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OpenResty® EC2 Test Cluster

Yichun Zhang (agentzh) , 25 Sep 2020 (created 21 Feb 2019)

The OpenResty EC2 test cluster (we'll call it "test cluster" from now on) is used by OpenResty core developers to run most of its software components' test suites in various different test modes on Amazon EC2. The latest official test report can always be browsed on the site website.

Over the years, this tool chain successfully captured various obscure regressions in new NGINX cores, new LuaJIT cores, as well as our own components.

On the highest level, it works like this:

  1. The user spawns the EC2 test cluster using her AWS API credentials locally in a terminal by invoking the command-line tool, dispatcher, provided by the opsboy github repository. The user specifies the test running time constraint and test tasks.

  2. The dispatcher command-line tool spawns one or more EC2 VM instances according to the test tasks and the time constraint specified by the user. It will try distributing the test jobs evenly across a minimum number of EC2 VM instances while meeting the total running time constraint at its best effort. The VM instances will keep running. Upon job completion or job failures, they will automatically upload the raw test run logs as tarballs to the server See the Spawn the test cluster section for more details.

  3. The user waits for a period of time approximately equal to the time constraint she specifies, until all the EC2 VM instances are terminated (by checking the EC2 console, for example).

  4. After all the VM instances are terminated, the user invokes the make pull command under the misc/logs/ directory of her local clone of the opsboy repository. This command will automatically download the raw test run logs as tarballs from the server into the local sub-directory ortest/.

  5. The user can now run the command make gen under the misc/logs/ directory to generate a new HTML report under the html/ sub-directory. This command will also print out newly unpacked .log files under ortest/. Sometimes the user may want to check out the raw test run log data in those .log files.

  6. The user can open the html/index.htmlfile locally with her favorite web browser to view the HTML version of the test report. But for the best result, one should setup a local nginx server so that one can avoid browsers' security constraints on opening local web pages directly.

How to save money

AWS EC2 is not a free service (though for new customers they offer free tier instances), it is important to use some tricks to minimize the monthly bill.

To prepare for a new OpenResty release, all projects in all test modes using the (new) version of the nginx core the new OpenResty release is going to use. But usually we first only run ./dispatcher with the t test target, that is, testing all projects using the "normal test mode" (which explains in details below in the Test job names section). If there is some big problems with the opsboy script or some projects themselves, we can fix it more quickly and without paying too much money for too many EC2 instances. If t is green, we then try tv and etc, one by one, or a few modes at a time. The easiest way to waste money is to run all test modes for all projects and then only to find there is a silly mistake somewhere.

Setup the environment

For security reasons, not everyone can directly perform the workflow explained above. The user must have access to our EC2 AMI images with names like ortest-x64-2019-02-06. Our AMI images always follow this naming convention. The date suffix indicates on which date the image was created. And the x64 infix indicates the CPU architecture (we also have i386 ones). The user can request permission by sending emails to Yichun Zhang. The user may also prepare her own AMI images if she wants to, but she must change the run-node script in the ops github repository, somewhere near here.

Also, the user needs to setup the Python-based AWS CLI tool chain and configure using the user's own AWS access key and secret access key locally. Make sure the aws command-line tool is visible to your PATH system environment so that opsboy's run-node tool can invoke it successfully.

Clone the opsboy github repository like this:

git clone git://

If you are a committer of that repository, change git:// to git@.

Then always switch the current working directory to the misc/logs/ directory of this local clone:

cd /path/to/opsboy/misc/logs/

Finally you need to prepare a shell script called sync (the name is important!) of the content like below in the current working directory:

#!/usr/bin/env bash

rsync -av ortest/ || exit 1
mkdir -p ortest/
cd ortest/ || exit 1
for tar in $(ls *.tar.gz); do
    if [ ! -f $log ]; then
        echo $tar
        tar -xzf $tar || exit 1

The user can change the server name in this script to her own server if her AMI images upload the test run log files to somewhere else.

Spawn the test cluster

Spawning a test cluster on EC2 is easy with the dispatch tool provided by opsboy. Usually we run the command like this:

./dispatcher -r -f -t 230 -a 'linux x86_64' t-lua-resty-redis to-lua-resty-websocket

The -f option passes the force=1 variable to the opsboy script for the EC2 test cluster, which effectively force a clean rebuild of all the NGINX C modules (like lua-nginx-module). The -t 230 option constraints the total running time to 230 minutes. This is just a soft limit and the actual running time may exceed this a bit if the job dispatcher cannot find a better way. The -a 'linux x86_64' option specifies that we use the "Linux x86_64" architecture for this test run. Another supported architecture is linux i386. They are defined internally inside the run-node script. Each architecture name corresponds to an AMI image (by their IDs). The -r option actually invokes the AWS CLI tool to spawn EC2 instances. Usually we first omit this option to do a "dry run", to see how many EC2 instances will be needed and how test jobs will be distributed among them. Below is an example for a "dry run":

$ ./dispatcher -f -t 230 -a 'linux x86_64' t-lua-resty-redis ngx_lua
Requires at least 3 machines.
bucket 1: tl-ngx_lua thv-ngx_lua force=1 (228 min)
bucket 2: twv-ngx_lua tv-ngx_lua tr-ngx_lua to-ngx_lua force=1 (228 min)
bucket 3: trv-ngx_lua tw-ngx_lua t-ngx_lua th-ngx_lua t-lua-resty-redis
force=1 (183 min)

Here we will need 3 machines each will take 228 or 183 minutes to complete. At his point you may wonder how does it know how long each job it will run? Actually it uses the meta data produced by the previous job run (generated by the command make gen). So initially it will simply assumes each job will take 5 minutes.

The metadata generated by each run is stored in the ast.json file in the misc/logs/ directory. Usually it is the make gen command which automatically updates it by analyzing the raw test run log files. The HTML report is also rendered from this data file.

The user can skip particular test jobs by passing the -e PATTERN option. This option takes a Perl regex so it can be quite powerful. The regex always work on expanded test job names, like to-ngx_lua.

By default, the dispatcher tool uses the EC2 instance type c5.large to run Linux x86_64 architecture jobs and c3.large to run the i386 architecture. It is also possible to change the EC2 instance type used by passing the -i INSTANCE-TYPE option to the ./dispatcher command line, like -i t3.small.

The -c option is also occasionally used to enforce the use of lua-resty-core to run the Lua related projects' tests (including ngx_lua). Also it injects Lua code require('resty.core.base').set_string_buf_size(1) require('resty.core.regex' ).set_buf_grow_ratio(1) to the init_by_lua* phase as well. It essentially passes the use_lua_resty_core=1 variable setting to the opsboy script.

By default, nginx 1.15.8 is used (which is changing by new OpenResty releases though). One can choose a different nginx core version by specifying the -v VERSION option of the ./dispatcher tool, like -v 1.13.6. Not all nginx version numbers will work. Make sure there is an OpenResty version which uses that version of the nginx core.

You can see more options by typing ./dispatcher -h and/or by directly looking at its Perl source code.

Test job names

In the dispatcher command line, we use test job names like t-lua-resty-redis and ngx_lua. They deserve a separate section to explain. Basically the test job names follow the following formats:

  • <test-mode>-<project-name>
  • <test-mode>
  • <project-name>

The <test-mode> component can take the values t, tr, tw, tv, trv, twv, th, thv, tl, to. They corresponds to the test modes shown on the HTML test report like the one on Still we explain them one by one below:

  • t

    Normal test mode.

  • tr

    Mockeagain reading test mode.

  • tw

    Mockeagain writing test mode

  • tv

    Valgrind test mode

  • trv

    Combination of the tr and tv test modes.

  • twv

    Combination of the tw and tv test modes.

  • th

    HUP reload test mode.

  • thv

    Combination of the th and tv test modes.

  • tl

    Leak check test mode.

  • to

    Builds with aggressive gcc optimization levels (-O3) and other options (like -funsigned-char).

Except to, all the test modes above are implemented by the Test::Nginx scaffold. You can read this free e-book section to learn more details about these Test::Nginx test modes.

The <project-name> component is defined as the target open source project names. NGINX modules follow the naming convention like ngx_lua, ngx_stream_lua, and ngx_set_misc. Lua libraries follow the naming convention like lua-resty-redis, lua-resty-websocket, and etc. There are also special projects like resty-cli and etc. When in doubt, you can always copy the project names from a rendered HTML page like on the site.

All the test modes and project names are internally defined in the gen-use-data Perl script in the opsboy repository. Use of unknown test modes or project names will lead to errors in this script.

If the user specify the test mode part alone, then all the projects will be tested under that test mode. For example, specifying t alone will result in all projects' test suites to be run using the normal test mode while to will lead to all projects to be tested under the aggressive optimization build mode. Therefore, to run all the projects under all test modes, one can simply run the command like below:

./dispatcher -r -f -t 230 -a 'linux x86_64' t tr tw tv trv twv th thv tl

Similarly, if the user specifies a project name alone, then all test modes will be run for that particular project. For example,

./dispatcher -r -f -t 230 -a 'linux x86_64' ngx_lua

is equivalent to

./dispatcher -r -f -t 230 -a 'linux x86_64' t-ngx_lua tr-ngx_lua tw-ngx_lua \
    tv-ngx_lua trv-ngx_lua twv-ngx_lua th-ngx_lua thv-ngx_lua tl-ngx_lua to-ngx_lua

The former is just much more concise and much less error-prone.

The expected test failure white-list

We maintain a white-list for expected test failures for particular test modes on particular architectures in the parse-logs Perl script. We can adjust existing white-list entries or add new entries by editing the Perl variable %white_list in that script file somewhere near here. Test result with expected failures only will be rendered by the orange color in the HTML test report (test results without any failures will be rendered green).

Special care must be taken when white-listing test failures. The patterns should be as specific as possible and they should only mark true false positives that are not easy to handle on the side of the test case itself. Too permissive white-lists would hide real problems and thus defeating the whole purpose of this test cluster. Don't do this unless there is no other way.

For valgrind false positives, we update the valgrind.suppress file in each project repository instead of white-listing them in parse-logs. The same caveat applies to valgrind suppression rules. One may hide true memory issues in the future with too aggressive rules.

Add new projects to test

To add a new project to the test cluster, the user needs to patch several files under the misc/logs/ directory of the opsboy source tree. The easiest way is to check how existing projects were specified:

$ grep websocket `ls -p |grep -v /|grep -v \~|grep -v json`
gen-report:    'lua-resty-websocket' => ['openresty', 'lua-resty-websocket'],
gen-user-data:    'resty-websocket', 'resty-lock',        'lua-resty-websocket' => '',
parse-logs:    'lua-resty-websocket' => [

We can see that lua-resty-websocket has information in the files gen-report, gen-user-data,, and parse-logs. The last one in parse-logs is not necessary since it is for the white-list of expected failures (see the The expected test failure white-list section for details). So we can simply add similar entries in the same way as lua-resty-websocket to the same places (or similar places).

We will also need to update the samples/ortest-ec2.ob.tt2 file to setup the testing logic.

Changing the test driver logic

The VM environment initialization, project building, and test suite running in each EC2 VM instance are all done by a Perl script called which is automatically generated by the opsboy compiler tool chain from the specification file named samples/ortest-ec2.ob.tt2. The opsboy tool chain always initializes the system incrementally.

From time to time, we'll need to edit this file to accommodate new changes in either the operating system or the target projects to be tested.

To change this oftest-ec2.ob.tt2 file, we need to

  1. switch the current working directory to the root directory of the opsboy clone,
  2. edit samples/ortest-ec2.ob.tt2 file for our needs,
  3. run make test to update the samples/ortest-ec2.ob file using the Perl TT2 tool chain, generate a Perl script using the opsboy compiler, and finally running the Perl script using the dry-run mode, and
  4. Commit the newly updated ortest-ec2.ob.tt2 and ortest-ec2.ob files to your own branch and create a GitHub pull request for review and merge.

Under the hood

Under the hood, the dispatcher script invokes gen-user-data script to generate final test job specification strings from the user's command-line arguments (see Test job names). This final test job specification is passed to the new EC2 VM instances as plain-text "user data". The dispatcher script invokes the run-node script which in turn runs the aws tool provided by the AWS CLI tool chain to spawn the EC2 instances with the specified "user data" from our pre-defined EC2 AMI images. Our EC2 AMI image registers the openresty-tester init script as a symlink under the VM's /etc/init.d/ directory such that new changes in this file in the GitHub repository does not require updates in the AMI image. This openresty-tester script in turn calls the openresty-tester-wrapper script. This openresty-tester-wrapper script does the heavy lifting of running the script which is automatically generated from the opsboy script template file using the Perl TT2 template tool chain and the opsboy compiler tool chain. Finally, upon completion, the openresty-tester-wrapper script invokes the ~/ortest-upload script bundled in the AMI image to upload the test run log file tarball to the remote server (by default, it is

The future

There are plans to migrate this tool chain over to the upcoming OpenResty Ops and OpenResty CI platforms developed by OpenResty Inc. in the future so that it would be much easier to use, to extend, and to maintain.


This document was written by Yichun Zhang, the creator of this OpenResty EC2 test cluster tool chain. Feel free to contact the author by sending emails to the address.

Feedback and patches

The source of this document resides in the openresty/ GitHub repository. You are welcome to create issues and/or pull requests if you have questions or edits for this document.

Translations to other languages are also welcome.

General feedback is welcome to send to the author of this document.