golang: +go1.17 -go1.15

Go1.17 is incremental improvement over Go1.16 with better and faster compiler,
runtime, module-mode improvements and faster generated code:

https://blog.golang.org/go1.17
https://golang.org/doc/go1.17

Drop support for Go1.15, as that release reached EOL and nothing currently uses
it in SlapOS.

Don't drop support for Go1.12 yet, as that long-ago-EOL and no longer supported
Go release is still being used by software/gitlab.

Remain default at Go1.16 yet.

Switch helloworld to Go1.17 and test this patch on that
software-release.

component/golang/buildout.cfg

@@ -42,15 +42,6 @@ md5sum = 6b607fc795391dc609ffd79ebf41f080
 environment-extra =
   GOROOT_BOOTSTRAP=${golang14:location}
 
-[golang1.15]
-<= golang-common
-url = https://golang.org/dl/go1.15.12.src.tar.gz
-md5sum = b3a5dafa7028fa00083ce4aeaf5bcb9a
-
-# go1.15 needs go1.4 to bootstrap
-environment-extra =
-  GOROOT_BOOTSTRAP=${golang14:location}
-
 [golang1.16]
 <= golang-common
 url = https://golang.org/dl/go1.16.8.src.tar.gz
@@ -60,6 +51,14 @@ md5sum = 92e69a5e1bb6ea5e7498d12d03160032
 environment-extra =
   GOROOT_BOOTSTRAP=${golang14:location}
 
+[golang1.17]
+<= golang-common
+url = https://golang.org/dl/go1.17.1.src.tar.gz
+md5sum = a78205838c2a7054522cb91c12982f26
+
+# go1.17 needs go1.4 to bootstrap
+environment-extra =
+  GOROOT_BOOTSTRAP=${golang14:location}
 
 # ---- infrastructure to build Go workspaces / projects ----
 

software/helloworld/software.cfg

@@ -32,6 +32,9 @@ parts =
 [python]
 part = python3
 
+[gowork]
+golang = ${golang1.17:location}
+
 # Macro for jinja templates. The filename is set in buildout.hash.cfg
 # in the section using this template
 [jinja-template]

[Kirill Smelkov]

Don't drop support for Go1.12 yet, as that long-ago-EOL and no longer supported Go release is still being used by software/gitlab.

/cc @alain.takoudjou, @jerome, @lpgeneau

[Levin Zimmermann]

@kirr This patch added the [gowork] section with explicit declaration of used go version to the helloworld SR. Was this done in order to support latest go version for helloworld (because it still took one more month until the default go version was set to go 1.17)? Or was this done in order to illustrate how to explicitly set the go version within a SlapOS SR?

I'm asking to understand if it's better to remove the explicit definition of the go version here or if it's better to update the definition to golang1.18.

[Kirill Smelkov]

@levin.zimmermann, if I remember correctly it was for the former: use more recent Go version in helloworld while the default was still at go1.16. I would say if software-release has a reason to use particular Go version - it should pin it inside it. But otherwise probably it should just use the default.

[Levin Zimmermann]

Thanks @kirr for clarifying!

[Kirill Smelkov]

You are welcome, @levin.zimmermann.