*: Add go-swagger as dependency, generate spec from server files

This change adds a dependency on `go-swagger/go-swagger`, and
uses it as part of `make generate` to regenerate the swagger
spec in `docs/generated/swagger/spec.json`, whenever
one of the APIv2 files in `pkg/server/` are changed.

The spec, once generated, can be served as docs using
the command:

    bin/swagger serve -p 8080 ./docs/generated/swagger/spec.json

Release note (build change): Adds go-swagger dependency, updates
Makefile to call it to rebuild spec in docs/generated/swagger/
which will eventually be used for API docs.

Makefile

@@ -384,6 +384,7 @@ bin/.bootstrap: $(GITHOOKS) vendor/modules.txt | bin/.submodules-initialized
 		github.com/cockroachdb/gostdlib/x/tools/cmd/goimports \
 		github.com/cockroachdb/stress \
 		github.com/goware/modvendor \
+		github.com/go-swagger/go-swagger/cmd/swagger \
 		github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway \
 		github.com/kevinburke/go-bindata/go-bindata \
 		github.com/kisielk/errcheck \
@@ -827,6 +828,9 @@ WKTPARSER_TARGETS = \
 
 PROTOBUF_TARGETS := bin/.go_protobuf_sources bin/.gw_protobuf_sources
 
+SWAGGER_TARGETS := \
+  docs/generated/swagger/spec.json
+
 DOCGEN_TARGETS := \
 	bin/.docgen_bnfs \
 	bin/.docgen_functions \
@@ -1155,7 +1159,7 @@ dupl: bin/.bootstrap
 
 .PHONY: generate
 generate: ## Regenerate generated code.
-generate: protobuf $(DOCGEN_TARGETS) $(OPTGEN_TARGETS) $(LOG_TARGETS) $(SQLPARSER_TARGETS) $(WKTPARSER_TARGETS) $(SETTINGS_DOC_PAGES) bin/langgen bin/terraformgen
+generate: protobuf $(DOCGEN_TARGETS) $(OPTGEN_TARGETS) $(LOG_TARGETS) $(SQLPARSER_TARGETS) $(WKTPARSER_TARGETS) $(SETTINGS_DOC_PAGES) $(SWAGGER_TARGETS) bin/langgen bin/terraformgen
 	$(GO) generate $(GOFLAGS) $(GOMODVENDORFLAGS) -tags '$(TAGS)' -ldflags '$(LINKFLAGS)' $(PKG)
 	$(MAKE) execgen
 
@@ -1595,6 +1599,8 @@ docs/generated/logging.md: pkg/util/log/gen/main.go pkg/util/log/logpb/log.proto
 	$(GO) run $(GOMODVENDORFLAGS) $^ logging.md $@.tmp || { rm -f $@.tmp; exit 1; }
 	mv -f $@.tmp $@
 
+docs/generated/swagger/spec.json: pkg/server/api*.go bin/.bootstrap
+
 pkg/util/log/severity/severity_generated.go: pkg/util/log/gen/main.go pkg/util/log/logpb/log.proto
 	$(GO) run $(GOMODVENDORFLAGS) $^ severity.go $@.tmp || { rm -f $@.tmp; exit 1; }
 	mv -f $@.tmp $@

WORKSPACE

@@ -81,16 +81,16 @@ go_repository(
     patches = [
         "@cockroach//build/patches:com_github_golang_protobuf.patch",
     ],
-    sum = "h1:+Z5KGCizgyZCbGh1KZqA0fcLLkwbsjIzS4aV2v7wJX0=",
-    version = "v1.4.2",
+    sum = "h1:JjCZWpVbqXDqFVmTfYWEVTMIYrL/NPdPSCHPJ0T/raM=",
+    version = "v1.4.3",
 )
 
 go_repository(
     name = "org_golang_google_genproto",
     build_file_proto_mode = "disable_global",
     importpath = "google.golang.org/genproto",
-    sum = "h1:jB9+PJSvu5tBfmJHy/OVapFdjDF3WvpkqRhxqrmzoEU=",
-    version = "v0.0.0-20200218151345-dad8c97a84f5",
+    sum = "h1:PDIOdWxZ8eRizhKa1AAvY53xsvLB1cWorMjslvY3VA8=",
+    version = "v0.0.0-20200825200019-8632dd797987",
 )
 
 # Load the go dependencies and invoke them.

build/variables.mk

@@ -128,6 +128,7 @@ define VALID_VARS
   STYLINT
   SUBTESTS
   SUFFIX
+  SWAGGER_TARGETS
   TAGS
   TAR
   TARGET

docs/generated/swagger/README

@@ -0,0 +1 @@
+This folder contains spec files generated by go-swagger.