Compresssed User-Data / Initial NoCloud Support

Compressed User-Data
* extends !23 to support more algorithms

NoCloud
* initial support for volume-based meta-data, user-data, and optional vendor-data
* depends on 'yx' tool to extract data from yaml

bin/imds

@@ -35,6 +35,12 @@ unset -f \
 CLOUD="${CLOUD:-unknown}"
 IMDS_ENDPOINT="169.254.169.254"
 
+_imds() {
+    wget --quiet --timeout 1 --output-document - \
+        --header "$(_imds_header)" \
+        "http://$IMDS_ENDPOINT/$IMDS_URI/$1$IMDS_QUERY"
+}
+
 _imds_ssh_keys() { _imds "$IMDS_SSH_KEYS"; }
 _imds_userdata() { _imds "$IMDS_USERDATA"; }
 
@@ -48,12 +54,6 @@ source /lib/tiny-cloud/"$CLOUD"/imds
 
 ### non-overrideable functions
 
-_imds() {
-    wget --quiet --timeout 1 --output-document - \
-        --header "$(_imds_header)" \
-        "http://$IMDS_ENDPOINT/$IMDS_URI/$1$IMDS_QUERY"
-}
-
 imds() {
     local cmd args key rv err=1
     if [ "$1" = "-h" ] || [ "$1" = "--help" ]; then

lib/tiny-cloud/init-final

@@ -3,10 +3,40 @@
 
 source /lib/tiny-cloud/init-common
 
+
+match_header() {
+    local bytes=$(echo -en "$1")
+    [ "$bytes" = $(dd bs=1 count=${#bytes} if="$2" 2>/dev/null) ]
+}
+
+# TODO: also do this for nocloud meta-data and vendor-data?
 save_userdata() {
     skip_action save_userdata && return
 
-    imds -e @userdata > "$TINY_CLOUD_VAR/$CLOUD_USERDATA"
+    local userdata="$TINY_CLOUD_VAR/$CLOUD_USERDATA"
+    local tmpfile=$(mktemp "$userdata.XXXXXX")
+    local cmd
+
+    imds -e @userdata > "$tmpfile"
+    if match_header '\037\213\010' "$tmpfile"; then
+        cmd='gzip -dc'
+    elif match_header 'BZh' "$tmpfile"; then
+        cmd='bzip2 -dc'
+    elif match_header '\3757zXZ\000' "$tmpfile"; then
+        cmd='xz -dc'
+    elif match_header '\135\0\0\0' "$tmpfile"; then
+        cmd='lzma -dc'
+    elif match_header '\211\114\132' "$tmpfile"; then
+        cmd='lzop -dc'
+    elif match_header '\002!L\030' "$tmpfile"; then
+        cmd='lz4 -dc'
+    elif match_header '(\265/\375' "$tmpfile"; then
+        cmd='zstd -dc'
+    else
+        cmd='cat'
+    fi
+    $cmd "$tmpfile" > "$userdata"
+    rm "$tmpfile"
 }
 
 is_userdata_script() {

lib/tiny-cloud/nocloud/imds

@@ -0,0 +1,59 @@
+# NoCloud Instance Metadata
+# vim: ts=4 et ft=sh:
+
+IMDS_HOSTNAME=meta-data/hostname
+IMDS_SSH_KEYS=meta-data/ssh-keys
+IMDS_USERDATA=user-data
+
+# have we loaded the nocloud meta/user/vendor data?
+is_nocloud_loaded() { [ -f "$TINY_CLOUD_VAR/.nocloud_loaded" ]; }
+
+# from location specified in kernel cmdline
+_load_nocloud_cmdline() {
+    # TODO
+}
+
+# from volume labeled cidata|CIDATA
+_load_nocloud_volume() {
+    local mntdir='/mnt/cidata'
+
+    mkdir "$mntdir"
+    mount -L cidata "$mntdir" || mount -L CIDATA "$mntdir" || return 1
+    for data in meta user vendor; do
+        if ! cp "$mntdir/$data-data" "$TINY_CLOUD_VAR/$data-data"; then
+            [ "$data" = vendor ] && continue
+            echo "ERROR: Required $data-data not found on CIDATA volume"
+            umount "$mntdir"
+            return 1
+        fi
+    done
+    umount "$mntdir"
+}
+
+load_nocloud() {
+    is_nocloud_loaded && return
+    if grep -qE ' ds=nocloud(-net)?[; ]' /proc/cmdline; then
+        if ! _load_nocloud_cmdline; then
+            echo 'ERROR: Unable to load nocloud data specified in kernel cmdline' >&2
+            return 1
+        fi
+    elif ! _load_nocloud_volume; then
+        echo 'ERROR: Unable to load nocloud data from CIDATA volume' >&2
+        return 1
+    fi
+    touch "$TINY_CLOUD_VAR/.nocloud_loaded"
+}
+
+_imds() {
+    local file="$TINY_CLOUD_VAR"/$(echo "$1" | cut -d/ -f1)
+    local key=$(echo "$1" | cut -d/ -f2-)
+    local data value
+
+    is_nocloud_loaded || load_nocloud || return 1
+
+    # does file exist?
+    [ -f "$file" ] || return 1
+
+    # use 'file/' to get top-level keys
+    [ "$1" = "$file" ] && cat "$file" || yx -f "$file" "$key"
+}