I have two projects:
/myproject
/sharedproject
both of them are managed by dep, I have execute go get -u github.com/golang/dep/cmd/dep in order to have latest dep version, and run dep ensure on both projects.
When I run myproject I get following error:
cannot use op (type *"myproject/vendor/github.com/go-openapi/spec".Operation) as type *"sharedproject/vendor/github.com/go-openapi/spec".Operation
What is wrong and how to fix this?
Looks like the situation is that sharedproject vendors the github.com/go-openapi/spec dependency while myproject
gets both sharedproject and github.com/go-openapi/spec dependencies from
GOPATH.
Now when you refer to github.com/go-openapi/spec in sharedproject, it refers to
the package inside the vendor directory, which is technically different from the
same package in GOPATH, even if both have the same content. So when you pass a
variable of type *github.com/go-openapi/spec.Operation from myproject to a
function in sharedproject, the package of the type differs from what's expected and compilation fails.
To solve this, make sure sharedproject is vendored inside myproject. When
you do this, dep ensure will put a copy of sharedproject without its vendor
directory into myproject's vendor directory. After this, both myproject and sharedproject will use the github.com/go-openapi/spec package from myproject's vendor directory.
That does make local development hard if you change sharedproject often and want
to immediately use those changes in myproject (can't use dep till the changes are pushed to the Git remote). I'd work around that by copying
over sharedproject into myproject's vendor directory manually without using dep (excluding the vendor directory of course). Be careful to not commit those manually copied changes to Git though!
Related
I am trying to download, make some tweaks and build a golang project from GitHub. The project's instructions are:
go get github.com/<vendor>/<projectName>
cd src/github.com/<vendor>/<projectName>
go build .
That used to work in the past — before enabling Go Modules.
Now I have GO111MODULE=on (go version go1.15.4 linux/amd64). When running the first command, go downloads the project as a module and all its dependencies.
But then there is no src/github.com/<vendor>/<projectName> folder anymore. Moreover, the is no folder named <projectName> anywhere in the system.
Instead, there is folder pkg/mod/github.com/<vendor> which contains the project folder with weird symbols in its name (exclamation marks etc.) and version identifiers.
How do I get the project folder available for making tweaks and builds?
As pointed by #Volker, good old git clone should be used.
It turns out that it should be used instead of go get github.com/<vendor>/<projectName> (no idea why the project vendor recommends that):
git clone git://github.com/<vendor>/<projectName>
cd <projectName>
go get ./...
# do tweaks here
go build .
If your goal is tweaks, the easiest way it use to use go mod vendor.
https://golang.org/ref/mod#go-mod-vendor
The go mod vendor command constructs a directory named vendor in the main module's root directory that contains copies of all packages needed to support builds and tests of packages in the main module
I am trying to fetch a Go project and copy the dependencies under the vendor/ directory so I have the complete source code of the project and its dependencies in my project. However, even after doing that, deleting the packages under $GOPATH/pkg/mod and rebuilding cause the Go compiler to re-fetch all dependencies, which takes a considerable of time.
This is what I did:
# Fetch the project, e.g. influx/telegraf
go get -d github.com/influxdata/telegraf
# CD into the project
cd $GOPATH/src/influxdata/telegraf
# Fetch the modules under vendor/ directory
go mod vendor
After calling the last command, Go will fetch all the dependencies under pkg/mod. Not sure why it is doing that, but I assume it is because it needs to build the project normally, and then move the fetched dependencies under the vendor/ folder. After that, I can build successfully. However, to make sure I no longer require those dependencies, I deleted the pkg/mod directory completely and rebuilt the project. Go compiler, for some reason, fetched the packages again.
Is there anything I am doing wrong?
Thanks!
The vendor folder is not used automatically in all cases.
To make sure dependencies are loaded from the main module's vendor folder, pass -mod=vendor to the go tool.
The vendor folder if present is only used automatically (if not specified otherwise with -mod=mod) if the go version specified by go.mod file is 1.14 or higher.
These are detailed in Command go: Maintaining module requirements:
If invoked with -mod=vendor, the go command loads packages from the main module's vendor directory instead of downloading modules to and loading packages from the module cache. The go command assumes the vendor directory holds correct copies of dependencies, and it does not compute the set of required module versions from go.mod files. However, the go command does check that vendor/modules.txt (generated by 'go mod vendor') contains metadata consistent with go.mod.
If invoked with -mod=mod, the go command loads modules from the module cache even if there is a vendor directory present.
If the go command is not invoked with a -mod flag and the vendor directory is present and the "go" version in go.mod is 1.14 or higher, the go command will act as if it were invoked with -mod=vendor.
Converting an existing project with a /vendor directory to use Go Modules (go version 1.12). I do go mod init to generate the go.mod file. Then I do go get -u ./... to populate the go.mod file. During this time, it tries to locate a package on github that no longer exists. It is vendored in my /vendor directory.
Until I can upgrade my code to use a different package, how can I continue the conversion to using modules? That is, I want to keep some things vendored (I also have some modified code under /vendor), while other things are handled by go modules.
You can't mix the vendor directory behavior and modules, each method of dependency resolution precludes the other. You can re-publish the missing package yourself somewhere that go mod can locate it, or you can redirect it directly to the existing vendored source in your module.
To redirect the source of a module, use the replace directive in the go.mod file
replace missing/package v0.0.1 => ./vendor/missing/package
I'm using go 1.11 with module support. I understand that the go tool now installs dependencies automatically on build/install. I also understand the reasoning.
I'm using docker to build my binaries. In many other ecosystems its common to copy over your dependency manifest (package.json, requirements.txt, etc) and install dependencies as a separate stage from build. This takes advantage of docker's layer caching, and makes rebuilds much faster since generally code changes vastly outnumber dependency changes.
I was wondering if vgo has any way to do this?
It was an issue #26610, which is fixed now.
So now you can just use:
go mod download
For this to work you need just the go.mod / go.sum files.
For example, here's how to have a cached multistage Docker build: (source)
FROM golang:1.17-alpine as builder
RUN apk --no-cache add ca-certificates git
WORKDIR /build
# Fetch dependencies
COPY go.mod go.sum ./
RUN go mod download
# Build
COPY . ./
RUN CGO_ENABLED=0 go build
# Create final image
FROM alpine
WORKDIR /
COPY --from=builder /build/myapp .
EXPOSE 8080
CMD ["./myapp"]
Also see the article Containerize Your Go Developer Environment – Part 2, which describes how to leverage the Go compiler cache to speed up builds even further.
You may use the go mod vendor command which will create a vendor folder in the main module's root folder, and copy all dependencies into it. After this you may pass the -mod=vendor param to the go tool, and then dependencies from the vendor folder will be used to build / compile / test your app.
So what you may do to speed up your builds:
Run the go mod vendor command to have an actual version of your dependencies.
Save / cache this vendor folder.
During builds, restore this vendor folder, and build / install your app by passing the -mod=vendor argument to the go tool, so no dependencies will be downloaded, but the content of the vendor folder will be used.
Quoting from go help mod:
Modules and vendoring
When using modules, the go command completely ignores vendor directories.
By default, the go command satisfies dependencies by downloading modules
from their sources and using those downloaded copies (after verification,
as described in the previous section). To allow interoperation with older
versions of Go, or to ensure that all files used for a build are stored
together in a single file tree, 'go mod vendor' creates a directory named
vendor in the root directory of the main module and stores there all the
packages from dependency modules that are needed to support builds and
tests of packages in the main module.
To build using the main module's top-level vendor directory to satisfy
dependencies (disabling use of the usual network sources and local
caches), use 'go build -mod=vendor'. Note that only the main module's
top-level vendor directory is used; vendor directories in other locations
are still ignored.
I wanted to re-download all the dependencies using go mod, this is what I did:
Go to your GOROOT
sudo rm -rf pkg/mod/
Go to the directory where the go.mod file exists
go mod download
You can use a package manager, There are many of them like dep, glide, and govendor. dep is newer and is going to be integrated into go toolchain as official dependency management tool.
We also make docker images for go applications and we use dind to make those images and we prepared a CI/CD image with all dependencies preinstalled to make the builds faster. Though, it took a little bit of scripting to glue everything together.
Moreover, layering up the dependencies could result in big size of docker images. I suggest try multi-stage builds which could help making images super lite.
My golang version is go1.10.2 linux/amd64. I can build and run my go project(under gopath/src) without any problem but I cannot see vendor directory under my project folder. I would like to know if the vendor folder is a hidden directory? What are the possible reasons the vendor folder is not generated?
Vendor directory is used as an alternative to GOPATH when resolving dependencies. A dependency is first looked up in /vendor then in GOPATH then in GOROOT.
If you go get all your dependencies they'll be in GOPATH/src instead of /vendor.
To start adding project specific dependencies to vendor dir you need to use a dependency manager such as glide or dep or manually copy everything to /vendor.
This SO answer goes into more detail on using vendor dir in Go - https://stackoverflow.com/a/37238226/1589165