mirror of https://github.com/k3s-io/k3s
Alex Robinson
commit
ce95c4920d
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# Variable expansion in pod command, args, and env
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## Abstract
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A proposal for the expansion of environment variables using a simple `$(var)` syntax.
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## Motivation
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It is extremely common for users to need to compose environment variables or pass arguments to
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their commands using the values of environment variables. Kubernetes should provide a facility for
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the 80% cases in order to decrease coupling and the use of workarounds.
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## Goals
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1. Define the syntax format
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2. Define the scoping and ordering of substitutions
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3. Define the behavior for unmatched variables
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4. Define the behavior for unexpected/malformed input
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## Constraints and Assumptions
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* This design should describe the simplest possible syntax to accomplish the use-cases
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* Expansion syntax will not support more complicated shell-like behaviors such as default values
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(viz: `$(VARIABLE_NAME:"default")`), inline substitution, etc.
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## Use Cases
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1. As a user, I want to compose new environment variables for a container using a substitution
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syntax to reference other variables in the container's environment and service environment
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variables
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1. As a user, I want to substitute environment variables into a container's command
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1. As a user, I want to do the above without requiring the container's image to have a shell
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1. As a user, I want to be able to specify a default value for a service variable which may
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not exist
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1. As a user, I want to see an event associated with the pod if an expansion fails (ie, references
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variable names that cannot be expanded)
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### Use Case: Composition of environment variables
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Currently, containers are injected with docker-style environment variables for the services in
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their pod's namespace. There are several variables for each service, but users routinely need
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to compose URLs based on these variables because there is not a variable for the exact format
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they need. Users should be able to build new environment variables with the exact format they need.
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Eventually, it should also be possible to turn off the automatic injection of the docker-style
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variables into pods and let the users consume the exact information they need via the downward API
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and composition.
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#### Expanding expanded variables
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It should be possible to reference an variable which is itself the result of an expansion, if the
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referenced variable is declared in the container's environment prior to the one referencing it.
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Put another way -- a container's environment is expanded in order, and expanded variables are
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available to subsequent expansions.
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### Use Case: Variable expansion in command
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Users frequently need to pass the values of environment variables to a container's command.
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Currently, Kubernetes does not perform any expansion of varibles. The workaround is to invoke a
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shell in the container's command and have the shell perform the substitution, or to write a wrapper
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script that sets up the environment and runs the command. This has a number of drawbacks:
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1. Solutions that require a shell are unfriendly to images that do not contain a shell
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2. Wrapper scripts make it harder to use images as base images
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3. Wrapper scripts increase coupling to kubernetes
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Users should be able to do the 80% case of variable expansion in command without writing a wrapper
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script or adding a shell invocation to their containers' commands.
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### Use Case: Images without shells
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The current workaround for variable expansion in a container's command requires the container's
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image to have a shell. This is unfriendly to images that do not contain a shell (`scratch` images,
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for example). Users should be able to perform the other use-cases in this design without regard to
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the content of their images.
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### Use Case: See an event for incomplete expansions
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It is possible that a container with incorrect variable values or command line may continue to run
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for a long period of time, and that the end-user would have no visual or obvious warning of the
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incorrect configuration. If the kubelet creates an event when an expansion references a variable
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that cannot be expanded, it will help users quickly detect problems with expansions.
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## Design Considerations
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### What features should be supported?
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In order to limit complexity, we want to provide the right amount of functionality so that the 80%
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cases can be realized and nothing more. We felt that the essentials boiled down to:
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1. Ability to perform direct expansion of variables in a string
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2. Ability to specify default values via a prioritized mapping function but without support for
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defaults as a syntax-level feature
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### What should the syntax be?
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The exact syntax for variable expansion has a large impact on how users perceive and relate to the
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feature. We considered implementing a very restrictive subset of the shell `${var}` syntax. This
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syntax is an attractive option on some level, because many people are familiar with it. However,
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this syntax also has a large number of lesser known features such as the ability to provide
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default values for unset variables, perform inline substitution, etc.
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In the interest of preventing conflation of the expansion feature in Kubernetes with the shell
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feature, we chose a different syntax similar to the one in Makefiles, `$(var)`. We also chose not
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to support the bar `$var` format, since it is not required to implement the required use-cases.
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Nested references, ie, variable expansion within variable names, are not supported.
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#### How should unmatched references be treated?
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Ideally, it should be extremely clear when a variable reference couldn't be expanded. We decided
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the best experience for unmatched variable references would be to have the entire reference, syntax
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included, show up in the output. As an example, if the reference `$(VARIABLE_NAME)` cannot be
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expanded, then `$(VARIABLE_NAME)` should be present in the output.
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#### Escaping the operator
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Although the `$(var)` syntax does overlap with the `$(command)` form of command substitution
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supported by many shells, because unexpanded variables are present verbatim in the output, we
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expect this will not present a problem to many users. If there is a collision between a varible
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name and command substitution syntax, the syntax can be escaped with the form `$$(VARIABLE_NAME)`,
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which will evaluate to `$(VARIABLE_NAME)` whether `VARIABLE_NAME` can be expanded or not.
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## Design
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This design encompasses the variable expansion syntax and specification and the changes needed to
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incorporate the expansion feature into the container's environment and command.
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### Syntax and expansion mechanics
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This section describes the expansion syntax, evaluation of variable values, and how unexpected or
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malformed inputs are handled.
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#### Syntax
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The inputs to the expansion feature are:
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1. A utf-8 string (the input string) which may contain variable references
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2. A function (the mapping function) that maps the name of a variable to the variable's value, of
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type `func(string) string`
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Variable references in the input string are indicated exclusively with the syntax
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`$(<variable-name>)`. The syntax tokens are:
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- `$`: the operator
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- `(`: the reference opener
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- `)`: the reference closer
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The operator has no meaning unless accompanied by the reference opener and closer tokens. The
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operator can be escaped using `$$`. One literal `$` will be emitted for each `$$` in the input.
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The reference opener and closer characters have no meaning when not part of a variable reference.
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If a variable reference is malformed, viz: `$(VARIABLE_NAME` without a closing expression, the
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operator and expression opening characters are treated as ordinary characters without special
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meanings.
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#### Scope and ordering of substitutions
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The scope in which variable references are expanded is defined by the mapping function. Within the
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mapping function, any arbitrary strategy may be used to determine the value of a variable name.
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The most basic implementation of a mapping function is to use a `map[string]string` to lookup the
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value of a variable.
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In order to support default values for variables like service variables presented by the kubelet,
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which may not be bound because the service that provides them does not yet exist, there should be a
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mapping function that uses a list of `map[string]string` like:
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```go
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func MakeMappingFunc(maps ...map[string]string) func(string) string {
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return func(input string) string {
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for _, context := range maps {
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val, ok := context[input]
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if ok {
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return val
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}
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}
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return ""
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}
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}
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// elsewhere
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containerEnv := map[string]string{
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"FOO": "BAR",
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"ZOO": "ZAB",
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"SERVICE2_HOST": "some-host",
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}
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serviceEnv := map[string]string{
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"SERVICE_HOST": "another-host",
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"SERVICE_PORT": "8083",
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}
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// single-map variation
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mapping := MakeMappingFunc(containerEnv)
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// default variables not found in serviceEnv
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mappingWithDefaults := MakeMappingFunc(serviceEnv, containerEnv)
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```
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### Implementation changes
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The necessary changes to implement this functionality are:
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1. Add a new interface, `ObjectEventRecorder`, which is like the `EventRecorder` interface, but
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scoped to a single object, and a function that returns an `ObjectEventRecorder` given an
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`ObjectReference` and an `EventRecorder`
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2. Introduce `third_party/golang/expansion` package that provides:
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1. An `Expand(string, func(string) string) string` function
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2. A `MappingFuncFor(ObjectEventRecorder, ...map[string]string) string` function
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3. Add a new EnvVarSource for expansions and associated tests
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4. Make the kubelet expand environment correctly
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5. Make the kubelet expand command correctly
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#### Event Recording
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In order to provide an event when an expansion references undefined variables, the mapping function
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must be able to create an event. In order to facilitate this, we should create a new interface in
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the `api/client/record` package which is similar to `EventRecorder`, but scoped to a single object:
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```go
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// ObjectEventRecorder knows how to record events about a single object.
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type ObjectEventRecorder interface {
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// Event constructs an event from the given information and puts it in the queue for sending.
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// 'reason' is the reason this event is generated. 'reason' should be short and unique; it will
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// be used to automate handling of events, so imagine people writing switch statements to
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// handle them. You want to make that easy.
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// 'message' is intended to be human readable.
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//
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// The resulting event will be created in the same namespace as the reference object.
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Event(reason, message string)
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// Eventf is just like Event, but with Sprintf for the message field.
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Eventf(reason, messageFmt string, args ...interface{})
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// PastEventf is just like Eventf, but with an option to specify the event's 'timestamp' field.
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PastEventf(timestamp util.Time, reason, messageFmt string, args ...interface{})
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}
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```
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There should also be a function that can construct an `ObjectEventRecorder` from a `runtime.Object`
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and an `EventRecorder`:
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```go
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type objectRecorderImpl struct {
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object runtime.Object
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recorder EventRecorder
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}
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func (r *objectRecorderImpl) Event(reason, message string) {
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r.recorder.Event(r.object, reason, message)
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}
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func ObjectEventRecorderFor(object runtime.Object, recorder EventRecorder) ObjectEventRecorder {
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return &objectRecorderImpl{object, recorder}
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}
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```
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#### Expansion package
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The expansion package should provide two methods:
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```go
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// MappingFuncFor returns a mapping function for use with Expand that
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// implements the expansion semantics defined in the expansion spec; it
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// returns the input string wrapped in the expansion syntax if no mapping
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// for the input is found. If no expansion is found for a key, an event
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// is raised on the given recorder.
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func MappingFuncFor(recorder record.ObjectEventRecorder, context ...map[string]string) func(string) string {
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// ...
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}
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// Expand replaces variable references in the input string according to
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// the expansion spec using the given mapping function to resolve the
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// values of variables.
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func Expand(input string, mapping func(string) string) string {
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// ...
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}
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```
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#### Expansion `EnvVarSource`
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In order to avoid changing the existing behavior of the `EnvVar.Value` field, there should be a new
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`EnvVarSource` that represents a variable expansion that an env var's value should come from:
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```go
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// EnvVarSource represents a source for the value of an EnvVar.
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type EnvVarSource struct {
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// Other fields omitted
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Expansion *EnvVarExpansion
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}
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type EnvVarExpansion struct {
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// The input string to be expanded
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Expand string
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}
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```
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#### Kubelet changes
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The Kubelet should change to:
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1. Correctly expand environment variables with `Expansion` sources
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2. Correctly expand references in the Command and Args
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### Examples
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#### Inputs and outputs
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These examples are in the context of the mapping:
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| Name | Value |
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|-------------|------------|
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| `VAR_A` | `"A"` |
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| `VAR_B` | `"B"` |
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| `VAR_C` | `"C"` |
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| `VAR_REF` | `$(VAR_A)` |
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| `VAR_EMPTY` | `""` |
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No other variables are defined.
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| Input | Result |
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|--------------------------------|----------------------------|
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| `"$(VAR_A)"` | `"A"` |
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| `"___$(VAR_B)___"` | `"___B___"` |
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| `"___$(VAR_C)"` | `"___C"` |
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| `"$(VAR_A)-$(VAR_A)"` | `"A-A"` |
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| `"$(VAR_A)-1"` | `"A-1"` |
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| `"$(VAR_A)_$(VAR_B)_$(VAR_C)"` | `"A_B_C"` |
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| `"$$(VAR_B)_$(VAR_A)"` | `"$(VAR_B)_A"` |
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| `"$$(VAR_A)_$$(VAR_B)"` | `"$(VAR_A)_$(VAR_B)"` |
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| `"f000-$$VAR_A"` | `"f000-$VAR_A"` |
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| `"foo\\$(VAR_C)bar"` | `"foo\Cbar"` |
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| `"foo\\\\$(VAR_C)bar"` | `"foo\\Cbar"` |
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| `"foo\\\\\\\\$(VAR_A)bar"` | `"foo\\\\Abar"` |
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| `"$(VAR_A$(VAR_B))"` | `"$(VAR_A$(VAR_B))"` |
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| `"$(VAR_A$(VAR_B)"` | `"$(VAR_A$(VAR_B)"` |
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| `"$(VAR_REF)"` | `"$(VAR_A)"` |
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| `"%%$(VAR_REF)--$(VAR_REF)%%"` | `"%%$(VAR_A)--$(VAR_A)%%"` |
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| `"foo$(VAR_EMPTY)bar"` | `"foobar"` |
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| `"foo$(VAR_Awhoops!"` | `"foo$(VAR_Awhoops!"` |
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| `"f00__(VAR_A)__"` | `"f00__(VAR_A)__"` |
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| `"$?_boo_$!"` | `"$?_boo_$!"` |
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| `"$VAR_A"` | `"$VAR_A"` |
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| `"$(VAR_DNE)"` | `"$(VAR_DNE)"` |
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| `"$$$$$$(BIG_MONEY)"` | `"$$$(BIG_MONEY)"` |
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| `"$$$$$$(VAR_A)"` | `"$$$(VAR_A)"` |
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| `"$$$$$$$(GOOD_ODDS)"` | `"$$$$(GOOD_ODDS)"` |
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| `"$$$$$$$(VAR_A)"` | `"$$$A"` |
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| `"$VAR_A)"` | `"$VAR_A)"` |
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| `"${VAR_A}"` | `"${VAR_A}"` |
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| `"$(VAR_B)_______$(A"` | `"B_______$(A"` |
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| `"$(VAR_C)_______$("` | `"C_______$("` |
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| `"$(VAR_A)foobarzab$"` | `"Afoobarzab$"` |
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| `"foo-\\$(VAR_A"` | `"foo-\$(VAR_A"` |
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| `"--$($($($($--"` | `"--$($($($($--"` |
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| `"$($($($($--foo$("` | `"$($($($($--foo$("` |
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| `"foo0--$($($($("` | `"foo0--$($($($("` |
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| `"$(foo$$var)` | `$(foo$$var)` |
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#### In a pod: building a URL
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Notice the `$(var)` syntax.
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```yaml
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apiVersion: v1beta3
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kind: Pod
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metadata:
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name: expansion-pod
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spec:
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containers:
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- name: test-container
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image: gcr.io/google_containers/busybox
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command: [ "/bin/sh", "-c", "env" ]
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env:
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- name: PUBLIC_URL
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valueFrom:
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expansion:
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expand: "http://$(GITSERVER_SERVICE_HOST):$(GITSERVER_SERVICE_PORT)"
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restartPolicy: Never
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```
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#### In a pod: building a URL using downward API
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```yaml
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apiVersion: v1beta3
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kind: Pod
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metadata:
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name: expansion-pod
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spec:
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containers:
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- name: test-container
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image: gcr.io/google_containers/busybox
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command: [ "/bin/sh", "-c", "env" ]
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env:
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- name: POD_NAMESPACE
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valueFrom:
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fieldRef:
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fieldPath: "metadata.namespace"
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- name: PUBLIC_URL
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valueFrom:
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expansion:
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expand: "http://gitserver.$(POD_NAMESPACE):$(SERVICE_PORT)"
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restartPolicy: Never
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```
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[]()
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@ -0,0 +1,98 @@
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package expansion
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const (
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operator = '$'
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referenceOpener = '('
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referenceCloser = ')'
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)
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// syntaxWrap returns the input string wrapped the expansion syntax.
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func syntaxWrap(input string) string {
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return string(operator) + string(referenceOpener) + input + string(referenceCloser)
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}
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// MappingFuncFor returns a mapping function for use with Expand that
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// implements the expansion semantics defined in the expansion spec; it
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// returns the input string wrapped in the expansion syntax if no mapping
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// for the input is found.
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func MappingFuncFor(context ...map[string]string) func(string) string {
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return func(input string) string {
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for _, vars := range context {
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val, ok := vars[input]
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if ok {
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return val
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}
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}
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return syntaxWrap(input)
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}
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}
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// Expand replaces variable references in the input string according to
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// the expansion spec using the given mapping function to resolve the
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// values of variables.
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func Expand(input string, mapping func(string) string) string {
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buf := make([]byte, 0, 2*len(input))
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checkpoint := 0
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for cursor := 0; cursor < len(input); cursor++ {
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if input[cursor] == operator && cursor+1 < len(input) {
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// Copy the portion of the input string since the last
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// checkpoint into the buffer
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buf = append(buf, input[checkpoint:cursor]...)
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// Attempt to read the variable name as defined by the
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// syntax from the input string
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read, isVar, advance := tryReadVariableName(input[cursor+1:])
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if isVar {
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// We were able to read a variable name correctly;
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||||
// apply the mapping to the variable name and copy the
|
||||
// bytes into the buffer
|
||||
buf = append(buf, mapping(read)...)
|
||||
} else {
|
||||
// Not a variable name; copy the read bytes into the buffer
|
||||
buf = append(buf, read...)
|
||||
}
|
||||
|
||||
// Advance the cursor in the input string to account for
|
||||
// bytes consumed to read the variable name expression
|
||||
cursor += advance
|
||||
|
||||
// Advance the checkpoint in the input string
|
||||
checkpoint = cursor + 1
|
||||
}
|
||||
}
|
||||
|
||||
// Return the buffer and any remaining unwritten bytes in the
|
||||
// input string.
|
||||
return string(buf) + input[checkpoint:]
|
||||
}
|
||||
|
||||
// tryReadVariableName attempts to read a variable name from the input
|
||||
// string and returns the content read from the input, whether that content
|
||||
// represents a variable name to perform mapping on, and the number of bytes
|
||||
// consumed in the input string.
|
||||
//
|
||||
// The input string is assumed not to contain the initial operator.
|
||||
func tryReadVariableName(input string) (string, bool, int) {
|
||||
switch input[0] {
|
||||
case operator:
|
||||
// Escaped operator; return it.
|
||||
return input[0:1], false, 1
|
||||
case referenceOpener:
|
||||
// Scan to expression closer
|
||||
for i := 1; i < len(input); i++ {
|
||||
if input[i] == referenceCloser {
|
||||
return input[1:i], true, i + 1
|
||||
}
|
||||
}
|
||||
|
||||
// Incomplete reference; return it.
|
||||
return string(operator) + string(referenceOpener), false, 1
|
||||
default:
|
||||
// Not the beginning of an expression, ie, an operator
|
||||
// that doesn't begin an expression. Return the operator
|
||||
// and the first rune in the string.
|
||||
return (string(operator) + string(input[0])), false, 1
|
||||
}
|
||||
}
|
||||
|
|
@ -0,0 +1,285 @@
|
|||
package expansion
|
||||
|
||||
import (
|
||||
"testing"
|
||||
|
||||
"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
|
||||
)
|
||||
|
||||
func TestMapReference(t *testing.T) {
|
||||
envs := []api.EnvVar{
|
||||
{
|
||||
Name: "FOO",
|
||||
Value: "bar",
|
||||
},
|
||||
{
|
||||
Name: "ZOO",
|
||||
Value: "$(FOO)-1",
|
||||
},
|
||||
{
|
||||
Name: "BLU",
|
||||
Value: "$(ZOO)-2",
|
||||
},
|
||||
}
|
||||
|
||||
declaredEnv := map[string]string{
|
||||
"FOO": "bar",
|
||||
"ZOO": "$(FOO)-1",
|
||||
"BLU": "$(ZOO)-2",
|
||||
}
|
||||
|
||||
serviceEnv := map[string]string{}
|
||||
|
||||
mapping := MappingFuncFor(declaredEnv, serviceEnv)
|
||||
|
||||
for _, env := range envs {
|
||||
declaredEnv[env.Name] = Expand(env.Value, mapping)
|
||||
}
|
||||
|
||||
expectedEnv := map[string]string{
|
||||
"FOO": "bar",
|
||||
"ZOO": "bar-1",
|
||||
"BLU": "bar-1-2",
|
||||
}
|
||||
|
||||
for k, v := range expectedEnv {
|
||||
if e, a := v, declaredEnv[k]; e != a {
|
||||
t.Errorf("Expected %v, got %v", e, a)
|
||||
} else {
|
||||
delete(declaredEnv, k)
|
||||
}
|
||||
}
|
||||
|
||||
if len(declaredEnv) != 0 {
|
||||
t.Errorf("Unexpected keys in declared env: %v", declaredEnv)
|
||||
}
|
||||
}
|
||||
|
||||
func TestMapping(t *testing.T) {
|
||||
context := map[string]string{
|
||||
"VAR_A": "A",
|
||||
"VAR_B": "B",
|
||||
"VAR_C": "C",
|
||||
"VAR_REF": "$(VAR_A)",
|
||||
"VAR_EMPTY": "",
|
||||
}
|
||||
mapping := MappingFuncFor(context)
|
||||
|
||||
doExpansionTest(t, mapping)
|
||||
}
|
||||
|
||||
func TestMappingDual(t *testing.T) {
|
||||
context := map[string]string{
|
||||
"VAR_A": "A",
|
||||
"VAR_EMPTY": "",
|
||||
}
|
||||
context2 := map[string]string{
|
||||
"VAR_B": "B",
|
||||
"VAR_C": "C",
|
||||
"VAR_REF": "$(VAR_A)",
|
||||
}
|
||||
mapping := MappingFuncFor(context, context2)
|
||||
|
||||
doExpansionTest(t, mapping)
|
||||
}
|
||||
|
||||
func doExpansionTest(t *testing.T, mapping func(string) string) {
|
||||
cases := []struct {
|
||||
name string
|
||||
input string
|
||||
expected string
|
||||
}{
|
||||
{
|
||||
name: "whole string",
|
||||
input: "$(VAR_A)",
|
||||
expected: "A",
|
||||
},
|
||||
{
|
||||
name: "repeat",
|
||||
input: "$(VAR_A)-$(VAR_A)",
|
||||
expected: "A-A",
|
||||
},
|
||||
{
|
||||
name: "beginning",
|
||||
input: "$(VAR_A)-1",
|
||||
expected: "A-1",
|
||||
},
|
||||
{
|
||||
name: "middle",
|
||||
input: "___$(VAR_B)___",
|
||||
expected: "___B___",
|
||||
},
|
||||
{
|
||||
name: "end",
|
||||
input: "___$(VAR_C)",
|
||||
expected: "___C",
|
||||
},
|
||||
{
|
||||
name: "compound",
|
||||
input: "$(VAR_A)_$(VAR_B)_$(VAR_C)",
|
||||
expected: "A_B_C",
|
||||
},
|
||||
{
|
||||
name: "escape & expand",
|
||||
input: "$$(VAR_B)_$(VAR_A)",
|
||||
expected: "$(VAR_B)_A",
|
||||
},
|
||||
{
|
||||
name: "compound escape",
|
||||
input: "$$(VAR_A)_$$(VAR_B)",
|
||||
expected: "$(VAR_A)_$(VAR_B)",
|
||||
},
|
||||
{
|
||||
name: "mixed in escapes",
|
||||
input: "f000-$$VAR_A",
|
||||
expected: "f000-$VAR_A",
|
||||
},
|
||||
{
|
||||
name: "backslash escape ignored",
|
||||
input: "foo\\$(VAR_C)bar",
|
||||
expected: "foo\\Cbar",
|
||||
},
|
||||
{
|
||||
name: "backslash escape ignored",
|
||||
input: "foo\\\\$(VAR_C)bar",
|
||||
expected: "foo\\\\Cbar",
|
||||
},
|
||||
{
|
||||
name: "lots of backslashes",
|
||||
input: "foo\\\\\\\\$(VAR_A)bar",
|
||||
expected: "foo\\\\\\\\Abar",
|
||||
},
|
||||
{
|
||||
name: "nested var references",
|
||||
input: "$(VAR_A$(VAR_B))",
|
||||
expected: "$(VAR_A$(VAR_B))",
|
||||
},
|
||||
{
|
||||
name: "nested var references second type",
|
||||
input: "$(VAR_A$(VAR_B)",
|
||||
expected: "$(VAR_A$(VAR_B)",
|
||||
},
|
||||
{
|
||||
name: "value is a reference",
|
||||
input: "$(VAR_REF)",
|
||||
expected: "$(VAR_A)",
|
||||
},
|
||||
{
|
||||
name: "value is a reference x 2",
|
||||
input: "%%$(VAR_REF)--$(VAR_REF)%%",
|
||||
expected: "%%$(VAR_A)--$(VAR_A)%%",
|
||||
},
|
||||
{
|
||||
name: "empty var",
|
||||
input: "foo$(VAR_EMPTY)bar",
|
||||
expected: "foobar",
|
||||
},
|
||||
{
|
||||
name: "unterminated expression",
|
||||
input: "foo$(VAR_Awhoops!",
|
||||
expected: "foo$(VAR_Awhoops!",
|
||||
},
|
||||
{
|
||||
name: "expression without operator",
|
||||
input: "f00__(VAR_A)__",
|
||||
expected: "f00__(VAR_A)__",
|
||||
},
|
||||
{
|
||||
name: "shell special vars pass through",
|
||||
input: "$?_boo_$!",
|
||||
expected: "$?_boo_$!",
|
||||
},
|
||||
{
|
||||
name: "bare operators are ignored",
|
||||
input: "$VAR_A",
|
||||
expected: "$VAR_A",
|
||||
},
|
||||
{
|
||||
name: "undefined vars are passed through",
|
||||
input: "$(VAR_DNE)",
|
||||
expected: "$(VAR_DNE)",
|
||||
},
|
||||
{
|
||||
name: "multiple (even) operators, var undefined",
|
||||
input: "$$$$$$(BIG_MONEY)",
|
||||
expected: "$$$(BIG_MONEY)",
|
||||
},
|
||||
{
|
||||
name: "multiple (even) operators, var defined",
|
||||
input: "$$$$$$(VAR_A)",
|
||||
expected: "$$$(VAR_A)",
|
||||
},
|
||||
{
|
||||
name: "multiple (odd) operators, var undefined",
|
||||
input: "$$$$$$$(GOOD_ODDS)",
|
||||
expected: "$$$$(GOOD_ODDS)",
|
||||
},
|
||||
{
|
||||
name: "multiple (odd) operators, var defined",
|
||||
input: "$$$$$$$(VAR_A)",
|
||||
expected: "$$$A",
|
||||
},
|
||||
{
|
||||
name: "missing open expression",
|
||||
input: "$VAR_A)",
|
||||
expected: "$VAR_A)",
|
||||
},
|
||||
{
|
||||
name: "shell syntax ignored",
|
||||
input: "${VAR_A}",
|
||||
expected: "${VAR_A}",
|
||||
},
|
||||
{
|
||||
name: "trailing incomplete expression not consumed",
|
||||
input: "$(VAR_B)_______$(A",
|
||||
expected: "B_______$(A",
|
||||
},
|
||||
{
|
||||
name: "trailing incomplete expression, no content, is not consumed",
|
||||
input: "$(VAR_C)_______$(",
|
||||
expected: "C_______$(",
|
||||
},
|
||||
{
|
||||
name: "operator at end of input string is preserved",
|
||||
input: "$(VAR_A)foobarzab$",
|
||||
expected: "Afoobarzab$",
|
||||
},
|
||||
{
|
||||
name: "shell escaped incomplete expr",
|
||||
input: "foo-\\$(VAR_A",
|
||||
expected: "foo-\\$(VAR_A",
|
||||
},
|
||||
{
|
||||
name: "lots of $( in middle",
|
||||
input: "--$($($($($--",
|
||||
expected: "--$($($($($--",
|
||||
},
|
||||
{
|
||||
name: "lots of $( in beginning",
|
||||
input: "$($($($($--foo$(",
|
||||
expected: "$($($($($--foo$(",
|
||||
},
|
||||
{
|
||||
name: "lots of $( at end",
|
||||
input: "foo0--$($($($(",
|
||||
expected: "foo0--$($($($(",
|
||||
},
|
||||
{
|
||||
name: "escaped operators in variable names are not escaped",
|
||||
input: "$(foo$$var)",
|
||||
expected: "$(foo$$var)",
|
||||
},
|
||||
{
|
||||
name: "newline not expanded",
|
||||
input: "\n",
|
||||
expected: "\n",
|
||||
},
|
||||
}
|
||||
|
||||
for _, tc := range cases {
|
||||
expanded := Expand(tc.input, mapping)
|
||||
if e, a := tc.expected, expanded; e != a {
|
||||
t.Errorf("%v: expected %q, got %q", tc.name, e, a)
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue