Welcome to the exciting world of riak_test
.
riak_test
is a system for testing Riak clusters. Tests are written
in Erlang, and can interact with the cluster using distributed Erlang.
riak_test
runs tests in a sandbox, typically $HOME/rt/riak
. The sanbox
uses git
to reset back to a clean state after tests are run. The
contents of $HOME/rt/riak
might look something like this:
$ ls $HOME/rt/riak
current riak-1.1.4 riak-1.2.1 riak-1.3.2
Inside each of these directories is a dev
folder, typically
created with your normal make [stage]devrel
. So how does
this sandbox get populated to begin with?
You'll create another directory that will contain full builds
of different version of Riak for your platform. Typically this directory
has been ~/test-releases
but it can be called anything and be anywhere
that you'd like. The dev/
directory from each of these
releases will be copied into the sandbox ($HOME/rt/riak
).
There are helper scripts in bin/
which will
help you get both ~/test-releases
and $HOME/rt/riak
all set up. A full
tutorial for using them exists further down in this README.
There is one folder in $HOME/rt/riak
that does not come from
~/test-releases
: current
. The current
folder can refer
to any version of Riak, but is typically used for something
like the master
branch, a feature branch, or a release candidate.
The $HOME/rt/riak/current
dev release gets populated from a devrel of Riak
that can come from anywhere, but is usually your 'normal' git checkout
of Riak. The bin/rtdev-current.sh
can be run from within that folder
to copy dev/
into $HOME/rt/riak/current
.
Once you have everything set up (again, instructions for this are below),
you'll want to run and write tests. This repository also holds code for
an Erlang application called riak_test
. The actual tests exist in
the test/
directory.
Running tests against a
development version of Riak is just one of the things that you can do
with riak_test. You can also test things involving upgrading from
previous versions of Riak. Together, we'll get your test environment
up and running. Scripts to help in this process are located in the
bin
directory of this project.
This script is for the lazy. It performs all of the setup steps described
in the other scripts, including installing the current "master" branch from
Github into "current". The releases will be built in your current working
directory, so create an empty one in a place you'd like to store these
builds for posterity, so that you don't have to rebuild them if your
installation path ($HOME/rt/riak
by the way this script installs it) gets into
a bad state.
If you do want to restore your $HOME/rt/riak
folder to factory condition, see
rtdev-setup-releases.sh
and if you want to change the current riak under
test, see rtdev-current.sh
.
The first one that we want to look at is rtdev-build-releases.sh
. If
left unchanged, this script is going to do the following:
- Download the source for the past three major Riak versions (e.g. 1.1.4, 1.2.1 and 1.3.2)
- Build the proper version of Erlang that release was built with, using kerl (which it will also download)
- Build those releases of Riak.
You'll want to run this script from an empty directory. Also, you might be thinking that you already have all the required versions of erlang. Great! You can crack open the script and set the paths to your installation or set them from the command-line:
R14B04=${R14B04:-$HOME/erlang-R14B04}
R15B01=${R15B01:-$HOME/erlang-R15B01}
Kerlveat: If you want kerl to build erlangs with serious 64-bit
macintosh action, you'll need a ~/.kerlrc
file that looks like this:
KERL_CONFIGURE_OPTIONS="--disable-hipe --enable-smp-support --enable-threads --enable-kernel-poll --enable-darwin-64bit"
The script will check that all these paths exist. If even one of them is missing, it will prompt you to install kerl, even if you already have kerl. If you say no, the script quits. If you say yes, or all of your erlang paths check out, then go get a cup of coffee, you'll be building for a little while.
The rtdev-setup-releases.sh
will get the releases you just built
into a local git repository. Run this script from the
same directory that you just built all of your releases into.
By default this script initializes the repository into $HOME/rt/riak
but
you can override $RT_DEST_DIR
.
rtdev-current.sh
is where it gets interesting. You need to run that
from the Riak source folder you're wanting to test as the current
version of Riak. Also, make sure that you've already run make devrel
or make stagedevrel
before you run rtdev-current.sh
. Like setting up
releases you can override $RT_DEST_DIR
so all your riak builds are in one place.
reset-current-env.sh
resets test environments setup using rtdev-current.sh
using the following process:
- Delete the current stagedevrel/devrel environment
make stagedevrel
for the Riak release being tested (current default is 2.0, overidden with the-v
flag). When the-c
option is specified,make devclean
will be executed before rebuilding.- Execute
rtdev-current.sh
for the Riak release being tested - Rebuild the current riak_test branch. When the
-c
option is specified, 'make clean' will be executed before rebuilding.
This script is intended to provide to cover the common test environment reset method -- not cover all possible testing configurations/scenarios. As such, it makes the following assumptions regarding the environment and test operation:
- Riak source trees will be symlinked into the riak_test root directory
as
riak-<version>
. - The script will be located in a sub-directory of <riak_test home>. It can be executed from any directory, but it uses the script location to determine the riak_test home directory.
Now that you've got your releases all ready and gitified, you'll need
to tell riak_test about them. The method of choice is to create a
~/.riak_test.config
that looks something like this:
{default, [
{giddyup_host, "localhost:5000"},
{giddyup_user, "user"},
{giddyup_password, "password"},
{rt_max_wait_time, 600000},
{rt_retry_delay, 1000},
{rt_harness, rtdev},
{rt_scratch_dir, "/tmp/riak_test_scratch"},
{basho_bench, "/home/you/basho/basho_bench"},
{spam_dir, "/home/you/basho/riak_test/search-corpus/spam.0"},
{platform, "osx-64"}
]}.
{rtdev, [
{rt_project, "riak"},
{rtdev_path, [{root, "/home/you/rt/riak"},
{current, "/home/you/rt/riak/current"},
{previous, "/home/you/rt/riak/riak-1.3.2"},
{legacy, "/home/you/rt/riak/riak-1.2.1"}
]}
]}.
The default
section of the config file will be overridden by the config
name you specify. For example, running the command below will use an
rt_retry_delay
of 500 and an rt_max_wait_time
of 180000. If your
defaults contain every option you need, you can run riak_test without
the -c
argument.
Some configuration parameters:
Default configuration parameters that will be used for nodes deployed by riak_test. Tests can override these.
{rtdev, [
{ rt_default_config,
[ {riak_core, [ {ring_creation_size, 16} ]} ] }
]}
You can generate a coverage report for a test run through Erlang Cover. Coverage information for all current code run on any Riak node started by any of the tests in the run will be output as HTML in the coverage directory. That is, legacy and previous nodes used in the test will not be included, as the tool can only work on one version of the code at a time. Also, cover starts running in the Riak nodes after the node is up, so it will not report coverage of application initialization or other early code paths. Each test module, via a module attribute, can specify what modules it wishes to cover compile:
-cover_modules([riak_kv_bitcask_backend, riak_core_ring]).
Or entire applications by using:
-cover_apps([riak_kv, riak_core]).
To enable this, you need to turn coverage in in your riak_test.config:
{cover_enabled, true}
Tests that do not include coverage annotations will, if cover is enabled, honor {cover_modules, [..]} and {cover_apps, [..]} from the riak_test config file.
When reporting is enabled, each test result is posted to Giddy Up. You can specify any number of webhooks that will also receive a POST request with JSON formatted test information, plus the URL of the Giddy Up resource page.
{webhooks, [
[{name, "Bishop"},
{url, "https://basho-engbot.herokuapp.com/riak_test"}]
]}
This is an example test result JSON message posted to a webhook:
{ "test": "verify_build_cluster",
"status": "fail",
"log": "Some really long lines of log output",
"backend": "bitcask",
"id": "144",
"platform": "osx-64",
"version": "riak-1.4.0-9-g740a58d-master",
"project": "riak",
"reason": "{{assertion_failed, and_probably_a_massive_stacktrace_and stuff}}",
"giddyup_url": "https://giddyup.basho.com/test_results/53" }
Notice that the giddyup URL is not the page for the test result, but a resource from which you can GET information about the test in JSON.
Run a test! ./riak_test -c rtdev -t verify_build_cluster
Did that work? Great, try something harder: ./riak_test -c rtdev_mixed -t upgrade
Intercepts are a powerful but easy to wield feature. They allow you to change the behavior of any function and affect global state in an extremely lightweight manner. You can modify the KV vnode to simulate dropped puts. You can sleep a call to discover what happens when certain calls take a long time to finish. You can even turn a call into a noop to really cause havoc on a cluster. These are just some examples. You should also be able to change any function you want, including dependency functions and even Erlang functions. You can also create intercepts using anonymous functions, either in compiled code or while debugging in an Erlang shell. Furthermore, any state you can reach from a function call can be affected such as function arguments and also ETS tables. This leads to the principle of intercepts.
If you can do it in Riak source code you can do it with an intercept.
Writing an intercept is nearly identical to writing any other Erlang source with a few easy-to-remember conventions added.
-
Intercepts used by tests living in this repository must live in the
intercepts
directory. Projects that keep their tests in the project repository (separate fromriak_test
) must have a directory that contains only intercept modules. These modules should not be compiled by the project. -
All intercept modules should be named the same as the module they affect with the suffix
_intercepts
added. E.g.riak_kv_vnode
=>riak_kv_vnode_intercepts
. -
You cannot call lager (the modules are not compiled with the parse transform). The
intercept.hrl
module includes macros to properly log messages. All intercept modules in this repository should includeintercept.hrl
. All intercept modules that live outside this repository cannot include it because it is not accessible. -
All intercept modules should declare the macro
M
whose value is the affected module with the suffix_orig
added. E.g. forriak_kv_vnode
add the line-define(M, riak_kv_vnode_orig)
. This, along with the next convention is needed to call into the original function. -
To call the origin function use the
?M:
followed by the name of the function with the_orig
suffix appended. E.g. to callriak_kv_vnode:put
you would type?M:put_orig
. -
To log a message use the
I_
macros. E.g. to log an info message use?I_INFO
-- see 3.
The easiest way to understand the above conventions is to see them all at work in an example.
-module(riak_kv_vnode_intercepts).
-compile(export_all).
-include("intercept.hrl").
-define(M, riak_kv_vnode_orig).
dropped_put(Preflist, BKey, Obj, ReqId, StartTime, Options, Sender) ->
NewPreflist = lists:sublist(Preflist, length(Preflist) - 1),
?I_INFO("Preflist modified from ~p to ~p", [Preflist, NewPreflist]),
?M:put_orig(NewPreflist, BKey, Obj, ReqId, StartTime, Options, Sender).
Intercepts can be used in two ways: 1) added via the config, 2) added
via rpc:call
in the test. The first way is most convenient, is
persistent (survives node restarts), and is in effect for all tests.
The second method requires additional code, is specific to a test, is
ephemeral (does not survive a node restart), but allows more fine
grained control.
In both cases intercepts can be disabled by adding the following to your config. By default intercepts will be loaded and compiled, but not added. That is, they will be available but not in effect unless you add them via one of the methods listed previously.
{load_intercepts, false}
Here is how you would add the dropped_put
intercept via the config.
{intercepts, [{riak_kv_vnode, [{{put,7}, dropped_put}]}]}
Breaking this down, the config key is intercepts
and its value is a
list of intercepts to add. Each intercept definition in the list
describes which functions to intercept and what functions to intercept
them with. The example above would result in all calls to
riak_kv_vnode:put/7
being intercepted by
riak_kv_vnode_intercepts:dropped_put/7
.
{ModuleToIntercept, [{{FunctionToIntercept, Arity}, InterceptFunction}]}
Note that anonymous functions may not be supplied as intercepts via config.
To add the dropped_put
intercept manually you would do the following.
rt_intercept:add(Node, {riak_kv_vnode, [{{put,7}, dropped_put}]})
You could alternatively supply an anonymous function as an intercept here. This requires that your module include the following compilation directive:
-compile({parse_transform, rt_intercept_pt}).
The general form for an anonymous function intercept is a 2-tuple:
{ListOfFreeVariables, AnonymousFunction}
The first element of the tuple is a list of free variables the anonymous function uses from its surrounding context, and the second element is the anonymous function itself. For example, the previous example using an anonymous function intercept might look like this:
rt_intercept:add(Node,
{riak_kv_vnode,
[{{put,7},
{[],
fun(Preflist,BKey,Obj,ReqId,StartTime,Options,Sender) ->
NewPreflist = lists:sublist(Preflist, length(Preflist)-1),
error_logger:info_msg("Preflist modified from ~p to ~p",
[Preflist, NewPreflist]),
riak_kv_vnode_orig:put_orig(NewPreflist,BKey,Obj,ReqId,
StartTime,Options,Sender)
end}}]})
Note how this version has no access to the ?I_INFO
and ?M
like in the
original example. For this reason, for an actual test this code would be
better written using a regular intercept rather than the anonymous function
approach shown here.
Since the anonymous function in this example uses no free variables from its surrounding context, the variable list in this example is empty. For cases like this where the list of free variables is empty, you can alternatively supply just the anonymous function in place of the 2-tuple.
If you pass an anonymous function intercept to rt_intercept:add/2
in an
Erlang shell, a list of free variables is not needed regardless of whether
the function uses such variables or not. This is because the shell tracks
these variables and makes a list of them available as part of the
function's context. Therefore you need supply only the function, not the
2-tuple.
Knowing the implementation details is not needed to use intercepts but this knowledge could come in handy if problems are encountered. There are two parts to understand: 1) how the intercept code works and 2) how intercepts are applied on-the-fly in Riak Test. It's important to keep one thing in mind.
Intercepts are based entirely on code generation and hot-swapping. The overhead of an intercept is always 1 or 2 function calls. 1 if a function is not being intercepted, 2 if it is and you call the original function.
The intercept code turns your original module into three. Based on
the mapping passed to intercept:add
code is generated to re-route
requests to your intercept code or forward them to the original code.
E.g. if defining intercepts on riak_kv_vnode
the following modules
will exist.
-
riak_kv_vnode_orig
- Contains the original code fromriak_kv_vnode
but modified so that all original functions have the suffix_orig
added to them and the original function definitions become passthrus toriak_kv_vnode
, the proxy. -
riak_kv_vnode_intercepts
- This contains code of your intercept as you defined it. No modification of the code is performed. -
riak_kv_vnode
- What once contained the original code is now a proxy. All functions passthru toriak_kv_vnode_orig
unless an intercept is registered in the mapping passed tointercept:add
, in which case the call will forward toriak_kv_vnode_intercepts
.
The interceptor code also modifies the original module and proxy to
export all functions. This fact, along with the fact that all the
original functions in riak_kv_vnode_orig
will callback into the
proxy, means that you can intercept private functions as well.
In order for Riak Test to use intercepts they need to be compiled, loaded, and registered on the nodes under test. You can't use the bytecode generated by Riak Tests' rebar because the Erlang version used will often be different from that included with your Riak nodes. You could require that the user compile with the oldest Erlang version supported but that is extra burden on the user and still doesn't guarantee things will work if there is a jump of more than 2 majors in Erlang version. No, this should be easy to use and thus the intercept code is compiled on the Riak nodes guaranteeing that the bytecode will be compatible.
After the code is compiled and loaded the intercepts need to be added.
All intercepts defined in the user's riak_test.config
will be added
automatically any time a node is started. Thus, intercepts defined in
the config survive restarts and are essentially always in play. A
user can also manually add an intercept by making an rpc
call from
the test code to the remote node. This method is ephemeral and the
intercept will not survive restarts.
To have bash shell complete test names, source the utils/riak_test.bash
file.
put utils/riak_test.zsh
somewhere on $fpath
.