armada_replace_grpc_with_helm_cli.md

Analysis: Replacing Armada gRPC calls with helm cli calls

Aramda gRPC usage by command

Most commands are in armada CLI and API, and behave similarly.

apply

gRPC calls

install:

• if no successful release found for chart
• returned release response ignored

update:

• if successful release found for chart
• returned release response ignored

uninstall:

• to clear failed release before installing
• if chart cleanup enabled

test:

• see test

status:

• upon failure of install/update/uninstall/test (for debugging purposes)
• to return release status after test

list:

• when cleanup enabled, to determine releases that need to be uninstalled (due to armada manifest changes)
• to determine failed releases (failed are unininstalled/re-installed, successful are updated)
• includes release config values used for diffing config values with release being updated

test

gRPC calls

list:

• to determine releases that exist to be able to test

release_content:

• to determine if a release has a test hook defined

test:

• to test the release

delete (command only in armada CLI currently)

gRPC calls

list:

• to determine releases that exist to be able to uninstall

uninstall:

• to uninstall the release

tiller status

gRPC calls

get_version:

• to get the tiller version

k8s api calls:

• to determine tiller status

tiller releases

gRPC calls

list: to list releases

Helm CLI equivalency:

all commands have exit code to represent success/failure

actions:

• install > install (--values can be used for input)
• update > upgrade (--values can be used for input)
• uninstall > delete
• test > test

Already has machine readable output:

• helm version --server --short
• helm status -o (json/yaml)
• helm get hooks
  • yaml output
  • could be used to see if a test is defined, or could just run helm test ... regardless:

    $ helm test mychart
    No Tests Found
    $ echo $?
    0

• helm get values
  • yaml output
  • for armada release update diff functionality

Helm CLI updates needed:

• helm list json/yaml output:

  • existing PR: helm/helm#2950

• Error message(s) capturability?

  • Exit code is just 0/1, so when exit code = 1:
    • is stderr (+stdout?) sufficient to use as error message?
    • do we need to captur multiple errors?

• helm upgrade/install json/yaml output?

  • not used by armada gRPC calls currently
  • would it return:
    • status?
      • currently armada only retrieves status on error
      • can get from helm status -o (json|yaml)
      • wasted status call by upgrade/install which cannot be disabled, could add --quiet mode to remove?
      • thus separate call makes sense?
    • release content?
      • not used/needed by armada currently
    • something else?

• ???