From 7c5b1e60c241a4740351dbc155a28e47f42db556 Mon Sep 17 00:00:00 2001 From: Misty Stanley-Jones Date: Tue, 23 May 2017 16:14:03 -0700 Subject: [PATCH] Remove registry/architecture.md from docs repo (#3365) This file is specifically not published to the site anyway --- docs/architecture.md | 52 -------------------------------------------- 1 file changed, 52 deletions(-) delete mode 100644 docs/architecture.md diff --git a/docs/architecture.md b/docs/architecture.md deleted file mode 100644 index c2aaa9f2..00000000 --- a/docs/architecture.md +++ /dev/null @@ -1,52 +0,0 @@ ---- -published: false ---- - -# Architecture - -## Design -**TODO(stevvooe):** Discuss the architecture of the registry, internally and externally, in a few different deployment scenarios. - -### Eventual Consistency - -> **NOTE:** This section belongs somewhere, perhaps in a design document. We -> are leaving this here so the information is not lost. - -Running the registry on eventually consistent backends has been part of the -design from the beginning. This section covers some of the approaches to -dealing with this reality. - -There are a few classes of issues that we need to worry about when -implementing something on top of the storage drivers: - -1. Read-After-Write consistency (see this [article on - s3](http://shlomoswidler.com/2009/12/read-after-write-consistency-in-amazon.html)). -2. [Write-Write Conflicts](http://en.wikipedia.org/wiki/Write%E2%80%93write_conflict). - -In reality, the registry must worry about these kinds of errors when doing the -following: - -1. Accepting data into a temporary upload file may not have latest data block - yet (read-after-write). -2. Moving uploaded data into its blob location (write-write race). -3. Modifying the "current" manifest for given tag (write-write race). -4. A whole slew of operations around deletes (read-after-write, delete-write - races, garbage collection, etc.). - -The backend path layout employs a few techniques to avoid these problems: - -1. Large writes are done to private upload directories. This alleviates most - of the corruption potential under multiple writers by avoiding multiple - writers. -2. Constraints in storage driver implementations, such as support for writing - after the end of a file to extend it. -3. Digest verification to avoid data corruption. -4. Manifest files are stored by digest and cannot change. -5. All other non-content files (links, hashes, etc.) are written as an atomic - unit. Anything that requires additions and deletions is broken out into - separate "files". Last writer still wins. - -Unfortunately, one must play this game when trying to build something like -this on top of eventually consistent storage systems. If we run into serious -problems, we can wrap the storagedrivers in a shared consistency layer but -that would increase complexity and hinder registry cluster performance.