30.6 Installing dependencies: Let the machines do it
In most cases you won’t need to think about how dependencies get installed – just declare them in your package’s DESCRIPTION and the installation will be handled automatically by R and devtools during the build process. The main exception is when a dependency relies on non-R software that R does not know how to install automatically. For example, rjags relies on JAGS, which might be installed in a different place on every machine. If your dependency falls in this category, you will know (because your CI builds will keep failing until you figure out how to fix it), but the exact details of the fix will differ for every case.