Track branches by polling

[lblackstone]

Proposed changes

Poll the specified git repo every 60 seconds and automatically
deploy the latest commit if it has changed.

Related issues (optional)

Fix #50

[lblackstone]

One open question I have is whether we should also track the default (master) branch if no branch or commit is specified. I currently only implemented tracking if a branch is explicitly set.

Alternatively, we could expose a flag to toggle branch tracking, but it seems like the tracking behavior is probably what users would expect if they explicitly opt into a branch rather than a commit.

[vivekpulumi]

One open question I have is whether we should also track the default (master) branch if no branch or commit is specified. I currently only implemented tracking if a branch is explicitly set.

Alternatively, we could expose a flag to toggle branch tracking, but it seems like the tracking behavior is probably what users would expect if they explicitly opt into a branch rather than a commit.

I think requiring a branch is reasonable. Currently the comments in the stack CR specification are our defacto documentation. Could you update the comments for branch and commit to clarify this behavior: https://github.com/pulumi/pulumi-kubernetes-operator/blob/master/pkg/apis/pulumi/v1alpha1/stack_types.go#L98?

[vivekpulumi]

We might also need to call out that every commit is not necessarily reflected by the operator in this mode. e.g. if multiple commits in short succession, the operator will only try to reflect the latest at the time of polling.

[vivekpulumi]

CC @elsesiy for comments/thoughts.

[mikhailshilkov]

I'm not super familiar with the operator but the change LGTM. I guess I'd expend master to work the same way by default but I'll leave this to your judgment.

[lblackstone]

I guess I'd expend master to work the same way by default but I'll leave this to your judgment.

I opened #164 to track the likely resolution to this difference.

[viveklak]

Any reason why the change to disable branch tracking if an explicit commit is specified?

[lblackstone]

I realized that branch and commit are mutually exclusive, so we should only need to check for the presence of branch.

pulumi-kubernetes-operator/pkg/apis/pulumi/v1alpha1/stack_types.go

Lines 96 to 101 in 597053a

	// (optional) Commit is the hash of the commit to deploy. If used, HEAD will be in detached mode. This
	// is mutually exclusive with the Branch setting. If both are empty, the `master` branch is deployed.
	Commit string `json:"commit,omitempty"`
	// (optional) Branch is the branch name to deploy, either the simple or fully qualified ref name. This
	// is mutually exclusive with the Commit setting. If both are empty, the `master` branch is deployed.
	Branch string `json:"branch,omitempty"`