README for morph
================

> **NOTA BENE:** This document is very much work-in-progress, and anything
> and everything may and will change at little or no notice. If you see
> problems, mail [email protected].

`morph` builds binaries for [Baserock](http://www.baserock.org/),
an appliance Linux solution. Please see the website for overall information.


Usage
-----

The Baserock builds are controlled by **morphology** files,
which are build recipes. See below for their syntax. Everything
in Baserock is built from git commits.
Morphologies must be committed in git before building. The `morph` tool is
used to actually run the build. The usual workflow is this:

* put the morphology for an upstream project with its source code
* put other morphologies in the `morphs` (note plural) repository
* run `morph` to build stuff

`morph --help` will provide some information, though a full guide is
really required. Meanwhile a short usage to build a disk image:

    morph init workspace
    cd workspace
    morph checkout baserock:baserock/definitions master
    cd master/baserock/baserock/definitions
    morph build base-system-x86_64-generic

For deploying you need to create a cluster morphology. Here is an
example to deploy to a raw disk image.

    name: foo
    kind: cluster
    systems:
    - morph: base-system-x86_64-generic
      repo: baserock:baserock/definitions
      ref: master
      deploy:
          my-raw-disk-image:
              type: rawdisk
              location: /src/tmp/testdev.img
              DISK_SIZE: 4G

To deploy it, you only need to run `morph deploy` with the cluster morphology
created:

    morph deploy foo

You can write a configuration file to avoid having to write options on
the command line every time. Put it in `~/.morph.conf` and make it look
something like this:

    [config]
    cachedir = /home/username/baserock/cache
    log = /home/username/baserock/morph.log
    log-max = 200M
    trove-host = git.baserock.org

All of the above settings apart from `log` are the defaults, so may be omitted.


Morphology file syntax
----------------------

YAML is used for the morphology syntax. For example, to build a chunk:

    name: foo
    kind: chunk
    configure-commands:
    - ./configure --prefix="$PREFIX"
    build-commands:
    - make
    test-commands:
    - make check
    install-commands:
    - make DESTDIR="$DESTDIR" install

For all morphologies, use the following fields:

* `name`: the name of the morphology; it must currently match the filename
  (without the `.morph` suffix); **required**
* `kind`: the kind of thing being built; **required**

For chunks, use the following fields:


* `build-system`: if the program is built using a build system known to
  `morph`, you can set this field and avoid having to set the various
  `*-commands` fields; the commands that the build system specifies can
  be overridden; the following build-systems are known:

  - `autotools`
  - `python-distutils`
  - `cpan`
  - `cmake`
  - `qmake`

  optional

* `pre-configure-commands`: a list of shell commands to run at
  the configuration phase of a build, before the list in `configure-commands`;
  optional
* `configure-commands`: a list of shell commands to run at the configuraiton
  phase of a build; optional
* `post-configure-commands`: a list of shell commands to run at
  the configuration phase of a build, after the list in `configure-commands`;
  optional

* `pre-build-commands`: a list of shell commands to run at
  the build phase of a build, before the list in `build-commands`;
  optional
* `build-commands`: a list of shell commands to run to build (compile) the
  project; optional
* `post-build-commands`: a list of shell commands to run at
  the build phase of a build, after the list in `build-commands`;
  optional

* `pre-test-commands`: a list of shell commands to run at
  the test phase of a build, before the list in `test-commands`;
  optional
* `test-commands`: a list of shell commands to run unit tests and other
  non-interactive tests on the built but un-installed project; optional
* `post-test-commands`: a list of shell commands to run at
  the test phase of a build, after the list in `test-commands`;
  optional

* `pre-install-commands`: a list of shell commands to run at
  the install phase of a build, before the list in `install-commands`;
  optional
* `install-commands`: a list of shell commands to install the built project;
  the install should go into the directory named in the `DESTDIR` environment
  variable, not the actual system; optional
* `post-install-commands`: a list of shell commands to run at
  the install phase of a build, after the list in `install-commands`;
  optional

* `max-jobs`: a string to be given to `make` as the argument to the `-j`
  option to specify the maximum number of parallel jobs; the only sensible
  value is `"1"` (including the quotes), to prevent parallel jobs to run
  at all; parallel jobs are only used during the `build-commands` phase,
  since the other phases are often not safe when run in parallel; `morph`
  picks a default value based on the number of CPUs on the host system;
  optional

* `chunks`: a key/value map of lists of regular expressions;
  the key is the name
  of a binary chunk, the regexps match the pathnames that will be
  included in that chunk; the patterns match the pathnames that get installed
  by `install-commands` (the whole path below `DESTDIR`); every file must
  be matched by at least one pattern; by default, a single chunk gets
  created, named according to the morphology, and containing all files;
  optional

For strata, use the following fields:

* `build-depends`: a list of strings, each of which refers to another
  stratum that the current stratum depends on. This list may be omitted
  or empty if the stratum does not depend on anything else.
* `chunks`: a list of key/value mappings, where each mapping corresponds
  to a chunk to be included in the stratum; the mappings may use the
  following keys: `name` is the chunk's name (may be different from the
  morphology name), `repo` is the repository in which to find (defaults to
  chunk name), `ref` identifies the commit to use (typically a branch
  name, but any tree-ish git accepts is ok), and `morph` is the name
  of the morphology to use and is optional. In addition to these keys,
  each of the sources MUST specify a list of build dependencies using the
  `build-depends` field. This field may be omitted to make the source
  depend on all other chunks that are listed earlier in the `chunks`
  list. The field may be an empty list to indicate that the chunk does
  not depend on anything else in the same stratum. To specify one or
  more chunk dependencies, `build-depends` needs to be set to a list
  that contains the names of chunks that the source depends on in the
  same stratum. These names correspond to the values of the `name`
  fields of the other chunks.

For systems, use the following fields:

* `strata`: a list of names of strata to be included in the system. Unlike
  chunks, the stratum morphs must all be in the same Git repository as the
  system morphology. The value of the `morph` field will be taken as the
  artifact name; if this causes ambiguity then an `alias` may be specified as
  well. **required**

Example chunk (simplified commands):

    name: eglibc
    kind: chunk
    configure-commands:
    - mkdir o
    - cd o && ../libc/configure --prefix=/usr
    build-commands:
    - cd o && make
    install-commands:
    - cd o && make install_root="$DESTDIR" install

Example stratum:

    name: foundation
    kind: stratum
    chunks:
    - name: fhs-dirs
      repo: upstream:fhs-dirs
      ref: baserock/bootstrap
      build-depends: []
    - name: linux-api-headers
      repo: upstream:linux
      ref: baserock/morph
      build-depends:
      - fhs-dirs
    - name: eglibc
      repo: upstream:eglibc
      ref: baserock/bootstrap
      build-depends:
      - linux-api-headers
    - name: busybox
      repo: upstream:busybox
      ref: baserock/bootstrap
      build-depends:
      - fhs-dirs
      - linux-api-headers

Example system:

    name: base
    kind: system
    strata:
    - morph: foundation
    - morph: linux-stratum

Note that currently, unknown keys in morphologies are silently ignored.


Build environment
-----------------

When `morph` runs build commands, it clears the environment of all
variables and creates new ones. This is so that the build will run
more consistently across machines and developers.

See the `morphlib/buildenvironment.py` file for details on what
environment variables are set.

Morph also constructs a staging area for every build, composed of its
build-dependencies, so everything that is used for a build is traceable
and reproducible.


Hacking morph
-------------

When running Morph from a Git checkout, remember to set PYTHONPATH to
point to your checkout. This will cause Morph to load the plugins and
write extensions from your checkout correctly.

Run the test suite with this command:

    ./check --full

If your /tmp is a tmpfs you may need to set TMPDIR to a different path,
as there are tests for large disk image deploys.

Install CoverageTestRunner (from <http://liw.fi/coverage-test-runner/>),
and check out the `cmdtest` utility (from <http://liw.fi/cmdtest/>).

Run the checks before submitting a patch, please.


Legalese
--------

Copyright (C) 2011-2014  Codethink Limited

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.