Dockerfile: remove APT_MIRROR build-arg

This option was originally added in 8ec8564691dc1ebf757c93fe51f6b64a8fcb49af,
at which time the upstream debian package repositories were not always
reliable, so using a mirror helped with CI stability and performance.

Debian's package repositories are a lot more reliable now, so there's no
longer a need to use a mirror.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Dockerfile

@@ -38,8 +38,6 @@ COPY --from=build-dummy /build /build
 FROM --platform=$BUILDPLATFORM ${GOLANG_IMAGE} AS base
 COPY --from=xx / /
 RUN echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache
-ARG APT_MIRROR
-RUN test -n "$APT_MIRROR" && sed -ri "s#(httpredir|deb|security).debian.org#${APT_MIRROR}#g" /etc/apt/sources.list.d/debian.sources || true
 RUN apt-get update && apt-get install --no-install-recommends -y file
 ENV GO111MODULE=off
 ENV GOTOOLCHAIN=local

Dockerfile.simple

@@ -14,10 +14,6 @@ FROM ${GOLANG_IMAGE}
 ENV GO111MODULE=off
 ENV GOTOOLCHAIN=local
 
-# allow replacing debian mirror
-ARG APT_MIRROR
-RUN test -n "$APT_MIRROR" && sed -ri "s#(httpredir|deb|security).debian.org#${APT_MIRROR}#g" /etc/apt/sources.list.d/debian.sources || true
-
 # Compile and runtime deps
 # https://github.com/docker/docker/blob/master/project/PACKAGERS.md#build-dependencies
 # https://github.com/docker/docker/blob/master/project/PACKAGERS.md#runtime-dependencies

Makefile

@@ -138,7 +138,6 @@ endif
 DOCKER_RUN_DOCKER := $(DOCKER_FLAGS) "$(DOCKER_IMAGE)"
 
 DOCKER_BUILD_ARGS += --build-arg=GO_VERSION
-DOCKER_BUILD_ARGS += --build-arg=APT_MIRROR
 DOCKER_BUILD_ARGS += --build-arg=DOCKERCLI_VERSION
 DOCKER_BUILD_ARGS += --build-arg=DOCKERCLI_REPOSITORY
 DOCKER_BUILD_ARGS += --build-arg=DOCKERCLI_INTEGRATION_VERSION

docker-bake.hcl

@@ -1,6 +1,3 @@
-variable "APT_MIRROR" {
-  default = ""
-}
 variable "DOCKER_DEBUG" {
   default = ""
 }
@@ -64,7 +61,6 @@ function "bindir" {
 target "_common" {
   args = {
     BUILDKIT_CONTEXT_KEEP_GIT_DIR = 1
-    APT_MIRROR = APT_MIRROR
     DOCKER_DEBUG = DOCKER_DEBUG
     DOCKER_STATIC = DOCKER_STATIC
     DOCKER_LDFLAGS = DOCKER_LDFLAGS