How Chocolatey knows which packages are installed and which aren’t

chocolateyinstallationpackage-management

Chocolatey is a package management system for Windows. First, you download and install Chocolatey, which is free and open-source software. You tell it what software you want, then (usually) answer one or more questions. Chocolatey will then download and silently install the software for you.

I'm trying to better understand how Chocolatey knows what it has already installed. This is in order so that I can understand whether or not interrupting a "chocolatey install" operation can cause Chocolatey to become permanently confused, forever.

Using Chocolatey 0.9.9.8, when I try to install a package (7zip) twice in a row, the first time succeeds and the second time does nothing but print a warning message. The message says:

7zip v9.38 already installed.
Use –force to reinstall, specify a version to install, or try upgrade.

Chocolatey installed 0/1 package(s).
See the log for details (C:\ProgramData\chocolatey\logs\chocolatey.log).

I looked into the Chocolatey source code in order to try to find the answer. It looks like the method call which checks whether or not a package is already installed is this one. But I couldn't find the source code for the FindPackage method.

How does Chocolatey know which packages it has already installed? Does it keep a central database somewhere on my machine which keeps track of what it has installed and what it hasn't?

Best Answer

It tracks that based on the actual packages on disk. Note that there is a lib folder in %ChocolateyInstall% e.g. 'C:\ProgramData\chocolatey\lib' in the default installed location.

In that folder are package folders, in each of those is a *.nupkg file. Each *.nupkg file represents an installed package.

For where you are looking, note the following -

Also, GitHub trick so you don't need webarchive links - once you've found the source code bit, press y to get the permanent link.

Source does not require a URL

Sources can be one of the following formats:

HTTP/HTTPS OData Feed
Local Directory
CIFS Share / UNC share

See https://github.com/chocolatey/choco/wiki/How-To-Host-Feed#local-folder--unc-share-cifs for more information.

Offline cache

We've updated this question based on content at https://stackoverflow.com/a/18596173/18475

We call this process internalization. You can do this manually or look at Chocolatey for Business to do this.

Typically package maintainers on the community package repository do not have distribution rights for the actual software binaries, so the package needs instructions to go download those resources and act on them. This is not a limitation when using Chocolatey internally.

Caching Downloads - Not Deterministic

While there are ways to set the original nupkg (with the version on it, not the one in the packages directory - use download from left side of packages page on the Chocolatey community package repository) and preset the downloaded binaries into the cache folder, it's not always deterministic that it will work. You can also override the cache location, so that the folder is somewhere not in TEMP. See choco config, choco config -h and choco config set cacheLocation c:\some\location to do this.

NOTE: The cache will only support the same architecture, as in you can't take the results from an x64 machine and expect the cache to have 32-bit installers also downloaded.

Create Your Own Packages - Better

For packages you need offline, you have the ability to manage your own packages and you can embed software right into the package. This is desired when you want to manage software offline as most things on the community repository are subject to copyright law and distribution rights (why they don't simply have the software they represent embedded).

Creating and working with your own packages is very secure, but it does tend to take up time. If you are doing this for yourself, then it could override any time-savings you get as a consumer using Chocolatey and the community repository.

For organizations, we've developed Package Builder, which creates full software deployments (packages) in 5-10 seconds. It can also create packages right out of existing installed software (Programs and Features) in under 60 seconds! Read more about Package Builder.

Internalized Packages - Best

The best thing you can do here is a process called internalizing, where you download and extract the package, download all of the resources and embed them in the package (or put them somewhere local), edit the scripts to use those embedded/local resources and recompile the package.

This allows you to take advantage of existing package logic without the issue of the internet.

For more details see Manually Internalizing Packages and Package Internalizer - Automatically Internalize Packages.

Organization Use of Chocolatey

Most organizations using Chocolatey are doing some combination of creating packages and internalizing packages, because they need absolute trust and control over those packages when being used in production scenarios.

Windows – Understand difference between Package Management (formerly OneGet) and Chocolatey, and Get Started using OneGet in Win10 RTM

It looks like it IS installed, and that the pre-release blog posts that say to type Import-Module -Name OneGet are no longer correct, for Win10 rtm.

However, you still need to manually add a package source like this, from an Administrator-privilege level PowerShell, in Windows 10 professional:

Register-PackageSource -Name chocolatey -Location https://chocolatey.org/api/v2 -Provider PSModule -Trusted -Verbose

You can search like this:

Find-Package paint -provider Chocolatey

Above should find the actual choco package name of Paint.net for me.

Then you can install something like this:

Install-Package paint.net -provider Chocolatey

(For example, to install Paint.NET).

If you can't find Install-package cmdlet (it appears like it is not installed?) switch from regular non-elevated powershell, to an elevated (Administrator) powershell.