Cutlery/caddy
1
0
Fork 0
mirror of https://github.com/caddyserver/caddy.git synced 2026-04-28 19:50:41 -04:00
Code Issues Actions Packages Projects Releases Wiki Activity

reverseproxy: Add ability to clear dynamic upstreams cache during retries (#7662)

Browse Source 
* reverseproxy: Add ability to clear dynamic upstreams cache during retries

This is an optional interface for dynamic upstream modules to implement if they cache results.

TODO: More documentation; this is an experiment.

* Add some godoc

* Export interface; update godoc
This commit is contained in:
Matt Holt 2026-04-28 09:16:18 -06:00 committed by Matthew Holt
parent 163910e74e
commit 4ec1ea5153
No known key found for this signature in database
2 changed files with 46 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
modules/caddyhttp/reverseproxy/reverseproxy.go
View File

@ -494,6 +494,17 @@ func (h *Handler) proxyLoopIteration(r *http.Request, origReq *http.Request, w h
// get the updated list of upstreams
upstreams := h.Upstreams
if h.DynamicUpstreams != nil {
if retries > 0 {
// after a failure (and thus during a retry), give dynamic upstream modules an opportunity
// to purge their relevant cache entries so we don't keep retrying bad upstreams
if cachingDynamicUpstreams, ok := h.DynamicUpstreams.(CachingUpstreamSource); ok {
if err := cachingDynamicUpstreams.ResetCache(r); err != nil {
if c := h.logger.Check(zapcore.ErrorLevel, "failed clearing dynamic upstream source's cache"); c != nil {
c.Write(zap.Error(err))
}
}
}
}
dUpstreams, err := h.DynamicUpstreams.GetUpstreams(r)
if err != nil {
if c := h.logger.Check(zapcore.ErrorLevel, "failed getting dynamic upstreams; falling back to static upstreams"); c != nil {
@ -1435,10 +1446,28 @@ type Selector interface {
// may be called during each retry, multiple times per request, and as
// such, needs to be instantaneous. The returned slice will not be
// modified.
//
// For upstream sources that cache results, implement the
// [CachingUpstreamSource] interface for optimal performance.
type UpstreamSource interface {
GetUpstreams(*http.Request) ([]*Upstream, error)
}
// CachingUpstreamSource is an upstream source that caches its upstreams.
// The relevant cache entry can be cleared/reset for a given request during
// retries if a request fails. This can help ensure that failing backends
// are not retried.
//
// EXPERIMENTAL: Subject to change.
type CachingUpstreamSource interface {
UpstreamSource
// ResetCache clears any cache entry related to the given request.
// The next time GetUpstreams is called, it should have new upstream
// information for the given request.
ResetCache(*http.Request) error
}
// Hop-by-hop headers. These are removed when sent to the backend.
// As of RFC 7230, hop-by-hop headers are required to appear in the
// Connection header field. These are the headers defined by the

21
modules/caddyhttp/reverseproxy/upstreams.go
View File

@ -119,6 +119,18 @@ func (su *SRVUpstreams) Provision(ctx caddy.Context) error {
return nil
}
func (su *SRVUpstreams) ResetCache(r *http.Request) error {
srvsMu.Lock()
if r == nil {
srvs = make(map[string]srvLookup)
} else {
suAddr, _, _, _ := su.expandedAddr(r)
delete(srvs, suAddr)
}
srvsMu.Unlock()
return nil
}
func (su SRVUpstreams) GetUpstreams(r *http.Request) ([]*Upstream, error) {
suAddr, service, proto, name := su.expandedAddr(r)
@ -554,8 +566,9 @@ var (
// Interface guards
var (
_ caddy.Provisioner = (*SRVUpstreams)(nil)
_ UpstreamSource = (*SRVUpstreams)(nil)
_ caddy.Provisioner = (*AUpstreams)(nil)
_ UpstreamSource = (*AUpstreams)(nil)
_ caddy.Provisioner = (*SRVUpstreams)(nil)
_ UpstreamSource = (*SRVUpstreams)(nil)
_ CachingUpstreamSource = (*SRVUpstreams)(nil)
_ caddy.Provisioner = (*AUpstreams)(nil)
_ UpstreamSource = (*AUpstreams)(nil)
)