ds-identify: exit 2 on disabled state from marker or cmdline

The cloud-init-generator no longer checks disabled state of
cloud-init from the kernel command line or marker file in
/etc/cloud/cloud-init.disabled.

This means ds-identify will be called during systemd generator
even in disabled cases.

Given that ds-identify parses the kernel commandline for datasource
discovery, allow it to check whether cloud-init=disabled is present
in kernel command line, KERNEL_CMDLINE or
/etc/cloud/cloud-init.disabled.

Add a new exit code(2) from ds-identify to allow
cloud-init-generator to allow differentation of disabled state due
to environment artifacts versus disabled due to no detected
datasources.

Additionally, factor the minimum operations needed for detecting
if cloud-init is disabled to earlier in ds-identify to allow an early
exit before more costly DMI read operations in collect_info.
There is no need to perform all collect_info in ds-identify when
cloud-init is fully disabled by commandline or
/etc/cloud/cloud-init.disabled.

systemd/cloud-init-generator.tmpl

@@ -64,8 +64,12 @@ main() {
     ds=$?
     debug 1 "ds-identify rc=$ds"
 
-    if [ "$ds" = "1" ]; then
-        debug 1 "cloud-init is enabled but no datasource found, disabling"
+    if [ "$ds" = "1" -o "$ds" = "2" ]; then
+        if [ "$ds" = "1" ]; then
+            debug 1 "cloud-init is enabled but no datasource found, disabling"
+        else
+            debug 1 "cloud-init is disabled by kernel commandline or etc_file"
+        fi
         if [ -f "$link_path" ]; then
             if rm -f "$link_path"; then
                 debug 1 "disabled. removed existing $link_path"

tests/unittests/test_ds_identify.py

@@ -329,6 +329,10 @@ def write_mock(data):
                 "ret": 1,
                 "err": "No dmidecode program. ERROR.",
             },
+            {
+                "name": "is_disabled",
+                "ret": 1,
+            },
             {
                 "name": "get_kenv_field",
                 "ret": 1,

tools/ds-identify

@@ -1039,6 +1039,23 @@ has_ovf_cdrom() {
     return 1
 }
 
+is_disabled() {
+    if [ -f /etc/cloud/cloud-init.disabled ]; then
+        debug 1 "disabled by marker file /etc/cloud-init.disabled"
+        return 0
+    fi
+    if [ "${KERNEL_CMDLINE:-}" = "cloud-init=disabled" ]; then
+        debug 1 "disabled by KERNEL_CMDLINE environment variable"
+        return 0
+    fi
+    case "$DI_KERNEL_CMDLINE" in
+       *cloud-init=disabled*)
+            debug 1 "disabled by kernel command line cloud-init=disabled"
+            return 0
+    esac
+    return 1
+}
+
 dscheck_OVF() {
     check_seed_dir ovf ovf-env.xml && return "${DS_FOUND}"
 
@@ -1517,10 +1534,7 @@ dscheck_VMware() {
 }
 
 collect_info() {
-    read_uname_info
-    read_virt
     read_pid1_product_name
-    read_kernel_cmdline
     read_config
     read_datasource_list
     read_dmi_sys_vendor
@@ -1795,6 +1809,12 @@ _main() {
 
     read_uptime
     debug 1 "[up ${_RET}s]" "ds-identify $*"
+    read_uname_info
+    read_virt
+    read_kernel_cmdline
+    if is_disabled; then
+        return 2
+    fi
     collect_info
 
     if [ "$DI_LOG" = "stderr" ]; then