Setting golang version uniformly accross repo and updating docs

.travis.yml

@@ -16,7 +16,7 @@ jobs:
     - &base-test
       stage: test
       go_import_path: github.com/openshift/odo
-      go: "1.13.1"
+      go: "1.12.x"
       install:
         - make goget-tools
       script:
@@ -38,7 +38,7 @@ jobs:
       init:
       - git config --system core.longpaths true
       go_import_path: github.com/openshift/odo
-      go: "1.13.1"
+      go: "1.12.x"
       install:
         - systeminfo.exe | grep '^OS'
         - choco install make
@@ -57,7 +57,7 @@ jobs:
       os:
         - osx
       go_import_path: github.com/openshift/odo
-      go: "1.13.1"
+      go: "1.12.x"
       install:
         - make goget-tools
       script:

Dockerfile.rhel

@@ -1,7 +1,7 @@
 # This Dockerfile builds an image containing the Linux, Mac and Windows version of odo
 # layered on top of the ubi7/ubi image.
 
-FROM registry.svc.ci.openshift.org/openshift/release:golang-1.11 AS builder
+FROM registry.svc.ci.openshift.org/openshift/release:golang-1.12 AS builder
 
 COPY . /go/src/github.com/openshift/odo
 WORKDIR /go/src/github.com/openshift/odo

docs/dev/development.adoc

@@ -9,10 +9,21 @@ toc::[]
 
 Requires *Go 1.12*
 
-**WARNING**: If you are adding any features that require a higher version of golang, such as golang 1.13
-for example, please contact maintainers to check of the releasing systems can handle the newer versions.
+Testing and release builds happen with the above version. Developers are advised to stick to this version if they can but it is not compulsory.
 
-If that is ok, please ensure you update the required golang version, both here and in the file link:/scripts/rpm-prepare.sh[`scripts/rpm-prepare.sh`]
+
+[WARNING]
+====
+If you are adding any features that require a higher version of golang, than the one mentioned above, please contact the maintainers in order to check if the releasing systems can handle the newer version. If that is ok, please ensure you update the required golang version, both here and in the files below, in your PR.
+
+.List of files to update for golang version
+ * link:/scripts/rpm-prepare.sh[`scripts/rpm-prepare.sh`]
+ * link:/.travis.yml[`.travis.yml`]
+ * link:/Dockerfile.rhel[`Dockerfile.rhel`]
+ * link:/openshift-ci/build-root/Dockerfile[`openshift-ci/build-root/Dockerfile`]
+====
+
+First setup your fork of the odo project, following the steps below
 
  . link:https://help.github.com/en/articles/fork-a-repo[Fork] the link:https://github.com/openshift/odo[`odo`] repository.
 

openshift-ci/build-root/Dockerfile

@@ -1,7 +1,7 @@
 # Dockerfile to bootstrap build and test in openshift-ci
 
-FROM registry.svc.ci.openshift.org/openshift/release:golang-1.13
+FROM registry.svc.ci.openshift.org/openshift/release:golang-1.12
 
 RUN yum -y install make wget gcc git httpd-tools
 
-RUN mkdir -p /tmp/secret
+RUN mkdir -p /tmp/secret