77 lines
1.9 KiB
Go
77 lines
1.9 KiB
Go
// package readiness implements a minimal health-checking mechanism for use as k8s readiness probes. It will always
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// return a "ready" state after the conditions have been met for the first time - it's not meant for monitoring.
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//
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// Uses a global singleton registry (similar to the Prometheus client's default behavior).
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package readiness
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import (
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"bytes"
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"fmt"
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"net/http"
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"sync"
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)
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var (
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mu = sync.Mutex{}
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registry = map[string]bool{}
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)
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type Component string
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// RegisterComponent registers the given component name such that it is required to be ready for the global check to succeed.
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func RegisterComponent(component Component) {
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mu.Lock()
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if _, ok := registry[string(component)]; ok {
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panic("component already registered")
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}
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registry[string(component)] = false
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mu.Unlock()
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}
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// SetReady sets the given global component state.
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func SetReady(component Component) {
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mu.Lock()
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if !registry[string(component)] {
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registry[string(component)] = true
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}
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mu.Unlock()
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}
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// Handler returns a net/http handler for the readiness check. It returns 200 OK if all components are ready,
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// or 412 Precondition Failed otherwise. For operator convenience, a list of components and their states
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// is returned as plain text (not meant for machine consumption!).
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func Handler(w http.ResponseWriter, r *http.Request) {
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ready := true
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resp := new(bytes.Buffer)
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_, err := resp.Write([]byte("[not suitable for monitoring - do not parse]\n\n"))
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if err != nil {
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panic(err)
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}
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_, err = resp.Write([]byte("[these values update AT STARTUP ONLY - see https://github.com/certusone/wormhole/blob/dev.v2/docs/operations.md#readyz]\n\n"))
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if err != nil {
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panic(err)
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}
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mu.Lock()
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for k, v := range registry {
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_, err = fmt.Fprintln(resp, fmt.Sprintf("%s\t%v", k, v))
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if err != nil {
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panic(err)
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}
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if !v {
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ready = false
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}
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}
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mu.Unlock()
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if !ready {
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w.WriteHeader(http.StatusPreconditionFailed)
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} else {
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w.WriteHeader(http.StatusOK)
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}
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_, _ = resp.WriteTo(w)
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}
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