[fix] Makefile fallback to using latest semver tag

[phoinixgrr]

Summary

Rationale

In case there is no Tag available, DIST_VER remains unitilized therefore building with an empty DIST_VER variable.
For example:

Build Linux amd64
env GOOS=linux GOARCH=amd64 go build -trimpath -ldflags '-X github.com/mattermost/mmctl/v6/commands.gitCommit=e58015f66734b77f223592a63d158652e94d5b82 -X github.com/mattermost/mmctl/v6/commands.gitTreeState="clean" -X github.com/mattermost/mmctl/v6/commands.buildDate='2022-05-31T08:20:04Z' -X github.com/mattermost/mmctl/v6/commands.Version=' -mod=vendor
tar cf build/linux_amd64.tar mmctl
md5sum < build/linux_amd64.tar | cut -d ' ' -f 1 > build/linux_amd64.tar.md5.txt
Build Linux arm64
env GOOS=linux GOARCH=arm64 go build -trimpath -ldflags '-X github.com/mattermost/mmctl/v6/commands.gitCommit=e58015f66734b77f223592a63d158652e94d5b82 -X github.com/mattermost/mmctl/v6/commands.gitTreeState="clean" -X github.com/mattermost/mmctl/v6/commands.buildDate='2022-05-31T08:20:04Z' -X github.com/mattermost/mmctl/v6/commands.Version=' -mod=vendor
tar cf build/linux_arm64.tar mmctl

In the above example, github.com/mattermost/mmctl/v6/commands.Version is empty.
And builds the following binary:

$ mmctl version
mmctl:
Version:
GitCommit:	e58015f66734b77f223592a63d158652e94d5b82
GitTreeState:	"clean"
BuildDate:	2022-05-31T08:20:04Z
GoVersion:	go1.17
Compiler:	gc
Platform:	linux/amd64

Proposal

In case DIST_VER is not defined, fallback to using latest semver tag available, instead of building with NULL DIST_VER

Ticket Link

Ticket: https://mattermost.atlassian.net/browse/DOPS-1049

[ghost]

💯 Nice work Akis

[isacikgoz]

LGTM 👍

[agnivade]

@phoinixgrr - We have an opportunity to create a dot release for mmctl. Let's use this to backport this one as well.

/cc @amyblais

[amyblais]

/cherry-pick release-7.0

[mattermod]

Cherry pick is scheduled.

[mattermod]

Error trying doing the automated Cherry picking. Please do this manually

fatal: No such remote 'upstream'

+++ Returning you to the master branch and cleaning up.

[amyblais]

Needs a manual cherry-pick.

[amyblais]

I think this is already in 7.0 branch https://github.com/mattermost/mmctl/commits/release-7.0.

[agnivade]

Yeah I see that. But is mmctl compiled with that fix? Because from the report here: #528 (comment), the version string isn't showing.

cc @phoinixgrr

[phoinixgrr]

I did cherrypick that manually 8 days ago.
Was the 7.0 release compiled before or after that cherry-pick ?

[agnivade]

Looking at this report: #528 (comment). The git commit sha contains your fix, but still the version is empty. Looks like we need to look at this again.

[agnivade]

Actually, without your fix, none of the mmctl commands will work. Because all commands run a pre-check to compare the version.

[phoinixgrr]

Thanks for the heads up @agnivade
Will investigate this further and revert.

[amyblais]

@phoinixgrr I've opened a ticket here https://mattermost.atlassian.net/browse/DOPS-1090.