So one of our developers needs me to batch a bunch of information and process it into an OVA to be presented back for download. This is an easy process using the long method (ie writing to the filesystem), but the developers want a cleaner, streamlined solution that will scale better. They have therefore requested that I stream the entire processes which is proving difficult. Can someone please give me some direction. Here are the steps that need to be accomplished:
- Get input from webserver (Webserver will pass these as stream eventually.)
- Random password
- XML file
- Modify boot script on file system (ie insert random password generated by server)
- Create ISO of XML file and boot script
- Calculate the SHA1 sum of ISO
- Append SHA1 sum of ISO to manifest file in OVF directory
- Create OVA from OVF directory
Here is an example directory structure (I outlined this in / just for simplicity)
/--
|
|--ISO/
| |
| |--boot.sh (Where the random password gets inserted)
| |--config.xml (This is handed from the web server. Needs to stream from server)
|
|--OVF/
|
|--disk.vmdk
|--ovf.xml
|--manifest.mf (Contains SHA1 of all files in OVF directory)
|--boot.iso (This file will exist once created from ISO directory)
Here is what I have so far (I'll explain the issues afterwards. Yes... there are a lot of issues):
cat /ISO/boot.sh | sed "s%DEFAULT%RANDOM%" | mkisofs /ISO/* | echo "SHA1(boot.iso)= " && sha1sum >> manifest.mf | tar -cvf success.ova /OVF/*
NOTE In boot.sh there is a variable set to DEFAULT like this (Just for testing purposes):
PASSWORD="DEFAULT"
NOTE This is what a line in the manifest file should look like:
SHA1(boot.iso)= 5fbc0d70 BLAH BLAH BLAH a91c9121bb
So I've never tried to write an entire script in one stream before. Usually I write to the filesystem a lot as I go. The first issue I see with this is that sed is replacing the string, but what it's piping over to mkisofs will not be used as mkiosfs is just going to make an iso of what it finds in /ISO. I dont even know if you can pass something like that to mkisofs. Piping is sometimes weird to think about.
Next, I think mkisofs is ok because I didnt specify a file output, therefore it should output to stdout which will be passed to sha1sum, but and here is the next problem I see. I need to append some additional text to the file before the SHA1 sum gets added which kinda interrupts the stream.
Finally, the last problem I see is how to pass everything to be tar into OVA without writing to the filesystem first (writing to manifest.mf).
Oh and the last BIG problem which I should have mentioned first is the config.xml file. Right now im dealing with it as just a file. The dev guys want to pass it to this script as a stream as well. I dont have a clue how to handle that.
Any help would be greatly appreciated. These concepts are a little beyond my knowledge.
Thanks!
UPDATE 12/11/13 2:11PM EST
Testing each part individually right now. Will report findings below soon.
UPDATE 12/11/13 2:14PM EST
The following works:
cat /ISO/boot.sh | sed "s%DEFAULT%RANDOM%"
and produces the following output:
RANDOM="RANDOM"
Exactly as expected.
You are correct NeronLeVelu, I will have to come back later and look at sed more carefully when real random passwords are being generated. ie. Making sure proper characters are escaped. Right now though, I'm just testing the logic. I will worry about regex and escaping later. We have not even decided on random password yet. It's only temporary and will most likely be alphanumeric.
Moving onto next part. Still not sure how to take the output from sed (stdout) and use it to include in ISO creation without actually creating a file that gets written to the file system. It may not be possible without writing to file system. More to come soon
