terraform/internal/initwd/doc.go

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// Package initwd contains various helper functions used by the "terraform init"
command: "terraform init" can partially initialize for 0.12upgrade There are a few constructs from 0.11 and prior that cause 0.12 parsing to fail altogether, which previously created a chicken/egg problem because we need to install the providers in order to run "terraform 0.12upgrade" and thus fix the problem. This changes "terraform init" to use the new "early configuration" loader for module and provider installation. This is built on the more permissive parser in the terraform-config-inspect package, and so it allows us to read out the top-level blocks from the configuration while accepting legacy HCL syntax. In the long run this will let us do version compatibility detection before attempting a "real" config load, giving us better error messages for any future syntax additions, but in the short term the key thing is that it allows us to install the dependencies even if the configuration isn't fully valid. Because backend init still requires full configuration, this introduces a new mode of terraform init where it detects heuristically if it seems like we need to do a configuration upgrade and does a partial init if so, before finally directing the user to run "terraform 0.12upgrade" before running any other commands. The heuristic here is based on two assumptions: - If the "early" loader finds no errors but the normal loader does, the configuration is likely to be valid for Terraform 0.11 but not 0.12. - If there's already a version constraint in the configuration that excludes Terraform versions prior to v0.12 then the configuration is probably _already_ upgraded and so it's just a normal syntax error, even if the early loader didn't detect it. Once the upgrade process is removed in 0.13.0 (users will be required to go stepwise 0.11 -> 0.12 -> 0.13 to upgrade after that), some of this can be simplified to remove that special mode, but the idea of doing the dependency version checks against the liberal parser will remain valuable to increase our chances of reporting version-based incompatibilities rather than syntax errors as we add new features in future.
2019-01-14 20:11:00 +01:00
// command to initialize a working directory.
//
// These functions may also be used from testing code to simulate the behaviors
// of "terraform init" against test fixtures, but should not be used elsewhere
// in the main code.
package initwd