In Golang, we can specify open source libraries on GitHub as dependencies. For example:
import "github.com/RichardKnop/somelibrary"
This will try to look for a branch based on your Go version and default to master if I understand correctly.
So there is no way to import a specific release of a dependency, e.g.:
import "github.com/RichardKnop/somelibrary#v1.4.8"
What is the best practise to manage dependencies in Go then?
I can see two approaches.
I. Version Modules
Is it to create new modules for major versions with breaking changes?
For example, my Go library could define modules v1 and v2 so then you could do:
import "github.com/RichardKnop/somelibrary/v1"
Or:
import "github.com/RichardKnop/somelibrary/v2"
Based on what you need. Any changes made to v1 or v2 would be required not to break any APIs or working functionality.
II. Forking
This would give you a complete control over a version of external dependency your Go code requires.
For example, you could fork github.com/RichardKnop/somelibrary into your own GitHub account and then in your code do:
import "github.com/ForkingUser/somelibrary"
Then you would have to fork all external dependencies which seems a bit overkill. However it would give you total control over versions. You could keep your forks at a version you know is working with your code and only update forks once you have checked that new releases of dependencies do not break anything.
Thoughts?
Feb. 2018: the vendoring approach presented below (in 2015/2016) might end up disappearing if vgo is integrated to the toolchain.
See my answer below.
August 2015 edition: Go 1.5 comes with a built-in (but still experimental) vendoring support. Setting the environment variable GO15VENDOREXPERIMENT will make go build and friends look for packages in ./vendor directory as well as GOPATH. See VonC's answer and the design document for more details.
III. Vendoring
AFAIK, this is the most widely used way of ensuring that your builds are reproducible and predictable. The Go team itself uses vendoring in their repo. The Go team is now discussing the unified dependency manifest file format. From the Go toolchain developers mailing list:
In Google’s internal source tree, we vendor (copy) all our dependencies into our source tree and have at most one copy of any given external library. We have the equivalent of only one GOPATH and rewrite our imports to refer to our vendored copy. For example, Go code inside Google wanting to use “golang.org/x/crypto/openpgp” would instead import it as something like “google/third_party/golang.org/x/crypto/openpgp”.
(...)
Our proposal is that the Go project,
officially recommends vendoring into an “internal” directory with import rewriting (not GOPATH modifications) as the canonical way to pin dependencies.
defines a common config file format for dependencies & vendoring
makes no code changes to cmd/go in Go 1.5. External tools such as “godep” or “nut” will implement 1) and 2). We can reevaluate including such a tool in Go 1.6+.
Note: June 2015, the first support for vendoring appears in Go 1.5!
See c/10923/:
When GO15VENDOREXPERIMENT=1 is in the environment, this CL changes the resolution of import paths according to the Go 1.5 vendor proposal:
If there is a source directory d/vendor, then, when compiling a source file within the subtree rooted at d, import "p" is interpreted as import "d/vendor/p" if that exists.
When there are multiple possible resolutions, the most specific (longest) path wins.
The short form must always be used: no import path can contain “/vendor/” explicitly.
Import comments are ignored in vendored packages.
Update January 2016: Go 1.6 will make vendoring the default.
And as detailed in the article "MOST GO TOOLS NOW WORK WITH GO15VENDOREXPERIMENT":
1.6 brings support for /vendor/ to most tools (like the oracle) out of the box; use the Beta to rebuild them.
issue 12278 has been resolved.
there still is an issue with goimports, and there is a CL that can be cherry-picked.
Update August 2018: this (vgo presented below) is now implemented with Go 1.11 and modules.
Update Feb. 2018, 3 years later.
There is a new approach developed by Russ Cox, from the core Golang development team.
The vgo project.
go get -u golang.org/x/vgo
This proposal:
keeps the best parts of go get,
adds reproducible builds,
adopts semantic versioning,
eliminates vendoring,
deprecates GOPATH in favor of a project-based workflow, and
provides a smooth migration path from dep and its predecessors.
It is based on a new MVS ("Minimal Version Selection") algorithm:
You can see:
the first articles in Go & Versioning
the discussion in this thread
the analysis of that thread by Jon Calhoun
the counter-point by Sam Boyer in "Thoughts on vgo and dep":
He was leading the private initiative of go dep
the first debate (YouTube) between Russ, Sam and Jesse Frazelle!
May 2018: Artifactory proposes a vgo proxy
The recent release of Artifactory 5.11 added support for vgo-compatible Go registries (and go proxy) giving the community a variety of capabilities when developing with Go.
Here are just a few of them:
Local repositories in Artifactory let you set up secure, private Go registries with fine-grained access control to packages according to projects or development teams.
A remote repository in Artifactory is a caching proxy for remote Go resources such as a GitHub project. Accessing a go proxy through Artifactory removes your dependency on the network, or on GitHub since all dependencies needed for your Go builds are cached in Artifactory and are therefore locally available. This also removes the risk of someone mutating or removing a dependency from version control, or worse, force-pushing changes to a remote Git tag thus changing what should be an immutable version which can create a lot of confusion and instability for dependent projects.
A virtual repository aggregates both local and remote Go registries giving you access to all Go resources needed for your builds from a single URL, hiding the complexity of using a combination of both local and remote resources.
also it is possible just describe dependencies in maven, if to use mvn-golang-wrapper, in the case it looks like in maven as below text
<plugin>
<groupId>com.igormaznitsa</groupId>
<artifactId>mvn-golang-wrapper</artifactId>
<version>1.1.0</version>
<executions>
<execution>
<id>golang-get</id>
<goals>
<goal>get</goal>
</goals>
<configuration>
<packages>
<package>github.com/gizak/termui</package>
</packages>
<buildFlags>
<flag>-u</flag>
</buildFlags>
<goVersion>1.6</goVersion>
</configuration>
</execution>
</plugin>
Related
Is it ok to use the master branch of lib/pq in production?
When you execute go get gitlab.com/lib/pq you get the master branch, but there is a release v1.0.0.
Would it be better to use releases instead of master branch?
lib/pq
Releases
v1.0.0
Initial tagged release. No major recent changes.
Merge pull request #778 from lib/go-mod
add a go.mod file in preparation for a tagged release
lib/pq v1.0.0 adds support for Go versioned modules.
For Go1.12, consider upgrading your production code for Go versioned modules.
The first beta release of Go 1.12 is scheduled for this week (Dec, 3, 2018).
Go 1.11 Release Notes
Modules, package versioning, and dependency management
Go 1.11 adds preliminary support for a new concept called “modules,”
an alternative to GOPATH with integrated support for versioning and
package distribution. Using modules, developers are no longer confined
to working inside GOPATH, version dependency information is explicit
yet lightweight, and builds are more reliable and reproducible.
Module support is considered experimental. Details are likely to
change in response to feedback from Go 1.11 users, and we have more
tools planned. Although the details of module support may change,
projects that convert to modules using Go 1.11 will continue to work
with Go 1.12 and later. If you encounter bugs using modules, please
file issues so we can fix them. For more information, see the go
command documentation.
Proposal: Versioned Go Modules
Go 1.11 Modules.
I'm getting my hands dirty with Go, and while I understand and appreciate the principle of simplicity that Go was built upon, I'd like to grasp the rationale behind forgoing a built-in package versioning method in their dependency-fetching tool go get and the import statement.
If I understand correctly, go get and import fetch the package from HEAD and they are unable to refer to a branch or a tag. While there are tools like gopkg.in that circumvent this limitation, the official toolchain:
Forces developers to create separate repos for major (breaking) versions of their products.
It doesn't allow consumers to downgrade between minor or micro versions in case bugs are found in newer ones.
Truth be told, things are not so easy because package versioning would require a strategy to deal with conflicting transitive dependencies, e.g. X depends on A and B, each of which depend on different versions of C.
Coming from a Java background, it does appear that this limitation poses some risks and problems, amongst others:
Product/package evolution and breakage of public APIs of 3rd party deps is unavoidable, therefore versioning must be a first-class citizen in the toolchain IMHO.
The Git-repo-per-version policy is highly inefficient:
The overall Git history of the package is lost or scattered across repos (merges between versions, backports, etc.)
Conflicts with transitive dependencies may still occur, and will go about undetected because the language nor the toolchain impose any semantics to allow detection in the first place.
Enterprise adoption may be hindered and development teams may shy away from the language, given that:
Always dragging in HEAD means that they can't control or freeze their 3rd party deps, leading to a potentially unpredictable end product.
May lack the manpower to keep their product constantly updated and tested with upstream's HEAD (not every company in the world is Google :)).
While I do understand that the latter risk can be – and must be – mitigated with Continuous Integration, it does not solve the underlying root of the problem.
What information am I missing? How do you deal with package upstream changes when deploying Go in an enterprise with limited manpower?
It is being addressed by vendoring which is part of Go 1.5 as an experimental feature, it can be enabled if the go command is run with GO15VENDOREXPERIMENT=1 in its environment, and will be a "full" feature in Go 1.6. Also see Vendor Directories.
The original discussion that led to the Go 1.5 Vedor Experiment can be found here.
The essence of vendoring is that you create a folder named vendor, and you put the exact version of the packages that your code relies on. Code inside the vendor folder is only importable by the code in the directory tree rooted at the parent of vendor, and you can import packages from vendor with an import path as if vendor would be the workspace/src folder (that is, with an import path that omits the prefix up to and including the vendor element).
Example:
/home/user/goworkspace/
src/
mymath/
mymath.go
vendor/
github.com/somebob/math
math.go
In this example github.com/somebob/math is an external package used by mymath package (from mymath.go). It can be used from mymath.go if it is imported like:
import "github.com/somebob/math"
(And not as import mymath/vendor/github.com/somebob/math which would be bad.)
While Go doesn't come with the standard package manager there are enough options to make builds reproducible (even in an enterprise with limited manpower).
Vendoring, which is described in another answer by #icza. This is almost complete equivalent of checking in versioned jar files in Java. This was very common approach with ant build tool before maven became popular. Actually vendoring is much better because you cannot lose source code.
This is slight variation of the first option. Instead of checking in vendored source code you can populate vendor folder during build by checking out predefined versions of the dependencies. There tools (e.g. glide) that automate this process.
Finally you can maintain predefined versions of all 3-rd party libraries in the internal repository and add it to GOPATH. This approach is described in detail in https://blog.gopheracademy.com/advent-2015/go-in-a-monorepo/
Note that incompatible transitive dependencies are not specific to Go. They exist in Java (and most other languages) too, though Java has a mechanism to partially solve this problem by making programs more complex - class loaders. Note that Go will report all incompatibilities at compile time while in Java some of the incompatibilities are triggered only at run time (because of late linking).
Java toolchain doesn't have concept of versions. It is provided by the external tool - maven. I believe by the time Go becomes more mature and popular a similar standard dependency management tool will emerge.
In Golang, we can specify open source libraries on GitHub as dependencies. For example:
import "github.com/RichardKnop/somelibrary"
This will try to look for a branch based on your Go version and default to master if I understand correctly.
So there is no way to import a specific release of a dependency, e.g.:
import "github.com/RichardKnop/somelibrary#v1.4.8"
What is the best practise to manage dependencies in Go then?
I can see two approaches.
I. Version Modules
Is it to create new modules for major versions with breaking changes?
For example, my Go library could define modules v1 and v2 so then you could do:
import "github.com/RichardKnop/somelibrary/v1"
Or:
import "github.com/RichardKnop/somelibrary/v2"
Based on what you need. Any changes made to v1 or v2 would be required not to break any APIs or working functionality.
II. Forking
This would give you a complete control over a version of external dependency your Go code requires.
For example, you could fork github.com/RichardKnop/somelibrary into your own GitHub account and then in your code do:
import "github.com/ForkingUser/somelibrary"
Then you would have to fork all external dependencies which seems a bit overkill. However it would give you total control over versions. You could keep your forks at a version you know is working with your code and only update forks once you have checked that new releases of dependencies do not break anything.
Thoughts?
Feb. 2018: the vendoring approach presented below (in 2015/2016) might end up disappearing if vgo is integrated to the toolchain.
See my answer below.
August 2015 edition: Go 1.5 comes with a built-in (but still experimental) vendoring support. Setting the environment variable GO15VENDOREXPERIMENT will make go build and friends look for packages in ./vendor directory as well as GOPATH. See VonC's answer and the design document for more details.
III. Vendoring
AFAIK, this is the most widely used way of ensuring that your builds are reproducible and predictable. The Go team itself uses vendoring in their repo. The Go team is now discussing the unified dependency manifest file format. From the Go toolchain developers mailing list:
In Google’s internal source tree, we vendor (copy) all our dependencies into our source tree and have at most one copy of any given external library. We have the equivalent of only one GOPATH and rewrite our imports to refer to our vendored copy. For example, Go code inside Google wanting to use “golang.org/x/crypto/openpgp” would instead import it as something like “google/third_party/golang.org/x/crypto/openpgp”.
(...)
Our proposal is that the Go project,
officially recommends vendoring into an “internal” directory with import rewriting (not GOPATH modifications) as the canonical way to pin dependencies.
defines a common config file format for dependencies & vendoring
makes no code changes to cmd/go in Go 1.5. External tools such as “godep” or “nut” will implement 1) and 2). We can reevaluate including such a tool in Go 1.6+.
Note: June 2015, the first support for vendoring appears in Go 1.5!
See c/10923/:
When GO15VENDOREXPERIMENT=1 is in the environment, this CL changes the resolution of import paths according to the Go 1.5 vendor proposal:
If there is a source directory d/vendor, then, when compiling a source file within the subtree rooted at d, import "p" is interpreted as import "d/vendor/p" if that exists.
When there are multiple possible resolutions, the most specific (longest) path wins.
The short form must always be used: no import path can contain “/vendor/” explicitly.
Import comments are ignored in vendored packages.
Update January 2016: Go 1.6 will make vendoring the default.
And as detailed in the article "MOST GO TOOLS NOW WORK WITH GO15VENDOREXPERIMENT":
1.6 brings support for /vendor/ to most tools (like the oracle) out of the box; use the Beta to rebuild them.
issue 12278 has been resolved.
there still is an issue with goimports, and there is a CL that can be cherry-picked.
Update August 2018: this (vgo presented below) is now implemented with Go 1.11 and modules.
Update Feb. 2018, 3 years later.
There is a new approach developed by Russ Cox, from the core Golang development team.
The vgo project.
go get -u golang.org/x/vgo
This proposal:
keeps the best parts of go get,
adds reproducible builds,
adopts semantic versioning,
eliminates vendoring,
deprecates GOPATH in favor of a project-based workflow, and
provides a smooth migration path from dep and its predecessors.
It is based on a new MVS ("Minimal Version Selection") algorithm:
You can see:
the first articles in Go & Versioning
the discussion in this thread
the analysis of that thread by Jon Calhoun
the counter-point by Sam Boyer in "Thoughts on vgo and dep":
He was leading the private initiative of go dep
the first debate (YouTube) between Russ, Sam and Jesse Frazelle!
May 2018: Artifactory proposes a vgo proxy
The recent release of Artifactory 5.11 added support for vgo-compatible Go registries (and go proxy) giving the community a variety of capabilities when developing with Go.
Here are just a few of them:
Local repositories in Artifactory let you set up secure, private Go registries with fine-grained access control to packages according to projects or development teams.
A remote repository in Artifactory is a caching proxy for remote Go resources such as a GitHub project. Accessing a go proxy through Artifactory removes your dependency on the network, or on GitHub since all dependencies needed for your Go builds are cached in Artifactory and are therefore locally available. This also removes the risk of someone mutating or removing a dependency from version control, or worse, force-pushing changes to a remote Git tag thus changing what should be an immutable version which can create a lot of confusion and instability for dependent projects.
A virtual repository aggregates both local and remote Go registries giving you access to all Go resources needed for your builds from a single URL, hiding the complexity of using a combination of both local and remote resources.
also it is possible just describe dependencies in maven, if to use mvn-golang-wrapper, in the case it looks like in maven as below text
<plugin>
<groupId>com.igormaznitsa</groupId>
<artifactId>mvn-golang-wrapper</artifactId>
<version>1.1.0</version>
<executions>
<execution>
<id>golang-get</id>
<goals>
<goal>get</goal>
</goals>
<configuration>
<packages>
<package>github.com/gizak/termui</package>
</packages>
<buildFlags>
<flag>-u</flag>
</buildFlags>
<goVersion>1.6</goVersion>
</configuration>
</execution>
</plugin>
I've read a whole bunch of articles and SO questions on importing 3rd party go packages which all seems straight forward, but what I don't understand is that none that I have read make any references to versioning. In Dartlang there's the pubspec file that defines your package including its version and its dependencies including their required versions. What if I do a go get github.com/gorilla/sessions and write my app then 6 months later I have to clear my directories and re get everything again, in which time that package has been update and broken backwards compatibility with my code that was using the older version?
The official version, from the GO FAQ:
If you're using an externally supplied package and worry that it might change in unexpected ways, the simplest solution is to copy it to your local repository. (This is the approach Google takes internally.) Store the copy under a new import path that identifies it as a local copy.
There are many alternative to that approach, mainly based on declaring the exact version of those projects you are using.
See for instance "Dead Simple Dependencies in Go -- Keep it simple and keep your sanity." (based on emil2k/vend)
The main different options for Go Dependency Management are listed at:
"Go Package Management -- A summary of dependency management in Go"
(And its associate GOPM mailing list)
Update July 2015:
the official vendoring approach from Go team is discussed here.
an alternative go build tool called "gb" is proposed at getgb.io by Dave Cheney.
Update Q4 2017: as mentioned below, go dep is the official tool for pinning version of dependencies (even though that pinning approach is not without criticism: see "The cargo cult of versioning").
It should be merged into the toolchain when Go 1.10 development begins, according to its roadmap.
Update Q2 2018: go dep has been replaced by go mod (modules) in Go 1.11, following works on vgo.
I use dep as a dependency management tool for golang project. Please use the following link dep tool for more info.
dep is a dependency management tool for Go. It requires Go 1.9 or newer to compile.
dep was the "official experiment." The Go toolchain, as of 1.11, has (experimentally) adopted an approach that sharply diverges from dep. As a result, we are continuing development of dep, but gearing work primarily towards the development of an alternative prototype for versioning behavior in the toolchain.
Current status: January 2019
dep is safe for production use.
Our development team has been fairly small and, until now, all working on a single Visual Studio 2012 solution. We are growing and wanting to create better separation with multiple solutions for different project teams.
However, there are occasions where the code in one solution will want to utilize code from another. We have decided using internal (i.e. private) NuGet packages will be a good way to manage these dependencies.
However, the question has come up on how to deal with multiple versions of the same package that are in different SDLC stages (e.g. Development, QA, Staging, Production, etc.)
Example: If we have these three solutions...
CoreStuff
CoolProject1
CoolProject2
If working in CoolProject1, and we need to utilize code from CoreStuff, we can add the NuGet package. Presumably this package will be the latest Production (stable) version of CoreStuff.
However, what if a developer working on CoolProject2 is aware of some changes in CoreStuff that are currently in Development and wants to utilize that version?
Not sure if the best approach is to create separate packages for each (seems to require changing your package references back and forth depending on what stage the solution is in) or somehow utilize multiple versions of the same package (not sure if that's easy to manage with NuGet).
Anyone tackle something like this?
The first thing to remember is that NuGet will not automatically update your package references, so if you have already 'linked' your solution to the latest stable package of CoreStuff (say 1.2.2) then there won't be any problems if a newer (unstable) version is provided (assuming that the package you're using doesn't disappear from the package repository). Obviously if you upgrade your package reference then you will get the unstable package.
So the simplest solution is to make sure that you 'link' your project to the stable package by getting it via the NuGet package manager before the other package is released. While the UI only allows you to get the latest version, the Package Manager Console can get any version of a package so you could use that to explicitly provide the version number, e.g.:
Install-Package CoreStuff -Version 1.2.2 -Project CoolProject1
If that is not a solution then there are several other options to tackle this problem:
Give the development version a different semantic version that indicates it is a unstable version, e.g. 1.2.3-alpha. In this case CoolProject1 could pull in package CoreStuff.1.2.2 (which should be latest stable version in your repository) and CoolProject2 could pull in CoreStuff.1.2.3-alpha (which would be the latest unstable version).
Have multiple repositories, e.g. one for stable (released) packages and one for unstable (development) versions. Then you can select your packages from the desired repositories. If you wanted to you could make it so that only your release process can push packages up to the stable repository and your CI build pushes up to the unstable one (so that you always have the latest packages available)
If the developer of CoolProject2 just wants to develop against the latest version (but will wait to release CoolProject2 until after CoreStuff v.next has been released) then he could potentially create a local package repository (i.e. a directory on his drive) and put the new package of core stuff there. That way other developers won't even see the package.
The most important thing will be to make sure that you don't get CoreStuff.1.2.2 and CoreStuff.v-next in the same repository if CoreStuff.v-next simply has a higher version number, because in that case the NuGet UI won't let you pick v1.2.2 (but the Package Manager Console does!).
If you would want to switch from one package type to another you'd have to do a manual update (which you always have to do when changing to the next package version anyway), but that's not a bad thing given that this forces a developer to at least check that the update of the package doesn't break anything.