Go 1.17 includes a breaking change to both net.ParseIP and net.ParseCIDR
functions to reject IPv4 address octets written with leading zeros.
Our use of these functions as part of the various CIDR functions in the
Terraform language doesn't have the same security concerns that the Go
team had in evaluating this change to the standard library, and so we
can't justify an exception to our v1.0 compatibility promises on the same
sort of security grounds that the Go team used to justify their
compatibility exception.
For that reason, we'll now use our own fork of the Go library functions
which has the new check disabled in order to preserve the prior behavior.
We're taking this path, rather than pre-normalizing the IP address before
calling into the standard library, because an additional normalization
layer would be entirely new code and additional complexity, whereas this
fork is relatively minor in terms of code size and avoids any significant
changes to our own calls to these functions.
Thanks to the Kubernetes team for their prior work on carving out a subset
of the "net" package for their similar backward-compatibility concern.
Our "ipaddr" package here is a lightly-modified fork of their fork, with
only the comments changed to talk about Terraform instead of Kubernetes.
This fork is not intended for use in any other future feature
implementations, because they wouldn't be subject to the same
compatibility constraints as our existing functions. We will use these
forked implementations for new callers only if consistency with the
behavior of the existing functions is a key requirement.
Go 1.17 has a new treatment of go.mod where it tracks more indirect
dependencies in return for needing to fetch and load fewer transitive
go.mod files.
This commit opts in to that new treatment and adds all of the additional
indirect dependencies which contain packages that Terraform directly or
indirectly makes use of.
There are more details on what's going on here in the "Lazy Module Loading"
design document:
http://golang.org/design/36460-lazy-module-loading
(the design document was written assuming this would land in Go 1.15, but
it actually landed in Go 1.17 and so it's "go 1.17" that selects the new
behavior in spite of the examples in that document.)
This includes the addition of the new "//go:build" comment form in addition
to the legacy "// +build" notation, as produced by gofmt to ensure
consistent behavior between Go versions. The new directives are all
equivalent to what was present before, so there's no change in behavior.
Go 1.17 continues to use the Unicode 13 tables as in Go 1.16, so this
upgrade does not require also upgrading our Unicode-related dependencies.
This upgrade includes the following breaking changes which will also
appear as breaking changes for Terraform users, but that are consistent
with the Terraform v1.0 compatibility promises.
- On MacOS, Terraform now requires macOS 10.13 High Sierra or later.
This upgrade also includes the following breaking changes which will
appear as breaking changes for Terraform users that are inconsistent with
our compatibility promises, but have justified exceptions as follows:
- cidrsubnet, cidrhost, and cidrnetmask will now reject IPv4 CIDR
addresses whose decimal components have leading zeros, where previously
they would just silently ignore those leading zeros.
This is a security-motivated exception to our compatibility promises,
because some external systems interpret zero-prefixed octets as octal
numbers rather than decimal, and thus the previous lenient parsing could
lead to a different interpretation of the address between systems, and
thus potentially allow bypassing policy when configuring firewall rules
etc.
This upgrade also includes the following breaking changes which could
_potentially_ appear as breaking changes for Terraform users, but that do
not in practice for the reasons given:
- The Go net/url package no longer allows query strings with pairs
separated by semicolons instead of ampersands. This primarily affects
HTTP servers written in Go, and Terraform includes a special temporary
HTTP server as part of its implementation of OAuth for "terraform login",
but that server only needs to accept URLs created by Terraform itself
and Terraform does not generate any URLs that would be rejected.
Add implementations of CanChainFrom and NestedWithin for
MoveEndpointInModule.
CanChainFrom allows the linking of move statements of the same address,
which means the prior destination address must equal the following
source address. If the destination and source addresses are of different
types, they must be covered by NestedWithin rather than CanChainFrom.
NestedWithin checks if the destination contains the source address. Any
matching types would be covered by CanChainFrom.
Extend the outputs JSON log message to support an `action` field (and
make the `type` and `value` fields optional). This allows us to emit a
useful output change summary as part of the plan, bringing the JSON log
output into parity with the text output.
While we do have access to the before/after values in the output
changes, attempting to wedge those into a structured log message is not
appropriate. That level of detail can be extracted from the JSON plan
output from `terraform show -json`.
