Add helper script for generating no_proxy option for ELM

utils/get_no_proxy.sh

@@ -0,0 +1,288 @@
+#!/usr/bin/env bash
+
+# SPDX-FileCopyrightText: 2024 SAP edge team
+# SPDX-FileContributor: Manjun Jiao (@mjiao)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+set -euo pipefail
+IFS=$'\n\t'
+
+usage="$(basename "${BASH_SOURCE[0]}") [Options] [domain.ltd,...] [!excluded.domain]
+
+Generates NO_PROXY settings for SAP Edge Lifecycle Management installation requiring HTTP proxy to access
+external resources.
+
+Additional domains can be given as arguments. If a domain is prefixed with '!', it will be
+excluded from the list. IOW, it will be proxied.
+
+If a (longer wildcard) domain is matched by a(nother) wildcard domain, it is excluded from the
+output.
+
+Requirements:
+- OpenShift client binaries (oc) must be installed and located in PATH.
+- The user must authenticated to the OpenShift cluster and be at least the cluster-reader.
+- awk in PATH
+
+Options:
+  -h | --help       Show this help message and exit.
+  -e | --elm        Compute NO_PROXY settings for ELM."
+readonly usage
+
+readonly mustHave=(
+    127.0.0.1
+    169.254.169.254
+
+    localhost
+    metadata.google.internal
+
+    *.local
+    *.cluster.local
+    *.internal
+    *.google.internal
+    *.svc
+)
+
+readonly mustHaveELM=(
+)
+
+readonly longOptions=(
+    help elm
+)
+
+# normalize reads the arguments and produces a newline-separated list of NO_PROXY entries.
+# If an argument contains a comma, it will be split.
+# If the first argument is `-e` only the entries prefixed with ! will be produced, otherwise
+# only non-prefixed entries will be produced.
+function normalize() {
+    local entry
+    local selectExcluded=0
+    if [[ "${1:-}" == -e ]]; then
+        selectExcluded=1
+        shift
+    fi
+
+    for entry in "$@"; do
+        # shellcheck disable=SC2001
+        if [[ "${entry}" =~ , ]]; then
+            local entries=()
+            readarray -t entries < <(tr ',' '\n' <<<"${entry}")
+            local args=()
+            if [[ "$selectExcluded" == 1 ]]; then
+                args+=( -e )
+            fi
+            # shellcheck disable=SC2068
+            normalize ${args[@]} "${entries[@]}"
+            continue
+        fi
+
+        entry="$(sed \
+            -e 's/\([[:space:]]\|,\)\+//g' \
+            -e 's/\.\+/./g' \
+            -e 's/\!\+/!/g' \
+            -e 's/\*\+/*/g' <<<"${entry:-}")"
+        if [[ -z "${entry:-}" ]]; then
+            continue
+        fi
+
+        case "$selectExcluded$entry" in
+            "0!"*)
+                continue
+                ;;
+            "1!"*)
+                entry="${entry##\!}"
+                ;;
+            "1"*)
+                continue
+                ;;
+        esac
+
+        case "${mode:-elm}" in
+            elm)
+                entry="${entry##\*}"
+                ;;
+            *)
+                if [[ "$entry" =~ ^\. ]]; then
+                    printf '*%s\n' "$entry"
+                    continue
+                fi
+                ;;
+        esac
+        printf '%s\n' "$entry"
+    done
+}
+
+# filterOutRedundancies reads newline-separated list of NO_PROXY entries from stdin, removes the
+# duplicates, removes subdomains of wildcard domains and moves wildcard entries to the while
+# trying to preserve the order of the items.
+# Limitations: does not care about CIDRs.
+function filterOutRedundancies() {
+    awk 3< <(printf '%s\n' "${excludes[@]}") '
+    {
+        if (isExcluded($0)) {
+            next
+        }
+        if ($0 ~ /^[*.]/) {
+            addWildcard($0)
+        } else {
+            addDomain($0, nonWildcards, nonWildcardList)
+        }
+    }
+
+    BEGIN {
+        split("", nonWildcardList)
+        split("", wildcardList)
+
+        while ((getline line <"/dev/fd/3") > 0) {
+            excludes[line]++
+        }
+    }
+
+    END {
+        for (i in nonWildcardList) {
+            domain = nonWildcardList[i]
+            if (isMatchedByAnyWildcard(domain)) {
+                continue
+            }
+            print domain
+        }
+        for (i in wildcardList) {
+            print wildcardList[i]
+        }
+    }
+
+    function isSubdomain(domain, wildcard,       w, i) {
+        w = wildcard
+        sub(/^\*/, "", w)
+        i = index(domain, w)
+        return i > 0 && i + length(w) >= length(domain)
+    }
+
+    function isMatchedByAnyWildcard(domain) {
+        for (w in wildcards) {
+            if (isSubdomain(domain, w)) {
+                return 1
+            }
+        }
+        return 0
+    }
+
+    function isExcluded(d) {
+        for (e in excludes) {
+            if (d == e) {
+                return 1
+            }
+        }
+        return 0
+    }
+
+    function removeWildcard(w) {
+        delete wildcards[w]
+        for (i in wildcardList) {
+            if (wildcardList[i] == w) {
+                delete wildcardList[i]
+                break
+            }
+        }
+    }
+
+    function addWildcard(w) {
+        for (w in wildcards) {
+            if (isSubdomain($0, w)) {
+                next
+            }
+            if (isSubdomain(w, $0)) {
+                removeWildcard(w)
+            }
+        }
+        addDomain($0, wildcards, wildcardList)
+    }
+
+    function addDomain(d, map, list) {
+        if (map[$0]++ == 0) {
+            list[length(list)] = $0
+        }
+    }'
+}
+
+function join() { local IFS="$1"; shift; echo "$*"; }
+
+function getOpenShiftNoProxyOrDie() {
+    local osNoProxy
+    osNoProxy="$(oc get proxy/cluster -o jsonpath='{.status.noProxy}')"
+    if [[ -z "${osNoProxy:-}" ]]; then
+        printf 'Failed to determine noProxy from OpenShift cluster!\n' >&2
+        printf 'Please configure noProxy first on the OpenShift cluster\n' >&2
+        printf 'and make sure the current user can read it.\n' >&2
+        exit 1
+    fi
+    printf '%s' "$osNoProxy"
+}
+
+function setExcludes() {
+    readarray -t excludes < <(normalize -e "$@")
+    if [[ "${#excludes[@]}" == 1 && -z "${excludes[0]:-}" ]]; then
+        excludes=()
+    fi
+}
+
+function assertDependencies() {
+    if [[ -z "$(command -v oc)" ]]; then
+        printf 'Please ensure oc binary is in PATH and its minor release matches the server!\n' >&2
+        exit 1
+    fi
+    if [[ "$(gawk 'END {split("a,b", a, /,/); print length(a)}' </dev/null)" != 2 ]]; then
+        printf 'Please ensure that GNU AWK is installed and present in the PATH!\n' >&2
+        exit 1
+    fi
+    if ! oc auth can-i list proxies.config.openshift.io --all-namespaces >/dev/null; then
+        printf 'Please ensure the current OpenShift user is logged-in and has at least the' >&2
+        printf ' cluster-reader role.\n' >&2
+        exit 1
+    fi
+}
+
+function computeNoProxy() {
+    local osNoProxy=() entries=()
+    readarray -t osNoProxy < <(getOpenShiftNoProxyOrDie | tr ',' '\n')
+    readarray -t entries < <({ \
+        normalize "${osNoProxy[@]}" "$@" "${mustHave[@]}"; \
+        case "${mode:-elm}" in
+            elm)
+                printf '%s\n' "${mustHaveELM[@]}";
+                ;;
+        esac; \
+    } | filterOutRedundancies)
+    join , "${entries[@]}"
+}
+
+TMPARGS="$(getopt -o he -l "$(join , "${longOptions[@]}")" -n "${BASH_SOURCE[0]}" -- "$@")"
+eval set -- "$TMPARGS"
+
+mode=elm
+excludes=()
+
+while true; do
+    case "$1" in
+        -h | --help)
+            printf '%s\n' "$usage"
+            exit 0
+            ;;
+        -e | --elm)
+            mode=elm
+            shift
+            ;;
+        --)
+            shift
+            break
+            ;;
+        *)
+            printf 'Unknown argument "%s"!\n' "$1" >&2
+            exit 1
+            ;;
+    esac
+done
+
+assertDependencies
+setExcludes "$@"
+computeNoProxy "$@"