Selective releasing (#708)

* Rejig the build process

During a build, we check and rebuild any dependencies prior to
potentially using them.

Build:
- DIND (this only produces a new docker image, no local code changes)
- fnserver (built as part of the testing)

On master, if everything works, then we release the built artifacts,
if necessary:
- DIND (this pushes a docker image and a tag)
- fnserver (this builds the docker image and releases it, if necessary).

Fnserver is dealt with last by the release script: all previous steps
in CI use locally-run go tests rather than a docker file.

When a commit happens, we need to know (a) if we need to rebuild
a set of tools and artifacts (or whether we can continue to use
published ones); and (b) if we need to release new versions of
those tools, if all tests pass.

We do this by identifying the previous release tag on origin/master
(which is the release branch), then checking for changes between
that point at the current one.

Those changes may appear in various places in the tree: some simple
boolean rules work out whether the change means we need to rebuild
and rerelease.

* Make the fnproject/fnserver build use the latest dind

As docker bumps from 17.12.x, use whatever dind we just built.

* Use bash

images/dind/build.sh

@@ -1,3 +1,17 @@
 set -ex
 
 docker build --build-arg HTTPS_PROXY --build-arg HTTP_PROXY -t fnproject/dind:latest .
+
+# Match version with Docker version
+version=$(docker run --rm -v "$PWD":/app treeder/bump  --extract --input "`docker -v`")
+echo "Version: $version"
+M=$(docker run --rm treeder/bump --format M --input "$version")
+Mm=$(docker run --rm treeder/bump --format M.m --input "$version")
+
+# Tag these up so that they're available for the local build process,
+# if necessary
+
+docker tag fnproject/dind:latest fnproject/dind:$version
+# be nice to have bump image do all of this tagging and pushing too (mount docker sock and do it all)
+docker tag fnproject/dind:$version fnproject/dind:$Mm
+docker tag fnproject/dind:$version fnproject/dind:$M

images/dind/release.sh

@@ -1,6 +1,19 @@
-set -ex
+#!/bin/bash
 
-# ./build.sh
+set -exo pipefail
+
+# Ensure working dir is clean
+git status
+if [[ -z $(git status -s) ]]
+then
+  echo "tree is clean"
+else
+  echo "tree is dirty, please commit changes before running this"
+  exit 1
+fi
+
+# This script should be run after its sibliing, build.sh, and
+# after any related tests have passed.
 
 # Match version with Docker version
 version=$(docker run --rm -v "$PWD":/app treeder/bump  --extract --input "`docker -v`")
@@ -8,12 +21,24 @@ echo "Version: $version"
 M=$(docker run --rm treeder/bump --format M --input "$version")
 Mm=$(docker run --rm treeder/bump --format M.m --input "$version")
 
+# Calculate new release version
+DIND_NEW=$(echo "$DIND_PREV" | perl -pe 's/\d+\.\d+\.\K(\d+)/$1+1/e')
+
+# Add appropriate docker tags
 docker tag fnproject/dind:latest fnproject/dind:$version
 # be nice to have bump image do all of this tagging and pushing too (mount docker sock and do it all)
 docker tag fnproject/dind:$version fnproject/dind:$Mm
 docker tag fnproject/dind:$version fnproject/dind:$M
+docker tag fnproject/dind:$version fnproject/dind:release-$DIND_NEW
  
 docker push fnproject/dind:$version
 docker push fnproject/dind:$Mm
 docker push fnproject/dind:$M
+docker push fnproject/dind:release-$DIND_NEW
 docker push fnproject/dind:latest
+
+# Mark this release with a tag
+# No code changes so only the tag requires a push
+git tag -f -a "$DIND_NEW" -m "DIND release $DIND_NEW of $version"
+git push origin "$DIND_NEW"
+