Add support for template arguments #179
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@prashantv, thanks for your PR! By analyzing the history of the files in this pull request, we identified @kriskowal, @blampe and @eklitzke to be potential reviewers. |
templateargs/argparser/arg.rl
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| Value string | ||
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| // Parse parses strings in the format, ${NAME} and ${NAME:VALUE}. |
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Add a Lit struct and return Term ( Lit | Var). Lit should produce a string with \$ => $ and \\ => \.
templateargs/process.go
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| return processMap(req, argsUnmarshalled) | ||
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| func processString(v string, args map[string]interface{}) (interface{}, error) { |
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This function should unconditionally parse the string in its DSL, including escaping \$ and \\. The grammar should return a simple AST with either a Lit or a Var term, and this function should just switch on that.
This leaves open the possibility of extending the grammar to support string interpolation like ${host}:${port}. We can forbid this for now.
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| service: foo | |||
| request: | |||
| name: ${user:foo | |||
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Needs test for \${user}. Would be good to test \\, \$.
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Might be good to test requests with embedded non-string arguments, e.g., as in yab -A peer-list:$(cat peers.yaml)
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We cover a lot of the edge cases such as \\ and \$ in TestProcessString and TestProcessMap already. but added a couple more to args.yaml -- it has a fallback which is not a string, a list replacement, and testing for escapes.
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templateargs/process.go
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| } | ||
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| // Anything that starts with "${ " should be processed as a template arg. | ||
| if !strings.HasPrefix(v, "${") { |
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| service: foo | |||
| request: | |||
| name: ${user:foo | |||
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We cover a lot of the edge cases such as \\ and \$ in TestProcessString and TestProcessMap already. but added a couple more to args.yaml -- it has a fallback which is not a string, a list replacement, and testing for escapes.
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| service: foo | |||
| headers: | |||
| header1: ${user:foo} | |||
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Note: this is not replaced at the moment, template arguments are used for request bodies.
Before 1.0, we may want to think about processing everything in the YAML file? We would probably decode the template to a map, use templateargs.ProcessMap, then pass it through mapdecode. Thoughts @kriskowal @abhinav
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Sounds reasonable. Although mapdecode expects to decode into a known struct shape, not dynamic Thrift shapes.
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Yep, we want to use it to load into the Template struct (known Go shape). Won't affect the body which is still a map.
Template arguments are of the format ${argname:fallback}. Arguments can
be specified on the commandline using `--arg` or `-A`. Arguments are
parsed as YAML values, and allow more complex types (e.g., lists) to be
specified as arguments.
We only use template arguments for request bodies currently.
Argument parsing is based on @abhinav's work for YARPC configuration.
options.go
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| @@ -52,6 +52,7 @@ type RequestOptions struct { | |||
| Health bool `long:"health" description:"Hit the health endpoint, Meta::health"` | |||
| Timeout timeMillisFlag `long:"timeout" default:"1s" description:"The timeout for each request. E.g., 100ms, 0.5s, 1s. If no unit is specified, milliseconds are assumed."` | |||
| YamlTemplate string `short:"y" long:"yaml-template" description:"Send a tchannel request specified by a yaml template"` | |||
| TemplateArgs map[string]string `short:"A" long:"arg" description:"A list of key-value template arguments"` | |||
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add example of key-value argument format to the help. Is it -A foo=bar or -A foo:bar?
Template arguments are of the format ${argname:fallback}. Arguments can
be specified on the commandline using
--argor-A. Arguments areparsed as YAML values, and allow more complex types (e.g., lists) to be
specified as arguments.
We only use template arguments for request bodies currently.
Argument parsing is based on @abhinav's work for YARPC configuration.