docker: refactor cache handling in Docker bake configuration

- Renamed cache functions for Go and web targets to clarify their purpose and prevent race conditions during parallel builds.
- Updated targets to use the new cache export functions, ensuring proper cache management.
- Revised README to reflect changes in cache usage and provide guidance on resolving potential CI issues related to cache schema changes.

deploy/docker/README.md

@@ -13,11 +13,15 @@
 
 Кэш registry (переменные bake):
 
-- `git.shts.su/<owner>/evobgp-buildcache:go-buildcache`
-- `git.shts.su/<owner>/evobgp-buildcache:web-buildcache`
+- `git.shts.su/<owner>/evobgp-buildcache:go-buildcache` — **запись** только из target `go-build-all`
+- `git.shts.su/<owner>/evobgp-buildcache:web-buildcache` — **запись** только из target `web-build`
+
+Остальные bake-target’ы только `cache-from` (чтение). Параллельный `cache-to` в один ref ломает manifest в registry (`content descriptor … not found`).
 
 Локально BuildKit также кэширует `/go/pkg/mod` и `~/.cache/go-build` через `RUN --mount=type=cache`.
 
+Если CI падает на «not found» после смены схемы кэша — один раз удалите теги `evobgp-buildcache:go-buildcache` и `:web-buildcache` в registry и пересоберите.
+
 ## Локальная сборка
 
 Из корня репозитория:

deploy/docker/docker-bake.hcl

@@ -32,7 +32,10 @@ function "go-cache-from" {
   result = notequal("", CACHE_REF_GO) ? ["type=registry,ref=${CACHE_REF_GO}"] : []
 }
 
-function "go-cache-to" {
+# Экспорт кэша — только go-build-all / web-build (один writer на ref).
+# Несколько target с cache-to в один ref и mode=max дают гонку в registry
+# (content descriptor not found при параллельном bake).
+function "go-cache-to-export" {
   params = []
   result = notequal("", CACHE_REF_GO) ? ["type=registry,ref=${CACHE_REF_GO},mode=max"] : []
 }
@@ -42,7 +45,7 @@ function "web-cache-from" {
   result = notequal("", CACHE_REF_WEB) ? ["type=registry,ref=${CACHE_REF_WEB}"] : []
 }
 
-function "web-cache-to" {
+function "web-cache-to-export" {
   params = []
   result = notequal("", CACHE_REF_WEB) ? ["type=registry,ref=${CACHE_REF_WEB},mode=max"] : []
 }
@@ -76,7 +79,6 @@ target "go-deps" {
   target     = "deps"
   platforms  = ["linux/amd64"]
   cache-from = go-cache-from()
-  cache-to   = go-cache-to()
 }
 
 target "go-build-all" {
@@ -88,7 +90,7 @@ target "go-build-all" {
     deps = "target:go-deps"
   }
   cache-from = go-cache-from()
-  cache-to   = go-cache-to()
+  cache-to   = go-cache-to-export()
 }
 
 target "go-birdc" {
@@ -97,7 +99,6 @@ target "go-birdc" {
   target     = "birdc"
   platforms  = ["linux/amd64"]
   cache-from = go-cache-from()
-  cache-to   = go-cache-to()
 }
 
 target "_go-runtime" {
@@ -109,7 +110,6 @@ target "_go-runtime" {
     build-all = "target:go-build-all"
   }
   cache-from = go-cache-from()
-  cache-to   = go-cache-to()
 }
 
 target "_go-runtime-birdc" {
@@ -122,7 +122,6 @@ target "_go-runtime-birdc" {
     birdc     = "target:go-birdc"
   }
   cache-from = go-cache-from()
-  cache-to   = go-cache-to()
 }
 
 function "image-tags" {
@@ -187,7 +186,6 @@ target "evobgp-agent" {
     build-all = "target:go-build-all"
   }
   cache-from = go-cache-from()
-  cache-to   = go-cache-to()
   tags       = image-tags("evobgp-agent")
 }
 
@@ -199,7 +197,6 @@ target "web-deps" {
   target     = "deps"
   platforms  = ["linux/amd64"]
   cache-from = web-cache-from()
-  cache-to   = web-cache-to()
 }
 
 target "web-build" {
@@ -211,7 +208,7 @@ target "web-build" {
     deps = "target:web-deps"
   }
   cache-from = web-cache-from()
-  cache-to   = web-cache-to()
+  cache-to   = web-cache-to-export()
 }
 
 target "evobgp-web" {
@@ -224,7 +221,6 @@ target "evobgp-web" {
   }
   args       = { EVOBGP_UPSTREAM = "evobgp-api" }
   cache-from = web-cache-from()
-  cache-to   = web-cache-to()
   tags       = image-tags("evobgp-web")
 }
 
@@ -238,7 +234,6 @@ target "evobgp-web-all" {
   }
   args       = { EVOBGP_UPSTREAM = "evobgp-all" }
   cache-from = web-cache-from()
-  cache-to   = web-cache-to()
   tags       = image-tags("evobgp-web-all")
 }