tfdiags

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 Go to latest Published: Aug 16, 2022 License: MPL-2.0 Imports: 13 Imported by: 0

Documentation

Overview

Package tfdiags is a utility package for representing errors and warnings in a manner that allows us to produce good messages for the user.

"diag" is short for "diagnostics", and is meant as a general word for feedback to a user about potential or actual problems.

A design goal for this package is for it to be able to provide rich messaging where possible but to also be pragmatic about dealing with generic errors produced by system components that _can't_ provide such rich messaging. As a consequence, the main types in this package -- Diagnostics and Diagnostic -- are designed so that they can be "smuggled" over an error channel and then be unpacked at the other end, so that error diagnostics (at least) can transit through APIs that are not aware of this package.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func DiagnosticCausedBySensitive 

func DiagnosticCausedBySensitive(diag Diagnostic) bool

DiagnosticCausedBySensitive returns true if the given diagnostic has an indication that it was caused by the presence of sensitive values during an expression evaluation.

This is a wrapper around checking if the diagnostic's extra info implements interface DiagnosticExtraBecauseSensitive and then calling its method if so.

func DiagnosticCausedByUnknown 

func DiagnosticCausedByUnknown(diag Diagnostic) bool

DiagnosticCausedByUnknown returns true if the given diagnostic has an indication that it was caused by the presence of unknown values during an expression evaluation.

This is a wrapper around checking if the diagnostic's extra info implements interface DiagnosticExtraBecauseUnknown and then calling its method if so.

func ExtraInfo 

func ExtraInfo[T any](diag Diagnostic) T

ExtraInfo tries to retrieve extra information of interface type T from the given diagnostic.

"Extra information" is situation-specific additional contextual data which might allow for some special tailored reporting of particular diagnostics in the UI. Conventionally the extra information is provided as a hidden type that implements one or more interfaces which a caller can pass as type parameter T to retrieve a value of that type when the diagnostic has such an implementation.

If the given diagnostic's extra value has an implementation of interface T then ExtraInfo returns a non-nil interface value. If there is no such implementation, ExtraInfo returns a nil T.

Although the signature of this function does not constrain T to be an interface type, our convention is to only use interface types to access extra info in order to allow for alternative or wrapping implementations of the interface.

func ExtraInfoNext 

func ExtraInfoNext[T any](previous interface{}) T

ExtraInfoNext takes a value previously returned by ExtraInfo and attempts to find an implementation of interface T wrapped inside of it. The return value meaning is the same as for ExtraInfo.

This is to help with the less common situation where a particular "extra" value might be wrapping another value implementing the same interface, and so callers can peel away one layer at a time until there are no more nested layers.

Because this function is intended for searching for _nested_ implementations of T, ExtraInfoNext does not consider whether value "previous" directly implements interface T, on the assumption that the previous call to ExtraInfo with the same T caused "previous" to already be that result.

func FormatCtyPath 

func FormatCtyPath(path cty.Path) string

FormatCtyPath is a helper function to produce a user-friendly string representation of a cty.Path. The result uses a syntax similar to the HCL expression language in the hope of it being familiar to users.

func FormatError 

func FormatError(err error) string

FormatError is a helper function to produce a user-friendly string representation of certain special error types that we might want to include in diagnostic messages.

This currently has special behavior only for cty.PathError, where a non-empty path is rendered in a HCL-like syntax as context.

func FormatErrorPrefixed 

func FormatErrorPrefixed(err error, prefix string) string

FormatErrorPrefixed is like FormatError except that it presents any path information after the given prefix string, which is assumed to contain an HCL syntax representation of the value that errors are relative to.

func GetAttribute 

func GetAttribute(d Diagnostic) cty.Path

GetAttribute extracts an attribute cty.Path from a diagnostic if it contains one. Normally this is not accessed directly, and instead the config body is added to the Diagnostic to create a more complete message for the user. In some cases however, we may want to know just the name of the attribute that generated the Diagnostic message. This returns a nil cty.Path if it does not exist in the Diagnostic.

Types

type Description 

type Description struct {
	Address string
	Summary string
	Detail  string
}

type Diagnostic 

type Diagnostic interface {
	Severity() Severity
	Description() Description
	Source() Source

	// FromExpr returns the expression-related context for the diagnostic, if
	// available. Returns nil if the diagnostic is not related to an
	// expression evaluation.
	FromExpr() *FromExpr

	// ExtraInfo returns the raw extra information value. This is a low-level
	// API which requires some work on the part of the caller to properly
	// access associated information, so in most cases it'll be more convienient
	// to use the package-level ExtraInfo function to try to unpack a particular
	// specialized interface from this value.
	ExtraInfo() interface{}
}

func AttributeValue 

func AttributeValue(severity Severity, summary, detail string, attrPath cty.Path) Diagnostic

AttributeValue returns a diagnostic about an attribute value in an implied current configuration context. This should be returned only from functions whose interface specifies a clear configuration context that this will be resolved in.

The given path is relative to the implied configuration context. To describe a top-level attribute, it should be a single-element cty.Path with a cty.GetAttrStep. It's assumed that the path is returning into a structure that would be produced by our conventions in the configschema package; it may return unexpected results for structures that can't be represented by configschema.

Since mapping attribute paths back onto configuration is an imprecise operation (e.g. dynamic block generation may cause the same block to be evaluated multiple times) the diagnostic detail should include the attribute name and other context required to help the user understand what is being referenced in case the identified source range is not unique.

The returned attribute will not have source location information until context is applied to the containing diagnostics using diags.InConfigBody. After context is applied, the source location is the value assigned to the named attribute, or the containing body's "missing item range" if no value is present.

func SimpleWarning 

func SimpleWarning(msg string) Diagnostic

SimpleWarning constructs a simple (summary-only) warning diagnostic.

func Sourceless 

func Sourceless(severity Severity, summary, detail string) Diagnostic

Sourceless creates and returns a diagnostic with no source location information. This is generally used for operational-type errors that are caused by or relate to the environment where Durgaform is running rather than to the provided configuration.

func WholeContainingBody 

func WholeContainingBody(severity Severity, summary, detail string) Diagnostic

WholeContainingBody returns a diagnostic about the body that is an implied current configuration context. This should be returned only from functions whose interface specifies a clear configuration context that this will be resolved in.

The returned attribute will not have source location information until context is applied to the containing diagnostics using diags.InConfigBody. After context is applied, the source location is currently the missing item range of the body. In future, this may change to some other suitable part of the containing body.

type DiagnosticExtraBecauseSensitive 

type DiagnosticExtraBecauseSensitive interface {
	// DiagnosticCausedBySensitive returns true if the associated diagnostic
	// was caused by the presence of sensitive values during an expression
	// evaluation, or false otherwise.
	//
	// Callers might use this to tailor what contextual information they show
	// alongside an error report in the UI, to avoid potential confusion
	// caused by talking about the presence of sensitive values if that was
	// immaterial to the error.
	DiagnosticCausedBySensitive() bool
}

DiagnosticExtraBecauseSensitive is an interface implemented by values in the Extra field of Diagnostic when the diagnostic is potentially caused by the presence of sensitive values in an expression evaluation.

Just implementing this interface is not sufficient signal, though. Callers must also call the DiagnosticCausedBySensitive method in order to confirm the result, or use the package-level function DiagnosticCausedBySensitive as a convenient wrapper.

type DiagnosticExtraBecauseUnknown 

type DiagnosticExtraBecauseUnknown interface {
	// DiagnosticCausedByUnknown returns true if the associated diagnostic
	// was caused by the presence of unknown values during an expression
	// evaluation, or false otherwise.
	//
	// Callers might use this to tailor what contextual information they show
	// alongside an error report in the UI, to avoid potential confusion
	// caused by talking about the presence of unknown values if that was
	// immaterial to the error.
	DiagnosticCausedByUnknown() bool
}

DiagnosticExtraBecauseUnknown is an interface implemented by values in the Extra field of Diagnostic when the diagnostic is potentially caused by the presence of unknown values in an expression evaluation.

Just implementing this interface is not sufficient signal, though. Callers must also call the DiagnosticCausedByUnknown method in order to confirm the result, or use the package-level function DiagnosticCausedByUnknown as a convenient wrapper.

type DiagnosticExtraUnwrapper 

type DiagnosticExtraUnwrapper interface {
	// If the reciever is wrapping another "diagnostic extra" value, returns
	// that value. Otherwise returns nil to indicate dynamically that nothing
	// is wrapped.
	//
	// The "nothing is wrapped" condition can be signalled either by this
	// method returning nil or by a type not implementing this interface at all.
	//
	// Implementers should never create unwrap "cycles" where a nested extra
	// value returns a value that was also wrapping it.
	UnwrapDiagnosticExtra() interface{}
}

DiagnosticExtraUnwrapper is an interface implemented by values in the Extra field of Diagnostic when they are wrapping another "Extra" value that was generated downstream.

Diagnostic recipients which want to examine "Extra" values to sniff for particular types of extra data can either type-assert this interface directly and repeatedly unwrap until they recieve nil, or can use the helper function DiagnosticExtra.

This interface intentionally matches hcl.DiagnosticExtraUnwrapper, so that wrapping extra values implemented using HCL's API will also work with the tfdiags API, but that non-HCL uses of this will not need to implement HCL just to get this interface.

type Diagnostics 

type Diagnostics []Diagnostic

Diagnostics is a list of diagnostics. Diagnostics is intended to be used where a Go "error" might normally be used, allowing richer information to be conveyed (more context, support for warnings).

A nil Diagnostics is a valid, empty diagnostics list, thus allowing heap allocation to be avoided in the common case where there are no diagnostics to report at all.

func (Diagnostics) Append 

func (diags Diagnostics) Append(new ...interface{}) Diagnostics

Append is the main interface for constructing Diagnostics lists, taking an existing list (which may be nil) and appending the new objects to it after normalizing them to be implementations of Diagnostic.

The usual pattern for a function that natively "speaks" diagnostics is: 

// Create a nil Diagnostics at the start of the function
var diags diag.Diagnostics

// At later points, build on it if errors / warnings occur:
foo, err := DoSomethingRisky()
if err != nil {
    diags = diags.Append(err)
}

// Eventually return the result and diagnostics in place of error
return result, diags

Append accepts a variety of different diagnostic-like types, including native Go errors and HCL diagnostics. It also knows how to unwrap a multierror.Error into separate error diagnostics. It can be passed another Diagnostics to concatenate the two lists. If given something it cannot handle, this function will panic.

func (Diagnostics) ConsolidateWarnings 

func (diags Diagnostics) ConsolidateWarnings(threshold int) Diagnostics

ConsolidateWarnings checks if there is an unreasonable amount of warnings with the same summary in the receiver and, if so, returns a new diagnostics with some of those warnings consolidated into a single warning in order to reduce the verbosity of the output.

This mechanism is here primarily for diagnostics printed out at the CLI. In other contexts it is likely better to just return the warnings directly, particularly if they are going to be interpreted by software rather than by a human reader.

The returned slice always has a separate backing array from the reciever, but some diagnostic values themselves might be shared.

The definition of "unreasonable" is given as the threshold argument. At most that many warnings with the same summary will be shown.

func (Diagnostics) Err 

func (diags Diagnostics) Err() error

Err flattens a diagnostics list into a single Go error, or to nil if the diagnostics list does not include any error-level diagnostics.

This can be used to smuggle diagnostics through an API that deals in native errors, but unfortunately it will lose naked warnings (warnings that aren't accompanied by at least one error) since such APIs have no mechanism through which to report these. 

return result, diags.Error()

func (Diagnostics) ErrWithWarnings 

func (diags Diagnostics) ErrWithWarnings() error

ErrWithWarnings is similar to Err except that it will also return a non-nil error if the receiver contains only warnings.

In the warnings-only situation, the result is guaranteed to be of dynamic type NonFatalError, allowing diagnostics-aware callers to type-assert and unwrap it, treating it as non-fatal.

This should be used only in contexts where the caller is able to recognize and handle NonFatalError. For normal callers that expect a lack of errors to be signaled by nil, use just Diagnostics.Err.

func (Diagnostics) ForRPC 

func (diags Diagnostics) ForRPC() Diagnostics

ForRPC returns a version of the receiver that has been simplified so that it is friendly to RPC protocols.

Currently this means that it can be serialized with encoding/gob and subsequently re-inflated. It may later grow to include other serialization formats.

Note that this loses information about the original objects used to construct the diagnostics, so e.g. the errwrap API will not work as expected on an error-wrapped Diagnostics that came from ForRPC.

func (Diagnostics) HasErrors 

func (diags Diagnostics) HasErrors() bool

HasErrors returns true if any of the diagnostics in the list have a severity of Error.

func (Diagnostics) InConfigBody 

func (diags Diagnostics) InConfigBody(body hcl.Body, addr string) Diagnostics

InConfigBody returns a copy of the receiver with any config-contextual diagnostics elaborated in the context of the given body. An optional address argument may be added to indicate which instance of the configuration the error related to.

func (Diagnostics) NonFatalErr 

func (diags Diagnostics) NonFatalErr() error

NonFatalErr is similar to Err except that it always returns either nil (if there are no diagnostics at all) or NonFatalError.

This allows diagnostics to be returned over an error return channel while being explicit that the diagnostics should not halt processing.

This should be used only in contexts where the caller is able to recognize and handle NonFatalError. For normal callers that expect a lack of errors to be signaled by nil, use just Diagnostics.Err.

func (Diagnostics) Sort 

func (diags Diagnostics) Sort()

Sort applies an ordering to the diagnostics in the receiver in-place.

The ordering is: warnings before errors, sourceless before sourced, short source paths before long source paths, and then ordering by position within each file.

Diagnostics that do not differ by any of these sortable characteristics will remain in the same relative order after this method returns.

func (Diagnostics) ToHCL 

func (diags Diagnostics) ToHCL() hcl.Diagnostics

ToHCL constructs a hcl.Diagnostics containing the same diagnostic messages as the receiving tfdiags.Diagnostics.

This conversion preserves the data that HCL diagnostics are able to preserve but would be lossy in a round trip from tfdiags to HCL and then back to tfdiags, because it will lose the specific type information of the source diagnostics. In most cases this will not be a significant problem, but could produce an awkward result in some special cases such as converting the result of ConsolidateWarnings, which will force the resulting warning groups to be flattened early.

type FromExpr 

type FromExpr struct {
	Expression  hcl.Expression
	EvalContext *hcl.EvalContext
}

type NonFatalError 

type NonFatalError struct {
	Diagnostics
}

NonFatalError is a special error type, returned by Diagnostics.ErrWithWarnings and Diagnostics.NonFatalErr, that indicates that the wrapped diagnostics should be treated as non-fatal. Callers can conditionally type-assert an error to this type in order to detect the non-fatal scenario and handle it in a different way.

func (NonFatalError) Error 

func (woe NonFatalError) Error() string

type Severity 

type Severity rune
const (
	Error   Severity = 'E'
	Warning Severity = 'W'
)

func (Severity) String 

func (i Severity) String() string

func (Severity) ToHCL 

func (s Severity) ToHCL() hcl.DiagnosticSeverity

ToHCL converts a Severity to the equivalent HCL diagnostic severity.

type Source 

type Source struct {
	Subject *SourceRange
	Context *SourceRange
}

func WarningGroupSourceRanges 

func WarningGroupSourceRanges(diag Diagnostic) []Source

WarningGroupSourceRanges can be used in conjunction with Diagnostics.ConsolidateWarnings to recover the full set of original source locations from a consolidated warning.

For convenience, this function accepts any diagnostic and will just return the single Source value from any diagnostic that isn't a warning group.

type SourcePos 

type SourcePos struct {
	Line, Column, Byte int
}

type SourceRange 

type SourceRange struct {
	Filename   string
	Start, End SourcePos
}

func SourceRangeFromHCL 

func SourceRangeFromHCL(hclRange hcl.Range) SourceRange

SourceRangeFromHCL constructs a SourceRange from the corresponding range type within the HCL package.

func (SourceRange) StartString 

func (r SourceRange) StartString() string

StartString returns a string representation of the start of the range, including the filename and the line and column numbers.

func (SourceRange) ToHCL 

func (r SourceRange) ToHCL() hcl.Range

ToHCL constructs a HCL Range from the receiving SourceRange. This is the opposite of SourceRangeFromHCL.

Source Files

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