6c26693fea
The old method of specifying a default module for a package was using a bit on the module definition itself. The new method is to specify the module name as part of the package definition itself. The new approach makes more sense for a couple reasons. 1) it doesn't make sense to have more than one "default" for a given package, and yet the old model didn't prevent this; the new one prevents it by construction. 2) The defaultness of a module is really an aspect of the package, not the module, who is generally unaware of the package containing it. The other reason is that I'm auditing the code for nondeterministic map enumerations, and this came up, which simply pushed me over the edge. |
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Mu
Mu is a framework and toolset for creating reusable stacks of services.
If you are learning about Mu for the first time, please see the overview document.
Architecture
Prerequisites
Mu is written in Go and uses Glide for dependency management. They must be installed:
If you wish to use the optional lint make target, you'll also need to install Golint:
go get -u github.com/golang/lint/golint
Building and Testing
To build Mu, first clone it into a standard Go workspace:
$ mkdir -p $GOPATH/src/github.com/marapongo
$ git clone git@github.com:marapongo/mu $GOPATH/src/github.com/marapongo/mu
A good default value for GOPATH is ~/go.
Mu needs to know where to look for its runtime, library, etc. By default, it will look in /usr/local/mu, however you
can override this with the MUPATH variable. Normally it's easiest just to create a symlink:
$ ln -s $GOPATH/src/github.com/marapongo/mu /usr/local/mu
There is one additional build-time dependency, golint, which can be installed using:
$ go get -u github.com/golang/lint/golint
And placed on your path by:
$ export PATH=$PATH:$GOPATH/bin
At this point you should be able to build and run tests from the root directory:
$ cd $GOPATH/src/github.com/marapongo/mu
$ glide update
$ make
This installs the mu binary into $GOPATH/bin, which may now be run provided make exited successfully.
Compilers
The Mu compilers are built and tested independently from the Mu tool and runtime written in Go. Please see the respective pages for details on this process for each compiler:
Debugging
The Mu tools have extensive logging built in. In fact, we encourage liberal logging in new code, and addding new logging when debugging problems. This helps to ensure future debugging endeavors benefit from your sleuthing.
All logging is done using Google's Glog library. It is relatively barebones, and adds basic leveled logging, stack dumping, and other capabilities beyond what Go's built-in logging routines offer.
The Mu command line has two flags that control this logging and that can come in handy when debugging problems. The
--logtostderr flag spews directly to stderr, rather than the default of logging to files in your temp directory. And
the --verbose=n flag (-v=n for short) sets the logging level to n. Anything greater than 3 is reserved for
debug-level logging, greater than 5 is going to be quite verbose, and anything beyond 7 is extremely noisy.
For example, the command
$ mu compile blueprint.yaml --logtostderr -v=5
is a pretty standard starting point during debugging that will show a fairly comprehensive trace log of a compilation.