Added mirror support to avoid hitting remote constantly

2026-05-10 06:12:07 +08:00
parent 075efa3348
commit 603313f736
6 changed files with 357 additions and 44 deletions
--- a/build.env
+++ b/build.env
@@ -57,3 +57,10 @@ APT_PROXY=
 # remote image repository prefix to push to
 # e.g. ghcr.io/monok8s
 IMAGE_REPOSITORY=
+
+# Mirror
+# You can host your local mirror by running (but you'll need to download them first)
+#   kubectl apply -f devtools/dep-pkg-mirror.yaml
+#   devtools/push-dep-pkg-mirror.sh
+# e.g. http://dep-pkg-mirror.default.svc.cluster.local/monok8s
+DEP_PKG_MIRROR=
--- a/devtools/dep-pkg-mirror.yaml
+++ b/devtools/dep-pkg-mirror.yaml
@@ -0,0 +1,101 @@
+# Hosts a mirror for dep pkg
+#   kubectl apply -f dep-pkg-mirror.yaml -n [namespace]
+#   kubectl -n [namespace] cp ./packages \ deploy/monok8s-mirror:/usr/share/nginx/html/monok8s/
+# Fetch helper contract:
+#   DEP_PKG_MIRROR=https://mirror.example.com/monok8s
+#   mirror URL = ${DEP_PKG_MIRROR}/packages/${mirror_path}
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: dep-pkg-mirror-data
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 20Gi
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: dep-pkg-mirror-nginx
+data:
+  default.conf: |
+    server {
+        listen 8080;
+        server_name _;
+
+        root /usr/share/nginx/html;
+
+        autoindex on;
+        autoindex_exact_size off;
+        autoindex_localtime on;
+
+        location /monok8s/packages/ {
+            try_files $uri =404;
+        }
+
+        location = /healthz {
+            access_log off;
+            return 200 "ok\n";
+        }
+    }
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: dep-pkg-mirror
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: dep-pkg-mirror
+  template:
+    metadata:
+      labels:
+        app: dep-pkg-mirror
+    spec:
+      containers:
+        - name: nginx
+          image: nginx:1.27-alpine
+          imagePullPolicy: IfNotPresent
+          ports:
+            - name: http
+              containerPort: 8080
+          readinessProbe:
+            httpGet:
+              path: /healthz
+              port: http
+          livenessProbe:
+            httpGet:
+              path: /healthz
+              port: http
+          volumeMounts:
+            - name: data
+              mountPath: /usr/share/nginx/html/monok8s/packages
+              subPath: packages
+              readOnly: false
+            - name: nginx-conf
+              mountPath: /etc/nginx/conf.d/default.conf
+              subPath: default.conf
+              readOnly: true
+      volumes:
+        - name: data
+          persistentVolumeClaim:
+            claimName: dep-pkg-mirror-data
+        - name: nginx-conf
+          configMap:
+            name: dep-pkg-mirror-nginx
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: dep-pkg-mirror
+spec:
+  type: ClusterIP
+  selector:
+    app: dep-pkg-mirror
+  ports:
+    - name: http
+      port: 80
+      targetPort: http
--- a/devtools/push-dep-pkg-mirror.sh
+++ b/devtools/push-dep-pkg-mirror.sh
@@ -0,0 +1,80 @@
+#!/bin/sh
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+NAMESPACE="${NAMESPACE:-default}"
+PACKAGES_DIR="$(realpath "$SCRIPT_DIR/../packages/")"
+APP_LABEL="${APP_LABEL:-app=dep-pkg-mirror}"
+CONTAINER="${CONTAINER:-nginx}"
+REMOTE_DIR="${REMOTE_DIR:-/usr/share/nginx/html/monok8s/packages}"
+
+if [ ! -d "$PACKAGES_DIR" ]; then
+    echo "error: package dir not found: $PACKAGES_DIR" >&2
+    exit 1
+fi
+
+need_cmd() {
+    command -v "$1" >/dev/null 2>&1 || {
+        echo "error: missing command: $1" >&2
+        exit 1
+    }
+}
+
+need_cmd kubectl
+need_cmd mktemp
+need_cmd tar
+need_cmd cp
+need_cmd find
+
+pod="$(
+    kubectl -n "$NAMESPACE" get pod \
+        -l "$APP_LABEL" \
+        --field-selector=status.phase=Running \
+        -o jsonpath='{.items[0].metadata.name}'
+)"
+
+if [ -z "$pod" ]; then
+    echo "error: no running pod found with label: $APP_LABEL in namespace: $NAMESPACE" >&2
+    exit 1
+fi
+
+echo "using pod: $pod"
+echo "remote dir: $REMOTE_DIR"
+
+echo "checking remote dir is writable"
+kubectl -n "$NAMESPACE" exec "$pod" -c "$CONTAINER" -- sh -c "
+    mkdir -p '$REMOTE_DIR' &&
+    touch '$REMOTE_DIR/.write-test' &&
+    rm -f '$REMOTE_DIR/.write-test'
+"
+
+stage="$(mktemp -d)"
+cleanup() {
+    rm -rf "$stage"
+}
+trap cleanup EXIT INT TERM
+
+mkdir -p "$stage/packages"
+
+echo "staging $PACKAGES_DIR/ as packages/"
+tar \
+    --exclude='.DS_Store' \
+    --exclude='.stamp-*' \
+    -C "$PACKAGES_DIR" \
+    -cf - . | tar -C "$stage/packages" -xf -
+
+echo "copying staged packages into mirror pod"
+kubectl -n "$NAMESPACE" cp \
+    "$stage/packages/." \
+    "$pod:$REMOTE_DIR" \
+    -c "$CONTAINER"
+
+echo "done"
+echo
+echo "Mirror base URL:"
+echo "  DEP_PKG_MIRROR=http://dep-pkg-mirror.${NAMESPACE}.svc.cluster.local/monok8s"
+echo
+echo "Example:"
+echo "  packages/kubernetes/kubelet-v1.35.3"
+echo "  -> http://dep-pkg-mirror.${NAMESPACE}.svc.cluster.local/monok8s/packages/kubernetes/kubelet-v1.35.3"
--- a/docker/download-packages.Dockerfile
+++ b/docker/download-packages.Dockerfile
@@ -1,13 +1,24 @@
+ARG DEP_PKG_MIRROR=
+ARG DEP_PKG_OFFLINE=0
+
 FROM alpine:3.23.0 AS base
+ARG DEP_PKG_MIRROR
+ARG DEP_PKG_OFFLINE
+ENV DEP_PKG_MIRROR="${DEP_PKG_MIRROR}"
+ENV DEP_PKG_OFFLINE="${DEP_PKG_OFFLINE}"
 RUN apk add --no-cache curl ca-certificates

+COPY scripts/fetch-artifact /usr/local/bin/fetch-artifact
+
 # ---- kubelet ----
 FROM base AS kubelet
 ARG KUBE_VERSION
 ARG ARCH
 WORKDIR /out/kubernetes
-RUN curl -fL --retry 3 -o "kubelet-${KUBE_VERSION}" \
-    "https://dl.k8s.io/${KUBE_VERSION}/bin/linux/${ARCH}/kubelet" && \
+RUN fetch-artifact \
+        "packages/kubernetes/kubelet-${KUBE_VERSION}" \
+        "kubelet-${KUBE_VERSION}" \
+        "https://dl.k8s.io/${KUBE_VERSION}/bin/linux/${ARCH}/kubelet" && \
    chmod +x "kubelet-${KUBE_VERSION}"

 # ---- kubeadm ----
@@ -15,8 +26,10 @@ FROM base AS kubeadm
 ARG KUBE_VERSION
 ARG ARCH
 WORKDIR /out/kubernetes
-RUN curl -fL --retry 3 -o "kubeadm-${KUBE_VERSION}" \
-    "https://dl.k8s.io/${KUBE_VERSION}/bin/linux/${ARCH}/kubeadm" && \
+RUN fetch-artifact \
+        "packages/kubernetes/kubeadm-${KUBE_VERSION}" \
+        "kubeadm-${KUBE_VERSION}" \
+        "https://dl.k8s.io/${KUBE_VERSION}/bin/linux/${ARCH}/kubeadm" && \
    chmod +x "kubeadm-${KUBE_VERSION}"

 # ---- kubectl ----
@@ -24,136 +37,190 @@ FROM base AS kubectl
 ARG KUBE_VERSION
 ARG ARCH
 WORKDIR /out/kubernetes
-RUN curl -fL --retry 3 -o "kubectl-${KUBE_VERSION}" \
-    "https://dl.k8s.io/${KUBE_VERSION}/bin/linux/${ARCH}/kubectl" && \
+RUN fetch-artifact \
+        "packages/kubernetes/kubectl-${KUBE_VERSION}" \
+        "kubectl-${KUBE_VERSION}" \
+        "https://dl.k8s.io/${KUBE_VERSION}/bin/linux/${ARCH}/kubectl" && \
    chmod +x "kubectl-${KUBE_VERSION}"

 # ---- busybox ----
 FROM base AS busybox
 ARG BUSYBOX_VERSION
+ARG BUSYBOX_TAR
 WORKDIR /out
-RUN curl -fL --retry 3 -o "busybox-${BUSYBOX_VERSION}.tar.gz" \
-    "https://github.com/mirror/busybox/archive/refs/tags/${BUSYBOX_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${BUSYBOX_TAR}" \
+        "busybox-${BUSYBOX_VERSION}.tar.gz" \
+        "https://github.com/mirror/busybox/archive/refs/tags/${BUSYBOX_VERSION}.tar.gz"

 # ---- e2fsprogs ----
 FROM base AS e2fsprogs
 ARG E2FSPROGS_VERSION
+ARG E2FSPROGS_TAR
 WORKDIR /out
-RUN curl -fL --retry 3 -o "e2fsprogs-v${E2FSPROGS_VERSION}.tar.gz" \
-    "https://github.com/tytso/e2fsprogs/archive/refs/tags/v${E2FSPROGS_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${E2FSPROGS_TAR}" \
+        "e2fsprogs-v${E2FSPROGS_VERSION}.tar.gz" \
+        "https://github.com/tytso/e2fsprogs/archive/refs/tags/v${E2FSPROGS_VERSION}.tar.gz"

 # ---- dpdk ----
 FROM base AS dpdk
 ARG DPDK_VERSION
+ARG DPDK_TAR
 WORKDIR /out/nxp/dpdk
-RUN curl -fL --retry 3 -o "${DPDK_VERSION}.tar.gz" \
-    "https://github.com/nxp-qoriq/dpdk/archive/refs/tags/${DPDK_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${DPDK_TAR}" \
+        "${DPDK_VERSION}.tar.gz" \
+        "https://github.com/nxp-qoriq/dpdk/archive/refs/tags/${DPDK_VERSION}.tar.gz"

 # ---- fmlib ----
 FROM base AS fmlib
 ARG FMLIB_VERSION
+ARG FMLIB_TAR
 WORKDIR /out/nxp/fmlib
-RUN curl -fL --retry 3 -o "${FMLIB_VERSION}.tar.gz" \
-    "https://github.com/nxp-qoriq/fmlib/archive/refs/tags/${FMLIB_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${FMLIB_TAR}" \
+        "${FMLIB_VERSION}.tar.gz" \
+        "https://github.com/nxp-qoriq/fmlib/archive/refs/tags/${FMLIB_VERSION}.tar.gz"

 # ---- fmc ----
 FROM base AS fmc
 ARG FMC_VERSION
+ARG FMC_TAR
 WORKDIR /out/nxp/fmc
-RUN curl -fL --retry 3 -o "${FMC_VERSION}.tar.gz" \
-    "https://github.com/nxp-qoriq/fmc/archive/refs/tags/${FMC_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${FMC_TAR}" \
+        "${FMC_VERSION}.tar.gz" \
+        "https://github.com/nxp-qoriq/fmc/archive/refs/tags/${FMC_VERSION}.tar.gz"

 # ---- vpp ----
 FROM base AS vpp
 ARG VPP_VERSION
+ARG VPP_TAR
 WORKDIR /out/nxp/vpp
-RUN curl -fL --retry 3 -o "${VPP_VERSION}.tar.gz" \
-    "https://github.com/nxp-qoriq/vpp/archive/refs/tags/${VPP_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${VPP_TAR}" \
+        "${VPP_VERSION}.tar.gz" \
+        "https://github.com/nxp-qoriq/vpp/archive/refs/tags/${VPP_VERSION}.tar.gz"

 # ---- MUSL CC ----
 FROM base AS aarch64_musl_cc
 WORKDIR /out
-RUN curl -fL --retry 3 -o "aarch64-linux-musl-cross.tgz" \
-    "https://musl.cc/aarch64-linux-musl-cross.tgz"
+RUN fetch-artifact \
+        "packages/aarch64-linux-musl-cross.tgz" \
+        "aarch64-linux-musl-cross.tgz" \
+        "https://musl.cc/aarch64-linux-musl-cross.tgz"

 # ---- ASK ----
 FROM base AS mono_ask
 ARG MONO_ASK_VERSION
+ARG MONO_ASK_TAR
 WORKDIR /out/ask
-RUN curl -fL --retry 3 -o "${MONO_ASK_VERSION}.tar.gz" \
-    "https://github.com/we-are-mono/ASK/archive/refs/tags/${MONO_ASK_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${MONO_ASK_TAR}" \
+        "${MONO_ASK_VERSION}.tar.gz" \
+        "https://github.com/we-are-mono/ASK/archive/refs/tags/${MONO_ASK_VERSION}.tar.gz"

 # ---- libnfnetlink ----
 FROM base AS libnfnetlink
 ARG LIBNFNETLINK_VERSION
+ARG LIBNFNETLINK_TAR
 WORKDIR /out/ask/libnfnetlink
-RUN curl -fL --retry 3 -o "${LIBNFNETLINK_VERSION}.tar.bz2" \
-    "https://www.netfilter.org/projects/libnfnetlink/files/libnfnetlink-${LIBNFNETLINK_VERSION}.tar.bz2"
+RUN fetch-artifact \
+        "${LIBNFNETLINK_TAR}" \
+        "${LIBNFNETLINK_VERSION}.tar.bz2" \
+        "https://www.netfilter.org/projects/libnfnetlink/files/libnfnetlink-${LIBNFNETLINK_VERSION}.tar.bz2"

 # ---- libnfct ----
 FROM base AS libnfct
 ARG LIBNFCT_VERSION
+ARG LIBNFCT_TAR
 WORKDIR /out/ask/libnfct
-RUN curl -fL --retry 3 -o "${LIBNFCT_VERSION}.tar.xz" \
-    "https://www.netfilter.org/projects/libnetfilter_conntrack/files/libnetfilter_conntrack-${LIBNFCT_VERSION}.tar.xz"
+RUN fetch-artifact \
+        "${LIBNFCT_VERSION_TAR}" \
+        "${LIBNFCT_VERSION}.tar.xz" \
+        "https://www.netfilter.org/projects/libnetfilter_conntrack/files/libnetfilter_conntrack-${LIBNFCT_VERSION}.tar.xz"

 # ---- libmnl ----
 FROM base AS libmnl
 ARG LIBMNL_VERSION
+ARG LIBMNL_TAR
 WORKDIR /out/ask/libmnl
-RUN curl -fL --retry 3 -o "${LIBMNL_VERSION}.tar.bz2" \
-    "https://www.netfilter.org/projects/libmnl/files/libmnl-${LIBMNL_VERSION}.tar.bz2"
+RUN fetch-artifact \
+        "${LIBMNL_TAR}" \
+        "${LIBMNL_VERSION}.tar.bz2" \
+        "https://www.netfilter.org/projects/libmnl/files/libmnl-${LIBMNL_VERSION}.tar.bz2"

 # ---- tclap ----
 FROM base AS tclap
 ARG TCLAP_VERSION
+ARG TCLAP_TAR
 WORKDIR /out/ask/tclap
-RUN curl -fL --retry 3 -o "${TCLAP_VERSION}.tar.gz" \
-    "https://sourceforge.net/projects/tclap/files/tclap-${TCLAP_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${TCLAP_TAR}" \
+        "${TCLAP_VERSION}.tar.gz" \
+        "https://sourceforge.net/projects/tclap/files/tclap-${TCLAP_VERSION}.tar.gz"

 # ---- libxml2 ----
 FROM base AS libxml2
 ARG LIBXML2_VERSION
+ARG LIBXML2_TAR
 WORKDIR /out/ask/libxml2
-RUN curl -fL --retry 3 -o "${LIBXML2_VERSION}.tar.xz" \
-    "https://download.gnome.org/sources/libxml2/2.11/libxml2-${LIBXML2_VERSION}.tar.xz"
+RUN fetch-artifact \
+        "${LIBXML2_TAR}" \
+        "${LIBXML2_VERSION}.tar.xz" \
+        "https://download.gnome.org/sources/libxml2/2.11/libxml2-${LIBXML2_VERSION}.tar.xz"

 # ---- libcli ----
 FROM base AS libcli
 ARG LIBCLI_VERSION
+ARG LIBCLI_TAR
 WORKDIR /out/ask/libcli
-RUN curl -fL --retry 3 -o "${LIBCLI_VERSION}.tar.gz" \
-    "https://github.com/dparrish/libcli/archive/refs/tags/V${LIBCLI_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${LIBCLI_TAR}" \
+        "${LIBCLI_VERSION}.tar.gz" \
+        "https://github.com/dparrish/libcli/archive/refs/tags/V${LIBCLI_VERSION}.tar.gz"

 # ---- libpcap ----
 FROM base AS libpcap
 ARG LIBPCAP_VERSION
+ARG LIBPCAP_TAR
 WORKDIR /out/ask/libpcap
-RUN curl -fL --retry 3 -o "${LIBPCAP_VERSION}.tar.xz" \
-    "https://www.tcpdump.org/release/libpcap-${LIBPCAP_VERSION}.tar.xz"
+RUN fetch-artifact \
+        "${LIBPCAP_TAR}" \
+        "${LIBPCAP_VERSION}.tar.xz" \
+        "https://www.tcpdump.org/release/libpcap-${LIBPCAP_VERSION}.tar.xz"

 # ---- alpine rootfs ----
 FROM base AS alpine_rootfs
 ARG ALPINE_SERIES
 ARG ALPINE_ARCH
-ARG ALPINE_VER
+ARG ALPINE_TAR
 WORKDIR /out
-RUN curl -fL --retry 3 -o "alpine-minirootfs-${ALPINE_VER}-${ALPINE_ARCH}.tar.gz" \
-    "https://dl-cdn.alpinelinux.org/alpine/v${ALPINE_SERIES}/releases/${ALPINE_ARCH}/alpine-minirootfs-${ALPINE_VER}-${ALPINE_ARCH}.tar.gz"
+RUN fetch-artifact \
+        "${ALPINE_TAR}" \
+        "alpine-minirootfs-${ALPINE_VER}-${ALPINE_ARCH}.tar.gz" \
+        "https://dl-cdn.alpinelinux.org/alpine/v${ALPINE_SERIES}/releases/${ALPINE_ARCH}/alpine-minirootfs-${ALPINE_VER}-${ALPINE_ARCH}.tar.gz"

 # ---- nxp linux ----
 FROM base AS nxp_linux
 ARG NXP_VERSION
+ARG NXP_TAR
 WORKDIR /out/nxp/kernel
-RUN curl -fL --retry 3 -o "${NXP_VERSION}.tar.gz" \
-    "https://github.com/nxp-qoriq/linux/archive/refs/tags/${NXP_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${NXP_TAR}" \
+        "${NXP_VERSION}.tar.gz" \
+        "https://github.com/nxp-qoriq/linux/archive/refs/tags/${NXP_VERSION}.tar.gz"

 # ---- crio ----
 FROM base AS crio
 ARG CRIO_VERSION
+ARG CRIO_TAR
 WORKDIR /out
-RUN curl -fL --retry 3 -o "${CRIO_VERSION}.tar.gz" \
-    "https://storage.googleapis.com/cri-o/artifacts/${CRIO_VERSION}.tar.gz"
+RUN fetch-artifact \
+        "${CRIO_TAR}" \
+        "${CRIO_VERSION}.tar.gz" \
+        "https://storage.googleapis.com/cri-o/artifacts/${CRIO_VERSION}.tar.gz"

 # ---- final exported artifact set ----
 FROM scratch
--- a/20
+++ b/20
@@ -7,7 +7,7 @@ TAG ?= dev
 PACKAGES_DIR := packages
 OUT_DIR      := out

-E2FSPROGS_TAR := $(PACKAGES_DIR)/e2fsprogs-$(E2FSPROGS_VERSION).tar.gz
+E2FSPROGS_TAR := $(PACKAGES_DIR)/e2fsprogs-v$(E2FSPROGS_VERSION).tar.gz
 BUSYBOX_TAR   := $(PACKAGES_DIR)/busybox-$(BUSYBOX_VERSION).tar.gz
 ALPINE_TAR    := $(PACKAGES_DIR)/alpine-minirootfs-$(ALPINE_VER)-$(ALPINE_ARCH).tar.gz
 NXP_TAR       := $(PACKAGES_DIR)/nxp/kernel/$(NXP_VERSION).tar.gz
@@ -127,6 +127,7 @@ $(OUT_DIR):
 $(DOWNLOAD_PACKAGES_STAMP): docker/download-packages.Dockerfile build.env makefile | $(PACKAGES_DIR)
 	docker build \
 		-f docker/download-packages.Dockerfile \
+		--build-arg DEP_PKG_MIRROR=$(DEP_PKG_MIRROR) \
 		--build-arg KUBE_VERSION=$(KUBE_VERSION) \
 		--build-arg ARCH=$(ARCH) \
 		--build-arg BUSYBOX_VERSION=$(BUSYBOX_VERSION) \
@@ -149,6 +150,23 @@ $(DOWNLOAD_PACKAGES_STAMP): docker/download-packages.Dockerfile build.env makefi
 		--build-arg ALPINE_VER=$(ALPINE_VER) \
 		--build-arg NXP_VERSION=$(NXP_VERSION) \
 		--build-arg CRIO_VERSION=$(CRIO_VERSION) \
+		--build-arg BUSYBOX_TAR=$(BUSYBOX_TAR) \
+		--build-arg E2FSPROGS_TAR=$(E2FSPROGS_TAR) \
+		--build-arg DPDK_TAR=$(DPDK_TAR) \
+		--build-arg FMLIB_TAR=$(FMLIB_TAR) \
+		--build-arg FMC_TAR=$(FMC_TAR) \
+		--build-arg VPP_TAR=$(VPP_TAR) \
+		--build-arg MONO_ASK_TAR=$(MONO_ASK_TAR) \
+		--build-arg LIBNFNETLINK_TAR=$(LIBNFNETLINK_TAR) \
+		--build-arg LIBMNL_TAR=$(LIBMNL_TAR) \
+		--build-arg LIBNFCT_TAR=$(LIBNFCT_TAR) \
+		--build-arg LIBCLI_TAR=$(LIBCLI_TAR) \
+		--build-arg LIBXML2_TAR=$(LIBXML2_TAR) \
+		--build-arg LIBPCAP_TAR=$(LIBPCAP_TAR) \
+		--build-arg TCLAP_TAR=$(TCLAP_TAR) \
+		--build-arg ALPINE_TAR=$(ALPINE_TAR) \
+		--build-arg NXP_TAR=$(NXP_TAR) \
+		--build-arg CRIO_TAR=$(CRIO_TAR) \
 		--output type=local,dest=./$(PACKAGES_DIR) .
 	@touch $@

--- a/scripts/fetch-artifact
+++ b/scripts/fetch-artifact
@@ -0,0 +1,40 @@
+#!/bin/sh
+set -eu
+
+# Fetch helper contract:
+#   DEP_PKG_MIRROR=https://mirror.example.com/monok8s
+#   mirror URL = ${DEP_PKG_MIRROR}/${mirror_path}
+
+if [ "$#" -ne 3 ]; then
+    echo "usage: fetch-artifact <mirror-path> <output-file> <upstream-url>" >&2
+    exit 2
+fi
+
+mirror_path="$1"
+out="$2"
+upstream_url="$3"
+
+mkdir -p "$(dirname "$out")"
+rm -f "$out"
+
+if [ -n "${DEP_PKG_MIRROR:-}" ]; then
+    mirror_url="${DEP_PKG_MIRROR%/}/${mirror_path}"
+    echo "fetch-artifact: trying mirror: ${mirror_url}" >&2
+    if curl -fL --retry 3 -o "$out" "$mirror_url"; then
+        exit 0
+    fi
+    rm -f "$out"
+
+    if [ "${DEP_PKG_OFFLINE:-0}" = "1" ]; then
+        echo "fetch-artifact: mirror miss and DEP_PKG_OFFLINE=1: ${mirror_url}" >&2
+        exit 1
+    fi
+fi
+
+if [ "${DEP_PKG_OFFLINE:-0}" = "1" ]; then
+    echo "fetch-artifact: DEP_PKG_OFFLINE=1 and no usable mirror for ${mirror_path}" >&2
+    exit 1
+fi
+
+echo "fetch-artifact: fetching upstream: ${upstream_url}" >&2
+curl -fL --retry 3 -o "$out" "$upstream_url"