distribution/doc/opensprint/kickoff.md

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Distribution
=========================
## Project intentions
**Problem statement and requirements**
* What is the exact scope of the problem?
Design a professional grade and extensible content distribution system, that allows docker users to:
... by default enjoy:
* an efficient, secured and reliable way to store, manage, package and exchange content
... optionally:
* can hack/roll their own on top of healthy open-source components
... with the liberty to:
* implement their own home made solution through good specs, and solid extensions mechanism
* Who will the result be useful to?
* users
* ISV (who distribute images or develop image distribution solutions)
* docker
* What are the use cases (distinguish dev & ops population where applicable)?
* Everyone (... uses docker push/pull).
* Why does it matter that we build this now?
* Shortcomings of the existing codebase are the #1 pain point (by large) for users, partners and ISV, hence the most urgent thing to address (?)
* That situation is getting worse everyday and killer competitors are going/have emerged.
* Who are the competitors?
* existing artifact storage solutions (eg: artifactory).
* emerging products that aim at handling pull/push in place of docker.
* ISV that are looking for alternatives to workaround this situation
**Current state: what do we have today?**
Problems of the existing system:
1. not reliable
* registry goes down whenever the hub goes down
* failing push result in broken repositories
* concurrent push is not handled
* python boto and gevent have a terrible history
* organically grown, under-designed features are in a bad shape (search)
2. inconsistent
* discrepancies between duplicated API (and *duplicated APIs*)
* unused features
* missing essential features (proper SSL support)
3. not reusable
* tightly entangled with hub component makes it very difficult to use outside of docker
* proper access-control is almost impossible to do right
* not easily extensible
4. not efficient
* no parallel operations (by design)
* sluggish client-side processing / bad pipeline design
* poor reusability of content (random ids)
* scalability issues (tags)
* too many useless requests (protocol)
* too much local space consumed (local garbage collection: broken + not efficient)
* no squashing
5. not resilient to errors
* no resume
* error handling is obscure or inexistent
6. security
* content is not verified
* current tarsum is broken
* random ids are a headache
7. confusing
* registry vs. registry.hub?
* layer vs. image?
8. broken features
* mirroring is not done correctly (too complex, bug-laden, caching is hard)
9. poor integration with the rest of the project
* technology discrepancy (python vs. go)
* poor testability
* poor separation (API in the engine is not defined enough)
10. missing features / prevents future
* trust / image signing
* naming / transport separation
* discovery / layer federation
* architecture + os support (eg: arm/windows)
* quotas
* alternative distribution methods (transport plugins)
**Future state: where do we want to get?**
* Deliverable
* new JSON/HTTP protocol specification
* new image format specification
* (new image store in the engine)
* new transport API between the engine and the distribution client code / new library
* new registry in go
* new authentication service on top of the trust graph in go
* What are the interactions with other components of the project?
* critical interactions with docker push/pull mechanism
* critical interactions with the way docker stores images locally
* In what way will the result be customizable?
* transport plugins allowing for radically different transport methods (bittorent, direct S3 access, etc)
* extensibility design for the registry allowing for complex integrations with other systems
* backend storage drivers API
## Kick-off output
**What is the expected output of the kick-off session?**
* draft specifications
* separate binary tool for demo purpose
* a mergeable PR that fixes 90% of the listed issues
* agree on a vision that allows solving all that are deemed worthy
* propose a long term battle plan with clear milestones that encompass all these
* define a first milestone that is compatible with the future and does already deliver some of the solutions
* deliver the specifications for image manifest format and transport API
* deliver a working implementation that can be used as a drop-in replacement for the existing v1 with an equivalent feature-set
**How is the output going to be demoed?**
docker pull
docker push
**Once demoed, what will be the path to shipping?**
A minimal PR that include the first subset of features to make docker work well with the new server side components.
## Pressing matters
* need a codename (ship, distribute)
* new repository
* new domains
* architecture / OS
* persistent ids
* registries discovery
* naming (quay.io/foo/bar)
* mirroring
## Assorted issues
* some devops want a docker engine that cannot do push/pull