perf: Go 1.26, BuildKit cache mounts

.dockerignore

@@ -0,0 +1,10 @@
+.git
+.github
+*.md
+LICENSE
+*.test
+*.prof
+*.out
+dist/
+pkg/
+coverage.out

.gitignore

@@ -53,3 +53,9 @@ coverage.out
 
 # Cross compiled binaries
 pkg
+
+# AI assistant config
+CLAUDE.md
+AGENTS.md
+GEMINI.md
+QWEN.md

Dockerfile

@@ -1,4 +1,5 @@
-FROM --platform=$BUILDPLATFORM golang:alpine AS builder
+# syntax=docker/dockerfile:1
+FROM --platform=$BUILDPLATFORM golang:1.26-alpine AS builder
 
 ARG VERSION="dev"
 ARG GIT_COMMIT
@@ -14,9 +15,15 @@ ENV GOOS=$TARGETOS \
 RUN apk add --no-cache ca-certificates && update-ca-certificates
 
 WORKDIR /src
+COPY go.mod go.sum ./
+RUN --mount=type=cache,target=/go/pkg/mod \
+    go mod download
+
 COPY . /src
 
-RUN go build -trimpath \
+RUN --mount=type=cache,target=/go/pkg/mod \
+    --mount=type=cache,target=/root/.cache/go-build \
+    go build -trimpath \
     -ldflags "-w -X server.serverVersion=${VERSION} -X server.gitCommit=${GIT_COMMIT}" \
     -o /out/pubsub .
 

go.mod

@@ -1,8 +1,6 @@
 module github.com/nats-io/nats-server/v2
 
-go 1.25.0
-
-toolchain go1.25.7
+go 1.26.0
 
 require (
 	github.com/antithesishq/antithesis-sdk-go v0.6.0-default-no-op