feat: yurthub automatically recognize nftables or iptables (#1135) (#…

…1327)

hack/dockerfiles/build/Dockerfile.yurthub

@@ -5,4 +5,6 @@ ARG TARGETOS TARGETARCH MIRROR_REPO
 RUN if [ ! -z "${MIRROR_REPO+x}" ]; then sed -i "s/dl-cdn.alpinelinux.org/${MIRROR_REPO}/g" /etc/apk/repositories; fi && \
     apk add ca-certificates bash libc6-compat iptables ip6tables && update-ca-certificates && rm /var/cache/apk/*
 COPY ./_output/local/bin/${TARGETOS}/${TARGETARCH}/yurthub /usr/local/bin/yurthub
+COPY hack/iptables-wrapper-installer.sh /
+RUN chmod +x /iptables-wrapper-installer.sh && /iptables-wrapper-installer.sh
 ENTRYPOINT ["/usr/local/bin/yurthub"]

hack/dockerfiles/release/Dockerfile.yurthub

@@ -11,4 +11,6 @@ ARG TARGETOS TARGETARCH MIRROR_REPO
 RUN if [ ! -z "${MIRROR_REPO+x}" ]; then sed -i "s/dl-cdn.alpinelinux.org/${MIRROR_REPO}/g" /etc/apk/repositories; fi && \
     apk add ca-certificates bash libc6-compat iptables ip6tables && update-ca-certificates && rm /var/cache/apk/*
 COPY --from=builder /build/_output/local/bin/${TARGETOS}/${TARGETARCH}/yurthub /usr/local/bin/yurthub
+COPY hack/iptables-wrapper-installer.sh /
+RUN chmod +x /iptables-wrapper-installer.sh && /iptables-wrapper-installer.sh
 ENTRYPOINT ["/usr/local/bin/yurthub"]

hack/iptables-wrapper-installer.sh

@@ -0,0 +1,208 @@
+#!/bin/sh
+
+# Copyright 2020 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Usage:
+#
+#   iptables-wrapper-installer.sh [--no-sanity-check]
+#
+# Installs a wrapper iptables script in a container that will figure out
+# whether iptables-legacy or iptables-nft is in use on the host and then
+# replaces itself with the correct underlying iptables version.
+#
+# Unless "--no-sanity-check" is passed, it will first verify that the
+# container already contains a suitable version of iptables.
+
+# NOTE: This can only use POSIX /bin/sh features; the build container
+# might not contain bash.
+
+set -eu
+
+# Find iptables binary location
+if [ -d /usr/sbin -a -e /usr/sbin/iptables ]; then
+    sbin="/usr/sbin"
+elif [ -d /sbin -a -e /sbin/iptables ]; then
+    sbin="/sbin"
+else
+    echo "ERROR: iptables is not present in either /usr/sbin or /sbin" 1>&2
+    exit 1
+fi
+
+# Determine how the system selects between iptables-legacy and iptables-nft
+if [ -x /usr/sbin/alternatives ]; then
+    # Fedora/SUSE style alternatives
+    altstyle="fedora"
+elif [ -x /usr/sbin/update-alternatives ]; then
+    # Debian style alternatives
+    altstyle="debian"
+else
+    # No alternatives system
+    altstyle="none"
+fi
+
+if [ "${1:-}" != "--no-sanity-check" ]; then
+    # Ensure dependencies are installed
+    if ! version=$("${sbin}/iptables-nft" --version 2> /dev/null); then
+        echo "ERROR: iptables-nft is not installed" 1>&2
+        exit 1
+    fi
+    if ! "${sbin}/iptables-legacy" --version > /dev/null 2>&1; then
+        echo "ERROR: iptables-legacy is not installed" 1>&2
+        exit 1
+    fi
+
+    case "${version}" in
+    *v1.8.[0123]\ *)
+        echo "ERROR: iptables 1.8.0 - 1.8.3 have compatibility bugs." 1>&2
+        echo "       Upgrade to 1.8.4 or newer." 1>&2
+        exit 1
+        ;;
+    *)
+        # 1.8.4+ are OK
+        ;;
+    esac
+fi
+
+# Start creating the wrapper...
+rm -f "${sbin}/iptables-wrapper"
+cat > "${sbin}/iptables-wrapper" <<EOF
+#!/bin/sh
+
+# Copyright 2020 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# NOTE: This can only use POSIX /bin/sh features; the container image
+# might not contain bash.
+
+set -eu
+
+# In kubernetes 1.17 and later, kubelet will have created at least
+# one chain in the "mangle" table (either "KUBE-IPTABLES-HINT" or
+# "KUBE-KUBELET-CANARY"), so check that first, against
+# iptables-nft, because we can check that more efficiently and
+# it's more common these days.
+nft_kubelet_rules=\$( (iptables-nft-save -t mangle || true; ip6tables-nft-save -t mangle || true) 2>/dev/null | grep -E '^:(KUBE-IPTABLES-HINT|KUBE-KUBELET-CANARY)' | wc -l)
+if [ "\${nft_kubelet_rules}" -ne 0 ]; then
+    mode=nft
+else
+    # Check for kubernetes 1.17-or-later with iptables-legacy. We
+    # can't pass "-t mangle" to iptables-legacy-save because it would
+    # cause the kernel to create that table if it didn't already
+    # exist, which we don't want. So we have to grab all the rules
+    legacy_kubelet_rules=\$( (iptables-legacy-save || true; ip6tables-legacy-save || true) 2>/dev/null | grep -E '^:(KUBE-IPTABLES-HINT|KUBE-KUBELET-CANARY)' | wc -l)
+    if [ "\${legacy_kubelet_rules}" -ne 0 ]; then
+        mode=legacy
+    else
+        # With older kubernetes releases there may not be any _specific_
+        # rules we can look for, but we assume that some non-containerized process
+        # (possibly kubelet) will have created _some_ iptables rules.
+        num_legacy_lines=\$( (iptables-legacy-save || true; ip6tables-legacy-save || true) 2>/dev/null | grep '^-' | wc -l)
+        num_nft_lines=\$( (iptables-nft-save || true; ip6tables-nft-save || true) 2>/dev/null | grep '^-' | wc -l)
+        if [ "\${num_legacy_lines}" -gt "\${num_nft_lines}" ]; then
+            mode=legacy
+        else
+            mode=nft
+        fi
+    fi
+fi
+
+EOF
+
+# Write out the appropriate alternatives-selection commands
+case "${altstyle}" in
+    fedora)
+cat >> "${sbin}/iptables-wrapper" <<EOF
+# Update links to point to the selected binaries
+alternatives --set iptables "/usr/sbin/iptables-\${mode}" > /dev/null || failed=1
+EOF
+    ;;
+
+    debian)
+cat >> "${sbin}/iptables-wrapper" <<EOF
+# Update links to point to the selected binaries
+update-alternatives --set iptables "/usr/sbin/iptables-\${mode}" > /dev/null || failed=1
+update-alternatives --set ip6tables "/usr/sbin/ip6tables-\${mode}" > /dev/null || failed=1
+EOF
+    ;;
+
+    *)
+cat >> "${sbin}/iptables-wrapper" <<EOF
+# Update links to point to the selected binaries
+for cmd in iptables iptables-save iptables-restore ip6tables ip6tables-save ip6tables-restore; do
+    rm -f "${sbin}/\${cmd}"
+    ln -s "${sbin}/xtables-\${mode}-multi" "${sbin}/\${cmd}"
+done 2>/dev/null || failed=1
+EOF
+    ;;
+esac
+
+# Write out the post-alternatives-selection error checking and final wrap-up
+cat >> "${sbin}/iptables-wrapper" <<EOF
+if [ "\${failed:-0}" = 1 ]; then
+    echo "Unable to redirect iptables binaries. (Are you running in an unprivileged pod?)" 1>&2
+    # fake it, though this will probably also fail if they aren't root
+    exec "${sbin}/xtables-\${mode}-multi" "\$0" "\$@"
+fi
+
+# Now re-exec the original command with the newly-selected alternative
+exec "\$0" "\$@"
+EOF
+chmod +x "${sbin}/iptables-wrapper"
+
+# Now back in the installer script, point the iptables binaries at our
+# wrapper
+case "${altstyle}" in
+    fedora)
+	alternatives \
+            --install /usr/sbin/iptables iptables /usr/sbin/iptables-wrapper 100 \
+            --slave /usr/sbin/iptables-restore iptables-restore /usr/sbin/iptables-wrapper \
+            --slave /usr/sbin/iptables-save iptables-save /usr/sbin/iptables-wrapper \
+            --slave /usr/sbin/ip6tables iptables /usr/sbin/iptables-wrapper \
+            --slave /usr/sbin/ip6tables-restore iptables-restore /usr/sbin/iptables-wrapper \
+            --slave /usr/sbin/ip6tables-save iptables-save /usr/sbin/iptables-wrapper
+	;;
+
+    debian)
+	update-alternatives \
+            --install /usr/sbin/iptables iptables /usr/sbin/iptables-wrapper 100 \
+            --slave /usr/sbin/iptables-restore iptables-restore /usr/sbin/iptables-wrapper \
+            --slave /usr/sbin/iptables-save iptables-save /usr/sbin/iptables-wrapper
+	update-alternatives \
+            --install /usr/sbin/ip6tables ip6tables /usr/sbin/iptables-wrapper 100 \
+            --slave /usr/sbin/ip6tables-restore ip6tables-restore /usr/sbin/iptables-wrapper \
+            --slave /usr/sbin/ip6tables-save ip6tables-save /usr/sbin/iptables-wrapper
+	;;
+
+    *)
+	for cmd in iptables iptables-save iptables-restore ip6tables ip6tables-save ip6tables-restore; do
+            rm -f "${sbin}/${cmd}"
+            ln -s "${sbin}/iptables-wrapper" "${sbin}/${cmd}"
+	done
+	;;
+esac
+
+# Cleanup
+rm -f "$0"