Warn when unable to snapshot locked files

[sitano]

The checksum snapshotting prevents service installation scenarios:

Package installation process looks like:

1. chocolateyInstall.ps1 run
2. download and unzip exe to choco/lib/package/something
3. register service
4. start service
   error here: 5) chocolatey checksum snapshot will fail to read ran exe file (service)

[ferventcoder]

This is no bueno.

I wouldn't want to disable snapshotting, because otherwise it can't uninstall the files.

[ferventcoder]

Rather add some fault tolerance around the snapshot and let it continue.

[sitano]

yeah, got it. anyway, this pushes developer to keep such files outside of choco package install path.

[ferventcoder]

I'll be addressing this quickly, so hopefully you won't need to.

What I'm stating here is:

1. Snapshotting is important.
2. Ignore the files that won't snapshot correctly.
3. Do not error and move on.

[sitano]

fully agree 👍 , but actually, it would be nice if those files will be snapshotted too! it just somehow had to be done before they start running and became unreadable. i think its complicated flow, coz snapshotting take place after package install script ran, and those kinda files became unavailable for reading (when it issues start-service call) inside chocoInstall script.

[ferventcoder]

Yes - although if the files are inside the package, they will be removed by nuget core when uninstalled as long as they have not changed.

[sitano]

they actually are downloading during installation from the web by chocolateyInstall.ps1, so they are not there in advance

[ferventcoder]

Well darn. That makes it a bit hard to capture. One thing we could do is explore the Volume Shadow Service to get those checksums if it errors. That would be a followup to this though.

[ferventcoder]

Any chance you can provide a log so I can see where this happens at?

[ferventcoder]

In testing this, I don't see it as an error, just a warning. I've added code to add a special snapshot code for locked files, but without using something like Volume Shadow Copy Service there is no way to snapshot the locked file.

[ferventcoder]

Was your package installation failing on this or just giving you a warning?

[ferventcoder]

I created #321 to followup on a VSS type of fix to snapshot locked files. It's not the easiest thing to achieve so it's move back. For now this issue is resolved with a special snapshot code and a warning when removing the file.

[ferventcoder]

Added messaging in 8a283d6