diff --git a/docs/Part_01.md b/docs/Part_01.md index 3beafe8..471be1f 100644 --- a/docs/Part_01.md +++ b/docs/Part_01.md @@ -11,6 +11,23 @@ But if you're writing microservices for enterprise customers, yes, you should use Go, and yes, you should use OpenAPI and Swagger. So here's how it's done. +All of the files for this tutorial are available from the +elfsternberg/go-swagger-tutorial repo at github. There are *two* phases +to this tutorial, and the first phase is the base Go Swagger +implementation. I strongly recommend that if you're going to check out +the source code in its entirety, that you start with the +[Basic Version](https://github.com/elfsternberg/go-swagger-tutorial/tree/0.2.0), +and only check out the +[Advanced version](https://github.com/elfsternberg/go-swagger-tutorial/tree/0.4.0) +when you get to Part 3. + +Just be aware that if you see stuff that looks like `<>`, or a +single `@` alone on a line, that's just part of my code layout; do *not* +include those in your source code, they're not part of Go or Swagger. +Sorry about that. + +## Go Swagger! + [Swagger](https://swagger.io/) is a specification that describes the ndpoints for a webserver's API, usually a REST-based API. HTTP uses verbs (GET, PUT, POST, DELETE) and endpoints (/like/this) to describe @@ -36,12 +53,12 @@ functions with your business logic. There are three things that are your responsibility: 1. Write the specification that describes *exactly* what the server -accepts as requests and returns as responses. +accepts as requests and returns as responses, and generate a server from +this specification. 2. Write the business logic. -3. Glue the business logic into the server generated from the -specification. +3. Glue the business logic into the generated server. In Go-Swagger, there is *exactly one* file in the generated code that you need to change. Every other file is labeled "DO NOT EDIT." This @@ -64,6 +81,7 @@ $ go get -u github.com/golang/dep/cmd/dep $ go get -u github.com/go-swagger/go-swagger/cmd/swagger ``` + ## Initialization Now you're going to create a new project. Do it in your src directory @@ -91,15 +109,18 @@ optional timezone as a JSON argument in the body of the POST. First, let's version our API. You do that with Basepaths: +``` <>= basePath: /timeofday/v1 @ +``` Now that we have a base path that versions our API, we want to define our endpoint. The URL will ultimately be `/timeofday/v1/time`, and we want to handle both GET and POST requests, and our responses are going to be **Success: Time of day** or **Timezone Not Found**. +``` <>= paths: /time: @@ -133,11 +154,13 @@ paths: schema: $ref: "#/definitions/NotFound" @ +``` The `$ref` entries are a YAML thing for referring to something else. -The octothorpe symbol `(#)` indicates "look in the current file. So +The octothorpe symbol `(#)` indicates "look in the current file." So now we have to create those paths: +``` <>= definitions: NotFound: @@ -158,6 +181,7 @@ definitions: properties: TimeOfDay: string @ +``` This is *really verbose*, but on the other hand it is *undeniably complete*: these are the things we take in, and the things we respond @@ -165,6 +189,7 @@ with. So now your file looks like this: +``` <>= swagger: "2.0" info: @@ -186,14 +211,19 @@ schemes: <> @ +``` Now that you have that, it's time to generate the server! `$ swagger generate server -f swagger.yml` It will spill out the actions it takes as it generates your new REST -server. **Do not** follow the advice at the end of the output. -There's a better way. +server. **Do not** follow the advice at the end of the output. There's +a better way. Use `dep`, which will automagically find all your +dependencies for you, download them to a project-specific `vendor/` +folder, and _lock_ the specific commit in the record so version creep +won't break your project in the future. `dep` has become even Google's +recommended dependency control mechanism. Just run: `$ dep init` @@ -224,4 +254,4 @@ $ curl http://localhost:8082/timeofday/v1/time Congratulations! You have a working REST server that does, well, nothing. -For part two, we'll make our server actually do things. +For Part 2, we'll make our server actually do things. diff --git a/docs/Part_02.md b/docs/Part_02.md index 27922bb..569d04c 100644 --- a/docs/Part_02.md +++ b/docs/Part_02.md @@ -1,36 +1,45 @@ # Review of Part One -In [Part One of Go-Swagger](TK:), we generated a on OpenAPI 2.0 server -with REST endpoints. The server builds and responds to queries, but -every valid query ends with "This feature has not yet been -implemented." +In +[Part One of Go-Swagger](http://www.elfsternberg.com/2018/03/30/writing-microservice-swagger-part-1-specification/), +we generated a on OpenAPI 2.0 server with REST endpoints. The server +builds and responds to queries, but every valid query ends with "This +feature has not yet been implemented." It's time to implement the feature. I want to emphasize that with Go Swagger there is *only* one generated -file you need to touch. Since our project is named `timezone`, the -file will be named `restapi/configure_timezone.go`. Our first step +file you need to touch. Since our project is named `timeofday`, the +file will be named `restapi/configure_timeofday.go`. Our first step will be to break those "not implemented" functions out into their own Go package. That package will be our business logic. The configure file and the business logic package will be the *only* things we change. +A reminder: The final source code for this project is available on +Github, however Parts One & Two deal with the most common +implementation, a server with hard-coded default values. For these +chapters, please consult +[that specific version of the code](https://github.com/elfsternberg/go-swagger-tutorial/tree/0.2.0). + ## Break out the business logic Create a new folder in your project root and call it `timeofday`. Open up your editor and find the file `restapi/configure_timeofday.go`. In your `swagger.yml` file you created two endpoints and gave them each -an `operationId`: `TimekPost` and `TimeGet`. Inside +an `operationId`: `TimePost` and `TimeGet`. Inside `configure_timeofday.go`, you should find two corresponding assignments in the function `configureAPI()`: `TimeGetHandlerFunc` and -`ClockPostHandlerFunc`. Inside those function calls, you'll find +`TimePostHandlerFunc`. Inside those function calls, you'll find anonymous functions. I want you to take those anonymous functions, cut them out, and paste them into a new file inside the `timeofday/` folder. You will also have to create a package name and import any packages being used. Now your -file, which I've called `timeofday/handlers.go`, looks like this: +file, which I've called `timeofday/handlers.go`, looks like this (note +that you'll have to change your import paths as you're probably not +elfsternberg. Heck, _I'm_ probably not elfsternberg): ``` <>= @@ -155,7 +164,7 @@ The good path is similar: Now might be a good time to go look in `models/` and `/restapi/options`, to see what's available to you. You'll need to do so anyway, because unless you go to the -[git repository](https://github.com/elfsternberg/go-swagger-tutorial) +[git repository](https://github.com/elfsternberg/go-swagger-tutorial/tree/0.2.0) and cheat, I'm going to leave it up to you to implement the PostTime(). There's still one thing missing, though: the actual time of day. We'll @@ -205,5 +214,9 @@ $ curl 'http://localhost:8020/timeofday/v1/time?timezone=America/Los_Angeles' ``` And that's the end of Part 2. If you've gotten this far, -congratulations! On to [Part 3](TK:). +congratulations! Just a reminder, a working version of this server is +available under the "0.2.0" tag +[at the repo](https://github.com/elfsternberg/go-swagger-tutorial/tree/0.2.0). + +On to [Part 3](TK) diff --git a/docs/Part_03.md b/docs/Part_03.md index 31af0cd..d3d3d08 100644 --- a/docs/Part_03.md +++ b/docs/Part_03.md @@ -1,17 +1,18 @@ -# Adding Command Line Arguments to the Swagger Server +The first two parts of my swagger tutorial +[[Part 1](http://www.elfsternberg.com/2018/03/30/writing-microservice-swagger-part-1-specification/), +[Part 2](http://www.elfsternberg.com/2018/03/30/writing-microservice-swagger-part-2-business-logic/)] +were dedicated to the straightforward art of getting swagger up and +running. While I hope they're helpful, the whole point of those was to +get you to the point where you had the Timezone project, so I could show +you how to add Command Line Arguments to a Swagger microservice. -The first two parts of my swagger tutorial were dedicated to the -straightforward art of getting swagger up and running. While I hope -they're helpful, the whole point of those was to get you to the point -where you had the Timezone project, so I could teach how to extend the -Command Line Arguments of a swagger project. - -Nobody else, so far as I know, knows how to do this. One thing that I -emphasized in [Go Swagger Part 2](TK:) was that `configure_timeofday.go` -is the *only* file you should be touching, it's the interface between -the server and your business logic. Every example of adding new flags -to the command line, even the ones provided by the GoSwagger authors, -starts by modifying the file `cmd/\-server/main.go`, one of +One thing that I emphasized in +[Go Swagger Part 2](http://www.elfsternberg.com/2018/03/30/writing-microservice-swagger-part-2-business-logic/) +was that `configure_timeofday.go` is the *only* file you should be +touching, it's the interface between the server and your business logic. +Every example of adding new flags to the command line, even +[the one provided by the GoSwagger authors](https://github.com/go-openapi/kvstore/blob/master/cmd/kvstored/main.go#L50-L57), +starts by modifying the file `cmd/-server/main.go`, one of those files clearly marked `// DO NOT EDIT`. We're not going to edit files marked `// DO NOT EDIT`. @@ -23,7 +24,7 @@ uses for handling command line arguments, `go-flags`. `go-flags` is the tool Swagger uses by default for handling command line arguments. It's a clever tool that uses Go's -[tags and retrospection](TK:) features to encade the details of the CLI +[tags and reflection](https://golang.org/pkg/reflect/) features to encade the details of the CLI directly into a structure that will hold the options passed in on the command line. @@ -129,9 +130,17 @@ do we set the context? The *correct* way is to modify the handlers so they have the context when they're called upon. The way we do that is via the oldest object-oriented technique of all time, one that dates all the way back -to 1959 and the invention of Lisp: *closures*. +to 1964 and the invention of Lisp: +*[closures](https://tour.golang.org/moretypes/25)*. A closure *wraps* +one or more functions in an environment (a collection of variables +outside those functions), and preserves handles to those variables even +when those functions are passed out of the environment as references. A +garbage-collected language like Go makes this an especially powerful +technique because it means that anything in the environment for which +you *don't* keep handles will get collected, leaving only what matters. -Remember these lines in `configure_timeofday.go`, from way back? +So, let's do it. Remember these lines in `configure_timeofday.go`, from +way back? ``` api.TestGetHandler = operations.TestGetHandlerFunc(func(params operations.TestGetParams) middleware.Responder { @@ -151,24 +160,25 @@ replace those lines, *again*, so they look like this: Those are no longer references to functions. They're *function calls*! What do those functions return? Well, we know TimeGetHandlerFunc() is -expecting a function, so so that function call had better return a -function. +expecting a referece to a function, so so that function call had better +return a reference to a function. -And indeed it does. +And indeed it does: ``` func GetTime(timezone *Timezone) func(operations.TimeGetParams) middleware.Responder{ defaultTZ := timezone.Timezone - + + // Here's the function we return: return func(params operations.TimeGetParams) middleware.Responder { - // Everything else is the same... except we need *two* levels of - // closing } at the end! + // Everything else is the same... except we need *two* levels of + // closing } at the end! ``` Now, instead of returning a function defined at compile time, we -returned a function that is finalized when GetTime() is called, and it -now holds a permanent reference to our Timezone object. Do the same -thing for `PostTime`. +returned a function reference that is finalized when GetTime() is +called, and it now holds a permanent reference to our Timezone object. +Do the same thing for `PostTime`. There's one more thing we have to do. We've moved our default timezone to the `configure_timeofday.go` file, so we don't need it here anymore: @@ -190,8 +200,31 @@ And that's it. That's everything. You can add all the command line arguments you want, and only preserve the fields that are relevant to the particular handler you're going to invoke. +You can now build and run the server, but with a command line: + +``` +$ go build ./cmd/timeofday-server/ +$ ./timeofday-server --port=8080 --timezone="America/Los_Angeles" +``` + +And test it with curl: + +``` +$ curl 'http://localhost:8020/timeofday/v1/time?timezone=America/New_York' +{"timeofday":"2018-03-30 23:44:47.701895604 -0400 EDT"} +$ curl 'http://localhost:8020/timeofday/v1/time' +{"timeofday":"2018-03-30 20:44:54.525313806 -0700 PDT"} +``` + +Note that the default timezone is now PDT, or Pacific Daily Time, which +corresponds to the America/Los_Angeles entry in the database in late +March. + And *that's* how you add command line arguments to Swagger servers -correctly. +correctly without exposing your CLI settings to every other function in +your server. If you want to see the entirely of the source code, the +[advanced version on the repository](https://github.com/elfsternberg/go-swagger-tutorial/tree/0.4.0) +has it all.