Delete vendored code and update CI to Go 1.13 (#158)

As the Go community transitions to using the modules ecosystem,
we want to only support one way of managing dependencies.
So this change moves to only using Go modules for dependency management.

This means that our effective minimum Go version increases to Go 1.11.
To account for this, we also update:
  - the documentation
  - Makefile
  - CI scripts

.travis.yml

@@ -1,7 +1,7 @@
 language: go
 sudo: false
 dist: bionic
-go: 1.12.x
+go: 1.13.x
 
 notifications:
   email: false
@@ -21,7 +21,7 @@ jobs:
       script: make
 
     - stage: presubmits
-      env: Generate, Format, and Lint
+      name: Generate, Format, and Lint
       install:
         - make tools
       script:
@@ -32,16 +32,19 @@ jobs:
         - make lint
 
     - &build
-      env: Build and Unit Tests
+      name: Build and Unit Tests
       install: skip
       script:
-        - go build github.com/google/fscrypt/cmd/fscrypt
+        - go get github.com/google/fscrypt/cmd/fscrypt
         - make
 
+    - <<: *build
+      go: 1.12.x
+
     - <<: *build
       go: 1.11.x
 
-    - env: Integration Tests
+    - name: Integration Tests
       sudo: required
       addons:
         apt:
@@ -57,7 +60,7 @@ jobs:
         - goveralls -coverprofile=coverage.out -service=travis-ci
 
     - stage: deploy
-      env: Release Binaries
+      name: Release Binaries
       install: skip
       script: skip
       before_deploy: make

CONTRIBUTING.md

@@ -64,7 +64,7 @@ checks you should make sure that in your submission:
 - If you made any changes to files ending in `.proto`, the corresponding
   `.pb.go` files should be regenerated with `make gen`.
 - Any issues found by `make lint` have been addressed.
-- If any dependencies have changed, run `go mod tidy` and `go mod vendor`.
+- If any dependencies have changed, run `go mod tidy`.
 - `make coverage.out` can be used to generate a coverage report for all of the
   tests, but isn't required for submission
   (ideally most code would be tested, we are far from that ideal).
@@ -75,7 +75,6 @@ make test-setup
 make all
 make test-teardown
 go mod tidy
-go mod vendor
 ```
 and everything succeeds, and no files are changed, you're good to submit.
 
@@ -114,11 +113,9 @@ test filesystem.
 
 ### Changing dependencies
 
-fscrypt's dependencies are managed using the [Go 1.11 module system](https://github.com/golang/go/wiki/Modules).
-If you add or remove a dependency, be sure to update `go.mod`, `go.sum`, and the
-`vendor/` directory by running `go mod tidy` and `go mod vendor`. fscrypt still
-vendor's it's dependencies for compatibility with older users, but this will
-probobly be removed once the module system becomes widespread.
+fscrypt's dependencies are managed using the
+[Go module system](https://github.com/golang/go/wiki/Modules).
+If you add or remove a dependency, be sure to update `go.mod` and `go.sum`.
 
 Also, when adding a dependency, the license of the package must be compatible
 with [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0). See the
@@ -139,17 +136,15 @@ your code.
   - Downloads [`protoc`](https://github.com/google/protobuf) to compile the
   `.proto` files.
   - Turns each `.proto` file into a matching `.pb.go` file using
-    [`protoc-gen-go`](https://github.com/golang/protobuf/tree/master/protoc-gen-go)
-    (built from source in `vendor/`).
+    [`protoc-gen-go`](https://github.com/golang/protobuf/tree/master/protoc-gen-go).
 
 `make format` runs:
   - [`goimports`](https://godoc.org/golang.org/x/tools/cmd/goimports)
-    (built from source in `vendor/`) on the `.go` files.
+    on the `.go` files.
   - [`clang-format`](https://clang.llvm.org/docs/ClangFormat.html)
     on the `.c` and `.h` files.
 
 `make lint` runs:
   - [`go vet`](https://golang.org/cmd/vet/) 
-  - [`golint`](https://github.com/golang/lint) (built from source in `vendor/`)
+  - [`golint`](https://github.com/golang/lint)
   - [`staticcheck`](https://github.com/dominikh/go-tools/tree/master/cmd/staticcheck)
-    (built from source in `vendor/`)

Makefile

@@ -71,9 +71,11 @@ DATE_FLAG := -X "main.buildTime=$(shell date)"
 
 override GO_LINK_FLAGS += $(VERSION_FLAG) $(DATE_FLAG) -extldflags "$(LDFLAGS)"
 override GO_FLAGS += --ldflags '$(GO_LINK_FLAGS)'
+# Always use Go modules
+export GO111MODULE = on
 
 ###### Find All Files and Directories ######
-FILES := $(shell find . \( -path ./vendor -o -path "./.*" \) -prune -o -type f -printf "%P\n")
+FILES := $(shell find . -path '*/.git*' -prune -o -type f -printf "%P\n")
 GO_FILES := $(filter %.go,$(FILES))
 GO_NONGEN_FILES := $(filter-out %.pb.go,$(GO_FILES))
 GO_DIRS := $(sort $(dir $(GO_FILES)))

README.md

@@ -106,7 +106,8 @@ information about each of the commands.
 ## Building and Installing
 
 fscrypt has a minimal set of build dependencies:
-*   [Go](https://golang.org/doc/install) 1.10 or higher
+*   [Go](https://golang.org/doc/install) 1.11 or higher. Older versions may work
+    but they are not tested or supported.
 *   A C compiler (`gcc` or `clang`)
 *   `make`
 *   Headers for [`libpam`](http://www.linux-pam.org/).

go.mod

@@ -1,6 +1,6 @@
 module github.com/google/fscrypt
 
-go 1.12
+go 1.11
 
 require (
 	github.com/golang/protobuf v1.2.0