.RoundTripper
}

// RoundTrip implements the http.RoundTripper interface.
func (t userAgentTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req.Header.Set("User-Agent", t.userAgent)
	return t.base.RoundTrip(req)
}

func (*Client) ExternalIP

func (c *Client) ExternalIP() (string, error)

ExternalIP returns the instance's primary external (public) IP address.

func (*Client) Get

func (c *Client) Get(suffix string) (string, error)

Get returns a value from the metadata service. The suffix is appended to "http://${GCE_METADATA_HOST}/computeMetadata/v1/".

If the GCE_METADATA_HOST environment variable is not defined, a default of 169.254.169.254 will be used instead.

If the requested metadata is not defined, the returned error will be of type NotDefinedError.

func (*Client) Hostname

func (c *Client) Hostname() (string, error)

Hostname returns the instance's hostname. This will be of the form "<instanceID>.c.<projID>.internal".

func (*Client) InstanceAttributeValue

func (c *Client) InstanceAttributeValue(attr string) (string, error)

InstanceAttributeValue returns the value of the provided VM instance attribute.

If the requested attribute is not defined, the returned error will be of type NotDefinedError.

InstanceAttributeValue may return ("", nil) if the attribute was defined to be the empty string.

func (*Client) InstanceAttributes

func (c *Client) InstanceAttributes() ([]string, error)

InstanceAttributes returns the list of user-defined attributes, assigned when initially creating a GCE VM instance. The value of an attribute can be obtained with InstanceAttributeValue.

func (*Client) InstanceID

func (c *Client) InstanceID() (string, error)

InstanceID returns the current VM's numeric instance ID.

func (*Client) InstanceName

func (c *Client) InstanceName() (string, error)

InstanceName returns the current VM's instance ID string.

func (*Client) InstanceTags

func (c *Client) InstanceTags() ([]string, error)

InstanceTags returns the list of user-defined instance tags, assigned when initially creating a GCE instance.

func (*Client) InternalIP

func (c *Client) InternalIP() (string, error)

InternalIP returns the instance's primary internal IP address.

func (*Client) NumericProjectID

func (c *Client) NumericProjectID() (string, error)

NumericProjectID returns the current instance's numeric project ID.

func (*Client) ProjectAttributeValue

func (c *Client) ProjectAttributeValue(attr string) (string, error)

ProjectAttributeValue returns the value of the provided project attribute.

If the requested attribute is not defined, the returned error will be of type NotDefinedError.

ProjectAttributeValue may return ("", nil) if the attribute was defined to be the empty string.

func (*Client) ProjectAttributes

func (c *Client) ProjectAttributes() ([]string, error)

ProjectAttributes returns the list of user-defined attributes applying to the project as a whole, not just this VM. The value of an attribute can be obtained with ProjectAttributeValue.

func (*Client) ProjectID

func (c *Client) ProjectID() (string, error)

ProjectID returns the current instance's project ID string.

func (*Client) Scopes

func (c *Client) Scopes(serviceAccount string) ([]string, error)

Scopes returns the service account scopes for the given account. The account may be empty or the string "default" to use the instance's main account.

func (*Client) Subscribe

func (c *Client) Subscribe(suffix string, fn func(v string, ok bool) error) error

Subscribe subscribes to a value from the metadata service. The suffix is appended to "http://${GCE_METADATA_HOST}/computeMetadata/v1/". The suffix may contain query parameters.

Subscribe calls fn with the latest metadata value indicated by the provided suffix. If the metadata value is deleted, fn is called with the empty string and ok false. Subscribe blocks until fn returns a non-nil error or the value is deleted. Subscribe returns the error value returned from the last call to fn, which may be nil when ok == false.

func (*Client) Zone

func (c *Client) Zone() (string, error)

Zone returns the current VM's zone, such as "us-central1-b".

type NotDefinedError

type NotDefinedError string

NotDefinedError is returned when requested metadata is not defined.

The underlying string is the suffix after "/computeMetadata/v1/".

This error is not returned if the value is defined to be the empty string.

func (NotDefinedError) Error

func (suffix NotDefinedError) Error() string