An example of a file-repo that mirrors central and clojars so that we don't touch the network, along with comments about weird error messages...

profiles.clj

;;Say I don't want to ever touch the internet.  Say I've written all my 
;;awesome clojure stuff, and I have built up a bunch of libraries in 
;;my local .m2 repo.  Important caveat: say none of these libraries 
;;got there via 'lein install', if they did....we got problems and 
;;likely will get wierd errors.  Let's say, for now, every lib 
;;is downloaded from either clojars or maven central.  

;;If we were to copy our .m2 folder to another place....say 
;;a network file folder, or just a local file folder like 
;;c:/Users/tom/repos/, we can force lein to look there 
;;and only there - when resolving external (that is 
;;dependencies that aren't cached to our local .m2 folder).

;;THe following profile sketches out how to do so..
{:user {:plugins [[joinr/lein-marginalia "0.9.1-SNAPSHOT"]]
        ;;CRITICAL: point the default central and clojars at our local 
        ;;file mirror, via the :mirrors profile.
        ;;:mirrors values take the same keys as :repositories.
        ;;the :url is a file:///... uri, which must point to the 
        ;;repository folder, not the root .m2 folder.
        ;;(note the added /repository/ on the file url)
        :mirrors {"central"  {:name "central"
                              :url  "file:///c:/Users/tom/repos/repository/"
                              :checksum :warn}
                 #"clojars" {:name  "internal repo"
                               :url  "file:///c:/Users/tom/repos/repository/"
                             :repo-manager true
                             :checksum :warn}
                 }
          ;;optionally, we can setup to deploy to our mirror.
          ;;this way, if we do 'lein deploy fs' our lib is installed there, and 
          ;;other donks can use it.  The most notable difference between this and
          ;;'lein install' is that 'lein install' doesn't provide the correct, 
          ;;magical metadata necessary for others to resolve it.  So, if we have 
          ;;anything in our .m2 cache that got there via 'lein install', if we 
          ;;copy it to our mirror, we'll end up with wierd errors...like
          ;;"number of bytes transferred cannot be negative", which is maven's 
          ;;crappy way of telling us we have garbage dependencies in our local 
          ;;cache and/or in our remote.  this is typically an artifact of 
          ;;going with 'lein install' instead of deploying, or copying our .m2 
          ;;without thinking...
          :deploy-repositories [["fs" {:url "file:///c:/Users/tom/repos/"
                                       :sign-releases false}]]
;;This is another way to define "local" repositories.  The only reason we used the 
;;:mirrors definition above is to, under production circumstances, prevent lein 
;;from running out to the internet (which we can't access), rather using the 
;;file-based mirrors. This mechanism just provides "extra" places to look, along
;;with any caveats about them.
        ;; :repositories [["blah" {:url "file:///c:/Users/tom/repos/repository/"
        ;;                           ;; If a repository contains releases only setting
        ;;                           ;; :snapshots to false will speed up dependencies.
        ;;                           :snapshots true
        ;;                           ;; Disable signing releases deployed to this repo.
        ;;                           ;; (Not recommended.)
        ;;                           :sign-releases false
        ;;                           ;; You can also set the policies for how to handle
        ;;                           ;; :checksum failures to :fail, :warn, or :ignore.
        ;;                           :checksum :warn
        ;;                           ;; How often should this repository be checked for
        ;;                           ;; snapshot updates? (:daily, :always, or :never)
        ;;                           :update :always
        ;;                           ;; You can also apply them to releases only:
        ;;                           }]]
        }
 :repl
 {:plugins
  [[cider/cider-nrepl "0.9.1"]
   ]}
 }

;;Noted errors:
;;"No algorthims available" => looks like it finds the libs, but fails to resolve.  Likely that you
;;didn't add on the "repository" folder to the file uri.
;;"Cannot transfer negative bytes" => garbage either in the remote or the local repo.  
;;You may have crap that was 'lein installed' or otherwise deployed.  This causes maven to 
;;freak out and think the repository is wrong or something.  Again, if you pulled everything 
;;from clojars or central, you shouldn't run into this problem.  Solution: wipe your mirror, ensure 
;;it only has jars from clojars/central (i.e. with a fresh .m2 local cache - or none - got to your project 
;;and do a lein deps - resolve dependencies - WITHOUT the aforementioned mirrors enabled).  After that, 
;;copy your - now "clean" .m2 - into the mirror location.  Turn on mirros in the profiles.clj  .  
;;Test out by wiping your .m2, then trying lein deps again from the same project.  It should fetch 
;;the exact dependencies you just dl'd.  If you posted your jars on the network, other people can 
;;use the file mirror as their clojars/central mirror too.