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CLI to upload image to openstack cloud

April 18th, 2012 by

I work on automatic testing of one of our products that creates other projects.
And because there is a lot of clouds everywhere I want to use them too. We
have internally an OpenStack cloud (still Diablo release). So I need to solve
automatic uploading of images built in the Build Service. Below I describe my working version.

At first, for other cloud related tasks we are using the nova command (which
e.g. has also image-delete, but not add). For uploading we use
glance. I found a few obstacles which I separately describe and also provide
a solution.


The first chalenge is authentication, as glance doesn`t use NOVA_*
environment variables. But it allows to use an authentication token. So we
just need to get such a token. With help of Martin Vidner we have this script,
that returns a valid token.

# cloud_auth_token.sh
AUTH_JSON="{\"auth\":{\"passwordCredentials\":{\"username\": \"$OS_USERNAME\", \"password\":\"$OS_PASSWORD\"}, \"tenantName\":\"$OS_TENANT_NAME\"}}"
curl -s \
    -d "$AUTH_JSON" -H "Content-type: application/json" \
    $OS_AUTH_URL/tokens \
    | python -c "import sys; import json; tok = json.loads(sys.stdin.read()); print tok['access']['token']['id'];"

What does it do? It calls OpenStack Identity API, passes credentials encoded
as JSON. The response is also JSON, so we use python that is already on the
system to parse the response and get the token.

Compressing the Image

The next challenge is compression of the image. We get a raw disk from the
build service and we extend it to have more than 15GB (we mirror there rpms
so we need this space). For resizing we use qemu-img from
virt-utils. If we simply upload this image it means that we send the whole
15GB over the network. Which is fine for one-time tasks, but for regular
testing it is a problem. Thanks to Christoph Thiel we solved it with the
conversion to qcow2. Qcow2 is also supported in OpenStack and qcow2 allows
compression. The final script for conversion:

qemu-img convert -c -f raw -O qcow2 img.raw img.qcow2
qemu-img resize img.qcow2 +10G

Using it Together

Now we have prepared an image and a helper script to get a cloud auth
token. So let’s upload the image.

cat img.qcow2 | glance -H cloud.example.com -A `sh cloud_auth_token.sh` add name='testing_img' is_public=False disk_format=qcow2 container_format=bare

Cleaning Up After Testing

We use it for testing and release new versions of the testing appliance often,
therefore we need cleaning up. It is quite simple with unix text utils:

for i in `nova image-list | grep "image_name" | sed "s/^|[[:space:]]\+\([[:xdigit:]-]\+\).*$/\1/"`; do nova image-delete $i; done

I hope that it helps you with automatic uploading of images to
OpenStack. It works for me with the Diablo release and there is no guarantee that it is the best way 🙂

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