This change overhauls the way we do object monikers. The old mechanism,
generating monikers using graph paths, was far too brittle and prone to
collisions. The new approach mixes some amount of "automatic scoping"
plus some "explicit naming." Although there is some explicitness, this
is arguably a good thing, as the monikers will be relatable back to the
source more readily by developers inspecting the graph and resource state.
Each moniker has four parts:
<Namespace>::<AllocModule>::<Type>::<Name>
wherein each element is the following:
<Namespace> The namespace being deployed into
<AllocModule> The module in which the object was allocated
<Type> The type of the resource
<Name> The assigned name of the resource
The <Namespace> is essentially the deployment target -- so "prod",
"stage", etc -- although it is more general purpose to allow for future
namespacing within a target (e.g., "prod/customer1", etc); for now
this is rudimentary, however, see marapongo/mu#94.
The <AllocModule> is the token for the code that contained the 'new'
that led to this object being created. In the future, we may wish to
extend this to also track the module under evaluation. (This is a nice
aspect of monikers; they can become arbitrarily complex, so long as
they are precise, and not prone to false positives/negatives.)
The <Name> warrants more discussion. The resource provider is consulted
via a new gRPC method, Name, that fetches the name. How the provider
does this is entirely up to it. For some resource types, the resource
may have properties that developers must set (e.g., `new Bucket("foo")`);
for other providers, perhaps the resource intrinsically has a property
that explicitly and uniquely qualifies the object (e.g., AWS SecurityGroups,
via `new SecurityGroup({groupName: "my-sg"}`); and finally, it's conceivable
that a provider might auto-generate the name (e.g., such as an AWS Lambda
whose name could simply be a hash of the source code contents).
This should overall produce better results with respect to moniker
collisions, ability to match resources, and the usability of the system.
This change adds custom serialization and deserialization to preserve
the ordering of resources in snapshot files. Unfortunately, because
Go maps are unordered, the results are scrambled (actually, it turns out,
Go will sort by the key). An alternative would be to resort the results
after reading in the file, or storing as an array, but this would be a
change to the MuGL file format and is less clear than simply keying each
resource by its moniker as we are doing today.
This change repivots the plan/apply commands slightly. This is largely
in preparation for performing deletes and updates of existing environments.
The old way was slightly confusing and made things appear more "magical"
than they actually are. Namely, different things are needed for different
kinds of deployment operations, and trying to present them each underneath
a single pair of CLI commands just leads to weird modality and options.
The new way is to offer three commands: create, update, and delete. Each
does what it says on the tin: create provisions a new environment, update
makes resource updates to an existing one, and delete tears down an existing
one entirely. The arguments are what make this interesting: create demands
a MuPackage to evaluate (producing the new desired state snapshot), update
takes *both* an existing snapshot file plus a MuPackage to evaluate (producing
the new desired state snapshot to diff against the existing one), and delete
merely takes an existing snapshot file and no MuPackage, since all it must
do is tear down an existing known environment.
Replacing the plan functionality is the --dry-run (-n) flag that may be
passed to any of the above commands. This will print out the plan without
actually performing any opterations.
All commands produce serializable resource files in the MuGL file format,
and attempt to do smart things with respect to backups, etc., to support the
intended "Git-oriented" workflow of the pure CLI dev experience.
This change adds support for serializing snapshots in MuGL, per the
design document in docs/design/mugl.md. At the moment, it is only
exposed from the `mu plan` command, which allows you to specify an
output location using `mu plan --output=file.json` (or `-o=file.json`
for short). This serializes the snapshot with monikers, resources,
and so on. Deserialization is not yet supported; that comes next.
