fix regression: remove dependency on dmidecode

[Mina Galić]

When we extended ds-identify to use dmidecode, we made it x86-only, which is the platforms that dmidecode supports (on FreeBSD): https://github.com/freebsd/freebsd-ports/commit/ea408d31b8d9d3b3bac932f8c351d2e883070e6b

it would be good if we could "fix" that, by removing our dependency on dmidecode, and instead use kenv(1) https://www.freebsd.org/cgi/man.cgi?kenv

[Scott Moser (smoser)]

We don't strictly have a dependency on dmidecode.
ds-identify will only try dmidecode if values in /sys/class/dmi/id/ are not present. That is desirable, as reading files from /sys is orders of magnitude faster than invoking a program to do the same.

I think calling kenv on freebsd would be fine.

something like this:

diff --git a/tools/ds-identify b/tools/ds-identify
index 4e5700fc6..7019b757d 100755
--- a/tools/ds-identify
+++ b/tools/ds-identify
@@ -198,6 +198,11 @@ dmi_decode() {
     _RET="$val"
 }

+read_kenv() {
+ # left as an excersize to the reader.
+ :
+}
+
 get_dmi_field() {
     local path="${PATH_SYS_CLASS_DMI_ID}/$1"
     _RET="$UNAVAILABLE"
@@ -210,7 +215,10 @@ get_dmi_field() {
         # do *not* fallback to dmidecode!
         return
     fi
- dmi_decode "$1" || _RET="$ERROR"
+ case "$DI_UNAME_KERNEL_NAME" in
+ FreeBSD) read_kenv "$1" || _RET="$ERROR";;
+ *) dmi_decode "$1" || _RET="$ERROR"
+ esac
     return
 }

[Mina Galić (minagalic)]

leaving an example from an Azure vm here for safekeeping

smbios.bios.reldate="06/02/2017"
smbios.bios.vendor="American Megatrends Inc."
smbios.bios.version="090007 "
smbios.chassis.maker="Microsoft Corporation"
smbios.chassis.serial="0294-2963-9005-7688-4363-4003-04"
smbios.chassis.tag="7783-7084-3265-9085-8269-3286-77"
smbios.chassis.version="7.0"
smbios.memory.enabled="16777216"
smbios.planar.location=""
smbios.planar.maker="Microsoft Corporation"
smbios.planar.product="Virtual Machine"
smbios.planar.serial="0000-0009-9589-8832-9763-2029-02"
smbios.planar.tag=""
smbios.planar.version="7.0"
smbios.socket.enabled="4"
smbios.socket.populated="4"
smbios.system.maker="Microsoft Corporation"
smbios.system.product="Virtual Machine"
smbios.system.serial="0000-0014-1815-7361-2091-5586-34"
smbios.system.uuid="1012cfc4-c520-ea4a-8a35-6f1ef5cbe756"
smbios.system.version="7.0"
smbios.version="2.3"

thanks to kevans91 from the FreeBSD community for providing this

[Mina Galić (minagalic)]

n.b.: I have started a PR here: https://github.com/canonical/cloud-init/pull/621

[Ed Maste (emaste)]

Pull request was merged

[James Falcon (falcojr)]

Thanks Ed. Yes, this was fixed with https://github.com/canonical/cloud-init/pull/621 and released in upstream 20.4.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3795