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package httpvar

import "gocloud.dev/runtimevar/httpvar"

Package httpvar provides a runtimevar implementation with variables backed by http endpoint. Use OpenVariable to construct a *runtimevar.Variable.


For runtimevar.OpenVariable, httpvar registers for the schemes "http" and "https". The default URL opener will use http.DefaultClient. To customize the URL opener, or for more details on the URL format, see URLOpener. See https://gocloud.dev/concepts/urls/ for background information.


httpvar exposes the following types for As:

- Snapshot: *http.Response
- Error: httpvar.RequestError, url.Error


// runtimevar.OpenVariable creates a *runtimevar.Variable from a URL.
// The "decoder" query parameter is optional, and is removed before fetching
// the URL.
ctx := context.Background()
v, err := runtimevar.OpenVariable(ctx, "http://myserver.com/foo.txt?decoder=string")
if err != nil {

snapshot, err := v.Latest(ctx)
_, _ = snapshot, err



Package Files



var Schemes = []string{"http", "https"}

Schemes are the URL schemes httpvar registers its URLOpener under on runtimevar.DefaultMux.

func OpenVariable Uses

func OpenVariable(client *http.Client, urlStr string, decoder *runtimevar.Decoder, opts *Options) (*runtimevar.Variable, error)

OpenVariable constructs a *runtimevar.Variable that uses client to retrieve the variable contents from the URL urlStr.


httpClient := http.DefaultClient
decoder := runtimevar.NewDecoder(MyConfig{}, runtimevar.JSONDecode)

// Construct a *runtimevar.Variable that watches the variable.
v, err := httpvar.OpenVariable(httpClient, "http://example.com", decoder, nil)
if err != nil {
defer v.Close()

// We can now read the current value of the variable from v.
snapshot, err := v.Watch(context.Background())
if err != nil {
cfg := snapshot.Value.(MyConfig)
_ = cfg

type Options Uses

type Options struct {
    // WaitDuration controls the rate at which the HTTP endpoint is called to check for changes.
    // Defaults to 30 seconds.
    WaitDuration time.Duration

Options sets options.

type RequestError Uses

type RequestError struct {
    Response *http.Response

RequestError represents an HTTP error that occurred during endpoint call.

func (*RequestError) Error Uses

func (e *RequestError) Error() string

type URLOpener Uses

type URLOpener struct {
    // The Client to use; required.
    Client *http.Client

    // Decoder specifies the decoder to use if one is not specified in the URL.
    // Defaults to runtimevar.BytesDecoder.
    Decoder *runtimevar.Decoder

    // Options specifies the options to pass to OpenVariable.
    Options Options

URLOpener opens HTTP URLs like "http://myserver.com/foo.txt".

The full URL, including scheme, is used as the endpoint, except that the the following URL parameters are removed if present:

- decoder: The decoder to use. Defaults to runtimevar.BytesDecoder.
    See runtimevar.DecoderByName for supported values.

func (*URLOpener) OpenVariableURL Uses

func (o *URLOpener) OpenVariableURL(ctx context.Context, u *url.URL) (*runtimevar.Variable, error)

OpenVariableURL opens a httpvar Variable for u.

Package httpvar imports 11 packages (graph) and is imported by 1 packages. Updated 2019-05-16. Refresh now. Tools for package owners.