release handling

[Vance Shipley]

When we packaged our first application for embedded use
we followed the instructions and examples as closely as
possible.  We had some difficulty but luckily at that
time we had a visitor from the Erlang group here and
he helped us through it.

What suprised us was that the release_handler did not
allow us to build an initial system.  It must have a
release upgrade specification file to complete the job
and there doesn't seem to be a valid syntax for
"upgrading" from nothing.

I was also somewhat suprised that it packaged all the
modules which were dependent including kernel and stdlib.
This makes the standard release file much larger than
needed.  I may change that one day but we generally stick
to the supported path as much as possible because we
create enough of our own problems. :)

My current steps to build and install a release are (assuming
that the we have written a Beta.rel "release resource file"
and an sample.app "application resource file"):

$ make
gcc -O -DUNIX -I.  -I/usr/include/dialogic \
	-I/usr/local/lib/erlang/lib/erl_interface-3.2/include \
      -o dialogic dialogic.c -lgc -ldxxx -ldti -lsrl -lLiS \
	-L/usr/local/lib/erlang/lib/erl_interface-3.2/lib \
	-lerl_interface -lei -lresolv
erlc sample.erl
erlc sample_sup.erl
erlc t1_fsm.erl
erlc e1_fsm.erl
erlc evasrv.erl
erlc spanfsm.erl
erlc cdrevh.erl
erlc logevh.erl
erlc evmgr.erl
erlc status.erl
erlc gentabs.erl

$ make install

install -d /usr/local/lib/erlang/lib/sample-2.0/ebin
install -d /usr/local/lib/erlang/lib/sample-2.0/include
install -d /usr/local/lib/erlang/lib/sample-2.0/src/c_src
install -d /usr/local/lib/erlang/lib/sample-2.0/src/e_src
install -d /usr/local/lib/erlang/lib/sample-2.0/priv/bin
install -d /usr/local/lib/erlang/lib/sample-2.0/priv/data
install Makefile /usr/local/lib/erlang/lib/sample-2.0/src/c_src
install *.rel /usr/local/lib/erlang/releases
install *.app /usr/local/lib/erlang/lib/sample-2.0/ebin
install *.hrl /usr/local/lib/erlang/lib/sample-2.0/include
install *.erl /usr/local/lib/erlang/lib/sample-2.0/src/e_src
install *.beam /usr/local/lib/erlang/lib/sample-2.0/ebin
install *.c /usr/local/lib/erlang/lib/sample-2.0/src/c_src
install -s dialogic /usr/local/lib/erlang/lib/sample-2.0/priv/bin
install *.c /usr/local/lib/erlang/lib/sample-2.0/src/c_src
install *.defs /usr/local/lib/erlang/lib/sample-2.0/priv/data
install *tab /usr/local/lib/erlang/lib/sample-2.0/priv/data

$ cd /usr/local/lib/erlang/releases
$ erl
Erlang (BEAM) emulator version 4.9.1 [source]

Eshell V4.9.1  (abort with ^G)
1> systools:make_script("Beta").
ok
2> systools:make_tar("Beta").
ok
3> halt().
$ cp Beta.tar.gz /home/otpuser/lib/erlang/releases
$ exit

login: otpuser
Password:

$ cd lib/erlang/releases
$ erl
Erlang (BEAM) emulator version 4.9.1 [source]

Eshell V4.9.1  (abort with ^G)
1> release_handler:unpack_release("Beta").
ok
2> halt().

$ vi RELEASES
[{release,"sample",
          "example-1.0",
          "4.9.1",
          [{kernel,"2.5","/home/otpuser/lib/erlang/lib/kernel-2.5"},
           {stdlib,"1.8.1","/home/otpuser/lib/erlang/lib/stdlib-1.8.1"},
           {sasl,"1.8.2","/home/otpuser/lib/erlang/lib/sasl-1.8.2"},
           {answer,"2.0","/home/otpuser/lib/erlang/lib/sample-2.0"}],
          unpacked},
 {release,"OTP  APN 181 01",
          "R6B",
          "4.9.1",
          [{kernel,"2.5","/home/otpuser/lib/erlang/lib/kernel-2.5"},
           {stdlib,"1.8.1","/home/otpuser/lib/erlang/lib/stdlib-1.8.1"},
           {sasl,"1.8.2","/home/otpuser/lib/erlang/lib/sasl-1.8.2"}],
          old}].

*** [ here we change the status of the new release from "unpacked" to "current"]
***

$ erl
Erlang (BEAM) emulator version 4.9.1 [source]

Eshell V4.9.1  (abort with ^G)
1> release_handler:make_permanent("example-1.0").
ok
2> halt()


At this point all that is needed to get an embedded system up and
running is to run /home/otpuser/lib/erlang/bin/start.


Now if the truth be known I usually skip the release_handler:unpack_release/1
step and just untar it manually.  As far as I know that's all it really does.

One day I'll have my makefile do all of this. :)

	-Vance