apriori

Go proxy with a special care for prior packages

Rationale

This go modules proxy is designed for building environments, where we desire to relieve a burden of numerous downloads and reduce an amount of weak links.

It is meant to be run locally, right on the builder machine and having some especially nasty packages pre-loaded in a predictable manner.

Design

This tool consists of two parts:

1. Cache generator apriori generate
2. Go modules proxy apriori serve

How cache generator works

Cache generator recieves a list of modules to store in cache. The list should look like

github.com/sirkon/message@v1.5.1
github.com/rs/zerolog
go.uber.org/zap@v1.9.1

where we requested to store version v1.5.1 of github.com/sirkon/message, version v1.9.1 of go.uber.org/zap and the latest version of github.com/rs/zerolog.

Now, the generator retrieves revision info, go.mod content and zipped source archvive for a requested version of a module and saves it in requested places (directory for go.mod files, directory for source archives and file to store apriori info in json format should be set, see apriori generate --help for details)

You can download each module dependencies as well: put -r or --recursive option for generate.

How server works

Server should get a path to saved apriori info file to get the stored info.

Now, when it recieves a request it looks for the module in the stored cache.

The situation when the cache has a requested module but lacks the requested version of the module is an error

So, requested module found the client gets stored data

In case there's no requested module in the cache the backing module fetcher (either legacy VCS or another go modules instance) is asked for it.

How to use

First generate apriori cache, then use it. Remember though, once you copy apriori cache somewhere in order to use it there you either must copy go.mod-s and source archives to exactly same paths or to appropriately change apriori info path values for these files.

Examples

Storing requested modules using legacy module fetcher

apriori generate --source modules.lst --dest apriori.json --gomod-dir ./gomods --source-dirs ./sources

Serving using just generated data using https://proxy.golang.org as module fetcher

apriori serve --listen 0.0.0.0:8181 --apriori apriori.json

Same, serving using just generated apriori data, but using company's internal go modules proxy

apriori --use-goproxy https://goproxy.company.com serve --listen 0.0.0.0:8181 --apriori apriori.json

Remember, module fetcher options are the same for both generation and serving