Commit Graph

6 Commits

Author SHA1 Message Date
Martin Atkins 954d38e870 lang: New file-hashing functions
In prior versions, we recommended using hash functions in conjunction with
the file function as an idiom for detecting changes to upstream blobs
without fetching and comparing the whole blob.

That approach relied on us being able to return raw binary data from
file(...). Since Terraform strings pass through intermediate
representations that are not binary-safe (e.g. the JSON state), there was
a risk of string corruption in prior versions which we have avoided for
0.12 by requiring that file(...) be used only with UTF-8 text files.

The specific case of returning a string and immediately passing it into
another function was not actually subject to that corruption risk, since
the HIL interpreter would just pass the string through verbatim, but this
is still now forbidden as a result of the stricter handling of file(...).

To avoid breaking these use-cases, here we introduce variants of the hash
functions a with "file" prefix that take a filename for a disk file to
hash rather than hashing the given string directly. The configuration
upgrade tool also now includes a rule to detect the documented idiom and
rewrite it into a single function call for one of these new functions.

This does cause a bit of function sprawl, but that seems preferable to
introducing more complex rules for when file(...) can and cannot read
binary files, making the behavior of these various functions easier to
understand in isolation.
2019-01-25 10:18:44 -08:00
Martin Atkins ecaaa91da9 lang/funcs: Factor out the various hash function implementations
These all follow the pattern of creating a hash and converting it to a
string using some encoding function, so we can write this implementation
only once and parameterize it with a hash factory function and an encoding
function.

This also includes a new test for the sha512 function, which was
previously missing a test and, it turns out, actually computing sha256
instead.
2019-01-25 10:18:44 -08:00
Kristin Laemmert c4f4dddff5 porting crypto functions 2018-10-16 18:49:20 -07:00
Kristin Laemmert eb1d8b7909 cleanup comments for nicer godocs 2018-10-16 18:49:20 -07:00
Kristin Laemmert 9aa9b18658 porting crypto functions 2018-10-16 18:49:20 -07:00
Martin Atkins 129f5fe74d lang/funcs: port some of Terraform's built-in functions
These implementations are adaptations of the existing implementations in
config/interpolate_funcs.go, updated to work with the cty API.

The set of functions chosen here was motivated mainly by what Terraform's
existing context tests depend on, so we can get the contexts tests back
into good shape before fleshing out the rest of these functions.
2018-10-16 18:48:28 -07:00