Merge master into breakout_swarm

Signed-off-by: Alex Ellis <alexellis2@gmail.com>
This commit is contained in:
Alex Ellis
2018-02-01 09:25:39 +00:00
parent afeb7bbce4
commit f954bf0733
1953 changed files with 614131 additions and 175582 deletions

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package api
import (
"errors"
"net/http"
"github.com/docker/distribution/health"
)
var (
updater = health.NewStatusUpdater()
)
// DownHandler registers a manual_http_status that always returns an Error
func DownHandler(w http.ResponseWriter, r *http.Request) {
if r.Method == "POST" {
updater.Update(errors.New("Manual Check"))
} else {
w.WriteHeader(http.StatusNotFound)
}
}
// UpHandler registers a manual_http_status that always returns nil
func UpHandler(w http.ResponseWriter, r *http.Request) {
if r.Method == "POST" {
updater.Update(nil)
} else {
w.WriteHeader(http.StatusNotFound)
}
}
// init sets up the two endpoints to bring the service up and down
func init() {
health.Register("manual_http_status", updater)
http.HandleFunc("/debug/health/down", DownHandler)
http.HandleFunc("/debug/health/up", UpHandler)
}

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package api
import (
"net/http"
"net/http/httptest"
"testing"
"github.com/docker/distribution/health"
)
// TestGETDownHandlerDoesNotChangeStatus ensures that calling the endpoint
// /debug/health/down with METHOD GET returns a 404
func TestGETDownHandlerDoesNotChangeStatus(t *testing.T) {
recorder := httptest.NewRecorder()
req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health/down", nil)
if err != nil {
t.Errorf("Failed to create request.")
}
DownHandler(recorder, req)
if recorder.Code != 404 {
t.Errorf("Did not get a 404.")
}
}
// TestGETUpHandlerDoesNotChangeStatus ensures that calling the endpoint
// /debug/health/down with METHOD GET returns a 404
func TestGETUpHandlerDoesNotChangeStatus(t *testing.T) {
recorder := httptest.NewRecorder()
req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health/up", nil)
if err != nil {
t.Errorf("Failed to create request.")
}
DownHandler(recorder, req)
if recorder.Code != 404 {
t.Errorf("Did not get a 404.")
}
}
// TestPOSTDownHandlerChangeStatus ensures the endpoint /debug/health/down changes
// the status code of the response to 503
// This test is order dependent, and should come before TestPOSTUpHandlerChangeStatus
func TestPOSTDownHandlerChangeStatus(t *testing.T) {
recorder := httptest.NewRecorder()
req, err := http.NewRequest("POST", "https://fakeurl.com/debug/health/down", nil)
if err != nil {
t.Errorf("Failed to create request.")
}
DownHandler(recorder, req)
if recorder.Code != 200 {
t.Errorf("Did not get a 200.")
}
if len(health.CheckStatus()) != 1 {
t.Errorf("DownHandler didn't add an error check.")
}
}
// TestPOSTUpHandlerChangeStatus ensures the endpoint /debug/health/up changes
// the status code of the response to 200
func TestPOSTUpHandlerChangeStatus(t *testing.T) {
recorder := httptest.NewRecorder()
req, err := http.NewRequest("POST", "https://fakeurl.com/debug/health/up", nil)
if err != nil {
t.Errorf("Failed to create request.")
}
UpHandler(recorder, req)
if recorder.Code != 200 {
t.Errorf("Did not get a 200.")
}
if len(health.CheckStatus()) != 0 {
t.Errorf("UpHandler didn't remove the error check.")
}
}

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package checks
import (
"errors"
"net"
"net/http"
"os"
"strconv"
"time"
"github.com/docker/distribution/health"
)
// FileChecker checks the existence of a file and returns an error
// if the file exists.
func FileChecker(f string) health.Checker {
return health.CheckFunc(func() error {
if _, err := os.Stat(f); err == nil {
return errors.New("file exists")
}
return nil
})
}
// HTTPChecker does a HEAD request and verifies that the HTTP status code
// returned matches statusCode.
func HTTPChecker(r string, statusCode int, timeout time.Duration, headers http.Header) health.Checker {
return health.CheckFunc(func() error {
client := http.Client{
Timeout: timeout,
}
req, err := http.NewRequest("HEAD", r, nil)
if err != nil {
return errors.New("error creating request: " + r)
}
for headerName, headerValues := range headers {
for _, headerValue := range headerValues {
req.Header.Add(headerName, headerValue)
}
}
response, err := client.Do(req)
if err != nil {
return errors.New("error while checking: " + r)
}
if response.StatusCode != statusCode {
return errors.New("downstream service returned unexpected status: " + strconv.Itoa(response.StatusCode))
}
return nil
})
}
// TCPChecker attempts to open a TCP connection.
func TCPChecker(addr string, timeout time.Duration) health.Checker {
return health.CheckFunc(func() error {
conn, err := net.DialTimeout("tcp", addr, timeout)
if err != nil {
return errors.New("connection to " + addr + " failed")
}
conn.Close()
return nil
})
}

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package checks
import (
"testing"
)
func TestFileChecker(t *testing.T) {
if err := FileChecker("/tmp").Check(); err == nil {
t.Errorf("/tmp was expected as exists")
}
if err := FileChecker("NoSuchFileFromMoon").Check(); err != nil {
t.Errorf("NoSuchFileFromMoon was expected as not exists, error:%v", err)
}
}
func TestHTTPChecker(t *testing.T) {
if err := HTTPChecker("https://www.google.cybertron", 200, 0, nil).Check(); err == nil {
t.Errorf("Google on Cybertron was expected as not exists")
}
if err := HTTPChecker("https://www.google.pt", 200, 0, nil).Check(); err != nil {
t.Errorf("Google at Portugal was expected as exists, error:%v", err)
}
}

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// Package health provides a generic health checking framework.
// The health package works expvar style. By importing the package the debug
// server is getting a "/debug/health" endpoint that returns the current
// status of the application.
// If there are no errors, "/debug/health" will return an HTTP 200 status,
// together with an empty JSON reply "{}". If there are any checks
// with errors, the JSON reply will include all the failed checks, and the
// response will be have an HTTP 503 status.
//
// A Check can either be run synchronously, or asynchronously. We recommend
// that most checks are registered as an asynchronous check, so a call to the
// "/debug/health" endpoint always returns immediately. This pattern is
// particularly useful for checks that verify upstream connectivity or
// database status, since they might take a long time to return/timeout.
//
// Installing
//
// To install health, just import it in your application:
//
// import "github.com/docker/distribution/health"
//
// You can also (optionally) import "health/api" that will add two convenience
// endpoints: "/debug/health/down" and "/debug/health/up". These endpoints add
// "manual" checks that allow the service to quickly be brought in/out of
// rotation.
//
// import _ "github.com/docker/distribution/registry/health/api"
//
// # curl localhost:5001/debug/health
// {}
// # curl -X POST localhost:5001/debug/health/down
// # curl localhost:5001/debug/health
// {"manual_http_status":"Manual Check"}
//
// After importing these packages to your main application, you can start
// registering checks.
//
// Registering Checks
//
// The recommended way of registering checks is using a periodic Check.
// PeriodicChecks run on a certain schedule and asynchronously update the
// status of the check. This allows CheckStatus to return without blocking
// on an expensive check.
//
// A trivial example of a check that runs every 5 seconds and shuts down our
// server if the current minute is even, could be added as follows:
//
// func currentMinuteEvenCheck() error {
// m := time.Now().Minute()
// if m%2 == 0 {
// return errors.New("Current minute is even!")
// }
// return nil
// }
//
// health.RegisterPeriodicFunc("minute_even", currentMinuteEvenCheck, time.Second*5)
//
// Alternatively, you can also make use of "RegisterPeriodicThresholdFunc" to
// implement the exact same check, but add a threshold of failures after which
// the check will be unhealthy. This is particularly useful for flaky Checks,
// ensuring some stability of the service when handling them.
//
// health.RegisterPeriodicThresholdFunc("minute_even", currentMinuteEvenCheck, time.Second*5, 4)
//
// The lowest-level way to interact with the health package is calling
// "Register" directly. Register allows you to pass in an arbitrary string and
// something that implements "Checker" and runs your check. If your method
// returns an error with nil, it is considered a healthy check, otherwise it
// will make the health check endpoint "/debug/health" start returning a 503
// and list the specific check that failed.
//
// Assuming you wish to register a method called "currentMinuteEvenCheck()
// error" you could do that by doing:
//
// health.Register("even_minute", health.CheckFunc(currentMinuteEvenCheck))
//
// CheckFunc is a convenience type that implements Checker.
//
// Another way of registering a check could be by using an anonymous function
// and the convenience method RegisterFunc. An example that makes the status
// endpoint always return an error:
//
// health.RegisterFunc("my_check", func() error {
// return Errors.new("This is an error!")
// }))
//
// Examples
//
// You could also use the health checker mechanism to ensure your application
// only comes up if certain conditions are met, or to allow the developer to
// take the service out of rotation immediately. An example that checks
// database connectivity and immediately takes the server out of rotation on
// err:
//
// updater = health.NewStatusUpdater()
// health.RegisterFunc("database_check", func() error {
// return updater.Check()
// }))
//
// conn, err := Connect(...) // database call here
// if err != nil {
// updater.Update(errors.New("Error connecting to the database: " + err.Error()))
// }
//
// You can also use the predefined Checkers that come included with the health
// package. First, import the checks:
//
// import "github.com/docker/distribution/health/checks
//
// After that you can make use of any of the provided checks. An example of
// using a `FileChecker` to take the application out of rotation if a certain
// file exists can be done as follows:
//
// health.Register("fileChecker", health.PeriodicChecker(checks.FileChecker("/tmp/disable"), time.Second*5))
//
// After registering the check, it is trivial to take an application out of
// rotation from the console:
//
// # curl localhost:5001/debug/health
// {}
// # touch /tmp/disable
// # curl localhost:5001/debug/health
// {"fileChecker":"file exists"}
//
// You could also test the connectivity to a downstream service by using a
// "HTTPChecker", but ensure that you only mark the test unhealthy if there
// are a minimum of two failures in a row:
//
// health.Register("httpChecker", health.PeriodicThresholdChecker(checks.HTTPChecker("https://www.google.pt"), time.Second*5, 2))
package health

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package health
import (
"encoding/json"
"fmt"
"net/http"
"sync"
"time"
"github.com/docker/distribution/context"
"github.com/docker/distribution/registry/api/errcode"
)
// A Registry is a collection of checks. Most applications will use the global
// registry defined in DefaultRegistry. However, unit tests may need to create
// separate registries to isolate themselves from other tests.
type Registry struct {
mu sync.RWMutex
registeredChecks map[string]Checker
}
// NewRegistry creates a new registry. This isn't necessary for normal use of
// the package, but may be useful for unit tests so individual tests have their
// own set of checks.
func NewRegistry() *Registry {
return &Registry{
registeredChecks: make(map[string]Checker),
}
}
// DefaultRegistry is the default registry where checks are registered. It is
// the registry used by the HTTP handler.
var DefaultRegistry *Registry
// Checker is the interface for a Health Checker
type Checker interface {
// Check returns nil if the service is okay.
Check() error
}
// CheckFunc is a convenience type to create functions that implement
// the Checker interface
type CheckFunc func() error
// Check Implements the Checker interface to allow for any func() error method
// to be passed as a Checker
func (cf CheckFunc) Check() error {
return cf()
}
// Updater implements a health check that is explicitly set.
type Updater interface {
Checker
// Update updates the current status of the health check.
Update(status error)
}
// updater implements Checker and Updater, providing an asynchronous Update
// method.
// This allows us to have a Checker that returns the Check() call immediately
// not blocking on a potentially expensive check.
type updater struct {
mu sync.Mutex
status error
}
// Check implements the Checker interface
func (u *updater) Check() error {
u.mu.Lock()
defer u.mu.Unlock()
return u.status
}
// Update implements the Updater interface, allowing asynchronous access to
// the status of a Checker.
func (u *updater) Update(status error) {
u.mu.Lock()
defer u.mu.Unlock()
u.status = status
}
// NewStatusUpdater returns a new updater
func NewStatusUpdater() Updater {
return &updater{}
}
// thresholdUpdater implements Checker and Updater, providing an asynchronous Update
// method.
// This allows us to have a Checker that returns the Check() call immediately
// not blocking on a potentially expensive check.
type thresholdUpdater struct {
mu sync.Mutex
status error
threshold int
count int
}
// Check implements the Checker interface
func (tu *thresholdUpdater) Check() error {
tu.mu.Lock()
defer tu.mu.Unlock()
if tu.count >= tu.threshold {
return tu.status
}
return nil
}
// thresholdUpdater implements the Updater interface, allowing asynchronous
// access to the status of a Checker.
func (tu *thresholdUpdater) Update(status error) {
tu.mu.Lock()
defer tu.mu.Unlock()
if status == nil {
tu.count = 0
} else if tu.count < tu.threshold {
tu.count++
}
tu.status = status
}
// NewThresholdStatusUpdater returns a new thresholdUpdater
func NewThresholdStatusUpdater(t int) Updater {
return &thresholdUpdater{threshold: t}
}
// PeriodicChecker wraps an updater to provide a periodic checker
func PeriodicChecker(check Checker, period time.Duration) Checker {
u := NewStatusUpdater()
go func() {
t := time.NewTicker(period)
for {
<-t.C
u.Update(check.Check())
}
}()
return u
}
// PeriodicThresholdChecker wraps an updater to provide a periodic checker that
// uses a threshold before it changes status
func PeriodicThresholdChecker(check Checker, period time.Duration, threshold int) Checker {
tu := NewThresholdStatusUpdater(threshold)
go func() {
t := time.NewTicker(period)
for {
<-t.C
tu.Update(check.Check())
}
}()
return tu
}
// CheckStatus returns a map with all the current health check errors
func (registry *Registry) CheckStatus() map[string]string { // TODO(stevvooe) this needs a proper type
registry.mu.RLock()
defer registry.mu.RUnlock()
statusKeys := make(map[string]string)
for k, v := range registry.registeredChecks {
err := v.Check()
if err != nil {
statusKeys[k] = err.Error()
}
}
return statusKeys
}
// CheckStatus returns a map with all the current health check errors from the
// default registry.
func CheckStatus() map[string]string {
return DefaultRegistry.CheckStatus()
}
// Register associates the checker with the provided name.
func (registry *Registry) Register(name string, check Checker) {
if registry == nil {
registry = DefaultRegistry
}
registry.mu.Lock()
defer registry.mu.Unlock()
_, ok := registry.registeredChecks[name]
if ok {
panic("Check already exists: " + name)
}
registry.registeredChecks[name] = check
}
// Register associates the checker with the provided name in the default
// registry.
func Register(name string, check Checker) {
DefaultRegistry.Register(name, check)
}
// RegisterFunc allows the convenience of registering a checker directly from
// an arbitrary func() error.
func (registry *Registry) RegisterFunc(name string, check func() error) {
registry.Register(name, CheckFunc(check))
}
// RegisterFunc allows the convenience of registering a checker in the default
// registry directly from an arbitrary func() error.
func RegisterFunc(name string, check func() error) {
DefaultRegistry.RegisterFunc(name, check)
}
// RegisterPeriodicFunc allows the convenience of registering a PeriodicChecker
// from an arbitrary func() error.
func (registry *Registry) RegisterPeriodicFunc(name string, period time.Duration, check CheckFunc) {
registry.Register(name, PeriodicChecker(CheckFunc(check), period))
}
// RegisterPeriodicFunc allows the convenience of registering a PeriodicChecker
// in the default registry from an arbitrary func() error.
func RegisterPeriodicFunc(name string, period time.Duration, check CheckFunc) {
DefaultRegistry.RegisterPeriodicFunc(name, period, check)
}
// RegisterPeriodicThresholdFunc allows the convenience of registering a
// PeriodicChecker from an arbitrary func() error.
func (registry *Registry) RegisterPeriodicThresholdFunc(name string, period time.Duration, threshold int, check CheckFunc) {
registry.Register(name, PeriodicThresholdChecker(CheckFunc(check), period, threshold))
}
// RegisterPeriodicThresholdFunc allows the convenience of registering a
// PeriodicChecker in the default registry from an arbitrary func() error.
func RegisterPeriodicThresholdFunc(name string, period time.Duration, threshold int, check CheckFunc) {
DefaultRegistry.RegisterPeriodicThresholdFunc(name, period, threshold, check)
}
// StatusHandler returns a JSON blob with all the currently registered Health Checks
// and their corresponding status.
// Returns 503 if any Error status exists, 200 otherwise
func StatusHandler(w http.ResponseWriter, r *http.Request) {
if r.Method == "GET" {
checks := CheckStatus()
status := http.StatusOK
// If there is an error, return 503
if len(checks) != 0 {
status = http.StatusServiceUnavailable
}
statusResponse(w, r, status, checks)
} else {
http.NotFound(w, r)
}
}
// Handler returns a handler that will return 503 response code if the health
// checks have failed. If everything is okay with the health checks, the
// handler will pass through to the provided handler. Use this handler to
// disable a web application when the health checks fail.
func Handler(handler http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
checks := CheckStatus()
if len(checks) != 0 {
errcode.ServeJSON(w, errcode.ErrorCodeUnavailable.
WithDetail("health check failed: please see /debug/health"))
return
}
handler.ServeHTTP(w, r) // pass through
})
}
// statusResponse completes the request with a response describing the health
// of the service.
func statusResponse(w http.ResponseWriter, r *http.Request, status int, checks map[string]string) {
p, err := json.Marshal(checks)
if err != nil {
context.GetLogger(context.Background()).Errorf("error serializing health status: %v", err)
p, err = json.Marshal(struct {
ServerError string `json:"server_error"`
}{
ServerError: "Could not parse error message",
})
status = http.StatusInternalServerError
if err != nil {
context.GetLogger(context.Background()).Errorf("error serializing health status failure message: %v", err)
return
}
}
w.Header().Set("Content-Type", "application/json; charset=utf-8")
w.Header().Set("Content-Length", fmt.Sprint(len(p)))
w.WriteHeader(status)
if _, err := w.Write(p); err != nil {
context.GetLogger(context.Background()).Errorf("error writing health status response body: %v", err)
}
}
// Registers global /debug/health api endpoint, creates default registry
func init() {
DefaultRegistry = NewRegistry()
http.HandleFunc("/debug/health", StatusHandler)
}

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package health
import (
"errors"
"fmt"
"net/http"
"net/http/httptest"
"testing"
)
// TestReturns200IfThereAreNoChecks ensures that the result code of the health
// endpoint is 200 if there are not currently registered checks.
func TestReturns200IfThereAreNoChecks(t *testing.T) {
recorder := httptest.NewRecorder()
req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health", nil)
if err != nil {
t.Errorf("Failed to create request.")
}
StatusHandler(recorder, req)
if recorder.Code != 200 {
t.Errorf("Did not get a 200.")
}
}
// TestReturns500IfThereAreErrorChecks ensures that the result code of the
// health endpoint is 500 if there are health checks with errors
func TestReturns503IfThereAreErrorChecks(t *testing.T) {
recorder := httptest.NewRecorder()
req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health", nil)
if err != nil {
t.Errorf("Failed to create request.")
}
// Create a manual error
Register("some_check", CheckFunc(func() error {
return errors.New("This Check did not succeed")
}))
StatusHandler(recorder, req)
if recorder.Code != 503 {
t.Errorf("Did not get a 503.")
}
}
// TestHealthHandler ensures that our handler implementation correct protects
// the web application when things aren't so healthy.
func TestHealthHandler(t *testing.T) {
// clear out existing checks.
DefaultRegistry = NewRegistry()
// protect an http server
handler := http.Handler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusNoContent)
}))
// wrap it in our health handler
handler = Handler(handler)
// use this swap check status
updater := NewStatusUpdater()
Register("test_check", updater)
// now, create a test server
server := httptest.NewServer(handler)
checkUp := func(t *testing.T, message string) {
resp, err := http.Get(server.URL)
if err != nil {
t.Fatalf("error getting success status: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusNoContent {
t.Fatalf("unexpected response code from server when %s: %d != %d", message, resp.StatusCode, http.StatusNoContent)
}
// NOTE(stevvooe): we really don't care about the body -- the format is
// not standardized or supported, yet.
}
checkDown := func(t *testing.T, message string) {
resp, err := http.Get(server.URL)
if err != nil {
t.Fatalf("error getting down status: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusServiceUnavailable {
t.Fatalf("unexpected response code from server when %s: %d != %d", message, resp.StatusCode, http.StatusServiceUnavailable)
}
}
// server should be up
checkUp(t, "initial health check")
// now, we fail the health check
updater.Update(fmt.Errorf("the server is now out of commission"))
checkDown(t, "server should be down") // should be down
// bring server back up
updater.Update(nil)
checkUp(t, "when server is back up") // now we should be back up.
}