provcat.config

Configuration sources.

A configuration is a dict with up to seven sections:

stores: named store instances, each {driver: ..., <options>}.
schemes: logical URI schemes and their templates (see resolver.py).
stages: stage pointers, {logical-uri: {stage-name: "kind:value"}}.
entries: rules for one logical name or prefix, {logical-uri: {target: ..., ref: ...}} (see resolver.py).
cache: {root: <folder>}.
tenants: {name: {stores: ..., stages: ..., entries: ..., cache: ...}}, the part of each tenant. The schemes are shared.
admin: {stores: ..., stages: ..., entries: ..., cache: ...}, the part that only the admin sees, such as a store with keys that read every tenant’s data.

The view of one tenant, which ConfigSource.load(tenant) gives, is the shared sections and that tenant’s part. With no tenant it is the admin’s view, the shared sections, the admin part and every tenant’s part. A tenant may name only its own stores, stages and entries, so that no tenant can take over another’s. Each scheme that names its tenant part, with tenant: org, says whose a URI is.

In etcd each tenant’s part lives under <prefix>/tenants/<name>/<section>, <prefix>/tenants/<name>/name marks the tenant, and <prefix>/tenants lists the names. The admin part lives under <prefix>/admin/<section>. A reader for one tenant reads only the shared keys and its own, so etcd’s access control on key prefixes can keep the tenants apart.

ConfigSource is the interface. load() returns the configuration with every ${oc.env:VAR} filled in from the environment of the reader. raw() returns it as written, with the ${...} left in. config push copies the raw form, so each reader of a shared etcd fills in its own environment.

YamlConfig reads a YAML file with PyYAML. EtcdConfig keeps each section as JSON under <prefix>/<section> and talks to the etcd v3 HTTP gateway, so it needs no etcd client library. save() replaces all sections in one etcd transaction, and deletes the sections that the new configuration does not have.

Parameter	Type	Default	Description
`cfg`	dict	required	The sections of the view
`tenant`	str \| None	required	The tenant whose view it is; None for the admin’s

Parameter	Type	Default	Description
`url`	str	required	etcd://host:port/prefix; the port defaults to 2379, and the prefix may be empty
`timeout`	float	`5.0`	Seconds to wait for each request to etcd

Parameter	Type	Default	Description
`key`	str	required	The full etcd key, prefix included
returns	str \| None		The value stored under the key; None when there is none or it is empty

Parameter	Type	Default	Description
`tenant`	str \| None	required	The tenant to read for; None for the admin, who reads everything
returns	dict		The shared sections and the tenant’s part alone, checked

class View

class ConfigSource

ConfigSource.raw

ConfigSource.raw_for

ConfigSource.load

ConfigSource.save

class EmptyConfig

EmptyConfig.raw

class YamlConfig

YamlConfig.raw

class EtcdConfig

EtcdConfig.get

EtcdConfig.raw

EtcdConfig.raw_for

EtcdConfig.save

open_config