myna
"Process virtualization for the people by the people with people." - People
Myna is a testing tool that captures and replays the output of command line programs. It's heavily inspired by SpectoLab's Hoverfly, which does capture and playback for http(s) web services.
Myna is written in Go and makes use of Boltdb for storage. It was initially built to facilitate testing of KubeFuse.
It does not work with interactive programs at this point in time, but it's
pretty baller with the rest
Installation
Myna uses the Glide build tool so you can just do:
glide install
go build
And you're laughing.
Usage
Capture the output of ls -al /
myna --capture ls -al /Or by setting the CAPTURE environment variable:
CAPTURE=1 myna ls -al /Play back the output of ls -al /
myna ls -al /By default myna will save all its state in a file called processes.db,
but we can override that by setting the DATABASE_LOCATION environment
variable:
DATABASE_LOCATION=/tmp/my.db myna --capture ls -al /
DATABASE_LOCATION=/tmp/my.db myna ls -al /To use the simulated process from our tests we can update our code to use myna
in place of the usual binary, but by writing a wrapper ls file and putting
this on the PATH we can seamlessly use myna from our tests without having to
change a single thing:
cat > ls <<EOF
#!/bin/bash
myna "\$0" "\$@"
EOF
chmod +x ls
export PATH="`pwd`:$PATH"Usage from the Shell
We can also specify a cheeky little alias to work with myna from the
command line, which is less useful for automated testing, but still manages to
provide fun for the whole family
$ alias ls="myna ls"
$ ls /
./myna does not know this process. Run the command in capture mode first.
$ export CAPTURE=1
$ ls /
drwxr-xr-x 24 root root 4096 May 14 12:29 .
drwxr-xr-x 24 root root 4096 May 14 12:29 ..
drwxr-xr-x 2 root root 12288 Mar 20 12:37 bin
drwxr-xr-x 4 root root 4096 May 14 12:30 boot
drwxrwxr-x 2 root root 4096 Aug 10 2015 cdrom
drwxr-xr-x 19 root root 4880 May 14 10:17 dev
drwxr-xr-x 159 root root 12288 May 14 12:29 etc
drwxr-xr-x 4 root root 4096 Aug 10 2015 home
lrwxrwxrwx 1 root root 32 May 14 12:29 initrd.img -> boot/initrd.img-4.2.0-36-generic
lrwxrwxrwx 1 root root 32 Apr 6 18:58 initrd.img.old -> boot/initrd.img-4.2.0-35-generic
drwxr-xr-x 29 root root 4096 Feb 17 21:13 lib
drwxr-xr-x 2 root root 4096 Feb 17 21:13 lib32
drwxr-xr-x 2 root root 4096 Feb 17 21:13 lib64
drwx------ 2 root root 16384 Aug 10 2015 lost+found
drwxr-xr-x 3 root root 4096 Aug 10 2015 media
drwxr-xr-x 2 root root 4096 Apr 17 2015 mnt
drwxr-xr-x 5 root root 4096 Apr 5 00:07 opt
dr-xr-xr-x 297 root root 0 May 13 22:34 proc
drwx------ 8 root root 4096 Nov 12 2015 root
drwxr-xr-x 30 root root 960 May 15 03:05 run
drwxr-xr-x 2 root root 12288 Mar 20 12:37 sbin
drwxr-xr-x 2 root root 4096 Apr 22 2015 srv
dr-xr-xr-x 13 root root 0 May 15 03:31 sys
drwxrwxrwt 12 root root 12288 May 15 04:49 tmp
drwxr-xr-x 12 root root 4096 Jan 30 15:09 usr
drwxr-xr-x 13 root root 4096 Apr 22 2015 var
lrwxrwxrwx 1 root root 29 May 14 12:29 vmlinuz -> boot/vmlinuz-4.2.0-36-generic
lrwxrwxrwx 1 root root 29 Apr 6 18:58 vmlinuz.old -> boot/vmlinuz-4.2.0-35-generic
$ export CAPTURE=0
$ ls /
drwxr-xr-x 24 root root 4096 May 14 12:29 .
drwxr-xr-x 24 root root 4096 May 14 12:29 ..
drwxr-xr-x 2 root root 12288 Mar 20 12:37 bin
drwxr-xr-x 4 root root 4096 May 14 12:30 boot
drwxrwxr-x 2 root root 4096 Aug 10 2015 cdrom
drwxr-xr-x 19 root root 4880 May 14 10:17 dev
drwxr-xr-x 159 root root 12288 May 14 12:29 etc
drwxr-xr-x 4 root root 4096 Aug 10 2015 home
lrwxrwxrwx 1 root root 32 May 14 12:29 initrd.img -> boot/initrd.img-4.2.0-36-generic
lrwxrwxrwx 1 root root 32 Apr 6 18:58 initrd.img.old -> boot/initrd.img-4.2.0-35-generic
drwxr-xr-x 29 root root 4096 Feb 17 21:13 lib
drwxr-xr-x 2 root root 4096 Feb 17 21:13 lib32
drwxr-xr-x 2 root root 4096 Feb 17 21:13 lib64
drwx------ 2 root root 16384 Aug 10 2015 lost+found
drwxr-xr-x 3 root root 4096 Aug 10 2015 media
drwxr-xr-x 2 root root 4096 Apr 17 2015 mnt
drwxr-xr-x 5 root root 4096 Apr 5 00:07 opt
dr-xr-xr-x 297 root root 0 May 13 22:34 proc
drwx------ 8 root root 4096 Nov 12 2015 root
drwxr-xr-x 30 root root 960 May 15 03:05 run
drwxr-xr-x 2 root root 12288 Mar 20 12:37 sbin
drwxr-xr-x 2 root root 4096 Apr 22 2015 srv
dr-xr-xr-x 13 root root 0 May 15 03:31 sys
drwxrwxrwt 12 root root 12288 May 15 04:49 tmp
drwxr-xr-x 12 root root 4096 Jan 30 15:09 usr
drwxr-xr-x 13 root root 4096 Apr 22 2015 var
lrwxrwxrwx 1 root root 29 May 14 12:29 vmlinuz -> boot/vmlinuz-4.2.0-36-generic
lrwxrwxrwx 1 root root 29 Apr 6 18:58 vmlinuz.old -> boot/vmlinuz-4.2.0-35-genericA Continuous Integration Workflow
For KubeFuse I have to generate more
than one test case. To keep this process repeatable I added a capture step
to my build system that I would run whenever the command under test (kubectl
in this case) was updated.
The build step looks something like this:
#!/bin/bash
# Put myna into capture mode
export CAPTURE=1
# Remove the old myna database if it exists
rm -f processes.db
# Run the commands I need for testing:
myna kubectl get namespaces
myna kubectl get pods --all-namespaces
myna kubectl get svc --all-namespaces
myna kubectl get rc --all-namespaces
....
# Export the results
myna --export | python -m json.tool > kubectl.jsonBefore I start running my tests I need to create the kubectl shim and import the definition:
cat > bin/kubectl <<EOF
#!/bin/bash
unset CAPTURE
myna kubectl "\$@"
EOF
chmod +x bin/kubectl
rm processes.db
myna --import kubectl.jsonAnd then I can start my tests with a modified PATH so that the tests pick up the shim first:
PATH="bin/:$PATH" nosetestsAnd that's it. Your uncle is Bob.
Using Myna in your Python Unit Tests
I actually kind of lied in the previous section, because since the release
of python-myna (see the contrib/python-myna/ directory) I don't have to
write any shims or modify my path, because I let this library take care of it
for me.
For this example I'm using nose and python-myna, which you can both install
using pip.
The KubeFuse repository is roughly structured like this:
kubefuse/kubefuse.py
kubefuse/all_the_rest.py
tests/test_kubefuse.py
tests/test_all_the_rest.py
tests/__init__.py
The kubefuse directory contains all the source code and the tests directory the
tests. I run the suite by starting nosetests in the root.
To make my tests work with Myna I use package level setUp and tearDown
functions that take care of handling the shim creation and PATH jumbling
for me. Luckily I can just import these functions straight from the python-myna
library, so my __init__.py looks like this:
from myna import *The only thing that is missing now is to create and then later import the simulations. This is similar to the steps describe above, and something for which I use Make, because I love Make and Make is awesome.
myna:
./kubectl.myna.sh
test:
DATABASE_LOCATION="`pwd`/kubectl.db" myna --import tests/kubectl.json
DATABASE_LOCATION="`pwd`/kubectl.db" nosetestsLicense
Apache License version 2.0 See LICENSE for details.
(c) SpectoLabs 2016.
