core

package
Version: v0.0.0-...-e28fab9 Latest Latest
Warning

This package is not in the latest version of its module.

Go to latest
Published: Oct 15, 2021 License: AGPL-3.0 Imports: 0 Imported by: 0

Documentation

Overview

Package core exists to hold concepts and pure logic pertaining to juju's domain. We'd call it "model code" if we weren't planning to rename "environ" to "model"; but that'd be quite needlessly confusing, so "core" it is.

This is a necessarily broad brush; if anything, it's most important to be aware what should *not* go here. In particular:

* if it makes any reference to MongoDB, it should not be in here.
* if it's in any way concerned with API transport, or serialization, it should
  not be in here.
* if it has to do with the *specifics* of any resource *substrate* (compute,
  storage, networking, ...) it should not be in here.

...and more generally, when adding to core:

* it's fine to import from any subpackage of "github.com/juju/juju/core"
* but *never* import from any *other* subpackage of "github.com/juju/juju"
* don't you *dare* introduce mutable global state or I will hunt you down
* like a dog

...although, of course, *moving* code into core is great, so long as you don't drag in forbidden concerns as you do so. At first glance, the following packages are good candidates for near-term corification:

* constraints (only dependency is instance)
* instance (only dependency is network)
* network (already core-safe)
* watcher-excluding-legacy (only depends on worker[/catacomb])
* worker-excluding-other-subpackages

...and these have significant core-worthy content, but will be harder to extract:

* environs[/config]-excluding-registry
* storage-excluding-registry (depends only on instance and environs/config)
* workload

...and, last but most, state, which deserves especially detailed consideration, because:

* it is by *far* the largest repository of business logic.
* much of the business logic is horribly entangled with mgo concerns
* plenty of bits -- pure model validation bits, status stuff, unit/machine
  assignment rules, probably a thousand more -- will be easy to extract

...but plenty of other bits will *not* be easy: in particular, all the business rules that concern consistency are really tricky, and somewhat dangerous, to extract, because (while those rules and relationships *are* business logic) we need to be able to *render* them into a mgo/txn representation to ensure DB consistency. If we just depend on implementing the state bits to match, rather than *use*, the core logic, we're basically completely screwed.

The one place we address these concerns is in the core/lease.Token interface, which includes functionality for communicating with the implementation of lease.Client currently in play; where the state code which is responsible for creating a mongo-based client is not entirely unjustified in making use of the trapdoor to extract mgo.txn operations from lease.Token~s passed back in.

There's probably some sort of generally-useful abstraction to be extracted there, but I'm not sure what it is yet.

Source Files

Directories

Path Synopsis
bundle
Package cache is responsible for keeping an in memory representation of the controller's models.
Package cache is responsible for keeping an in memory representation of the controller's models.
downloader
Package downloader is a generated GoMock package.
Package downloader is a generated GoMock package.
repository/mocks
Package mocks is a generated GoMock package.
Package mocks is a generated GoMock package.
Package leadership holds code pertaining to application leadership in juju.
Package leadership holds code pertaining to application leadership in juju.
mocks
Package mocks is a generated GoMock package.
Package mocks is a generated GoMock package.
Package lxdprofile defines a set of functions and constants that can interact with LXD Profiles.
Package lxdprofile defines a set of functions and constants that can interact with LXD Profiles.
mocks
Package mocks is a generated GoMock package.
Package mocks is a generated GoMock package.
Package os provides access to operating system related configuration.
Package os provides access to operating system related configuration.
transientfile
Package transientfile provides helpers for creating files that do not survive machine reboots.
Package transientfile provides helpers for creating files that do not survive machine reboots.
The presence package works on the premise that an agent it alive if it has a current connection to one of the API servers.
The presence package works on the premise that an agent it alive if it has a current connection to one of the API servers.
raft

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
t or T : Toggle theme light dark auto
y or Y : Canonical URL