support helm v3

[nwsparks]

With work on Helm 3 progressing at a steady pace, are there any plans to make this plugin work with it? Currently it seems to not be functional and exits with this:

Error: context deadline exceeded
context deadline exceeded
Error: plugin "diff" exited with error
helm.go:76: [debug] plugin "diff" exited with error
main.loadPlugins.func2
        /go/src/helm.sh/helm/cmd/helm/load_plugins.go:95
helm.sh/helm/vendor/github.com/spf13/cobra.(*Command).execute
        /go/src/helm.sh/helm/vendor/github.com/spf13/cobra/command.go:762
helm.sh/helm/vendor/github.com/spf13/cobra.(*Command).ExecuteC
        /go/src/helm.sh/helm/vendor/github.com/spf13/cobra/command.go:850
helm.sh/helm/vendor/github.com/spf13/cobra.(*Command).Execute
        /go/src/helm.sh/helm/vendor/github.com/spf13/cobra/command.go:800
main.main
        /go/src/helm.sh/helm/cmd/helm/helm.go:75
runtime.main
        /usr/local/go/src/runtime/proc.go:200
runtime.goexit
        /usr/local/go/src/runtime/asm_amd64.s:1337

[mumoshu]

I'm willing to support it, but definitely appreciate it if anyone could take it and submit a PR :)

I'm sharing what I know for anyone interested.

Helm 3 seems to have a different go module name which allows us to import both helm v2 and v3 as go libraries and make helm-diff works against both versions of helm.

The part of the problem I thought difficult was how helm-diff should determine which version of helm the plugin was called by.

Fortunately, Helm v3 seems to pass a different set of envvars to plugins:

v3: https://github.com/helm/helm/blob/97e7461e41455e58d89b4d7d192fed5352001d44/pkg/plugin/plugin.go#L217
v2: https://github.com/helm/helm/blob/0e7f3b6637f7af8fcfddb3d2941fcc7cbebb0085/pkg/plugin/plugin.go#L172

So basically helm-diff should be able to determine the version of helm by checking the existence of TILLER_HOST.

After that, helm-diff should create a v3-flavored Helm storage instance to obtain the Helm release to be processed for diff. Also fortunately we have a great example of code for creating v3 helm storage instance in helm-2to3: https://github.com/hickeyma/helm-2to3/blob/f92469cdd5e2be44153ebbf10c26238e72fdbee8/pkg/v3/connect.go#L62

Currently, helm-diff does this over API provided by Tiller.

helm-diff/cmd/helpers.go

Line 33 in 28e6832

func createHelmClient() helm.Interface {

is code we use to create the API client and

helm-diff/cmd/release.go

Line 83 in 28e6832

releaseResponse1, err := d.client.ReleaseContent(d.releases[0])

is an example of how the client is used to get Helm releases. For v3 we should use the store described above.

[karuppiah7890]

@mumoshu Are you working on this? 😄

[mumoshu]

@karuppiah7890 Yep. Please take a look at #149 😃

[mumoshu]

FYI helm 3 needs helm/helm#6385 in order for helm upgrade diff --detailed-exitcode to work.

[databus23]

I'm closing this now that #151 is merged and released

[bakayolo]

Hey guys,
Trying to use diff with helm 3 but does not work.

$ helm plugin install https://github.com/databus23/helm-diff --version helm3-beta3
...
Use "helm [command] --help" for more information about a command./plugins/helm-diff/bin: File name too long
Failed to install helm-diff
\tFor support, go to https://github.com/databus23/helm-diff.
Error: plugin install hook for "diff" exited with error

or

$ helm plugin install https://github.com/databus23/helm-diff --version master
...
Installed plugin: diff

$ helm version
version.BuildInfo{Version:"v3.0.0", GitCommit:"e29ce2a54e96cd02ccfce88bee4f58bb6e2a28b6", GitTreeState:"clean", GoVersion:"go1.13.4"}

$ helm plugin list
NAME	VERSION   	DESCRIPTION
diff	3.0.0-rc.7	Preview helm upgrade changes as a diff

$ helm diff upgrade my-chart . --detailed-exitcode --allow-unreleased --namespace default
Error: context deadline exceeded
context deadline exceeded
Error: plugin "diff" exited with error

[mumoshu]

@bappr Hey! It doesn't fail with context deadline exceeded for me, at least. I'm wondering if you have connectivity issue with your k8s api? Does helm list work?

[bakayolo]

@mumoshu yep it works

NAME                 NAMESPACE	REVISION	UPDATED                             	STATUS  	CHART                      	APP VERSION
my-chart	default  	5       	2019-11-14 08:30:29.933171 +0800 HKT	deployed	my-chart-0.0.1

And I have upgraded my chart this morning.
Anyway I can get more logs?

[mumoshu]

@bappr Could you run it with --debug like helm --debug dfff ...?

Also, does it work if you used a non-local chart?

[bakayolo]

@mumoshu

With --debug

Error: context deadline exceeded
context deadline exceeded
Error: plugin "diff" exited with error
helm.go:76: [debug] plugin "diff" exited with error

However with a non-local chart -> it seems that my helm diff still rely on helm 2 (tiller). 🤨

$ helm diff upgrade my-release stable/postgresql
Error: Couldn't load repositories file (repository/repositories.yaml).
You might need to run `helm init` (or `helm init --client-only` if tiller is already installed)
Couldn't load repositories file (repository/repositories.yaml).
You might need to run `helm init` (or `helm init --client-only` if tiller is already installed)
Error: plugin "diff" exited with error