[Airship-discuss] [sig][airship-bootstrap] airshipctl golang module vs. airshipctl interacting with a docker container

[Roman Gorshunov]

Alan,

The go-diskfs doesn’t seem support manipulation of existing ISO’s. README says
that “Any attempt to Mkdir() or OpenFile() in write/append/create modes or Write()
to the file will result in an error.” [0].

Therefore, there would be a need to extract contents of existing iso, and rebuild it
(go-diskfs supports El Torito cd-rom spec, which allows cd’s to be bootable).

[0] https://github.com/diskfs/go-diskfs#read-only-filesystems

Best regards,
—
Roman Gorshunov

> On 9 Aug 2019, at 00:42, MEADOWS, ALAN <am240k at att.com> wrote:
> 
> Roman,
> 
> The go-lang library I had been looking at that supported reading and writing iso9660 (iso) images was diskfs:
> 
> https://github.com/diskfs/go-diskfs
> 
> The code samples on the README will walk you through filesystem manipulation.  With regard to iso9660 filesystems, this does seem to have the ability to create iso9660 filesystems (https://github.com/diskfs/go-diskfs/blob/master/filesystem/iso9660/iso9660.go#L49-L64) however I have not found or found the right examples that simply demonstrate manipulating an existing ISO (e.g. dropping in a file).  Certain comments (like this one https://github.com/diskfs/go-diskfs/blob/master/filesystem/iso9660/iso9660.go#L49-L64) have me wondering if there are some gaps or I have simply not spent enough time with it to understand the interfaces correctly.
> 
> This presumed that operators would come to the table with (LiveCD) ISOs already generated and the responsibility of `airshipctl bootstral isogen` (or perhaps a better name) would be strictly to open up the path to the ISO, write cloud-init data in the right location, and write it back, preferably as a new image on the disk so the original remains untouched.  To help operators generate custom LiveCDs though that have the packages they want pre-installed, I had envisioned we would be providing a separate toolkit to help build these images (whether this is containerized, bash, python, go-lang was entirely the choice of this toolkit.  This would be an alternative to operators using out of the box LiveCDs from vendors.
> 
> Anyways, this was the idea behind many of my comments on that call.
> 
> As I mentioned on the etherpad, while having airshipctl call out to a runtime environment with an agreed upon interface to launch an operator provided container that would do this manipulation adds a dependency on airshipctl<->containers, it may make the operation of building that LiveCD more repeatable as the container image to use would be part of your declaration.  In the above, it was a separate out of band process you would follow.
> 
> Alan Meadows
> 
> On 8/8/19, 7:17 AM, "Roman Gorshunov" <paye600 at gmail.com> wrote:
> 
>    Hello team,
>    Hello Alan,
> 
>    Following up on an Airship-bootstrap call we have had yesterday, Alan
>    described his alternative (lines 92-95 here
>    https://urldefense.proofpoint.com/v2/url?u=https-3A__etherpad.openstack.org_p_Airship-5Fbootstrap&d=DwIGaQ&c=LFYZ-o9_HUMeMTSQicvjIg&r=OI-s0Rr_BtNj0OcKWGZyuA&m=39e3KOJnyQM7A29deZ-dZk7USCOUThcpuXal7e2-zVM&s=EJ4k-ZQq9rUccFvreOF8yFdVt1QeKZURrJ71OdPNyAU&e=, search for "isogen
>    uses native go-lang library") which he was talking about close to the
>    end of the call.
> 
>    I remember Alan has described this approach previously on one of
>    design calls, I did not forget about it and I love this solution. What
>    I was thinking about yesterday, was that creating a golang module for
>    the airshipctl would be more complicated (at least for me) than to
>    create a container image for a proof-of-concept stage. I'm all for not
>    having containerd dependency in release version of airshipctl.
>    I'd like to hear your feedback on this.
> 
>    Alan,
>    What was the golang library you were talking about which could open
>    and amend ISO image contents?
> 
>    And another question is what are the standard ISO images (esp. LiveCD)
>    provided by vendors which have built-in cloud-init?
> 
>    Recording: https://urldefense.proofpoint.com/v2/url?u=https-3A__attcorp.webex.com_attcorp_lsr.php-3FRCID-3Da05f4d1d798f40d79dfda57c9fa0e131&d=DwIGaQ&c=LFYZ-o9_HUMeMTSQicvjIg&r=OI-s0Rr_BtNj0OcKWGZyuA&m=39e3KOJnyQM7A29deZ-dZk7USCOUThcpuXal7e2-zVM&s=gOk3Ob1SfPyaSoEOgsC5DfYYDKur9gXSPJJVHEbR_VU&e=
>    Recording password: HkYjdjq3
>    Recordings are stored on the server for 30 days only.
> 
>    Best regards,
>    --
>    Roman Gorshunov
> 
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